December 5, 2018

Board Workshop of the Capitol Region Watershed District (CRWD) Board of Managers, for Wednesday, December 5, 2018 5:00 p.m. at the office of the CRWD, 1410 Energy Park Drive, Suite 4, St. Paul, Minnesota.

WORKSHOP AGENDA I. Call to Order of Board Workshop II. Como Lake Management Plan Update III. Adjourn Board Workshop Regular Meeting of the Capitol Region Watershed District (CRWD) Board of Managers, for Wednesday, December 5, 2018 6:00 p.m. at the office of the CRWD, 1410 Energy Park Drive, Suite 4, St. Paul, Minnesota.

I.

REGULAR MEETING AGENDA Call to Order of Regular Meeting (President Joe Collins) A) Attendance B) Review, Amendments, and Approval of the Agenda

Materials Enclosed

II.

Public Comment – For Items not on the Agenda (Please observe a limit of three minutes per person.)

III.

Permit Applications and Program Updates (Permit Process: 1) Staff Review/Recommendation, 2) Applicant Response, 3) Public Comment, and 4) Board Discussion and Action.)

No permits.

IV.

Special Reports – TBI H & H Modeling Update (Nathan Campeau, Barr Engineering)

V.

Action Items A) AR: Approve Minutes of the November 20, 2018 Regular Meeting (Sylvander) B) AR: Approve 2019 Partner Grants (Schwantes) C) AR: Appoint Cheryl Braun to the Citizen Advisory Committee (Doneux)

VI.

Unfinished Business A) Diversity Plan Update (Doneux) B) Snelling Midway Update (Eleria) C) TBI Easement Acquisition Project Update (Eleria) D) Master Water Steward Program Update (Schwantes) E) H2O to Go – Innovative, Participatory Display Update (Frisvold)

VII.

General Information A) Board of Manager’s Updates B) Administrator’s Report (Doneux)

VIII. Next Meetings A) Wednesday, December 12, 2018 CAC Meeting Our mission is to protect, manage and improve the water resources of Capitol Region Watershed District

IX.

Adjournment

Our mission is to protect, manage and improve the water resources of Capitol Region Watershed District

December 5, 2018 Board Workshop Como Lake Management Plan Update (Belden) DATE: TO: FROM: RE:

November 28, 2018 CRWD Board of Managers Britta Belden, Water Resource Project Manager Como Lake Management Plan Update – Potential In-Lake & Watershed Management Actions

Background The development of the Como Lake Management Plan has been underway since April 2018. The CRWD Board of Managers and the Citizen Advisory Committee have been involved throughout the development process by providing input and guidance on key deliverables along the way. In addition, two stakeholder groups were established to inform the development of the Como Lake Management Plan—the Agency Advisory Group (AAG) and the Public Advisory Group (PAG). The first meetings for both the AAG and the PAG and were focused on gathering input on Como Lake issues and goals. The second meetings for both groups are being held fall 2018 and will focus on reviewing potential actions for in-lake management and watershed management to achieve total phosphorus (TP) load reductions in Como Lake.

Issues Staff have been evaluating potential actions for in-lake and watershed management for Como Lake. These were/will be reviewed at the fall 2018 meetings with the AAG (11/8/18), the CAC (11/14/18), and PAG (12/6/18, 6pm-8pm). Please find enclosed the guidance review document that was shared with the AAG and CAC that provides context and background of the potential in-lake and watershed management actions.

Staff will review the lists of potential actions for in-lake and watershed management that were developed for Como Lake with the Board of Managers.

Requested Action Review and comment on the potential in-lake and watershed management actions tables. enc: Guidance document for reviewing the Como Lake potential in-lake and watershed management actions tables

W:\06 Projects\Como Lake Projects\2018 Como Lake Management Plan\Board & CAC\Brd Memo_CLMP_Dec 5 2018 Update_11-28-18.docx

Our Mission is to protect, manage and improve the water resources of Capitol Region Watershed District

DATE: TO: FROM: RE:

November 5, 2018 Como Lake Management Plan Agency Advisory Group (AAG) Britta Belden, Water Resource Project Manager Guidance document for reviewing the Como Lake potential in-lake and watershed management actions tables

Background The development of the Como Lake Management Plan has been underway since April 2018. Two stakeholder groups were established to inform the development of the Como Lake Management Plan—the Agency Advisory Group (AAG) and the Public Advisory Group (PAG).

The first meetings for both the AAG and the PAG were held in this past summer 2018 and were focused on gathering input on Como Lake issues and goals. The second meetings for both groups are being held fall 2018 and will focus on reviewing potential actions for in-lake management and watershed management to achieve total phosphorus (TP) load reductions in Como Lake. The second AAG meeting is scheduled for November 8th, 2018 (10am-12pm). The PAG meeting will be held on December 6th, 2018 (6pm-8pm).

Purpose of Memo The purpose of this memo to provide guidance to the AAG for reviewing the potential in-lake and watershed management actions. The potential actions for both in-lake and watershed management are organized into a series of tables which are included as enclosures in this memo. Ahead of the AAG meeting on November 8th, it is requested that the AAG review each table and come prepared to discuss them. Each table includes a significant amount of technical information, so this memo can be used as a guide for review and provides interpretation of the purpose of each table and what the numbers and descriptions represent. At the meeting, we will be seeking feedback on: •

•

Which action(s) do you think has the best potential to achieve goals in Como Lake and why?

Any action that isn't on this table that should be considered and why?

Potential In-Lake Management Actions Table 1 is a list of potential in-lake management actions that could be considered for Como Lake. Eventually, in-lake management actions will be selected from this table based on their ability to meet the stated goals and objectives in the Como Lake Management Plan. This is not a table of recommended actions specifically for Como Lake, but instead presents a menu of options for more detailed consideration. Once actions are selected from this menu of options, they will be further refined into recommended strategies (i.e. timing of selected actions and/or combination of actions in the near-term and long-term). The final Como Lake Management Plan will include Table 1 to show that many common in-lake management actions were appropriately considered.

The options listed in Table 1 under “Management Action” are a suite of literature-based lake management strategies that are typically applied to lakes for reducing internal phosphorus loads, managing algae, and restoring ecosystem balance. For each management action listed, the table describes the intended “control type” of the action (biological, physical, chemical), a brief description of what each action entails, and what Our Mission is to protect, manage and improve the water resources of Capitol Region Watershed District

component of the in-lake water quality driver is being targeted by the specific management action (e.g. algae, anoxia, food web, internal P load, etc). In addition, the table identifies which actions could realistically be applied to Como Lake, the reliability of that action for being effective, the time commitment required for each action, and a general magnitude of cost to be expected. Pros and cons are also listed to assist in understanding the implications and limitations of each action. From this table of potential in-lake management actions, we will select actions that will work towards identified goals that are applicable for conditions in Como Lake.

At the AAG meeting, LimnoTech will review each of these possible actions and describe their feasibility for Como Lake.

Potential Watershed Management Actions The watershed recommendations in the 2002 Como Lake Strategic Management Plan (2002 CLSMP) were based on a watershed model calibrated in 2000. Since then, there have been some changes in land use and other model input parameters in the Como watershed. In addition, technology improvements (i.e. improved GIS layers) have resulted in a greater capability to fine-tune the watershed model. To ensure that the best estimates of watershed loads were utilized in the updated Como Lake Management Plan, a model recalibration was completed fall 2018. The watershed model recalibration includes the most recent land use conditions and considers the numerous structural BMPS that have been constructed since the year 2000.

Figure 1 shows a map of the new Como subwatershed delineations and the updated subwatershed naming convention (Como A-M). The new delineations were determined during the model recalibration effort and are based on: 1) storm sewer discharge points (outfalls) to Como Lake, and 2) the subsurface storm sewer network extending upstream of the discharge point.

The storm sewer networks in the Como watershed are complex, particularly in the Como B subwatershed.

Figure 2 is a schematic of generalized flow routing in the Como B subwatershed to help illustrate how overflow is routed through four separate outfalls during certain flow conditions. Under normal flow conditions, all of Como B subwatershed discharges through one outfall to Como Lake. Under high flow conditions, overflow from the Como B subwatershed main pipe is routed to four separate outfall pipes that discharge directly to Como Lake. It is important to understand the Como B subwatershed flow routing during overflow events because the model outputs for TP loads are directly affected. For the model recalibration effort, the Como B subwatershed flow routing was factored into the watershed loading calculations.

Table 2 provides a summary of the Como subwatershed model calibration outputs for TP loads to Como Lake.

The table includes subwatershed name, subwatershed area, baseline TP load (year 2000), and current TP load (year 2018). “Baseline TP Load (Year 2000)” refers to modeled Como subwatershed TP loads in the year 2000 and only includes watershed BMPs that were installed before the year 2000. The “Current TP Load (Year 2018)” refers to present-day modeled TP loads and includes load reductions achieved through BMPs installed since the year 2000. Table 2 also lists TP load reductions achieved since 2000 by BMPs (Baseline TP Load Current TP Load = TP Reduction (lbs)) and the percent TP load reduction achieved (Current) for each subwatershed since baseline.

Since the 2002 CLSMP, several watershed BMP feasibility studies have been completed that evaluate optimal locations for BMP placement within the Como watershed to work toward achieving TP load reductions. Table 3 provides a list of specific potential structural BMP projects that have been identified in these existing feasibility studies and their estimated load reductions by practice in pounds/year. Each potential structural BMP is listed under the Como subwatershed that it would be constructed in. The “BMP Type” is listed for each potential BMP but are generalized into broad structural BMP categories (e.g. Filtration, Infiltration, Bioretention, etc) instead of a specific project description. It is important to emphasize that the BMPs listed in Table 3 are potential projects and have not been constructed to date.

Our Mission is to protect, manage and improve the water resources of Capitol Region Watershed District

Table 4 is the Como Watershed TP Load Reduction Plan and provides a summary of load reductions achieved through existing BMPs (Year 2018) and potential structural and non-structural BMPs to be implemented in the future. The table is set up so that “Baseline TP Load (Year 2000)” is listed in the first row and all following rows of BMPs categorized under “TP Load Reductions (lbs)” are subtracted from baseline to reach the “Total Target TP Load” and “Total Target Reduction (%)”. The “Total Target TP Load” represents the projected TP load to Como Lake by subwatershed following the implementation of the BMPs listed under “TP Load Reductions (lbs)”. There are five different categories of “TP Load Reductions (lbs)” BMPs listed in Table 4: 1. Existing Practices – includes the total TP load reductions from existing BMPs that have been constructed since the year 2000.

2. Structural - Identified – a summation of the total estimated load reductions from potential structural BMPs listed in Table 3 for each subwatershed. These potential projects were identified in existing feasibility studies.

3. Structural – Unidentified – includes unforeseen or unplanned future structural BMP opportunities in the Como watershed, such as curb cut rain gardens or innovative BMP practices.

4. Permit BMPs – includes future potential redevelopment projects in the Como subwatershed that could be subject to CRWD’s permitting rules (i.e. parcels ≥ 1 acre). Potential load reductions from these BMP projects were estimated.

5. Non-Structural – includes a TP load reduction estimate for non-structural BMP practices (e.g. street sweeping, storm drain maintenance, community leaf cleanups) based on enhanced street sweeping studies. The estimation considers the total area of connected impervious in each subwatershed.

The last column “All” sums the total “TP Load Reductions”, the “Total Target TP Load”, and the “Total Target Reduction (%)” from the individual subwatersheds to evaluate reductions on the whole watershed scale. From this, a total target reduction of 68% is achieved for the whole Como watershed if all existing and potential TP Load Reduction BMPs are implemented over time. This exceeds the 60% watershed reduction goal listed in the TMDL. Overall, Table 4 helps guide where continued efforts should be focused on the subwatershed scale to achieve watershed-wide load reduction goals.

Requested Action Please review tables ahead of the second AAG meeting on November 8, 2018 (10:00am-12:00pm) and come prepared to discuss them. If you are unable to attend the meeting, comments or questions may be submitted to Britta Belden (britta@capitolregionwd.org). enc:

Table 1— Potential in-lake management actions for Como Lake Table 2— Subwatershed total phosphorus loads to Como Lake Table 3— Potential structural BMP projects from existing feasibility studies Table 4— Como Watershed Total Phosphorus Load Reduction Plan Figure 1— Map of Como subwatershed delineations (2018) Figure 2— Schematic of the Como B subwatershed generalized flow routing

Our Mission is to protect, manage and improve the water resources of Capitol Region Watershed District

Table 1: Potential in-lake management actions for Como Lake

Management Action

Control Type

Algaecides

chemical

Hypolimnetic aeration/oxygenation

physical

Brief Description of Action

Chemical application to kill standing stock of algae Algae Typically a mechanical system that circulates or oxygenates water Anoxia to prevent anoxia.

Inflow/end-of-pipe chemical treatment (e.g. alum based compounds) chemical Biomanipulation through Fisheries Mgmt biological (Long-term) Biomanipulation through Fisheries Mgmt biological (Short-term)

Treatment of stormwater with a chemical agent that binds with phosphorus before it enters the lake.

Altering of the biological community (typically fish) to increase abundance of predators or herbivores.

Altering of the biological community (typically fish) to increase abundance of predators or herbivores.

Drawdown Shoreline restoration/riparian management

Drains large volumes of water for extended periods of time.

May include bank stablization, erosion control, native plant, and/or habitat restoration actions.

physical physical

P coagulants (Alum & alum-based compounds)

chemical

P coagulants (Ca & Fe)

chemical

P coagulants (Other)

chemical

Dilution and flushing

physical

Mechanical harvesting

physical

Native plant community restoration

Target

Chemical application to the lake with a compound that binds with phosphorus in water column and phosphorus diffusing from sediments.

Addition of metals salts binds with phosphorus making it unavailable to algae.

Addition of proprietary compounds (e.g. Phoslock) that bind with phosphorus making it unavailable to algae.

Reducing the nutrient concentration by adding more water (dilution) and increases the water exchange (flushing).

Would this action work towards Reliability goals for Como Lake?

Duration

Application

General Magnitude of Cost

yes

High

Short

Frequent-Seasonal

Medium

yes

High

Short

Continuous

Medium-High

External P load

yes

Medium

Long

Continuous

High-Medium

Food web

yes

High

Medium

Occasional

Food web

yes

Low

Medium

Food web

yes

Medium

Medium

Habitat, erosion control.

yes

High

Medium-Lon Variable

Pros

Immediate response; cost-effective Effective at improving DO when designed correctly & maintained

Cons Short duration, can promote Cyanobacteria growth, not a sustainable management action Can be costly to maintain

Low-HIgh

Very effective at reducing P load to receiving waters Improves ecological function; can reduce algal density through zooplankton feeding

Need storage capacity / settling basin for flocculated water Requires long-term maintenance; Ineffective w/o additional management actions in eutrophic lakes

Seasonal

Low-Medium

Can improve fishery in short-term.

Short-term responses not expected

Occasional

Low-High

Can be effective for macrophyte control Helps to reduce sediment inputs, improves ecological function.

Can be costly and labor intensive.

Limited cons are action specific.

Needs a buffer in alkaline lakes, which can add to cost. May need multiple applications depending on extent of eutrophication and sediment P. Often under-dosed; requires special handling Implications for pH and dissolved oxgen - requires special considerations; requires special handling Implications for pH and dissolved oxgen - requires special considerations; requires special handling

Low-High

Internal P load

yes

High

Variable

Variable

Medium-low

Internal P load

yes

High

Variable

Variable

Medium-low

Internal P load

yes

High

Variable

Variable

Medium-low

Very effective and safe when dosed properly; well-tested, broadly applied and understood; cost-effective Long-record of application/effectiveness; based on well understood geochemical reactions Long-record of application/effectiveness; based on well understood geochemical reactions

Internal P load

yes

High

Short

Continuous

Low-High

Indirect control of internal P loading observed

Macrophyte control

yes

Medium

Short

Seasonal

Medium-High

biological

Mechanical raking/removal of nuisance, rooted-vegetation.

Removal of nuisance vegetation and establishment of native vegetation.

Macrophytes

yes

Medium

Medium

Variable

Low

Removes dense macrophyte growth in short-term low-effort restoration, community egnagement opportunities

Herbicides

chemical

Chemical application to kill nuisance / invasive macrophytes.

High

Short

Seasonal

Low-Medium

Dredging

physical

Medium

Long

Rare

High

Microbes and enzymes

biological

Algae

no

Untested

N/A

N/A

N/A

Shading Dye

chemical

Dredgeing and removal of sediments.

Typically proprietary compounds that claim to control algae or manipulate nutrients.

Addition of dye to lake to limit light penetration to control algal growth.

Macrophytes yes Reduced internal loading through removal yes of nutrient-rich sediments.

Algae

no

Untested

Medium

Seasonal

Low

Artificial Circulation

physical

Typically a mechanical system that extends the depth of circulated water/prevents anoxia/stratification.

Anoxia

no

High

Short

Continuous

Medium

Hypolimnetic withdrawal

physical

Removal of nutrient-rich hypolimnetic water.

Nutrient reduction

no

High

Long

Continuous

Medium

Some products can be selective Removes P in sediment thereby reducting internal loading

Increased vertical mixing; decreased algal excretory products Operationally difficult; expensive machinery for single lake use; usually requires mulitple applications; not effective from some macrophytes; not species selective may require biotic and abiotic controls to be successful; more challenging when invasive species are problematic Toxicity; public perception; predicting reemergent community Expensive, labor intensive Unknown efficacy

reduces photosynthecally available light; non-toxic

May not control surface or shallow water blooms

Effective at improving DO when designed correctly & maintained; chemical oxydation of reduced substances Reduced anoxic duration, removes nutrients from the system

Some adverse affects could include cyanobacteria promotion, resuspension of particulate P, reduced clarity Thermal imbalance, need storage capacity or treatment option for withdrawn water

Table 2: Subwatershed TP loads to Como Lake - Baseline, current and reductions Current TP Load (Year 2018) (lbs)

Overflow Subwatershed

Como A

--

36.6

2%

11.2

11.2

0

0%

Como Ba

--

1173.9

69%

388.8

294.1

94.7

24%

--

Como B2

51.3

3%

11.5

11

0.5

4%

--

Como B3

78.8

5%

10.2

10.2

0

0%

--

Como B4

177.4

10%

32.2

32.2

0

0%

--

Como B5

814.8

48%

31.6

16.5

15.1

48%

Como C

--

80.8

5%

20.9

18.1

2.8

13%

Como D

--

195.3

11%

98.3

92.5

5.8

6%

Como E

--

72.2

4%

41.3

41.3

0

0%

Como F

--

44.5

3%

25.6

15.6

10

39%

Como G

--

20.7

1%

16.2

6.2

10

62%

Como H

--

17.8

1%

10.5

9.5

0.9

9%

Como I

--

11.7

1%

6.3

3.2

3.1

49%

Como J

--

19

1%

10

10

0

0%

Como K

--

15.4

1%

8.1

8.1

0

0%

Como L

--

0.5

0.03%

0

0

0

0%

Como M

--

16.9

1%

9.4

9.4

0

0%

732.1

589.1

142.9

20%

Total a

Baseline TP Load (Year 2000) (lbs)

Subwatershed

Subwatershed Area (Acres)

1705.3

% of Total Como Watershed Area

TP Reduction (lbs)

TP Reduction %

Como B subwatershed has four overflow subwatersheds that discharge to separate outfalls during certain flow conditions. See Como B schematic for flow routing.

Table 3: Identified Potential Structural BMP Projects and TP Load Reductions from Existing Feasibility Studies Potential Structural BMP Projects

BMP Type

Como TP Load Reduction Target (lbs/year)

Como B Golf Course Parking Lot Reconstruction Lexington & Como Blvd Intersection Como Blvd Reconstruction - Regional Treatment East Golf Course Ponds IESF

1

NW Golf Course Pond - IESF Bench Golf Course Parking Lot Pond - IESF Bench Zoo Combo - Filtration Basin & Infiltration Basin Como Pavilion North - Rain Gardens

Filtration/Infiltration Infiltration Filtration/Infiltration Stormwater Pond Retrofit Stormwater Pond Retrofit Stormwater Pond Retrofit Filtration/Infiltration Bioretention Subwatershed Total

1.8 2.6 40.7 21.7 24.2 18.7 19.5 1.6

Infiltration

8.9

130.8

Como C Como Pavilion south Regional 2 - Infiltration Stream and Underground Infiltration

8.9

Subwatershed Total Como D McMurray Field Capture and Reuse - Regional Treatment Lexington, Como & Horton Ave Median Rain Garden at Horton and Van Slyke

Reuse/Infiltration Filtration/Infiltration Bioretention Subwatershed Total

40.3 5.8 1.0

Filtration/Infiltration Bioretention Bioretention Subwatershed Total

28.9 2.6 0.3

Bioretention Subwatershed Total

1.2

Filtration/Infiltration Subwatershed Total

2.6

Filtration/Infiltration Subwatershed Total

2.5

Filtration/Infiltration Subwatershed Total

2.0

Filtration/Infiltration Subwatershed Total

2.4

47.1

Como E Chatsworth St - Regional Treatment Median Rain Gardens at Argyle and Van Slyke Rain gardens

31.8

Como F Nagasaki Road

1.2

Como H Como Blvd Reconstruction - Regional Treatment1 Como J Como Blvd Reconstruction - Regional Treatment1 Como K Como Blvd Reconstruction - Regional Treatment1 Como M Como Blvd Reconstruction - Regional Treatment1

1

The Como Blvd reconstruction load reduction estimate is based on regional treatment encompassing multiple subwatersheds. The total estimated reduction was apportioned to each subwatershed based on its contributing area.

2.6

2.5

2.0

2.4

Table 4: Como Watershed TP Load Reduction Plan Subwatershed Como A Baseline TP Load (Year 2000) (lbs) Existing Practices (Year 2018) Potential Structural - Identifieda TP Load Reductions Potential Structural - Unidentifiedb (lbs) Future Permit BMPsc Potential Non-Structurald Total Target TP Load (lbs) Total Target Reduction (%)

11.2 0.0 0.0 ?

0.0 0.8 10.4 7%

Como B

Como C

474.3 110.3 130.8 ?

45.4 28.4 159.4 66%

20.9 2.8 8.9 ?

0.0 2.0 7.1 66%

a

Projects evaluated in existing feasibility studies

b

Unforseen or unplanned future opportunities. E.g. curb cut rain gardens, innovative practices

c

Estimated future redevelopment projects subject to CRWD rules

d

Reduction estimates based on enhanced street sweeping studies. Actual practices may vary.

Como D 98.3 5.8 47.1 ?

33.3 3.8 8.3 92%

Como E 41.3 0.0 31.8 ?

0.0 1.9 7.5 82%

Como F 25.6 10.0 1.2 ?

0.6 1.6 12.2 52%

Como G 16.2 10.0 0.0 ?

1.7 0.6 3.9 76%

Como H 10.5 1.0 2.6 ?

0.0 0.9 6.0 43%

Como I 6.3 3.1 0.0 ?

0.0 0.7 2.5 61%

Como J 10.0 0.0 2.5 ?

0.0 1.4 6.1 39%

Como K 8.1 0.0 2.0 ?

0.0 1.1 5.0 39%

Como L 0.0 0.0 0.0 ?

0.0 0.0 0.0 0%

Como M 9.4 0.0 2.4 ?

0.0 1.6 5.5 42%

All 732.1 143.0 229.3 0.0 81.0 44.9 233.8 68%

B5_6a

B5_6b

ComoB5

ComoB4 B5_6c

B4_2

ComoB2 B3_1

B2_1 B5_5a

B5_5b

ComoB3

B5_5j B2_2

B5_5e

B5_4h B5_4k

B5_4j B5_4f

B5_4g

B5_5f

B5_5c

B5_5d

B5_2

B5_5g B5_5h B5_5i

B5_4e

B1_2

B5_4i

A_1

B5_4b

B5_4d

B5_3k

B2_0

ComoB1

B5_4a

B5_4c

B1_3 B5_3a

B5_3b

B5_3j

B1_4

B5_3e

B5_3c

B5_0

B5_1a

K_2 A_2

ComoL K_3 K_1

C_1

B5_3g C_2

C_4b

J_1

A_9 C_6b C_5

ComoI

A_10

C_4d

C_4c

M_2

ComoK

L_1

B5_1b

B5_3f B5_3h

ComoM

M_1

B1_5

B5_3d B5_3i

B4_1

B1_1

ComoC

C_3

I_2

ComoH

A_3

ComoJ

C_4a

H_1a H_1c

C_6a I_1

A_4

D_1

H_1b

A_8

D_2 C_7

D_4e

A_5

D_3b

ComoA

D_4c D_4b D_5d

D_3a D_5c

G_2b

A_7

D_4a

D_4d

A_6 F_1

E_1

ComoG G_1

D_5a F_2

E_2

D_5b

F_3b

ComoE

ComoD

F_3c D_6

G_2a

E_3

F_3a

ComoF F_4

D_7

Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, © OpenStreetMap contributors, and the GIS User Community

¯

Como Park P8 Subwatersheds

Figure 1 - Como Lake Outfall Subwatersheds

Cities

Scale: AS SHOWN

Outfall Non-Contributing Como2

0

750

1,500

3,000 Feet

Drawn by: HRR

Checked by: AJS

Project No.: 6475-021

Sheet: Date: 10/24/2018 1 of 1

Figure 2: Schematic of the Como B Subwatershed Generalized Flow Routing

B1

B2

B3

B4

B5

B2

B3

B4

B5

Subwatershed

Golf Course Ponds

B

Normal Flow Overflow

Outfall

December 5, 2018 Board Meeting IV. Special Report - TBI H/H Model Update (Eleria)

DATE: TO: FROM: RE:

November 28, 2018 CRWD Board of Managers Anna Eleria, CRWD Division Manager and Nathan Campeau, Barr Engineering TBI H/H Model Update Report

Background Two years ago, CRWD’s Board of Managers approved a work order to update the TBI hydrologic/hydraulic (H/H) model under two phases. The first phase involved utilizing Atlas 14 precipitation data for several design storm events and updating other input data including impervious coverage data and storm sewer data in the existing model. In the second phase of the project, the model was recalibrated using CRWD monitoring data. Flood prone areas due to surcharging of TBI were identified and prioritized based on model results and an impact analysis.

Issues CRWD and Barr Engineering staff have completed the TBI H/H Model Update Work. The updated and calibrated TBI model is now capable of capturing and conveying the Atlas 14 2-, 10-, 100- and 500-year storm events. The model results indicate that no sections of TBI surcharge, or exceed its capacity, during the 2- and 10-year storm events. In larger storm events, TBI surcharges in a number of locations and approximately 200 structures during 100-year storm event and approximately 400 structures during 500year storm event are impacted with a third of them classified as residential.

Based on this information, Barr identified nine distinct flood areas that are caused by surcharging of TBI (See attached Figure 64). These areas were evaluated using scoring criteria to prioritize areas and flood mitigation alternatives. CRWD and Barr Engineering staff will review the results of the TBI model update and discuss potential next steps at the Board meeting. An electronic copy of the full report is provided for your review. If you’d like a paper copy of the full report, please contact us.

Action Requested Accept TBI H/H Model Update Report

enc:

Figure 64: Flood Prioritization Areas (paper copy) TBI Model Update Report (electronic only)

W:\06 Projects\Trout Brook Interceptor\Modeling\Model Update - Atlas 14\Board Memos\BM TBI Model Update 12-05-18.docx

Our Mission is to protect, manage and improve the water resources of Capitol Region Watershed District.

FA04

FA05

Ramsey County

$

FA07 Trout Brook Interceptor (TBI) Municipal Boundary

FA06

Flood Prioritization Area Inundation Area

Barr Footer: ArcGIS 10.4, I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Flood Prioritization Areas\Figure1_TBI_Flood_Prioritization_Areas.mxd User: HNH

FA03

2-Year

FA08

10-Year

100-Year

FA01

500-Year

FA02

S a i n t Pa u l

I 0

1,000

2,000

Feet

FA09 Imager y Source: Digit alGlo be 20 16

FLOOD PRIORITIZATION AREAS Trout Brook Stormsewer Interceptor Capitol Region Watershed District FIGURE 64

Technical Report: Atlas 14 Trout Brook Interceptor XP-SWMM Model Updates

Capitol Region Watershed District Saint Paul, MN Barr Engineering Co.

Revised November 2018

Technical Report: Atlas 14 Trout Brook Interceptor XP-SWMM Model Updates

BY CAPITOL REGION WATERSHED DISTRICT

Barr Engineering Co.

Saint Paul, Minnesota Revised November 2018

Technical Report: Atlas 14 Trout Brook Interceptor XP-SWMM Model Updates Revised November 2018

Contents 1.0

Background ................................................................................................................................................................................ 1

2.0

Uncalibrated Model Construction ..................................................................................................................................... 4 2.1

2.2

Model Updates............................................................................................................................................................. 4 2.1.1

I-35E-Cayuga Street Interchange Project & TBI Realignment .................................................. 4

2.1.2

2014 Farrington Watershed Modeling ............................................................................................... 4

2.1.3

2016 Willow Reserve Watershed Improvements ........................................................................... 4

2.1.4

Como Lake Park Modeling Details ....................................................................................................... 5

2017 Model Development ....................................................................................................................................... 5 2.2.1

2.2.2

3.0

Hydrology ...................................................................................................................................................... 5 2.2.1.1

Subwatershed Delineation ................................................................................................. 5

2.2.1.2

Atlas 14 Rainfall Data ........................................................................................................... 5

2.2.1.3

2016 Ramsey County Impervious Coverage ............................................................... 6

2.2.1.4

Watershed Slope and Width ............................................................................................. 8

2.2.1.5

Infiltration Data ....................................................................................................................... 9

2.2.1.6

Depression Storage Assumptions ................................................................................... 9

Hydraulic Parameters ..............................................................................................................................10 2.2.2.1

2011 Ramsey County lidar................................................................................................10

2.2.2.2

Reevaluation of Landlocked Subwatersheds ............................................................10

2.2.2.3

Pipe Network .........................................................................................................................10

2.2.2.4

Atlas 14 Volume Capture and Overland Flow ..........................................................13

Model Calibration ..................................................................................................................................................................14 3.1

3.2

Review of 2016 Monitoring Data and Calibration Assessment ..............................................................14 3.1.1

Precipitation Data .....................................................................................................................................14

3.1.2

Flow Monitoring Data .............................................................................................................................17

Calibration and Validation Events ......................................................................................................................21 3.2.1

Selection of Rainfall Events ...................................................................................................................21

3.2.2

Adjustment of Rainfall Events ..............................................................................................................25

i P:\Mpls\23 MN\62\2362944\WorkFiles\2016 XP-SWMM\Report\Final - Draft 5 - Revised with Flood Prioritization\Atlas 14 TBI XPSWMM Model Updates _Report_RevNov2018 to CRWD.docx

3.3

3.2.3

Starting Water Surface Elevations ......................................................................................................25

3.2.4

Baseflow........................................................................................................................................................26

Hydraulic Calibration ...............................................................................................................................................28 3.3.1

3.4

Calibration Method and Results..........................................................................................................................33 3.4.1

3.4.2

3.4.3

3.5

4.0

Rating Curve Analysis ..............................................................................................................................28 Uncalibrated Model Results .................................................................................................................33 3.4.1.1

August 10, 2016 3.0-inch Rainfall Event .....................................................................33

3.4.1.2

August 24, 2016 1.2-inch Rainfall Event .....................................................................37

Calibration Parameters ...........................................................................................................................41 3.4.2.1

Directly Connected Impervious Area ...........................................................................42

3.4.2.2

Width Parameter ..................................................................................................................45

Calibration Event Results .......................................................................................................................45 3.4.3.1

August 10, 2016 3.0-inch Rainfall Event .....................................................................45

3.4.3.2

August 24, 2016 1.2-inch Rainfall Event .....................................................................50

3.4.3.3

Validation Event Results ....................................................................................................55

Calibrated Model Atlas 14 Inundation Results and Conclusion .............................................................61 3.5.1

Design Storm Results ..............................................................................................................................61

3.5.2

Conclusion ...................................................................................................................................................69

Flood Prioritization Analysis ..............................................................................................................................................70 4.1

Background .................................................................................................................................................................70

4.2

Scoring Criteria Selection .......................................................................................................................................72 4.2.1

4.3

4.4

Scoring Values............................................................................................................................................73

Flood Prioritization Results ...................................................................................................................................74 4.3.1

Flood Area 1: West Maryland Avenue and North Grotto Street...........................................78

4.3.2

Flood Area 2: West Maryland Avenue and Norton Street ......................................................78

4.3.3

Flood Area 3: West Orange Avenue and Farrington Street ....................................................79

4.3.4

Flood Area 4: West Wheelock Parkway and Marion Street ....................................................80

4.3.5

Flood Area 5: West Nebraska Avenue and Albemarle Street ................................................80

4.3.6

Flood Area 6: East Arlington Avenue and railroad .....................................................................81

4.3.7

Flood Area 7: East Arlington Avenue and Westminster Street ..............................................81

4.3.8

Flood Area 8: East Hyacinth Avenue and Westminster Street, I-35E ..................................82

4.3.9

Flood Area 9: Lafayette Road and North John Street ...............................................................83

Conclusions and Recommendations .................................................................................................................84

ii

5.0

Recommendations ................................................................................................................................................................86

References .............................................................................................................................................................................................87

iii

List of Tables Table 1

Atlas 14 design event precipitation depths .............................................................................................. 6

Table 2

2016 Ramsey County impervious coverage impervious and DCIA assumptions ...................... 8

Table 3

NRCS Soil Infiltration Parameters ................................................................................................................. 9

Table 4

Pipe material descriptions and roughness coefficients ....................................................................12

Table 5

CRWD 2016 monitoring data summary ...................................................................................................14

Table 6

CRWD 2016 rainfall gauge summary .......................................................................................................16

Table 7

Rainfall events observed at monitoring stations .................................................................................22

Table 8

Total Depths (in.) at Rain Gage Locations ..............................................................................................23

Table 9

Starting water surface elevations for CRWD monitored water bodies ........................................26

Table 10

Initial and final baseflow for calibration and validation events ......................................................28

Table 11

Changes to Model at Monitoring Locations ..........................................................................................29

Table 12

Uncalibrated model results verses monitored data for the August 10, 2016 event...............37

Table 13

Uncalibrated model results verses monitored data for the August 24, 2016 event...............41

Table 14

Calibrated model results verses monitored data for the August 10, 2016 event ....................50

Table 15

Calibrated model results verses monitored data for the August 24, 2016 event ....................55

Table 16

Validation model results verses monitored data for the October 4, 2016 event ....................60

Table 17

Atlas 14 Calibrated Model Design Storm Results ................................................................................61

Table 18

Atlas 14 Uncalibrated Model Design Storm Results ...........................................................................61

Table 19

Scoring criteria for study area ......................................................................................................................72

Table 20

Flood area score and summary of impacts .............................................................................................75

List of Figures Figure 1

Trout Brook Interceptor watershed boundary and update locations ............................................ 3

Figure 2

Trout Brook Interceptor watershed directly-connected impervious area .................................... 7

Figure 3

Trout Brook Interceptor study area pipe network ...............................................................................11

Figure 4

CRWD 2016 Monitoring Locations.............................................................................................................15

Figure 5

Daily rainfall total from five (5) rainfall gauges .....................................................................................16

Figure 6

UMN precipitation data compared to TBO flow data ........................................................................17

Figure 7

Uncalibrated rating curve comparison at TBO ......................................................................................18

Figure 8

Uncalibrated rating curve comparison at TBEB .....................................................................................18

Figure 9

Uncalibrated rating curve comparison at TBWB ...................................................................................19 iv

Figure 10

Uncalibrated rating curve comparison at TBO-SP ...............................................................................19

Figure 11

Uncalibrated rating curve comparison at West-TB Circle .................................................................20

Figure 12

August 10, 2016 Rain Gage and NEXRAD Rainfall Distribution Comparison............................23

Figure 13

August 24, 2016 Rain Gage and NEXRAD Rainfall Distribution Comparison............................24

Figure 14

October 4, 2016 Rain Gage and NEXRAD Rainfall Distribution Comparison ............................24

Figure 15

NEXRAD Rainfall distribution comparison for TRT17 and surrounding subwatersheds.......25

Figure 16

Monitored discharge at the TBI Outlet.....................................................................................................27

Figure 17

Calibrated rating curve comparison at Lake McCarrons ...................................................................30

Figure 18

Calibrated rating curve comparison at Como Lake .............................................................................30

Figure 19

Calibrated rating curve comparison at TBO ...........................................................................................31

Figure 20

Calibrated rating curve comparison at TBEB ..........................................................................................31

Figure 21

Calibrated rating curve comparison at TBWB ........................................................................................32

Figure 22

Calibrated rating curve comparison at TBO-SP. ...................................................................................32

Figure 23

Calibrated rating curve comparison at West-TB Circle ......................................................................33

Figure 24

August 10, 2016: Uncalibrated hydrograph at the TBI Outlet monitoring station .................34

Figure 25

August 10, 2016: Uncalibrated hydrograph at the TBI-East Branch monitoring station ......34

Figure 26

August 10, 2016: Uncalibrated hydrograph at the TBI-West Branch monitoring station ....35

Figure 27

August 10, 2016: Uncalibrated hydrograph at the TBI West-TB Circle monitoring station ....................................................................................................................................................................35

Figure 28

August 10, 2016: Uncalibrated hydrograph at the TBI-Saint Paul monitoring station..........36

Figure 29

August 10, 2016: Uncalibrated hydrograph – combined TBO and TBI-SP Outlet ...................36

Figure 30

August 24, 2016: Uncalibrated hydrograph at the TBI Outlet monitoring station .................38

Figure 31

August 24, 2016: Uncalibrated hydrograph at the TBI-East Branch monitoring station ......38

Figure 32

August 24, 2016: Uncalibrated hydrograph at the TBI-West Branch monitoring station ....39

Figure 33

August 24, 2016: Uncalibrated hydrograph at the TBI West-TB Circle monitoring station ....................................................................................................................................................................39

Figure 34

August 24, 2016: Uncalibrated hydrograph at the TBI-Saint Paul monitoring station..........40

Figure 35

August 24, 2016: Uncalibrated hydrograph – combined TBO and TBI-SP Outlet ...................40

Figure 36

Uncalibrated directly connected impervious percentages ...............................................................43

Figure 37

Calibrated directly connected impervious percentages ....................................................................44

Figure 38

August 10, 2016: Calibrated hydrograph at the TBO monitoring station ..................................46

Figure 39

August 10, 2016: Calibrated hydrograph at the TBEB monitoring station .................................46

Figure 40

August 10, 2016: Calibrated hydrograph at the TBWB monitoring station ...............................47

v

Figure 41

August 10, 2016: Calibrated hydrograph at the West-TB Circle monitoring station .............47

Figure 42

August 10, 2016: Calibrated hydrograph at the TBO-SP monitoring station ...........................48

Figure 43

August 10, 2016: Calibrated TBO-Combined hydrograph................................................................48

Figure 44

August 10, 2016: Calibrated stage hydrograph at Arlington-Jackson South Bay ...................49

Figure 45

August 24, 2016: Calibrated hydrograph at the TBO monitoring station ..................................51

Figure 46

August 24, 2016: Calibrated hydrograph at the TBEB monitoring station .................................51

Figure 47

August 24, 2016: Calibrated hydrograph at the TBWB monitoring station ...............................52

Figure 48

August 24, 2016: Calibrated hydrograph at the West-TB Circle monitoring station .............52

Figure 49

August 24, 2016: Calibrated hydrograph at the TBO-SP monitoring station ...........................53

Figure 50

August 24, 2016: Calibrated Combined-TBO hydrograph................................................................53

Figure 51

August 24, 2016: Calibrated stage hydrograph at Arlington-Jackson South Bay ...................54

Figure 52

October 4, 2016: Calibrated hydrograph at the TBO monitoring station ...................................56

Figure 53

October 4, 2016: Calibrated hydrograph at the TBEB monitoring station .................................56

Figure 54

October 4, 2016: Calibrated hydrograph at the TBWB monitoring station ...............................57

Figure 55

October 4, 2016: Calibrated hydrograph at the West-TB Circle monitoring station .............57

Figure 56

October 4, 2016: Calibrated hydrograph at the TBO-SP monitoring station ............................58

Figure 57

October 4, 2016: Calibrated Combined-TBO hydrograph ................................................................58

Figure 58

October 4, 2016: Calibrated stage hydrograph at Arlington-Jackson South Bay....................59

Figure 59

2-year calibrated flood map .........................................................................................................................64

Figure 60

10-year calibrated flood map.......................................................................................................................65

Figure 61

100-year calibrated flood map ....................................................................................................................66

Figure 62

500-year calibrated flood map ....................................................................................................................67

Figure 63

100- and 500-year Trunk TBI surcharging nodes .................................................................................68

Figure 64

Flood Prioritization Areas...............................................................................................................................71

Figure 65

Trout Brook Interceptor flood prioritization metric ............................................................................77

Figure 66

Flood Area 1: West Maryland Avenue and North Grotto Street ...................................................78

Figure 67

Flood Area 2: West Maryland Avenue and Norton Street ...............................................................79

Figure 68

Flood Area 3: West Orange Avenue and Farrington Street ............................................................79

Figure 69

Flood Area 4: West Wheelock Parkway and Marion Street.............................................................80

Figure 70

Flood Area 5: West Nebraska Avenue and Albemarle Street .........................................................81

Figure 71

Flood Area 6: East Arlington Avenue and railroad .............................................................................81

Figure 72

Flood Area 7: East Arlington Avenue and Westminster Street ......................................................82

vi

Figure 73

Flood Area 8: East Hyacinth Avenue and Westminster Street, I-35E...........................................83

Figure 74

Flood Area 9: Lafayette Road and North John Street........................................................................83

List of Appendices Appendix A

2-, 10-, 100-, and 500-year calibrated flood area mapbook

Appendix B

Atlas 14 Trout Brook Interceptor XP-SWMM Model Updates – Phase 1 Memo

Certifications I hereby certify that this report was prepared by me or under my direct supervision and that I am a duly Licensed Professional Engineer under the laws of the State of Minnesota.

11/16/2018 Nathan Campeau

Date

PE #: 44917

vii

1.0

Background

Hydrologic and hydraulic models based on reasonable design assumptions can be used to guide management decisions and identify flood prone areas. Models can be useful in evaluating and designing improvements to and modifications of storm sewer infrastructure. The Capitol Region Watershed District (CRWD) developed an XP-SWMM model as part of the Trout Brook Storm Sewer Interceptor (TBI) Hydraulic Evaluation (TKDA, June 30, 2005). The model was subsequently revised and calibrated by Barr Engineering Co. (Barr) in 2012 (Hydrologic and Hydraulic Modeling of the Trout Brook Storm Sewer Interceptor and Detailed Assessment of North TBI Study Area, Barr, June 2012). Since 2012, Barr has performed maintenance to the model, incorporating revisions that include the 2012 TBI Realignment project (2012), the Farrington watershed study (2014), the Willow Reserve watershed study (2016), and other revisions to the model based on minor modifications to the TBI and additional data. The extent of the TBI model is shown in Figure 1.

Since the last major model update in 2012, NOAA released new precipitation data for Minnesota, Atlas 14, which replaces the precipitation data (Technical Paper No. 40, or TP-40) used in the 2012 model. The Atlas 14 precipitation frequency estimates for the TBI watershed are higher than the TP-40 estimates, up to 1.5 inches higher in the 24-hour, 100-year precipitation event (5.9 inches in TP-40, 7.4 inches in Atlas 14).

Additionally, CRWD requested that Barr evaluate a higher 24-hour precipitation depth of 10.5 inches, which corresponds to the 24-hour, 500-year event (and closely corresponds to the 95th percentile of the Atlas 14 100-year, 24 rainfall of 10.0 inches as well as the Minnehaha Creek Watershed District (MCWD) climate change projected moderate increase in 100-year, 24-hour rainfall of 10.23 inches).

Modeling precipitation events larger than the standard 100-year event allows CRWD to evaluate hydraulic vulnerabilities in the TBI to help CRWD plan for a more resilient conveyance system. The importance of this analysis is underscored by the increasing frequency of storms with higher intensities and depths that are occurring in Minnesota, attributed to climate change. Updating and re-calibrating the TBI model will be useful for assessing potential impacts of climate change, thus ensuring that new stormwater infrastructure will be capable of handling future events.

The model was updated and re-calibrated by first addressing many of the recommendations from the 2012 report. These recommendations, including how they were addressed, are summarized below: 1.

The model was updated to include repairs to the system after 2012 such as the MNDOT proposed revisions along I-35E, the Farrington watershed study, and the Willow Reserve watershed study.

2.

The impervious assumptions in the model was updated to Ramsey County 2016 impervious dataset as outlined in Section 2.2.1.3.

3.

The XP-SWMM model with re-calibrated and validated with additional high-intensity and lowintensity storm events.

1

4.

The current monitoring program for the TBI and tributary stormwater ponds was continued, and monitoring data was used to re-calibrate the XP-SWMM model.

5.

Additional monitoring station locations were provided, including the TBI-West Trout Brook Circle station and the Saint Paul Tunnel station. Data from these additional monitoring locations were used to re-calibrate the model.

6.

Additional monitoring at the southern cell of Arlington-Jackson Pond was used to validate the XPSWMM model.

Barr used the re-calibrated model to identify flood-prone areas associated with surcharging of the TBI. Barr then developed an impact analysis of nine distinct flood areas to help CRWD prioritize flood mitigation in flood areas associated with TBI.

2

Little Canada Little Canada 36

Roseville

£ ¤

51

61

Maplewood

Lake McCarrons

Barr Footer: ArcGIS 10.4.1, 2017-03-15 09:58 File:I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Reports\Figure 1_2016 TBI Watershed Boundary .mxdUser: hnh

Falcon Heights

Falcon Heights

Maplewood

Roseville

Saint Paul

04 Arlington-Jackson Pond

02

Willow Reserve

Como Lake Loeb Lake

03

TBI Model Revision Locations 01

Trout Brook Interceptor

Sims-Agate Pond Saint Paul

Waterbodies CRWD Legal Boundary

Projects Included in Updated TBI XP-SWMM Model No.

Completed Project

Year(s)

01

I-35E Cayuga Street Interchange Project & TBI Realignment

02

Farrington Watershed Modeling

03

Willow Reserve Stormwater Pond Watershed Improvements

04

Como Lake Park Watershed Modeling

94

Subwatersheds 5

Municipal Boundary

0

§ ¦ ¨ 94

2016 2018

; !

N

2012-2016 2014

§ ¦ ¨

§ ¦ ¨ 35E

1,000

2,000

3,000

Feet

£ ¤ 61

STUDY AREA 61 MODEL ATLAS 14 UPDATES XP-SWMM Trout Brook Stormsewer Interceptor Capitol Region Watershed District

£ ¤

FIGURE 1 the GIS User Community Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and

2.0 2.1

Uncalibrated Model Construction

Model Updates

The following subsections describe the major updates that were incorporated into the revised, uncalibrated TBI XP-SWMM model since the most recent model update. These locations are shown in Figure 1.

2.1.1

I-35E-Cayuga Street Interchange Project & TBI Realignment

From 2012 until 2016, MNDOT reconstructed I-35E and made several interchange improvements. MNDOT provided CRWD and Barr with information detailing improvements to be incorporated into the updated TBI XP-SWMM model. The information from MNDOT includes a final drainage design report (DDR), an existing conditions XP-SWMM model, a proposed conditions XP-SWMM model, existing and proposed drainage figures, proposed infrastructure dimensions and alignments, subwatershed divides, and CAD plans. Barr incorporated this data into the Atlas 14 TBI XP-SWMM model by: a.

Updating subwatershed divides where new features from the Cayuga Bridge Project do not align with 2011 lidar data used for the rest of the TBI watershed;

b. Adding new infrastructure from the Cayuga Bridge Project DDR, drainage maps, and proposed conditions XP-SWMM model to connect updated divides to the TBI; c.

Adding nodes and storage data for new ponds constructed for the Cayuga Bridge Project matching the storage curves provided in the MNDOT proposed conditions XP-SWMM model; and

d. Updating lidar storage curves and hydrologic data to match the updated subwatershed divides.

Due to MNDOT’s project to reconstruct I-35E and add a new interchange at Cayuga Street, CRWD replaced an approximately 740-foot section of TBI with a new approximately 809-foot alignment. The realigned section was constructed during 2012-2013 and completed in fall 2013.

2.1.2

2014 Farrington Watershed Modeling

In response to localized flooding concerns, in 2014 CRWD and Barr performed detailed hydrologic and hydraulic modeling of an approximately 50-acre watershed tributary to the TBI in order to evaluate the localized flooding issue and to evaluate potential long-term solutions. This update required adding a higher level of resolution and detail to the TBI model in the 50-acre study area.

2.1.3

2016 Willow Reserve Watershed Improvements

In 2016, CRWD and Barr investigated water quality improvement options and flood mitigation alternatives within the Willow Reserve watershed tributary to the TBI. As part of this work, Barr reviewed and updated hydraulic and hydrologic modeling within the Willow Reserve watershed. Additional detail and resolution added to the Willow Reserve watershed was incorporated into the TBI model.

4

2.1.4

Como Lake Park Modeling Details

In January 2018, additional detail was added to the Como Lake watershed. The 1,850-acre watershed draining to Como Lake was subdivided into eleven watersheds in order to incorporate the modeling of three ponds in the Como Park Golf Course. A 42.5 cfs three-pump pump station was added to the model where high flows from the most downstream pond are pumped to Como Lake.

2.2

2017 Model Development

XP-SWMM is a hydrologic and hydraulic model which generates and routes surface runoff generated by rainfall events through networks of pipes, surface channels, and storage basins. As described in Section 2.1, the 2017 TBI XP-SWMM model was developed from the existing 2012 TBI XP-SWMM model using best available data sources and modeling methodology similar to the methodology outlined in the Barr 2012 report, entitled: Hydrologic and Hydraulic Modeling of the Trout Brook Storm Sewer Interceptor and Detailed Assessment of North TBI Study Area (Barr, June 2012). The following subsections outline the methodology used to develop the 2017 TBI XP-SWMM model.

2.2.1

Hydrology

Since completion of the 2012 XP-SWMM modeling, several data sources utilized for that modeling effort have been updated or new data sources have been published that supersede previously-utilized data sources. The following subsections outline the 2017 TBI XP-SWMM hydrologic modeling methodology, with special emphasis given to new and updated data sources.

2.2.1.1

Subwatershed Delineation

During the 2012 TBI XP-SWMM modeling effort, the approximately 8,150-acre TBI study area was delineated into subwatersheds ranging in size from 0.14 acres to 646 acres (not including the watersheds tributary to Como Lake and Lake McCarrons). Subwatershed resolution varies throughout the watershed, but typically subwatersheds were delineated to the scale of catch basin clusters, major storm sewer trunk lines, and hydraulic features such as wet detention ponds and lakes. The majority of subwatersheds originally developed in 2012 were not updated during this modeling effort, with the exception of updates in the model areas outlined in Section 2.1. See Section 2.1 for descriptions of how subwatersheds were updated in these areas.

2.2.1.2

Atlas 14 Rainfall Data

Barr modeled the Atlas 14 2-, 10-, 100-, and 500-year 24-hour design rainfall events using the Midwest/Southeast Type 3 (MSE3) rainfall distribution. Barr identified Atlas 14 cumulative precipitation depth for each return interval using point precipitation frequency estimates generated from the centroid of the TBI watershed. Unique design event hyetographs were developed by applying precipitation depths to the normalized MSE3 rainfall distribution, as recommended by the Natural Resources Conservation Service (NRCS). Atlas 14 cumulative precipitation depths for each modeled design event are shown in Table 1.

5

Table 1

Atlas 14 design event precipitation depths

Recurrence Interval 2-Year 10-Year 100-Year 500-Year 2.2.1.3

24-Hour Rainfall Depth (in) 2.81 4.20 7.40 10.40

2016 Ramsey County Impervious Coverage

In 2016, Ramsey County published an impervious coverage dataset. Within this dataset, impervious surfaces county wide were hand-digitized and delineated by impervious surface type (e.g., road surface, roof, sidewalk, etc.). Using this data source, Barr reevaluated total and directly-connected impervious area for all subwatersheds within the TBI project area as shown in Figure 2. Total impervious and directlyconnected impervious adjustment (DCIA) factors for each impervious surface type within the TBI watershed are outlined in Table 2.

The DCIA factor represents the fraction of total imperviousness which is assumed to be directly connected to the storm water conveyance system (i.e., the fraction of impervious surfaces which drain directly to storm sewer infrastructure without running over any pervious surfaces). DCIA factors shown in Table 2 were determined through evaluation of each impervious type in study areas throughout the TBI watershed. As can be seen, the majority of impervious types were assigned a DCIA value of 1 (e.g., paved road) or a value of 0 (e.g., trial or golf path). Non 0-or-1 values (e.g., 0.15 for residential roofs) were assigned through manual evaluation of small study areas throughout the TBI watershed. For these impervious types, the most-representative DCIA values determined from analysis of study areas was assigned. Using the values shown in Table 2, the total impervious and directly connected impervious fraction for each subwatershed was determined through spatial analysis of the 2016 Ramsey County impervious dataset within each subwatershed.

The total impervious and directly connected impervious areas calculated from the 2016 Ramsey County dataset were updated in watersheds where the I-35E-Cayuga Street Interchange Project are not reflected in the dataset. These updated watersheds are shown in Figure 2.

6

Little Canada 36

£ ¤

Barr Footer: ArcGIS 10.4.1, 2017-03-15 09:58 File: I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Reports\Figure 2_2016 TBI Update Directly Connected ImperviousNEW.mxd User: hnh

51

61

Falcon Heights

Maplewood

Roseville

Saint Paul

Updated Imperviousness based on I-35E-Cayuga Street Improvement Project

Trout Brook Interceptor Subwatersheds using 2016 Ramsey County Impervious Dataset

§ ¦ ¨ 35E

Subwatersheds with Updated Imperviousness to reflect I-35ECayuga Street Project 5

Municipal Boundary

; !

N

0

Directly-Connected Impervious Percentage 0%

50%

10%

95%

15%

100%

§ ¦ ¨ 94

§ ¦ ¨ 94

1,000

2,000

3,000

Feet

£ ¤ 61

DIRECTLY CONNECTED IMPERVIOUS 61 MODEL ATLAS 14 UPDATES XP-SWMM Trout Brook Stormsewer Interceptor Capitol Region Watershed District

£ ¤

FIGURE 2 the GIS User Community Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and

Table 2

2016 Ramsey County impervious coverage impervious and DCIA assumptions

2016 Ramsey Co. Impervious Category Pervious Paved Parking Lot Unpaved Parking Lot Canopy Garage Non-Residential Outbuilding Other Patio Deck Residential Under Construction Alley Driveway Paved Median Paved Road Sidewalk (residential) Sidewalk (commercial) Trail or Golf path Unpaved Road Basketball Court Volleyball Court Concrete Pad Loading Dock Tank, Gas Tank, Unknown River/Stream Lake Railroad 2.2.1.4

Total Imperviousness (%) 0% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 0%

DCIA 0.00 1.00 1.00 1.00 0.50 0.95 0.00 0.00 0.00 0.15 0.00 1.00 1.00 1.00 1.00 0.10 1.00 0.00 1.00 0.00 0.00 1.00 1.00 1.00 1.00 1.00 1.00 0.00

Watershed Slope and Width

XP-SWMM generates runoff from each of the subwatersheds as the product of velocity (from Manning’s equation, based on the difference between total depth and depression storage and the average subwatershed slope), depth, and width (flow area). If overland flow is visualized as running down-slope off an idealized, rectangular subwatershed, then the width of the subwatershed is the physical width of overland flow. The lateral flow per unit width is computed and multiplied by the width to obtain the runoff rate. Therefore, watershed slope and width are critical XP-SWMM model inputs.

8

The average slope (ft/ft) for each watershed was estimated using ArcGIS and a 30m Digital Elevation Model (DEM) created from 2011 lidar data for Ramsey County. In urban areas, high resolution DEMs (e.g., 1-meter resolution) can report buildings or other small anomalies as ground elevations, thus creating artificially high slope estimates. When coarser resolution DEMs are used (e.g., 30-meters), abrupt elevation changes associated with building, overpasses, etc. are not detected and therefore do not impact slope calculations. For this reason, data Barr resampled the 2011 lidar to 30-meter resolution in order to generate slope values for all subwatersheds.

Watershed “width” is a key parameter in establishing the generalized shape of subwatersheds in XPSWMM which impacts the subwatershed time of concentration. Following methodology in the 2012 TBI report (Barr, June 2012), watershed width was calculated by dividing the watershed area by the longest flow path.

2.2.1.5

Infiltration Data

Barr updated the 2012 TBI XP-SWMM infiltration parameters model-wide using 2016 NRCS soils data.

Horton soil infiltration assumptions applied to each Hydrologic Soil Group (HSG) are shown in Table 3. For all areas where HSG soil type was undefined in the 2016 NRCS dataset, infiltration parameters for B soils were used.

Table 3

NRCS Soil Infiltration Parameters

Hydrologic Soil Group

F0 (in/hr)1

Fc (in/hr)2

A

5.0

0.50

0.00115

B

3.0

0.20

0.00115

C

2.0

0.10

0.00115

D

1.0

0.03

0.00115

1

F0 is the maximum infiltration rate.

2

Fc is the minimum or asymptotic infiltration rate

3

k (sec-1)3

k is the decay coefficient that defines the rate at which the maximum infiltration rate (F0) decays to the minimum infiltration rate (Fc): F = Fc + (F0 – Fc)e-kt, where F is the infiltration rate at time t.

Composite infiltration values for each subwatershed were calculated by computing weighted-average values based on the percentage of each HSG soil type within each subwatershed.

2.2.1.6

Depression Storage Assumptions

Depression storage represents the initial loss of water caused by surface ponding, surface wetting, and interception. Depression storage for both pervious and impervious areas were set within the general range of published values. The model handles depression storage differently for pervious and impervious areas. The impervious depression storage is replenished during dry simulation periods by evaporation.

The water stored as pervious depression storage is subject to both infiltration and evaporation.

9

Calibration adjustments developed during the 2012 TBI XP-SWMM calibration project (e.g., impervious depression storage raised from the typical value of 0.06 inches to 0.1 inches) were disregarded and typical assumptions (i.e., impervious depression storage of 0.06 inches and pervious depression storage of 0.17 inches) were applied to the model. All calibration adjustments were reevaluated, as described in Section 3.0.

“Zero percent detention” is a model parameter that specifies the fraction of impervious area that has no depression storage (e.g., water surfaces). The zero percent detention value was calculated by dividing the water area from the 2016 Ramsey County impervious dataset by the subwatershed total impervious area.

2.2.2 2.2.2.1

Hydraulic Parameters 2011 Ramsey County lidar

Barr updated storage model-wide based on 1-meter resolution lidar data collected in Ramsey County in 2011, which is the most recent lidar dataset available from the State of Minnesota Geospatial Information Office (http://www.mngeo.state.mn.us/chouse/elevation/lidar.html). Compared to County data available during the 2012 TBI XP-SWMM calibration project (collected in 2007), the updated lidar database typically predicts more storage volume due to improvements in remote sensing penetration through tree canopies and dense vegetation. In addition to updating model storage curves, Barr evaluated and updated node inverts of storage basins, initial depths, and overflow elevations as necessary.

2.2.2.2

Reevaluation of Landlocked Subwatersheds

Barr reincorporated subwatersheds identified as landlocked (i.e., no outflow during the TP-40 100-year, 24-hour event) during the 2012 TBI XP-SWMM calibration project (Barr, June 2012). Because the Atlas 14 500-year, 24-hour design event is larger than any events modeled during the 2012 TBI XP-SWMM project, subwatersheds formerly identified as being landlocked may fill, overflow, and contribute runoff volume to the TBI watershed during the 500-year Atlas 14 event. For this reason, it was necessary to incorporate and reevaluate outflow from all subwatersheds potentially tributary to the TBI.

2.2.2.3

Pipe Network

The pipe network for the TBI study area is shown in Figure 3. Additions to the pipe network from the 2012 TBI XP-SWMM report (Barr, June 2012) were made during the updates described in Section 2.1.

Creation of the pipe network before the additions described in Section 2.1 is outlined in the Barr 2012 TBI report.

Pipe material was used to determine the roughness coefficient (i.e., Manning’s n value) applied to each pipe conduit in the model. Table 4 shows references for roughness coefficients assigned to various pipe materials. When material type was not assigned, a default Manning’s n roughness value of 0.013 (concrete) was assumed.

10

Little Canada 36

£ ¤

51

Falcon Heights

61

Maplewood

Roseville

Barr Footer: ArcGIS 10.4.1, 2017-03-15 09:58 File:I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Reports\Figure 3_2016 TBI Pipe Networknew.mxdUser: hnh

Saint Paul

Trout Brook Interceptor XP-SWMM Links Waterbodies Subwatersheds

§ ¦ ¨ 35E

Municipal Boundary 5

; !

N

0

1,000

2,000

3,000

Feet

§ ¦ ¨ 94

§ ¦ ¨ 94

£ ¤ 61

MODELED PIPE NETWORK 61 MODEL ATLAS 14 UPDATES XP-SWMM Trout Brook Stormsewer Interceptor Capitol Region Watershed District

£ ¤

FIGURE 3 the GIS User Community Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and

Table 4

Pipe material descriptions and roughness coefficients

Material

Description

n

CMP

Corrugated Metal Pipe

0.024

PVC

Polyvinyl Chloride Pipe

0.011

RCP

Reinforced Concrete Pipe

TBI (original cast in place concrete)

Trout Brook Interceptor

0.015

TBI (2008 and 2012 precast box culvert replacement sections)

Trout Brook Interceptor

0.011

0.011-0.013*

*Pipes added to the model during the I-35E Cayuga Project update were given the same roughness values as in the XP-SWMM model provided by MNDOT.

Entrance and exit loss values were referenced from the Wurbs and James 2002 Water Resources Engineering textbook indicated in the Barr 2012 TBI report (Barr, June 2012). In order to accurately model flows into the system through inlets (i.e., flared end sections), all flared end sections were assigned an inlet type in XP-SWMM, which defines the flow conditions at the inlet point. If no information was known about the flared end section, the section was assumed to have a grooved end, which projects from the surrounding surface.

The TBI system includes two different “pipe-in-pipe” sections (Mainline station 207+00 to station 229+42 and East Extension station 02+39 to station 09+86). Met Council filled and abandoned the sanitary pipe within the “pipe-in-pipe” section in the East Extension in 2016. For both pipe-in-pipe sections, a “userdefined” pipe was used in the XP-SWMM model to accurately model the flow characteristics of the pipes.

However, it should be noted that for one of the pipe-in-pipe sections, the graphic representation shown in the XP-SWMM model is misleading because of XP-SWMM’s graphical interpretation of the entered data. The XP-SWMM model requires a variety of input parameters associated with increasing elevations within a pipe including flow depth, cross-sectional area, wetted perimeter, and top width. XP-SWMM uses these input parameters to make assumptions about the pipe and create a graphical representation. More specifically, XP-SWMM assumes the pipe is symmetrical, which is not the case for this pipe-in-pipe section since the pipe-in-pipe section is notched only on one side. Regardless of the graphical representation in XP-SWMM, analysis of flow data used in the model shows that the pipe is modeled correctly.

The TBI system also includes horseshoe-shaped pipes, arch sections, and box pipes. Box culverts or rectangular pipe sections were used for multiple sections of the TBI, including a portion of the TBI that was repaired in 2008. The Barr 2012 TBI report provides additional detail on how the TBI was modeled in XP-SWMM (Barr, June 2012). No variations to the existing pipe network in the 2012 XP-SWMM model were made with the exception of the updates discussed in Sections 2.1 and 3.0.

12

2.2.2.4

Atlas 14 Volume Capture and Overland Flow

To capture and convey the Atlas 14 500-year design event, Barr extended storage curves, raised spill crests, and reevaluated overflow conveyances model wide. New road and overland overflow conveyances were added consistent with methodology developed during the 2012 TBI XP-SWMM calibration project (i.e., overland and ditch conveyances modeled as natural cross-sections and road overflows were modeled using a typical 30-foot right curb section). New and existing overflow conveyances were compared to Atlas 14 inundation mapping and adjusted as needed to avoid double-counting storage volume.

A roughness coefficient of 0.25 was assigned to pervious surfaces (e.g., turf), and a roughness coefficient of 0.015 was assigned to all impervious surfaces within the study area as outlined in the Barr 2012 TBI report (Barr, June 2012).

13

3.0 3.1

Model Calibration

Review of 2016 Monitoring Data and Calibration Assessment

During 2016, CRWD monitored velocity, water levels, and precipitation at locations throughout the TBI watershed (Table 5 and Figure 4). The following subsections outline steps taken to review and validate received monitoring data.

Table 5

CRWD 2016 monitoring data summary

Station ID Trout Brook Outlet (TBO) Trout Brook-East Branch (TBEB) Trout Brook-West Branch (TBWB) TBI West-TB Circle (West-TB Circle)

TBO-SP Tunnel (TBO-SP) Arlington-Jackson S. Bay Arlington-Jackson Sims-Agate Willow Reserve Westminster-Mississippi UMN Precip.

TBEB Precip.

Villa Park Precip.

Fire station Precip.

Western Dist. Police Precip.

3.1.1

Data Collected Level-velocity Level-velocity Level-velocity Level-velocity Level-velocity Level (stage) Level (stage) Level (stage) Level (stage) Level (stage) Precipitation Precipitation Precipitation Precipitation Precipitation

Precipitation Data

Barr compared precipitation on an event-basis at the five (5) precipitation monitoring locations. Because the University of Minnesota (UMN) rainfall gauge provided the most complete dataset in 2016, rainfall totals collected from other monitoring locations were compared to the UMN dataset. As shown in Table 6, 2016 precipitation totals collected at other rainfall gauges were close to but slightly less than the UMN total. This was expected, as the UMN precipitation dataset begins January 1, 2016, while the other four monitoring location do not begin reporting precipitation until late March 2016.

14

Little Canada

Villa Park Precip

. !

Falcon Heights

Maplewood

Roseville

Arlington-Jackson

Barr Footer: ArcGIS 10.4.1, 2017-09-20 13:59 File: I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Reports\Figure 4_CRWD 2016 Monitoring Locations.mxd User: mbm

UMN Precip

. !

TBI West-TB Circle Willow Reserve

! . . ! . !

. !

Saint Paul

Arlington-Jackson S. Bay

Westminster-Mississippi

. ! !! . . TBEB Precip

Trout Brook-West Branch

Trout Brook -East Branch

Sims-Agate

. !

2016 Monitoring Data

! . . ! . !

Level-Velocity

Trout Brook Outlet

. !

Level (Stage) Western Dist Police Precip

Precipitation Trout Brook Interceptor

TBO-SP Tunnel

. !

Subwatersheds Municipal Boundary

; !

N

0

2,000

4,000

Feet

CRWD 2016 MONITORING LOCATIONS Trout Brook Stormsewer Interceptor Capitol Region Watershed District FIGURE 4

Firestation Precip

. !

Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community

Table 6

CRWD 2016 rainfall gauge summary

Station ID UMN Precip.

TBEB Precip.* Villa Park Precip.

Fire station Precip.

Western Dist. Police Precip.

Total Rainfall (in) 32.24 18.24 29.53 29.46 24.69

Max. Daily Rainfall Recorded (in) 2.17 1.39 2.52 1.99 1.94

* The Trout Brook-East Branch (TBEB) rainfall gauge stopped collecting data through the majority of June and July.

Daily rainfall totals at the five rainfall gauges were compared graphically to one another (Figure 5) and to flow rate monitoring data (Figure 6) to look for anomalies in the dataset (e.g., rainfall events with no corresponding increase in observed flowrate; large rainfall events observed at only one of the five rainfall gauges; etc.). Precipitation data from CRWD was also compared to Next Generation Weather Radar (NEXRAD) precipitation data downloaded from the National Centers for Environmental Information (NCEI) webpage. Based on this comparison, NEXRAD data was used to calibrate the TBI model. See Section 3.2 for details on the comparison of CRWD provided precipitation data and NEXRAD data.

Figure 5

Daily rainfall total from five (5) rainfall gauges

16

Figure 6

3.1.2

UMN precipitation data compared to TBO flow data

Flow Monitoring Data

As shown in Table 5, the CRWD collected level-velocity-flow data at five (5) monitoring locations. CRWD selected these locations based on conclusions and monitoring recommendations outlined in the 2012 TBI XP-SWMM calibration project report. To evaluate the level of effort which may be required to calibrate the updated model to the 2016 monitoring data, Barr compared monitored rating curves to modeled rating curves at each of the five flow monitoring locations. This analysis is summarized in the attached memo, Appendix B. Observed and modeled rating curves at each of the five monitoring locations are shown in Figure 7 through Figure 11.

17

Figure 7

Uncalibrated rating curve comparison at TBO

Figure 8

Uncalibrated rating curve comparison at TBEB

18

Figure 9

Uncalibrated rating curve comparison at TBWB

Figure 10

Uncalibrated rating curve comparison at TBO-SP

19

Figure 11

Uncalibrated rating curve comparison at West-TB Circle

20

3.2

Calibration and Validation Events

Model calibration is the process by which input parameters are adjusted to minimize the difference between modeled and observed results. The general process used to calibrate the hydraulic and hydrologic XP-SWMM model is outlined, below: 1.

Develop rating curves from flow and depth data collected at monitoring stations;

2.

Calibrate model hydraulics to observed rating curves;

3.

Select initial calibration rainfall event and develop rainfall inputs;

4.

Calibrate model for initial rainfall event;

5.

Select validation event and develop rainfall inputs;

6.

Test initial parameter calibration using validation event; and

7.

Iterate steps (4) through (6) until calibration is successful for initial and validation events.

Calibration of the XP-SWMM model developed for the TBI watershed is discussed in the sections below.

3.2.1

Selection of Rainfall Events

Barr evaluated precipitation data provided by CRWD (Section 3.1.1) and selected two (2) calibration events and one (1) validation event. Calibration and validation events were chosen based on magnitude, rainfall distribution, and isolation from surrounding rain events. An option when modeling an observed rainfall event in XP-SWMM is to apply rainfall collected at a monitoring station within the study area to all subwatersheds within the model area. In XP-SWMM, this rainfall modeling approach is referred to as a “global storm”, as the same incremental rainfall depths are applied to every subwatershed within the study area. Performing modeling using global storms is typically a fine assumption for small study areas, but because the TBI study area spans over 8,000 acres, rainfall depth and intensity for a given event can vary significantly from one corner of the watershed to the other. For this reason, rainfall data collected at the gauges provided by CRWD were compared to data collected by the National Oceanic and Atmospheric Administration’s (NOAA) Next Generation Weather Radar (NEXRAD) system, and unique rainfall hyetographs were developed for subwatersheds throughout the study area using advanced spatial processing techniques in PCSWMM. PCSWMM is a GIS engine and graphical user interface (GUI) for the USEPA’s SWMM5 hydrologic and hydraulic modeling program. PCSWMM contains many advanced GIS processing tools, including a tool which can create unique rainfall hyetographs for individual subwatersheds from publically available NEXRAD precipitation data. Although NEXRAD data has coverage across the entire Continental United States and can help define the rainfall intensity across the watershed, it does not predict total rainfall depth as accurately as local rainfall gauges. For this reason, historical NEXRAD data was compared to the local monitoring data provided by CRWD to verify similar distributions, total depths, and peak intensities.

The selection of rainfall events used to calibrate the model should be based on the intended use of the model. Because the primary intended use of the TBI model is to evaluate flooding and flood prone areas,

21

rainfall events on the scale of the 10-year, 24-hour rainfall event or larger would be ideal for calibration. A summary of rainfall events observed at TBI monitoring stations in 2016 are shown in Table 7. Blue bars indicate magnitude and are relative to the maximum and minimum values within each column.

Table 7

Rainfall events observed at monitoring stations

Duration Event Start Date (hr) 8/10/2016 8/16/2016 8/23/2016 9/21/2016 10/6/2016 4/24/2016 4/27/2016 4/20/2016 8/19/2016 8/29/2016 9/23/2016 4/18/2016 8/12/2016 9/15/2016 9/25/2016 10/4/2016

Total Precip.

2

(in) 18 13 8 24 18 11 8 18 4 5 5 12 4 6 17 11

1,2

Avg. Intensity (in/hr) 2

3.05 1.10 1.21 1.52 0.98 1.17 1.06 0.45 0.48 0.51 0.37 0.22 0.23 0.85 0.20 0.66

0.17 0.08 0.15 0.06 0.05 0.10 0.13 0.02 0.13 0.10 0.08 0.02 0.06 0.15 0.01 0.06

1

Total precipitation is the average total precipitation at each of the 5 CRWD rain gages.

2

Blue bars indicate magnitude and are relative to the maximum and minimum values within each column.

Table 7 indicates that the largest rainfall event in terms of cumulative precipitation depth was the approximately 3.0 inch event recorded on August 10, 2016. Because the August 10 event was the largest event recorded during the 2016 monitored period and the event was captured at all five monitoring locations, the August 10 event was selected as a calibration event. The smaller, isolated event occurring on August 24, 2016 with a total depth of approximately 1.2 inches was chosen as the second calibration event. Validation of the model was conducted using a single 0.7-inch event on October 4, 2016. Table 8 and Figure 12 through Figure 14 compare the NEXRAD data for these events to the rain gage data provided by CRWD. Barr verified the NEXRAD data by comparing the data to total rainfall depths and precipitation intensity hydrographs. Total rainfall depths were compared between the CRWD gages and the NEXRAD data at the subwatershed closest to each gage. Since only two of the five gages provided by CRWD are located within the TBI study area (TBEB and Villa Park gages), Barr used these two gages.

For the August 10 event, the total precipitation from the CRWD gage was less than the total precipitation from the NEXRAD data. However, the opposite is true for the Villa Park gage. Often, NEXRAD data is scaled so the total precipitation matches that of the closest gage. In this case, the NEXRAD data could not be scaled uniformly to match both gages. A visual comparison of the intensity hydrographs between the two sources appear to match closely in magnitude and shape, thus validating the NEXRAD data.

22

For the October 4 and August 24 events, the total precipitation depths for the NEXRAD data appear less than the total depths from the nearest CRWD gages. However, the intensity hydrographs peaks from the NEXRAD subwatersheds are higher or matching the peak intensities from the nearest CRWD gage. From strictly a visual standpoint, the intensity hydrograph shapes generally match between the two sources.

Since scaling the NEXRAD data would increase the peak intensities higher than the gages, the NEXRAD data was not adjusted. These comparisons validate the use of NEXRAD data to recalibrate the model.

Table 8

Total Depths (in.) at Rain Gage Locations

Location ID Event August 10, 2016 August 24, 2016 October 4, 2016

Event Type Calibration Calibration Validation

Precipitation Source* NEXRAD Rain Gage NEXRAD Rain Gage NEXRAD Rain Gage

UMN 2.99 3.28 0.72 1.20 0.38 0.60

TBEB 2.95 2.55 0.89 1.39 0.50 0.70

Villa Park 3.05 3.57 0.68 0.94 0.40 0.72

STP Fire station 2.59 3.11 1.20 1.42 0.38 0.63

* NEXRAD total depths were pulled from the closest subwatershed to the corresponding rain gage location

Figure 12

August 10, 2016 Rain Gage and NEXRAD Rainfall Distribution Comparison

23

WD Police Station 2.96 2.75 1.09 1.10 0.43 0.63

Figure 13

August 24, 2016 Rain Gage and NEXRAD Rainfall Distribution Comparison

Figure 14

October 4, 2016 Rain Gage and NEXRAD Rainfall Distribution Comparison

24

3.2.2

Adjustment of Rainfall Events

After further reviewing the 0.7-inch October 4, 2016 validation event, we noted a spike in rainfall intensity for a single 660-acre subwatershed (TRT17). Because short duration, small rainfall events can produce highly variable rainfall patterns across large watersheds, it is possible that modeled hyetographs produced from NEXRAD and rainfall gauge data in PCSWMM did not accurately reflect observed rainfall patterns.

Figure 15 below shows the rainfall intensities (in mm/hr) of subwatershed TRT17 and surrounding subwatersheds. TRT17 reaches a peak intensity of 25 mm/hr, which is significantly higher than the peak intensities of surrounding subwatersheds. TRT17 is one of only a few subwatersheds draining to the Saint Paul Tunnel and contributes 96% of the drainage area. Because of its size and scale of modeling, the highintensity rainfall distribution assigned to TRT17 generates considerably more runoff than likely occurred.

The hydrograph for the Saint Paul Tunnel at the CRWD monitoring location has a significantly greater volume and peak flow than the observed data (see Figure 15). Because it appears the NEXRAD data is over-predicting runoff for this subwatershed, the hyetograph for the October 4 event at subwatershed TRT17 was scaled to reflect peak intensities of the surrounding subwatersheds. This adjustment generated more reasonable results, matching the trends of the other monitoring locations.

Figure 15

3.2.3

NEXRAD Rainfall distribution comparison for TRT17 and surrounding subwatersheds

Starting Water Surface Elevations

Starting water surface elevations unique to each calibration event at the five (5) level-monitored ponds and two (2) level-monitored lakes (Como and McCarrons) were incorporated into the model by adjusting the initial depths for nodes representing each of the monitored ponds and lakes. Starting water surface elevations were chosen from the monitored stage data at the time and date of first time step in the model. If no monitoring data were available for the event, the outlet control elevations were used to establish the initial depth. Table 9 summarizes starting water surface elevations used in the model for each event.

25

Table 9

Starting water surface elevations for CRWD monitored water bodies

Monitored Water Body Lake McCarrons Como Lake Willow Reserve Arlington Jackson Pond Arlington Jackson (South) Pond Sims-Agate Pond Westminster Pond

Starting water surface elevations in NAVD88, feet (Saint Paul Datum, feet) August 10, 2016 840.37 (146.11) 880.52 (186.26) 844.37 (150.11) 813.11 (118.85) 807.76 (113.50) 777.38 (83.12) 801.89 (107.63)

August 24, 2016 840.53 (146.27) 880.79 (186.53) 844.46 (150.20) 812.96 (118.70) 807.90 (113.64) 777.52 (83.26) 801.89 (108.19)*

October 05, 2016 840.57 (146.31) 880.57 (186.31) 844.2 (149.94)* 812.89 (118.63) 807.88 (113.62) 777.38 (84.00)* 801.89 (108.19)*

* No monitoring data were available during rainfall event. The outlet control elevation was used to define the starting water surface elevation.

3.2.4

Baseflow

Based on the flow data provided by CRWD, baseflow appears to be generally consistent throughout the year between rainfall and runoff events (Figure 16).

26

Figure 16

Monitored discharge at the TBI Outlet

Baseflow could be the result of groundwater infiltration or inflow from contributing lakes and ponds. To account for this important component of the monitored flow, baseflow was added in the XP-SWMM model upstream of each of the five flow monitoring locations representative of the baseflow conditions leading up to each event. Initial and final baseflow unique to each event are shown in Table 10. Baseflows were added as user-defined inflows to nodes upstream of the monitoring location. Initial baseflow was entered at the first time-step, and final baseflow was entered at the time of peak flow at the monitoring location, thus creating a linear increase in baseflow through the rising limb of the event. These additions to the model served as the base for calibration.

27

Table 10

Initial and final baseflow for calibration and validation events

August 10, 2016 Monitoring Location

TBEB TBWB West-TB Circle TBO TBO-SP

Initial1 Baseflow (cfs)

August 24, 2016

Final2 Baseflow (cfs)

0.5 5.0 1.8 7.0 1.2

Initial Baseflow (cfs)

3.5 0.0 0.0 0.0 1.2

0.5 0.0 17.0 0.0 1.0

Final Baseflow (cfs)

October 5, 2016 Initial Baseflow (cfs)

2.0 0.0 0.0 14.0 1.0

Final Baseflow (cfs)

0.0 0.0 1.0 5.0 1.2

1.4 8.7 4.3 5.0 1.5

1Locations

where no initial baseflow was added indicates that baseflow was accounted for upstream or is negligible to calibration model results.

2 Locations where no final baseflow was added indicates the model did not return to baseflow conditions before the end of the simulation. In these instances, additional baseflow would elevate the receding limb of the hydrograph above monitored data.

3.3

Hydraulic Calibration

3.3.1

Rating Curve Analysis

Starting from the uncalibrated flow monitoring rating curves shown in Section 3.1.2, hydraulic modeling assumptions were adjusted to improve the fit between monitored and modeled data at each of flow monitoring location. On July 6, 2017, CRWD also provided monitoring data for Como Lake and Lake McCarrons. Rating curves developed from monitoring data at these two (2) lake monitoring stations were evaluated in addition to the five (5) flow monitoring datasets originally provided.

The changes made to the model at each of the seven (7) monitoring locations are summarized in Table 11.

28

Table 11

Changes to Model at Monitoring Locations

Station ID

Change to Outlet Pipe

Trout Brook Outlet (TBO)

Increased exit loss from 0.1 to 0.5

Trout Brook-East Branch (TBEB)

Increased exit loss from 0.5 to 1.0

Trout Brook-West Branch (TBWB)

No change to model*

TBI West-TB Circle (West-TB Circle)

Increased pipe roughness from 0.011 to 0.015 and exit loss from 0.1 to 1.0

TBO-SP Tunnel (TBO-SP)

No change to model

Como Lake

No change to model

Lake McCarrons

No change to model

* Various iterations to match TBI-West Branch monitoring data were unsuccessful, therefore no changes were made to the outlet pipe at this location.

Figure 17 through Figure 23 show the effects of hydraulic calibration updates on the rating curves at each flow monitoring location. Barr performed an iterative analysis to improve hydraulic calibration at the TBIWest Branch monitoring location, including reducing all losses through the pipes and increasing the pipe sizes by 25%. As shown in Figure 21, these alternatives did not significantly improve calibration at low flow rates. For this reason, no change was made to the TBI model at this monitoring location.

29

Figure 17

Calibrated rating curve comparison at Lake McCarrons

Figure 18

Calibrated rating curve comparison at Como Lake

30

Figure 19

Calibrated rating curve comparison at TBO

Figure 20

Calibrated rating curve comparison at TBEB

31

Figure 21

Calibrated rating curve comparison at TBWB

Figure 22

Calibrated rating curve comparison at TBO-SP.

32

Figure 23

3.4

Calibrated rating curve comparison at West-TB Circle

Calibration Method and Results

After updating hydrologic modeling parameters based on best available data, adjusting the starting water surface elevations appropriately for each calibration and validation event (Section 3.2.3), and performing hydraulic calibration at all flow monitoring sites (Section 3.3.1), the calibration and validation events were run through the uncalibrated model. After evaluating results from the uncalibrated model (Section 3.4.1), Barr identified potential calibration parameters (Section 3.4.2), iteratively evaluated the impact of calibration adjustments on all calibration events simultaneously, and adjusted identified calibration parameters to achieve the best cumulative hydrograph calibration at all monitoring stations for all calibration events (Section 3.4.3). Calibration methodology and results are discussed in greater detail in the following subsections.

3.4.1 3.4.1.1

Uncalibrated Model Results August 10, 2016 3.0-inch Rainfall Event

Uncalibrated model results for the 3.0-inch rainfall event recorded on August 10, 2016 are compared to observed flow data collected at each of the five (5) monitoring locations in Figure 24 through Figure 29 below. As shown in Figure 29, The TBI Outlet and Saint Paul Tunnel event hydrographs were combined into a single hydrograph. Because the two tunnel systems can transfer flow back and forth throughout the duration of a storm event in multiple locations, it is more accurate to calibrate the performance of both tunnels as a system, rather than as two individual conveyance systems.

33

Figure 24

August 10, 2016: Uncalibrated hydrograph at the TBI Outlet monitoring station

Figure 25

August 10, 2016: Uncalibrated hydrograph at the TBI-East Branch monitoring station

34

Figure 26

August 10, 2016: Uncalibrated hydrograph at the TBI-West Branch monitoring station

Figure 27

August 10, 2016: Uncalibrated hydrograph at the TBI West-TB Circle monitoring station

35

Figure 28

August 10, 2016: Uncalibrated hydrograph at the TBI-Saint Paul monitoring station

Figure 29

August 10, 2016: Uncalibrated hydrograph – combined TBO and TBI-SP Outlet

Initial comparison of modeled and observed flow hydrographs for the August 10th event indicate that the uncalibrated model generally under-predicts peaks and over-predicts total event volume, but accurately predicts the timing and shape of the hydrograph for each of the five monitoring locations (Table 12). In addition assessing the difference in total volume and peak flows, statistical methods were used to evaluate the performance of the uncalibrated model. The Nash-Sutcliffe Efficiency coefficient (NSE) is 36

widely used to evaluate the predictive performance of hydrologic and hydraulic models (Nash and Sutcliffe, 1970). The NSE was calculated at each monitoring location for each modeled event to evaluate the “goodness of fit” between modeled results and measured data. The value of the NSE can range from negative infinity (-∞) to one (1). A value of one indicates that the model perfectly predicts observed results, and a negative value indicates that the mean of the observed data is more predictive of individual observations than the model. From experience calibrating urban watersheds of similar scale, Barr considers that NSE values greater than 0.6 indicate a successful calibration. Calculated NSE values for each monitoring location are presented in Table 12, as well.

Uncalibrated model results verses monitored data for the August 10, 2016 event

TBEB TBWB West-TB Circle TBOCombined 3.4.1.2

% Error

Modeled

% Error

Modeled

Observed

Time to Peak Flow (min)

Peak Discharge (cfs) % Error

Modeled

Monitoring Location

Observed

Volume (ac-ft)

Observed

Table 12

Event NSE

59

53

-11%

101

74

-27%

84

77

-8%

0.74

266

320

20%

441

484

10%

79

78

-1%

0.70

121

157

30%

251

329

31%

79

75

-5%

0.14

423

515

22%

1034

1094

6%

79

74

-6%

0.81

August 24, 2016 1.2-inch Rainfall Event

Uncalibrated model results for the 1.2-inch rainfall event recorded on August 24, 2016 are compared to observed flow data collected at each of the five (5) monitoring locations in Figure 30 through Figure 35 below. As in the August 10, 2016 event, the TBI Outlet and Saint Paul Tunnel event hydrographs were combined into a single hydrograph as shown in Figure 35.

37

Figure 30

August 24, 2016: Uncalibrated hydrograph at the TBI Outlet monitoring station

Figure 31

August 24, 2016: Uncalibrated hydrograph at the TBI-East Branch monitoring station

38

Figure 32

August 24, 2016: Uncalibrated hydrograph at the TBI-West Branch monitoring station

Figure 33

August 24, 2016: Uncalibrated hydrograph at the TBI West-TB Circle monitoring station

39

Figure 34

August 24, 2016: Uncalibrated hydrograph at the TBI-Saint Paul monitoring station

Figure 35

August 24, 2016: Uncalibrated hydrograph – combined TBO and TBI-SP Outlet

Initial comparison of modeled and observed flow hydrographs for the August 24 event indicate that the uncalibrated model generally under-predicts volume but accurately predicts the timing and shape of the hydrograph for each of the five monitoring locations (Table 13). Calculated NSE values for each monitoring location are presented in Table 13.

40

Uncalibrated model results verses monitored data for the August 24, 2016 event

Time to Peak Flow (min) Event NSE

-19%

58

43

-25%

291

281

-3%

0.86

TBWB West-TB Circle

75

66

-12%

224

191

-15%

291

243

-16%

0.85

34

30

-11%

94

139

48%

281

237

-16%

0.66

150

123

-18%

428

506

18%

281

279

-1%

0.91

TBOCombined

3.4.2

% Error

% Error

16

Modeled

20

Modeled

TBEB

Modeled

Observed

Peak Discharge (cfs) % Error

Monitoring Location

Observed

Volume (ac-ft)

Observed

Table 13

Calibration Parameters

From the initial results shown in Figure 24 through Figure 35 and Table 12 and Table 13, it appears initial assumptions related to hydraulic routing (e.g., pipe and overland flow manning’s roughness, pipe energy losses, etc.) accurately capture the overall timing and shape of outflow hydrographs at the five monitoring stations. However, initial hydrologic assumptions (e.g., subwatershed width, directly connected impervious area, soil infiltration parameters, etc.) result in the uncalibrated model overestimating runoff volume during the August 10 rainfall event but underestimate runoff volume during the August 24 event. For this reason, an iterative adjustment of hydrologic parameters related to runoff generation were prioritized during review of initial modeling assumptions.

A calibration parameter sensitivity analysis performed for the TBI study area was conducted. During the calibration process, many of the inputs for both the hydrology and the hydraulics of the model were varied in an effort to more closely match modeled and observed data. Ultimately, most of the parameters were returned to their initial values with the exception of the directly-connected impervious area and subwatershed width. Model parameters that were varied during some part of the calibration process included: •

Watershed width

•

Initial infiltration

•

Minimum infiltration

•

Infiltration decay rate

•

Manning’s n roughness assumption for pipes (from 0.012 to 0.015 for the TBI)

•

Directly connected impervious area

•

Pervious depression storage

•

Impervious depression storage

41

The calibration parameter sensitivity analysis showed that assumptions related to directly-connected impervious area have the greatest potential to impact modeled event volume and peak flow, followed by assumptions related to subwatershed width.

Review of the uncalibrated modeling results for the two calibration events showed that most of the total runoff at all five monitoring stations was generated from impervious surfaces. Initial calibration efforts showed that adjusting soil infiltration parameters and depression storage had minimal impact on model hydrographs. For this reason, the calibration process began with review and adjustment of assumptions related to directly connected impervious area.

3.4.2.1

Directly Connected Impervious Area

The directly-connected impervious percentage applied to each subwatershed as described in Section 2.2.1.3 is shown in Figure 36. The figure shows that the commercial and retail areas at the intersection of I-94 and 35E, as well as along Rice Street were initially assigned directly-connected impervious values ranging from 60 to 100 percent, the BNSF railyard was assigned values ranging from the 30 to 60 percent, and the remaining portion of the watershed (majority single family detached) was assigned values ranging from 0 to 30 percent.

Based on the uncalibrated results for the 3.0-inch August 10 event, the model predicts that large storms generate significantly greater runoff volumes on the receding limb than monitoring data indicates.

Decreasing the total DCIA area by 15% watershed-wide is within the reasonable range for directly-connected impervious area in the TBI watershed. Figure 37 shows the directly-connected impervious percentages for each subwatershed with the 15% reduction. The subwatersheds for commercial and retail areas at the intersection of I-94 and 35E, as well as along Rice Street range from 50 to 85 percent, the BNSF rail yard ranges from the 25 to 50 percent, and the remaining portion of the watershed (majority single family detached) ranges from 0 to 25 percent directly-connected impervious.

Reducing the DCIA by 15% watershed-wide has the greater impact on total runoff volume during the larger 3.0-inch August 10 event than the smaller 1.2-inch August 24 event. During larger, more intense rainfall events, pervious areas are quickly saturated and initial abstractions (i.e., depression storage) is quickly filled by a small percentage of the total runoff volume produced. During smaller, less intense rainfall events, pervious areas take longer to saturate and depression storage abstracts a larger percentage of the total runoff produced. The amount of directly connected impervious area has less of an impact on total runoff volume for smaller events than for larger events. For this reason, the reduction in directly connected impervious area only slightly reduces the total runoff volume in the 1.2-inch event, and this reduction in volume can be compensated for by increasing subwatershed width.

42

36

£ ¤

Barr Footer: ArcGIS 10.4.1, 2017-09-14 15:54 File: I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Reports\Figure 36_2016 TBI Update Watershed Directly Connected Impervious.mxd User: mbm

51

61

Trout Brook Interceptor

Directly-Connected Impervious Percentage 0-15% 15-30% 30-45%

§ ¦ ¨ 35E

45-60% 5

60-100%

; !

N

0

§ ¦ ¨ 94

§ ¦ ¨ 94

1,000

2,000

3,000

Feet

£ ¤ 61

UNCALIBRATED DCIA PERCENTAGE 61 MODEL ATLAS 14 UPDATES XP-SWMM Trout Brook Stormsewer Interceptor Capitol Region Watershed District

£ ¤

FIGURE 36the GIS User Community Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and

36

£ ¤

Barr Footer: ArcGIS 10.4.1, 2017-09-14 15:55 File: I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Reports\Figure 37_2016 TBI Update Watershed Calibrated Directly Connected Impervious.mxd User: mbm

51

61

Trout Brook Interceptor

Directly-Connected Impervious Percentage 0-15% 15-30% 30-45%

§ ¦ ¨ 35E

45-60% 5

60-100%

; !

N

0

§ ¦ ¨ 94

§ ¦ ¨ 94

1,000

2,000

3,000

Feet

£ ¤ 61

CALIBRATED DCIA PERCENTAGE 61 MODEL ATLAS 14 UPDATES XP-SWMM Trout Brook Stormsewer Interceptor Capitol Region Watershed District

£ ¤

FIGURE 37the GIS User Community Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and

3.4.2.2

Width Parameter

Reducing the directly-connected impervious area not only decreases total volume, but also decreases peak flows. In order to raise peak flows to match monitoring data and to generate more volume for the smaller 1.2-inch event, the subwatershed width was increased by 50%. XP-SWMM generates runoff from each of the subwatersheds as the product of velocity (from Manning’s equation, based on the difference between total depth and depression storage and the average subwatershed slope), depth, and width (flow area). If overland flow is visualized as running down-slope off an idealized, rectangular subwatershed, then the width of the subwatershed is the physical width of overland flow. The lateral flow per unit width is computed and multiplied by the width to obtain the runoff rate. Therefore, watershed width is a critical XP-SWMM model input and a key calibration parameter. Typically, a good estimate for the width is the area of the subcatchment divided by the average path length of overland flow. However, this assumes runoff experiences overland and channelized flow as it moves through the subwatershed. In many cases, the most hydraulically remote point in a subwatershed will enter the stormsewer and quickly be routed to the TBI. Therefore, even though many of the urban TBI subwatersheds may be very large, the average length of overland flow may actually be much shorter than would be estimated through a GIS analysis.

Increasing the width parameter for means of calibration accounts for this and generates peak flows which more accurately match monitoring data.

3.4.3

Calibration Event Results

Calibration event model results are shown and discussed in the following subsections. As discussed in Section 3.4.2, the calibration results were generated by lowering the directly-connected impervious area by 15% and increasing subwatershed width by 50% in all subwatersheds. Although the impact of calibration varies based on the particular rainfall event and monitoring station, in general, the calibration update had the effect of lowering total generated runoff volume while minimizing decrease in modeled peak flow rates.

3.4.3.1

August 10, 2016 3.0-inch Rainfall Event

Figure 38 through Figure 43 compare the calibrated model results for the 3.0-inch rainfall event recorded on August 10, 2016 to observed flow data collected at each of the five (5) monitoring locations. Barr also compared the lake level model results to the monitoring data provided by CRWD at the outlet of the Arlington-Jackson Pond (South Bay). Figure 44 shows that the model closely matches the observed stage for the August 10 event at the Arlington-Jackson South Bay.

45

Figure 38

August 10, 2016: Calibrated hydrograph at the TBO monitoring station

Figure 39

August 10, 2016: Calibrated hydrograph at the TBEB monitoring station

46

Figure 40

August 10, 2016: Calibrated hydrograph at the TBWB monitoring station

Figure 41

August 10, 2016: Calibrated hydrograph at the West-TB Circle monitoring station

47

Figure 42

August 10, 2016: Calibrated hydrograph at the TBO-SP monitoring station

Figure 43

August 10, 2016: Calibrated TBO-Combined hydrograph

48

Figure 44

August 10, 2016: Calibrated stage hydrograph at Arlington-Jackson South Bay

Table 14 shows the difference in total volume, peak flows, peak timing, and NSE coefficient at each monitoring location for the August 10 event. Because the East Extension was under predicting total volume and peak flows in the uncalibrated model, the reduction in directly-connected impervious area reduced the total event volume at the East Extension even more. For this reason, the NSE coefficient decreases for the TBEB but is still approximately within the acceptable range of 0.6 or greater. At all other monitoring locations, the percent difference in total volume and the NSE coefficient are more favorable in the calibrated model.

49

Table 14

Calibrated model results verses monitored data for the August 10, 2016 event

Modeled

% Error

53 320

-12% 20%

101 441

74 484

-27% 10%

84 79

77 78

-8% -1%

0.74 0.70

121

157

30%

251

329

31%

79

75

-5%

0.14

423

515

22%

1034

1094

6%

79

74

-6%

0.81

Event NSE

Modeled

% Error

48 268

-19% 1%

101 441

70 449

-30% 2%

84 79

77 78

-8% -1%

0.59 0.80

121

124

3%

251

304

21%

79

75

-5%

0.41

423

442

4%

1034

1110

7%

79

74

-6%

0.89

3.4.3.2

% Error

Observed

59 266

Modeled

% Error

TBEB TBWB West-TB Circle TBOCombined

Observed

Monitoring Location

Modeled

Time to Peak Flow (min)

Observed

Calibrated Model Results (August 10, 2016 Event) Volume (ac-ft) Peak Discharge (cfs)

% Error

Observed

59 266

Modeled

% Error

TBEB TBWB West-TB Circle TBOCombined

Observed

Monitoring Location

Modeled

Time to Peak Flow (min)

Observed

Uncalibrated Model Results (August 10, 2016 Event) Volume (ac-ft) Peak Discharge (cfs)

Event NSE

August 24, 2016 1.2-inch Rainfall Event

Figure 45 through Figure 50 compare the calibrated model results for the 1.2-inch rainfall event recorded on August 24, 2016 to observed flow data collected at each of the five (5) monitoring locations in below.

The model was also compared to the monitoring data provided by CRWD at the outlet of the ArlingtonJackson Pond (South Bay). Figure 51 shows that the model closely matches the observed stage for the August 24 event at the Arlington-Jackson South Bay.

50

Figure 45

August 24, 2016: Calibrated hydrograph at the TBO monitoring station

Figure 46

August 24, 2016: Calibrated hydrograph at the TBEB monitoring station

51

Figure 47

August 24, 2016: Calibrated hydrograph at the TBWB monitoring station

Figure 48

August 24, 2016: Calibrated hydrograph at the West-TB Circle monitoring station

52

Figure 49

August 24, 2016: Calibrated hydrograph at the TBO-SP monitoring station

Figure 50

August 24, 2016: Calibrated Combined-TBO hydrograph

53

Figure 51

August 24, 2016: Calibrated stage hydrograph at Arlington-Jackson South Bay

Table 15 shows the difference in total volume, peak flows, peak timing, and NSE coefficient at each monitoring location for the August 24 event. Because the model was calibrated both for an event which over-predicts runoff volume and an event which under-predicts runoff volume, an iterative process to achieve the best results between the two events was required. In order to significantly reduce total runoff volume for the larger August 10 event, the August 24 event incurred a reduction in total runoff volume, as well. This explains why the percent difference in total runoff volume at each of the monitoring locations increases in the calibrated model. This also explains why the NSE coefficients are slightly smaller in the calibrated model than in the uncalibrated model. As shown in Figure 45 through Figure 50 above, however, these calibration updates produce very minor changes in the overall event hydrographs at the monitoring locations and NSE values are still within the acceptable range of 0.6 or greater.

54

Calibrated model results verses monitored data for the August 24, 2016 event

Modeled

% Error

Modeled

% Error

16 66

-18% -12%

58 224

43 191

-25% -15%

291 291

281 243

-3% -16%

0.86 0.85

34

30

-12%

94

139

48%

281

237

-16%

0.66

150

123

-18%

428

506

19%

281

279

-1%

0.91

3.4.3.3

Observed

Modeled

% Error

Modeled

% Error

Time to Peak Flow (min)

20 75

15 55

-27% -26%

58 224

41 191

-29% -15%

291 291

281 243

-3% -16%

0.76 0.75

34

23

-33%

94

138

47%

281

237

-16%

0.62

150

140

-7%

428

496

16%

281

279

-1%

0.87

Modeled

Observed

Event NSE

% Error

TBEB TBWB West-TB Circle TBOCombined

Observed

Observed

20 75

Calibrated Model Results (August 24, 2016 Event) Volume (ac-ft) Peak Discharge (cfs) Monitoring Location

Time to Peak Flow (min)

% Error

TBEB TBWB West-TB Circle TBOCombined

Modeled

Monitoring Location

Observed

Uncalibrated Model Results (August 24, 2016 Event) Volume (ac-ft) Peak Discharge (cfs)

Observed

Table 15

Event NSE

Validation Event Results

Upon completion of the calibration process, a third event on October 4, 2016 was used to validate the model changes. Calibrated model results for the 0.7-inch rainfall event are compared to the uncalibrated model and observed flow data in Figure 52 through Figure 57 below.

The model was also compared to the monitoring data provided by CRWD at the outlet of the ArlingtonJackson Pond (South Bay). Figure 58 shows that the model closely matches the observed stage for the October 4 event at the Arlington-Jackson South Bay.

55

Figure 52

October 4, 2016: Calibrated hydrograph at the TBO monitoring station

Figure 53

October 4, 2016: Calibrated hydrograph at the TBEB monitoring station

56

Figure 54

October 4, 2016: Calibrated hydrograph at the TBWB monitoring station

Figure 55

October 4, 2016: Calibrated hydrograph at the West-TB Circle monitoring station

57

Figure 56

October 4, 2016: Calibrated hydrograph at the TBO-SP monitoring station

Figure 57

October 4, 2016: Calibrated Combined-TBO hydrograph

58

Figure 58

October 4, 2016: Calibrated stage hydrograph at Arlington-Jackson South Bay

Table 16 shows the difference in total volume, peak flows, peak timing, and NSE coefficient at each monitoring location for the October 4 validation event. Results indicate that the calibration of the model generates total runoff volumes closer to the runoff volume at each monitoring site. The NSE coefficients slightly decrease or greatly improve with the calibration updates, and at the combined TBI outlet, the calibrated model peak is closer to the observed data. Although the NSE value at the TBEB and TBOcombined monitoring location are less than the desired 0.6 for a successful calibration, additional changes to imperviousness and watershed width would continue to decrease the NSE values at the TBWB and West-TB Circle. Therefore, the results shown below are considered optimized.

59

Table 16

Validation model results verses monitored data for the October 4, 2016 event

Uncalibrated Model Results (October 4, 2016 Event)

% Error

Modeled

Time to Peak Flow (min) Observed

% Error

Modeled

Observed

Peak Discharge (cfs)

% Error

Modeled

Monitoring Location

Observed

Volume (ac-ft)

Event NSE

TBEB

7

4

-39%

19

18

-7%

488

465

-5%

0.51

TBWB

49

33

-33%

85

89

5%

463

464

0%

0.86

West TBCircle

15

11

-26%

53

53

0%

463

450

-3%

0.79

TBOCombined

87

56

-36%

135

208

54%

458

464

1%

-0.08

Calibrated Model Results (October 4, 2016 Event)

% Error

Modeled

Time to Peak Flow (min) Observed

% Error

Modeled

Observed

Peak Discharge (cfs)

% Error

Modeled

Monitoring Location

Observed

Volume (ac-ft)

Event NSE

TBEB

7

5

-31%

19

19

-4%

488

465

-5%

0.40

TBWB

49

46

-6%

85

91

7%

463

465

0%

0.84

West TBCircle

15

12

-22%

53

52

-3%

463

450

-3%

0.77

TBOCombined

87

76

-12%

135

184

36%

458

464

1%

0.46

Based on the calibration and validation results for the three rainfall events, the calibration of the 2017 TBI XP-SWMM model was considered successful.

60

3.5

Calibrated Model Atlas 14 Inundation Results and Conclusion

3.5.1

Design Storm Results

Using the calibrated TBI model, Barr evaluated peak flow results through monitored portions of the TBI system (Table 17) and generated inundation mapping for the 2-, 10-, 100-, and 500-year Atlas 14 design storms. Table 18 shows peak flow results from the uncalibrated model for comparison purposes. Atlas 14 inundation mapping for the 2-, 10-, 100-, and 500-year 24-hour design events developed for the calibrated model are shown in Figure 59, Figure 60, Figure 61, and Figure 62, respectively. Appendix A contains a zoomed in mapbook of all inundated areas adjacent to the TBI for each design event from the calibrated model. The model also contains storage areas and flooding in watersheds upstream of the TBI, however, only flooding adjacent to the trunk of TBI is included. In general, peak flows and inundation depths and extents are smaller in the calibrated model than in the uncalibrated model.

Table 17

Monitoring Location

Atlas 14 Calibrated Model Design Storm Results

Atlas 14 Storm Event, Peak Flow (cfs)1 2-Year

TBEB

100-Year

500-Year

86

185

795

713

675

1,050

1,312

1,382

465

796

931

890

1,438

2,473

3,005

3,176

TBWB West-TB Circle TBOCombined

10-Year

1 Model

results are from Link 9524-Mnew for the TBWB monitoring station, Link 12570-W for the West-TB Circle monitoring station, Link 0062-E for the TBEB monitoring station, and the sum of the hydrographs at Link 1099-M and Link 15607 for the TBO-Combined monitoring station.

Table 18

Monitoring Location TBEB TBWB West-TB Circle TBOCombined

Atlas 14 Uncalibrated Model Design Storm Results

Atlas 14 Storm Event, Peak Flow (cfs)1 2-Year

10-Year

100-Year

500-Year

88

190

721

793

703

1,051

1,282

1,372

481

794

904

901

1,493

2,465

3,159

3,155

1 Model

results are from Link 9524-Mnew for the TBWB monitoring station, Link 12570-W for the West-TB Circle monitoring station, Link 0062-E for the TBEB monitoring station, and the sum of the hydrographs at Link 1099-M and Link 15607 for the TBO-Combined monitoring station.

61

Level of service is defined as the capacity provided by a drainage system to remove runoff and prevent significant interference with normal daily transportation, commerce, or access that might result from a rainstorm. For example, gutters might run full, but when the runoff arrives at a catch basin, it would enter the catch basin and be carried away by the storm sewer. Intersections would not flood, and public infrastructure would operate normally. The current standard of practice is that conveyance systems are designed for the “10-year” storm event, which means that there is roughly a 10% probability in any year that the system will be overtaxed and unable to meet these criteria. The City of Saint Paul generally designs their conveyance systems to accommodate at least the 5-year event and up to the 10-year event.

The Atlas 14 XP-SWMM modeling results indicate that no portions of the trunk TBI surcharge (i.e., experience surface flooding) during the 2-year event or the 10-year event. The lack of a surcharged condition indicates that the TBI system is currently providing a 10-year level of service for the area.

Level of protection is defined as the capacity provided by a municipal drainage system to prevent property damage and assure a reasonable degree of public safety following a precipitation event. For example, runoff might bypass a catch basin and collect in low-lying areas such as intersections, but would not cause flood damage to structures. Accumulated water might temporarily interfere with traffic or access, but public infrastructure should operate normally. The drainage system must have the capacity (in terms of pipe capacity and overland overflow capacity) to limit the flood elevation to acceptable levels for an event representing the protection criteria.

A 100-year frequency event is usually recommended as a standard for design of ponding basins, thus providing a 100-year ‘level of protection’ to adjacent property owners. Federal and state programs use criteria based on an event with 1% probability to define the floodplain along rivers and streams, and cities and other drainage authorities commonly extend this standard to other areas. The criterion for level of protection has broader application, as well. In addition to ponding areas, lakes, and streams, this criterion should be applied to all locations served by the drainage system where there are depressed intersections or other areas subject to temporary, unplanned flooding.

Because the Atlas 14 precipitation data for the TBI watershed is significantly higher than the previously modeled TP-40 data (up to 1.5 inches higher in the 24-hour, 100-year precipitation event), increased surcharging and inundation compared to the 2012 model report is expected. Under TP-40 conditions, no structures were impacted during the 100-year event (Barr, June 2012); however, using the Ramsey County impervious dataset published in 2016 to define structure boundaries (Section 2.2.1.3), under Atlas 14 conditions, approximately 194 structures are impacted by the 100-year event. Of these 194 structures, 70 are classified as ‘residential’. The remaining structures are a combination of the following: outbuilding, patio, parking ramp, skyway, canopy, garage, greenhouse, mobile home, non-residential, under construction, and other.

The areas that surcharge along the trunk TBI during the 100-year event are shown in Figure 63.

Surcharging occurs along the TBI Mainline from the intersection of Cottage Avenue West and Sylvan Street to the Trout Brook Circle. Along the West Extension, surcharging occurs from the intersection of Marion Street and Nebraska Avenue West to the Rice and Arlington Field parking lot east of Rice Street.

62

Along the East Extension, surcharging occurs at the intersection of Westminster Street and Hyacinth Avenue East and from the north-bound I-35E frontage road to the south-bound I-35E frontage road on the north side of Maryland Avenue East. Downstream of the confluence with the East Extension, surcharging occurs along the TBI Mainline north of the Sims Agate pond to the west of I-35E at approximate station 67+00 to a point just upstream of the TBI realignment (approximate station 59+70).

Lastly, surcharging occurs along the Mainline just north of Lafayette Road at approximate station 26+00 down to the end of the TBI (station 00+00).

The 500-year event was also evaluated in order to consider the effects of projected climate change; therefore, the Atlas 14 500-year event of 10.5 total inches of rainfall was modeled. Under these conditions, 382 structures are impacted by the 500-year event. Of these 382 structures, 134 are classified as ‘residential’. The remaining structures are a combination of the following: outbuilding, patio, parking ramp, skyway, canopy, garage, greenhouse, mobile home, non-residential, under construction, and other.

Surcharging during the 500-year event along the trunk TBI is also shown in Figure 63. In addition to the flooding locations described above for the 100-year event, surcharging occurs along the Mainline at two locations upstream of the confluence with the West Extension; at L’Orient Street near the I-35E-Cayuga Street Interchange Cottonwood and Cook filtration basins; and at two locations just upstream of Phalen Boulevard. Additional surcharging also occurs along the Mainline downstream of the Trout Brook Circle down to the confluence with the East Extension. Along the West Extension, additional surcharging occurs between Park Street and Sylvan Street. At these five locations, only three additional non-residential buildings are impacted due to surcharging of the trunk TBI during the 500-year event. No additional residential buildings are affected.

In 2015, Barr developed a 5-Year Maintenance, Repair, and Capital Improvement Plan (CIP) for the TBI (Barr Engineering, 2015). The purpose of this CIP was to recommend a repair schedule for the TBI, highlighting specific improvements necessary to improve and maintain the tunnel system. Since the development of this plan, CRWD has addressed one of the recommended actions to maintain and improve the TBI, performing in-pipe repairs from Mainline station 0+00 to station 28+49 in 2016 and 2017. The CIP also recommends a new Farrington inlet and ditch stabilization at the approximate Mainline station 168+00 and in-pipe repairs from Mainline station 135+06 to station 180+29.

These two CIP locations span the portion of the TBI Mainline just downstream of Willow Reserve. As shown on Figure A-11 and Figure A-12 in Appendix A, residential and commercial flooding is likely to occur along North Farrington Street just north of the railroad, at the intersection of North Albemarle Street and West Cottage Avenue, and at the confluence with the TBI West Extension during large storm events. The TBI is also surcharges at Mainline station 160+00 during the Atlas 14 500-year event. When performing these CIP repairs, we recommend CRWD assess the potential to address the flooding in these locations.

63

Little Canada 36

£ ¤

Barr Footer: ArcGIS 10.4.1, 2017-09-14 15:59 File: I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Reports\Figure 59_2 Year 2016 TBI Update Calibrated Inundation Map.mxd User: mbm

51

Falcon Heights

61

Maplewood

Roseville

Saint Paul

Trout Brook Interceptor Subwatersheds Municipal Boundary 2-Year Inundation Area

§ ¦ ¨ 35E

5

; !

N

0

§ ¦ ¨ 94

§ ¦ ¨ 94

1,000

2,000

3,000

Feet

£ ¤ 61

2-YEAR CALIBRATED INUNDATION MAP 61 MODEL ATLAS 14 UPDATES XP-SWMM Trout Brook Stormsewer Interceptor Capitol Region Watershed District

£ ¤

FIGURE 59the GIS User Community Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and

Little Canada 36

£ ¤

Barr Footer: ArcGIS 10.4.1, 2017-09-14 15:58 File: I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Reports\Figure 60_10 Year 2016 TBI Update Calibrated Inundation Map.mxd User: mbm

51

Falcon Heights

61

Maplewood

Roseville

Saint Paul

Trout Brook Interceptor Subwatersheds Municipal Boundary 10-Year Inundation Area

§ ¦ ¨ 35E

5

; !

N

0

§ ¦ ¨ 94

§ ¦ ¨ 94

1,000

2,000

3,000

Feet

£ ¤ 61

10-YEAR CALIBRATED INUNDATION MAP 61 MODEL ATLAS 14 UPDATES XP-SWMM Trout Brook Stormsewer Interceptor Capitol Region Watershed District

£ ¤

FIGURE 60the GIS User Community Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and

Little Canada 36

£ ¤

Barr Footer: ArcGIS 10.4.1, 2017-09-14 15:59 File: I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Reports\Figure 61_100 Year 2016 TBI Update Calibrated Inundation Map.mxd User: mbm

51

Falcon Heights

61

Maplewood

Roseville

Saint Paul

Trout Brook Interceptor Subwatersheds Municipal Boundary 100-Year Inundation Area

§ ¦ ¨ 35E

5

; !

N

0

§ ¦ ¨ 94

§ ¦ ¨ 94

1,000

2,000

3,000

Feet

£ ¤ 61

100-YEAR CALIBRATED INUNDATION MAP XP-SWMM61MODEL ATLAS 14 UPDATES Trout Brook Stormsewer Interceptor Capitol Region Watershed District

£ ¤

FIGURE 61the GIS User Community Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and

Little Canada 36

£ ¤

Barr Footer: ArcGIS 10.4.1, 2017-09-14 15:59 File: I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Reports\Figure 62_500 Year 2016 TBI Update Calibrated Inundation Map.mxd User: mbm

51

Falcon Heights

61

Maplewood

Roseville

Saint Paul

Trout Brook Interceptor Subwatersheds Municipal Boundary 500-Year Inundation Area

§ ¦ ¨ 35E

5

; !

N

0

§ ¦ ¨ 94

§ ¦ ¨ 94

1,000

2,000

3,000

Feet

£ ¤ 61

500-YEAR CALIBRATED INUNDATION MAP XP-SWMM61MODEL ATLAS 14 UPDATES Trout Brook Stormsewer Interceptor Capitol Region Watershed District

£ ¤

FIGURE 62the GIS User Community Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and

Little Canada 36

£ ¤

51

Barr Footer: I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Reports\Figure 63_500 and 100 Year 2016 TBI Update Calibrated Surcharging Nodes.mxd User: hnh

Falcon Heights

61

Maplewood

Roseville

Saint Paul

( ! ! ( ! ! ( ! ! ( ! ! ( ! ! ! ( ( ( ( ( ( ! ( ! ( ! ( ( ! ( ! ! ! ! ( ! ( ( (

! ( ! ( ! ( ! (! ( (! (! ! ! ( ( (! (!(!

( ! ! (

( ! ! ( ! ( ( ! ! (

! ( ! (

( !

100 Year Surcharging Nodes

! (

500 Year Surcharging Nodes Trout Brook Interceptor XP-SWMM Links

! ( ! ( ( ! ! ( ( ! (! ! ! ( ( ! (

Subwatersheds Municipal Boundary *DISCLAIMER: Only surcharging nodes along the Trunk TBI are shown in this figure. Additional nodes in the St. Paul stormsewer may also be surcharging during the events.

! (! (

§ ¦ ¨ 35E

5

( ! ( ! ! ( ( ! ! ( ( ! ! ( ( ! ! (

0

94

1,000

2,000

3,000

Feet

( ! ! (

§ ¦ ¨

; !

N

( ! ! ( ( !

§ ¦ ¨ 94

61 AND 500-YEAR TRUNK TBI 100SURCHARGING NODES XP-SWMM61MODEL ATLAS 14 UPDATES Trout Brook Stormsewer Interceptor Capitol Region Watershed District

£ ¤

£ ¤

FIGURE 63the GIS User Community Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and

3.5.2

Conclusion

The worst 100- and 500-year flooding (where the largest number of structures are impacted) caused by surcharging of the trunk TBI occurs along the West Extension from the intersection of Marion Street and Nebraska Avenue West to the Rice and Arlington Field parking lot east of Rice Street (see Figure A-3).

Flooding along the Mainline from the intersection of Cottage Avenue West and Sylvan Street to the Trout Brook Circle (see Figure A-12) potentially impacts several properties. The flooding along the East Extension, at the intersection of Westminster Street and Hyacinth Avenue East (see Figure A-14) also has the potential to impact multiple properties. In order to provide recommendations on flood mitigation strategies, Barr identified nine distinct flood areas caused by surcharging of the TBI and developed a scoring matrix using ten independent scoring criteria for the purpose of ranking the flood areas based on the number of impacted structures and roads. We recommend prioritizing the locations identified in Section 4.0 of this report when considering infrastructure improvements.

69

4.0 4.1

Flood Prioritization Analysis

Background

In 2017, Barr updated and re-calibrated the 2012 Trout Brook Interceptor (TBI) XP-SWMM model. The update included incorporation of TBI repairs and revisions after 2012, updated impervious assumptions based on Ramsey County’s 2016 impervious dataset, and additional monitoring data at the TBI-West Trout Brook Circle, Saint Paul Tunnel, and southern cell of Arlington-Jackson Pond. Using the calibrated model, Barr evaluated several 24-hour precipitation events using Atlas 14, up to the 500-year event (0.2% annual exceedance probability, or AEP). Because the Atlas 14 precipitation estimates for the TBI watershed are higher than the previously modeled TP-40 estimates, results indicate that more buildings and infrastructure may be at risk than previously identified in the 2012 report. As a result of the updated modeling efforts, Barr estimates that there are nine distinct flood areas adjacent to the TBI as shown in Figure 64. Flood areas were identified at locations where surface flooding impacted roads and surface structures. Within a flood area, Barr evaluated flooding elevations (i.e., the elevation of the flood water surface) to ensure that flood areas were distinct and were not in fact (a) comprised of multiple flood areas with different flooding elevations or (b) hydraulically connected to other nearby flood areas. Using a scoring methodology developed in conjunction with the Capitol Region Watershed District (CRWD), Barr developed a scoring matrix for the nine flood areas using ten independent scoring criteria. Using the scoring matrix, Barr identified a final score to rank the priority for each flood area.

70

FA04

FA05

Ramsey County

$

FA07 Trout Brook Interceptor (TBI) Municipal Boundary

FA06

Flood Prioritization Area Inundation Area

Barr Footer: ArcGIS 10.4, I:\Client\CapitolRegionWD\Projects\23620944 2016 XP-SWMM\Maps\Flood Prioritization Areas\Figure1_TBI_Flood_Prioritization_Areas.mxd User: HNH

FA03

2-Year

FA08

10-Year

100-Year

FA01

500-Year

FA02

S a i n t Pa u l

I 0

1,000

2,000

Feet

FA09 Imager y Source: Digit alGlo be 20 16

FLOOD PRIORITIZATION AREAS Trout Brook Stormsewer Interceptor Capitol Region Watershed District FIGURE 64

4.2

Scoring Criteria Selection

Barr and CRWD selected scoring criteria based on potentially impacted buildings and infrastructure within each of the flood areas during the following Atlas 14, 24-hour storm events: 2-year (2.81 inch rainfall depth), 10-year (4.20 inch rainfall depth), 100-year (7.40 inch rainfall depth), and 500-year (10.40 inch rainfall depth). Table 19 lists the criteria that were initially considered to determine the final score for each flood area. As indicated in the table, Barr narrowed this list to 10 independent scoring criteria applicable within the study areas.

Table 19

Scoring criteria for study area

Criterion

Score Applicability

Comment

Major Road

5

Applicable

Road Flooding > 2 ft

3

Applicable

A major road is defined as any county or state roads.

Major roads have a higher impact weight than municipal streets.

Any road that has over two feet of flooding.

Flood Duration

0-3

Applicable

Apartments

2

Applicable

Flood duration was weighted based on hours flooding.

If hours flooding is < 1 hr, score is 0.

If hours flooding is  1 hr and < 5 hrs, score is 1.

If hours flooding is  5 hrs and < 10 hrs, score is 2.

If hours flooding is  10 hrs, score is 3.

Apartments are impacted during an event.

Commercial Buildings Homeless Shelter

2

Applicable

Commercial buildings are impacted during an event.

2

Applicable

Homeless shelters are impacted during an event.

Overtopping Rail

2

Applicable

The railroad is overtopped during an event.

Smaller Residential Structures Garages

2

Applicable

Residential structures are impacted during an event.

1

Applicable

Garages are impacted during an event.

Park

0

Applicable

Daycare

NA

Not Applicable

Flooding impacts to parks are identified, but not considered for prioritization.

No daycares are impacted within study area.

Evacuation Route

NA

Not Applicable

No evacuation routes were identified within study area.

Hospital

NA

Not Applicable

No hospitals are impacted within study area.

Public Building

NA

Not Applicable

No public buildings are impacted within the study area.

Regional Flooding

NA

Not Applicable

School

NA

Not Applicable

All flooding within study areas are considered "regional flooding".

No schools are impacted within study area.

Senior Housing

NA

Not Applicable

No senior facilities are impacted within study area.

Water Facility

NA

Not Applicable

No water facilities are impacted within the study area.

72

4.2.1

Scoring Values

Based on coordination with and input from CRWD, Barr assigned “score” values to each of the criteria listed in Table 19. The magnitude of the score value is a representation of the severity of the impact, with a higher score representing more consequential flood impacts (e.g., major road flooded), and lower scores representing less consequential flood impacts (e.g., residential garage inundated). The scoring value applied to each of the ten criteria is discussed in greater detail, below: •

Apartments (score = 2) Barr applied a score of 2 to all habitable structures. Because flood impacts to habitable structures pose a public safety risk in addition to structural damage costs, impacts to habitable structures (e.g., apartments) were assigned a higher score value than non-habitable structures (e.g., garages).

•

Commercial Buildings (score = 2) Barr applied a score of 2 to all commercial structures because they are regularly occupied by people presenting a safety risk and have important economic and employment value.

•

Flood Duration (score = 0 to 3) Barr calculated flood duration by the number of hours the lowest structure or road within a flood area was impacted (e.g., inundated) during an event. The lowest impact elevation was determined using 2011 lidar data. Barr applied a range of score values based on the number of hours of flood duration. If the lowest structure or road was impacted for less than one hour, the score was 0; one to five hours, the score was 1; five to 10 hours, the score was 2; and more than 10 hours, the score was 3. This score was then added to the flood area score in addition to other individual scores.

•

Non-habitable Structures (score = 1) Barr assigned a score of 1 to flood impacts to non-habitable structures. These include garages, warehouses, and outbuildings. Because these facilities are non-habitable, they were assigned a lower relative consequence score than structures regularly occupied by people.

•

Homeless Shelter (score = 2) Barr applied a score of 2 to all habitable structures. Because flood impacts to habitable structures pose a public safety risk in addition to structural damage costs, impacts to habitable structures (e.g., apartments) were assigned a higher score value than non-habitable structures (e.g., garages).

•

Major Roads (score = 5) Flood impacts to major roads (e.g., highways) pose a significant public safety risk and can prevent access to emergency facilities and emergency vehicles. For this reason, Barr assigned major road the highest applied score value of 5.

73

•

Overtopping Rail (score = 2) Barr assigned a score of 2 to impacts to rail corridors. Flooding of rail can prevent delivery of freight and pose significant delays along connected rail infrastructure.

•

Park (score = 0) Because parks are prone to inundation and are often designed to inundate during large rainfall events, Barr did not assign a consequence score value to parks. Barr retained this criterion in the analysis so that impacts to parks could be tracked.

•

Road Flooding > 2 feet (score = 3) Road inundation of over two feet is considered impassable and can limit accessibility to impacted neighborhoods. Depth of flooding along road corridor was determined by comparing the maximum flood elevation to the LiDAR-derived minimum elevation along the road segment. Due to the public safety concerns associated with limited road accessibility during an emergency, Barr assigned a higher consequence score value of 3.

•

Smaller Residential Structures (score = 2) Barr applied a score of 2 to all habitable structures. Because flood impacts to habitable structures pose a public safety risk in addition to structural damage costs, impacts to habitable structures (e.g., apartments) were assigned a higher score value than non-habitable structures (e.g., garages). Residential homes are defined as single-family or duplex homes. Due to the large number of impacted residential structures, this criterion had the greatest overall weight in determining the priority of each of the nine flood prioritization areas.

4.3

Flood Prioritization Results

Based on the scoring criteria in Table 19 Scoring criteria for study area, Barr calculated the total score for each flood area specific to each storm event. For a given flood area and storm event, the total number of instances a criterion was impacted was multiplied by the respective criteria score. The total event score is the sum of each weighted criterion score. For example, within Flood Area 2, the following impacts occur during the 100-year storm event: •

13 smaller residential homes (score = 2 each);

•

22 non-habitable structures (score = 1 each);

•

1 apartment complex (score = 2 each);

•

1 major road flooding (West Maryland Avenue) (score = 5 each);

•

2 instances of road flooding > 2 feet (score = 3 each); and

•

a flood duration of 2 hours (score = 1)

Therefore, the total score for Flood Area 2 during the 100-year storm event is 62 (13 x 2 + 22 x 1 + 1 x 2 + 1 x 5 + 2 x 3 + 1 = 62).

Barr created Figure 65 which summarizes the impact score for each study area during each storm event.

The amount of overall “risk” (i.e., the combination of the consequence and likelihood of a flooding impact) 74

increases from the top-left to the bottom-right of the figure. For example, a points toward the top-left of the figure shows that a large rainfall event (low likelihood) causes relatively few flooding impacts (low consequence) resulting in low overall relative risk, while a point towards the bottom right shows that a small rainfall event (high likelihood) causes many flood impacts (high consequence) resulting in high overall relative risk.

A normalized impact score for each flood area during each storm event was used to generate the flood area curves shown in Figure 65. A single composite score was also determined for each flood area by calculating the probability-weighted impact score for each area (e.g. impact score multiplied by the event return interval). The composite score is used to compare the overall “risk” as determined by the evaluation of all modeled storm events from the 2-year (50% AEP) to the 500-year (0.2% AEP) events, and can be used to compare flood impact risk of each of the flood areas. The composite scores for each flood area are shown as single symbols on the right hand side matching the color and symbol of the flood area curve. The results for each flood area are summarized in Table 20, and described in further detail below.

Table 20

Flood area score and summary of impacts

Flood Area 2 Maryland Ave. W. & N. Norton St.

Composite Score 6.1

TBI Station 192+00M 1 Maryland Ave. W. & Grotto St. N.

5.5

TBI Station 225+00M 6 Arlington Ave. E. & railroad

4.1

TBI Station 130+00M 5 Nebraska Ave. W. & Albemarle St.

3.4

TBI Station 20+00W

Summary of Potential Impacts (2-year event up to 500-year event) • 22 smaller residential structures impacted • 2 apartment complex impacted • 2 commercial buildings impacted • 29 non-habitable structures impacted • West Maryland Avenue (major road) impacted • road flooding >2 feet (Mackubin Street and Norton Street)

• 9 smaller residential structures impacted • 15 non-habitable structures impacted

• 2 commercial buildings impacted • 24 non-habitable structures impacted • North Jackson Street (major road) impacted • road flooding >2 feet (Mayre Street, Jackson Street, West Cottage Avenue, Sylvan Street, East Arlington Avenue and Trout Brook Circle) • 11 smaller residential structures impacted • 1 apartment complex impacted • 1 commercial buildings impacted • 7 non-habitable structures impacted • North Rice Street (major road) impacted • road flooding >2 feet (Albemarle Street)

75

Flood Area 8 Hyacinth Ave. E. & Westminster St., I-35E

Composite Score 3.3

TBI Station 00+00M 4 W. Wheelock Pkwy. & Marion St. TBI Station 40+00W 7 Arlington Ave. E. & Westminster St. TBI Station 40+00E 3 Orange Ave. W. & Farrington St. TBI Station 165+00M 9 Lafayette Rd. & N. John St. TBI Station 20+00M

Summary of Potential Impacts (2-year event up to 500-year event) • 19 smaller residential structures impacted • 1 apartment complex impacted • 2 commercial buildings impacted • 17 non-habitable structures impacted • I-35E (major road) impacted • road flooding >2 feet (L’Orient St., I-35E and on and off ramps, Mississippi St., Westminster St., E. Hyacinth Ave., Westminster Pl.) • rail overtopped

1.5 • 3 smaller residential structures impacted • 1 apartment complex impacted • 4 non-habitable structures impacted 0.8

0.4

0.2

• 2 smaller residential structures impacted • 3 apartment complexes impacted • 15 non-habitable structures impacted • road flooding >2 feet (East Arlington Avenue, Akwright Street) • 3 smaller residential structures impacted • 4 non-habitable structures impacted • road flooding >2 feet (West Orange Avenue) Within planned CIP Area No. 4: In-Pipe Repairs Mainline Station 135+06 to 180+29 • 1 homeless shelter impacted • road flooding >2 feet (Union Gospel Mission driveway and parking lot) Within planned CIP Area No. 1: In-Pipe Repairs Mainline Station 0+00 to 28+49

76

Figure 65 Trout Brook Interceptor flood prioritization metric

Low Risk

Composite Impact Score

High Risk 0.0

0.0

500‐Year

7

FA01 FA02 0.5

FA03

6 0.5

FA04

100‐Year

5

FA05 1.0

FA06

1.0

FA07

4

FA08 FA09

1.5

1.5

3

10‐Year 2.0

2 2.0

2.5

1

2.5

0 2‐Year

4.3.1

Flood Area 1: West Maryland Avenue and North Grotto Street Flood Area 1 is located south of West Maryland Avenue and north of West Rose Avenue between East Como Boulevard and North Grotto Street. Flooding occurs north of the Como Park Senior High parking lot and impacts many residential homes along West Maryland Avenue during large storm events. Flood Area 1 has a composite score of 5.5, which is the second highest score compared to the other 8 flood areas. The overall score is relatively large because 1 smaller residential structure and 5 non-habitable structures are potentially impacted during the 2-year event.

Figure 66

4.3.2

Flood Area 1: West Maryland Avenue and North Grotto Street

Flood Area 2: West Maryland Avenue and Norton Street Flood Area 2 is located at and south of West Maryland Avenue, along North Norton Street and North Mackubin Street. Flooding occurs primarily on Mackubin and North Norton Street, as well as, West Maryland Avenue (major road) during the 100- and 500-year events. Flood Area 2 has a composite score of 6.1, which is the highest score compared to the other 8 flood areas. This is primarily because it impacts many smaller residential homes, non-habitable structures, and West Maryland Avenue during large storm events.

78

Figure 67

4.3.3

Flood Area 2: West Maryland Avenue and Norton Street

Flood Area 3: West Orange Avenue and Farrington Street Flood Area 3 is located east of Willow Reserve and west of North Farrington Street. During the 100-year event, 1 smaller residential structure is potentially impacted. During the 500-year event, 3 smaller residential structures are potentially impacted, and West Orange Avenue has more than 2 feet of flooding. Flood Area 3 has a composite score of 0.4 and is located within the planned TBI Capital Improvement Plan (CIP) Area No. 4: In-Pipe Repairs Mainline Station 135+06 to 180+29.

Figure 68

Flood Area 3: West Orange Avenue and Farrington Street

79

4.3.4

Flood Area 4: West Wheelock Parkway and Marion Street Flood Area 4 is located at the intersection of West Wheelock Parkway and North Marion Street.

During the 100-year event, 2 smaller residential structures are potentially impacted. During the 500-year event, 3 smaller residential structures, 5 non-habitable structures, and 1 apartment complex are potentially impacted. Flood Area 4 has a composite score of 1.5.

Figure 69

4.3.5

Flood Area 4: West Wheelock Parkway and Marion Street

Flood Area 5: West Nebraska Avenue and Albemarle Street Flood Area 5 is located along West Nebraska Street, south of West Hoyt Street and west of North Rice Street. An apartment complex is potentially impacted during the 10-year event, along with two smaller residential structures. During the 100-year event, North Rice Street (major road) is inundated. Flood Area 5 has a composite score of 3.4.

80

Figure 70

4.3.6

Flood Area 5: West Nebraska Avenue and Albemarle Street

Flood Area 6: East Arlington Avenue and railroad Flood Area 6 is an industrial area located along and south of East Arlington Avenue, north of the railroad, and west of North Jackson Street. All of the potentially impacted buildings in Flood Area 6 are non-habitable storage units, with the exception of two commercial buildings. Trout Brook Circle and West Arlington Avenue (minor roads) have more than 2 feet of flooding beginning in the 10-year event. Flood Area 6 has a composite score of 4.1.

Figure 71

4.3.7

Flood Area 6: East Arlington Avenue and railroad

Flood Area 7: East Arlington Avenue and Westminster Street Flood Area 7 is a residential area located along and north of East Arlington Avenue, between North Westminster Street and North Arkwright Street. The green space to the west of Arlington Field is impacted during all events down to the 2-year storm. The apartment complex to the north

81

of East Arlington Avenue becomes potentially impacted during the 100-year event. In addition, East Arlington Avenue has more than 2 feet of flooding during the 100-year event. While the number of potentially impacted structures is relatively high in this area, the probability of impacts is very low, with many impacts only occurring during the 500-year event. Therefore, the overall score is only 0.8.

Figure 72

4.3.8

Flood Area 7: East Arlington Avenue and Westminster Street

Flood Area 8: East Hyacinth Avenue and Westminster Street, I-35E Flood Area 8 is located along I-35E, north of West Maryland Avenue. Flooding also occurs along East Hyacinth Avenue, I-35E, North Westminster Street, Westminster Place, East Hyacinth Avenue, and Mississippi Street. 17 smaller residential structures are potentially impacted during the 100year event. During the 500-year event, both the railroad and I-35E are inundated. Flood Area 8 has a composite score of 3.3.

82

Figure 73

4.3.9

Flood Area 8: East Hyacinth Avenue and Westminster Street, I-35E

Flood Area 9: Lafayette Road and North John Street Flood Area 9 is primarily comprised of the Union Gospel Mission located north of North Lafayette and east of North John Street. This is the only potentially impacted structure, and is only potentially impacted during the 500-year event. In addition, the parking lot and driveway leading up to the building are inundated by more than 2 feet of flooding starting in the 100-year event.

Flood Area 9 has a composite score of 0.2 and is located within planned CIP Area No. 1: In-Pipe Repairs Mainline Station 0+00 to 28+49.

Figure 74

Flood Area 9: Lafayette Road and North John Street

83

4.4

Conclusions and Recommendations

Figure 65 shows that Flood Area 2 and Flood Area 1 have the highest composite impact scores of the nine flood areas evaluated. The result that Flood Area 1 has the second highest composite risk score might initially be surprising, as four other flood areas have higher event-based risk scores during the 100- and 500-year events. In particular, Flood area 8 has scores nearly as high as Flood Area 2 for the 100- and 500-year events, yet only has the fifth highest composite score. What explains the high composite score of Flood Area 1 and the lower composite score for Flood Area 8 is that, as explained in Section 3.0, the composite score is a probability-weighted score which considers the probability (or likelihood) that a given rainfall event and resulting flood impact will occur. Flood Area 1 has a higher impact score during the 2-year event (50% AEP) than any other flood area and the 2nd highest score during the 10-year event (10% AEP), while Flood Area 8 has relatively low impact scores during these more-frequent return interval events. Flood Area 8 and Flood Area 2 are distinguished by having higher impact scores during the 100and 500-year events, but because these events have a low likelihood of occurring in a given year (1% and 0.2% AEP, respectively), the higher scores during these events have lower overall weight on composite impact score than impact scores recorded during the 2- and 10-year events.

Flood Areas 1 and 2 are located along the upstream end of the TBI – Mainline. Flood Area 1 is just downstream of the Como Lake inlet, near Station 225+00. Flood Area 2 is located on the east side of Willow Reserve at the intersection of North Norton Street and West Maryland Avenue near Station 192+00. The following is a summary of notable potential impacts within the TBI flood areas: •

Impacted Structures (habitable and non-habitable)

Flood Area 2 has the greatest number of potentially impacted structures during the 100- and 500-year events (55 structures) compared to the other flood areas. Flood Area 8 has the second-largest number of potentially impacted structures during the 100- and 500-year events but does not have any potentially impacted structures during the more frequent 2- and 10-year events.

•

Road Flooding

Seven of the nine flood areas result in road flooding by more than 2 feet during the 100-year and 500year storms. Only Flood Area 6 has more than 2 feet of road flooding during the 10-year storm. Flood Areas 6 and 8 result in the greatest number of inundated roads during the 500-year event (6 and 8 roads with more than 2 feet of flooding, respectively).

Four of the nine flood areas result in flooding on major roads (defined as county or state roads) during the 500-year event. The four affected roads are: West Maryland Avenue, North Jackson Street, I-35E, and West Orange Avenue.

•

Rail Overtopping

Flood Area 8 is the only location where overtopping of the railroad occurs. Rail overtopping occurs only during the 500-year event.

84

â&#x20AC;˘

Flood Duration

Flood Area 1 has the largest flood duration of approximately 15 hours during the 500-year event, indicating that a structure or road is potentially impacted for 15 hours. The second longest flooding duration of 9 hours occurs during the 500-year event in Flood Area 8. Flood Areas 2, 4, and 9 have relatively much shorter flood durations of only 1-2 hours during the 500-year event.

Barr recommends that CRWD use the overall composite impact score (see Figure 65) to help prioritize flood mitigation alternatives and studies within each of the nine flood areas. In addition to composite impact scores, there are other drivers (opportunities) which may impact prioritization of flood mitigation alternatives in each areas (e.g., upcoming road reconstruction projects and CIP projects). For example, based on review of the CRWDâ&#x20AC;&#x2122;s 5-year maintenance and CIP plan, there are scheduled in-pipe repairs and inlet and ditch stabilization projects planned for 2020-2021 in the vicinity of Flood Area 2 and Flood Area 3 (near the Farrington neighborhood, station 180+00 to 130+50). In consideration of these upcoming CIP projects, there may be value in assigning higher priority to evaluation of flood mitigation alternatives in these flood areas to ensure that an opportunity to address flood impacts in these areas during upcoming CIP projects is not missed.

Determination of optimal flood mitigation strategies for each flood area will vary and will be based on the unique conditions and circumstances within the flood area (e.g., available space, opportunities to improve storm sewer infrastructure, etc.). Using the composite impact score prioritization information presented in this memorandum, Barr recommends that CRWD evaluate and select flood areas for individual flood mitigation studies. The goal of the flood mitigation studies should be to (a) determine the hydrologic and hydraulic causes of flooding, (b) identify alternatives to mitigate surface flooding, and (c) compare identified alternatives and benefit/cost ratios to determine the optimal flood mitigation strategy for the flood area. Flood mitigation can take many forms, but some common strategies for flood mitigation include: o o o o

Flood detention through surface and underground storage projects; Storm sewer infrastructure improvement to increase outflow rate from flood areas; Strategic protection through land forming; and Land and property acquisition.

85

5.0

Recommendations

These revisions and re-calibration efforts allow this model to be used to simulate and assess impacts of future development and infrastructure improvements. Based on the results of the model described in this report, Barr provides the following recommendations: 1.

Update the TBI XP-SWMM model with system modifications as needed

2.

Update watershed storage and slopes when more recent lidar data is released

3.

Work with the City of Saint Paul to incorporate any detailed subwatershed modeling they have or are planning to perform

4.

Using the composite impact score prioritization information presented in Section 4.0, evaluate and select from the nine flood areas for individual flood mitigation studies.

5.

Add additional detail to the XP-SWMM model at locations with high composite impact scores presented in Section 4.0 and at locations identified for future flood mitigation studies

6.

When performing CIP repairs on TBI at Mainline station 135+06 to station 180+29 and Mainline station 0+00 to 28+49, assess the potential to incorporate measures to reduce flooding and surcharging at the respective flood areas 3 and 9 shown on Figure 64

7.

Continue the current monitoring program for the TBI, Saint Paul Tunnel outlet, and tributary stormwater ponds as it provides valuable calibration and validation data at numerous points throughout the TBI system. It is particularly useful to continue to monitor the Saint Paul Tunnel outlet in order to determine the combined flow at the TBI outlet.

86

References Barr Engineering. 2012. Hydrologic and Hydraulic Modeling of the Trout Brook Storm Sewer Interceptor and Detailed Assessment of North TBI Study Area.

Barr Engineering. 2015. 5-Year Maintenance, Repair, and Capital Improvement Plan for the Trout Brook Storm Sewer Interceptor.

Nash, J.E., and J. V. Sutcliffe. 1970. River Flow Forecasting through Conceptual Models Part I â&#x20AC;&#x201C; A Discussion of Principles. Journal of Hydrology. 10(3). 282-290.

87

December 5, 2018 Board Meeting V. Action Item A) Approve Minutes of November 20, 2018 DRAFT Regular Board Meeting (Sylvander)

Regular Meeting of the Capitol Region Watershed District (CRWD) Board of Managers, for Wednesday, November 20, 2018, 6:00 p.m. at the office of CRWD, 1410 Energy Park Drive, Suite 4, St. Paul, Minnesota.

REGULAR MEETING MINUTES I.

A)

Call to Order of Regular Meeting (President Joe Collins)

Managers Joe Collins, absent w/notice Seitu Jones, absent w/notice Shirley Reider Rick Sanders Mary Texer

B)

Staff Present Mark Doneux, CRWD Elizabeth Hosch, CRWD Michelle Sylvander, CRWD

Public Attendees

Review, Amendments and Approval of the Agenda.

Vice President Texer asked for any additions or changes to the agenda. No changes were requested to the agenda.

Motion 18-213: Approve the Agenda of November 20, 2018.

Reider/Sanders Unanimously Approved II.

Public Comment â&#x20AC;&#x201C; For Items not on the Agenda

No Comments.

III.

Permit Applications and Program Updates A)

Permit #14-026 Pleasant Ridge - Closure (Hosch)

Ms. Hosch reviewed permit #14-026 Pleasant Ridge. This permit was issued for the development of 8 new singlefamily residential lots at Ramsey and 35E in St. Paul. Stormwater requirements were met with one underground filtration system under the front yards. The site is stable, and the stormwater treatment practice has been confirmed functional. $3,600 surety is available for return.

Motion 18-214: Approve Certificate of Completion for permit #14-026 Pleasant Ridge â&#x20AC;&#x201C; Closure and approve $3,600 surety return.

Our Mission is to protect, manage and improve the water resources of Capitol Region Watershed District

Reider/Sanders Unanimously Approved B)

Permit #14-034 East 7th Street Apartments/The Cambric â&#x20AC;&#x201C; Closure (Hosch)

Ms. Hosch reviewed permit #14-034. This permit was issued for construction of a new multi-use residential building at East 7th and Bates in St. Paul. Stormwater requirements were met with one raingarden and one underground filtration system. The underground filtration system outlet was not initially constructed to plan which resulted in the system not drawing down in the required 48 hours. Recent repairs have corrected this, and the system is now functional as expected. The site is stable and all temporary BMPs have been removed. $6,650 surety is available to return.

Motion 18-215: Approve Certificate of Completion for permit #14-034 East 7th Street Apartments/The Cambric and approve $6,650 surety return.

Reider/Sanders Unanimously Approved IV.

Special Reports.

No Special Report.

V.

Action Items A)

AR:

Approve Minutes of the November 7, 2018 Workshop (Sylvander).

Motion 18-216: Approve Minutes of the November 7, 2018 Workshop Meeting.

Reider/Sanders Unanimously approved B)

AR:

Approve Minutes of the November 7, 2018 Regular Meeting (Sylvander).

Motion 18-217: Approve Minutes of the November 7, 2018 Regular Meeting.

Reider/Sanders Unanimously approved C)

AR:

Approve Accounts Payable/Receivables for October (Sylvander)

Motion 18-218: Approve October 2018 Accounts Payable/Receivable and Budget Report, direct Treasurer and Board President to endorse and disperse checks for these payments.

Reider/Sanders Unanimously approved VI.

Unfinished Business A) Building Update (Doneux) Our Mission is to protect, manage and improve the water resources of Capitol Region Watershed District

Administrator Doneux reviewed the progress at the new office building. The project is on schedule.

Temporary permit of occupancy will be issued on Monday, November 26th. The server is being shut down and moved on Thursday, November 29th. Staff will be leaving for MAWD on Thursday afternoon. Staff will begin working at the new building on Monday, December 3rd. The cistern was delivered on Saturday, November 17.

Administrator Doneux shared some photos of the cistern delivery.

VII. A)

General Information

Board of Managers Updates

Manager Reider shared a flyer on Human Rights Day in Falcon Heights. The event will be held at Falcon Heights Church on Monday, December 10th at 6:30 p.m. The theme of the event is discrimination in housing.

Manager Texer shared that she has forwarded, to Managers, an email from Emily Javens regarding the resolutions for MAWD. VIII.

Next Meetings

A) B)

Wednesday, December 5, 2018 Regular Board Meeting, workshop at 5:00.

Wednesday, December 12, 2018, CAC Meeting, Manager Texer will attend.

IX.

Adjournment

Motion 18-219: Adjournment of the November 20, 2018 Regular Board Meeting at 6:25 p.m.

Reider/Sanders Unanimously Approved Respectfully submitted, Michelle Sylvander

Our Mission is to protect, manage and improve the water resources of Capitol Region Watershed District

December 5, 2018 Board Meeting V. Action Items B) Approve 2019 Partner Grants (Schwantes)

DATE: TO: FROM: RE:

November 28, 2018 CRWD Board of Managers Lindsay Schwantes Approve 2019 Partner Grants

Background Following the 2018 Partner Grant review process, the Committee provided feedback on ways to improve the application and review process for the 2019 Partner Grant Program. Staff took this feedback and made some program changes for this grant cycle.

At the 2017 Annual Meeting, Managers Jones and Reider were appointed to the Partner Grant Review Committee and President Collins was appointed as an alternate. In September, the CAC identified members Arbeit and MacDonald to serve on the Review Committee.

Update The Board approved distribution of the 2019 Partner Grant Request for Proposals at the August 15, 2018 meeting. A workshop was held on September 11 for prospective grantees to discuss the application and contracting process and present program priorities with the goal of receiving stronger proposals. Fifteen attendees from 13 organizations attended.

CRWD received 20 Partner Grant applications totaling $270,438. The 2019 Partner Grants budget is $100,000. The Partner Grant Review Committee reviewed applications and ranked them as strong, medium or weak in an effort to streamline the review process for Committee members. Staff compiled Committee feedback and presented draft funding recommendations for review at the November 26 Partner Grant Review Committee meeting.

The Partner Grant Committee, comprised of President Collins and Manager Reider and CAC members MacDonald and Arbeit, reviewed the 2019 Partner Grant applications. The Committee developed recommendations totaling $102,040 for 13 proposals. The enclosed table includes the award recommendations. Proposal submissions are available upon request. The Committee also discussed how to support long-term grantees as well as new ideas and streamlining the proposal pool by identifying a priority project or audience each year. Staff will follow up with the Committee on these ideas and return to the Board for a future discussion.

Request Action Approve 2019 Partner Grant funding and authorize the Administrator to enter into grant agreements with the applicants. enc:

2019 CRWD Partner Grant Committee Funding Recommendations

W:\07 Programs\Stewardship Grant Program\Partner Grants\2019 Grants\Board Memo_Approve 2019 Partner Grants.docx

2019 Partner Grant Funding Recommendation overall ranking

Organization

Project name

Proposal tasks and associated budget requested.1

Task budget Total request (committee (committee recommendation) recommendation)

Strong

District 6 Planning Council ‐ North End

Meet Willow Reserve

Task 1. Interpretive signage Task 2. New arrival tour and seminar

$2,025.00 ($0) $1,000.00

Task 3. Tour and education seminar

$1,000.00

Task 4. 2 Clean‐ups

$975.00

Task 1. Trash and recycling containers

$12,128.00 ($0) $2,420.00

Strong

District 10 Planning Council ‐ Como Community Council

Como Lake Cleanup

Task 2. Lake cleanup Task 3. Boulevard signs Task 4. Lawn signs for Como Curb Cleanup

Strong

Strong

Friends of the Mississippi River

Frogtown Green

Youth Environmental Stewards Program and Trout Brook Initiative (350, 8‐18 YO)

Splashdown! Water Stewardship in Frogtown

Task 1. Recruit & cultivate schools/groups to participate

$2,725.00 ($0) $1,200.00 ($0) $1,270.00

Task 2. Plan & coordinate education and stewardship activities

$2,230.00

Task 3. Lead stewardship activities with youth

$4,240.00

Task 4. Conduct follow‐up and program evaluation Task 5. Project management and reporting

$720.00 $610.00

Task 1. Mobile watershed education

$3,300.00

Task 2. Festival participation

$2,200.00

Task 3. Media messaging (Reduce to $1,000)

$2,950.00 ($1,000) $1,550.00

Task 4. Climate change center exhibit planning

$5,000 ($2,975)

$18,473 ($2,420)

$9,070 ($9,070)

$10,000 ($8,050)

1

Strong

Great River Greening

Field Learning for Teens in CRWD (150 Youth)

Task 1. Youth engagement (reduce to $12,000)

Task 2. Program evaluation

$15,000.00 ($12,000)

$15,000 ($12,000)

Strong

Lawn Chair Gardener

Water Heroes

Task 1. Work with rec. centers to design / refine camps

$240.00

$20,000 ($10,360)

Task 2. Work with rec. centers to submit camps to $180.00 be publicized in programming brochure

Strong

Strong

Strong

Parkview Center School

Saint Paul Parks and Recreation

Parkview Water Project

Parks Ambassadors (100 people)

Urban Roots (100 middle Youth Conservation – high – school youth) Internships

Task 3. Hold (2) four 5‐day camps at rec. centers (education) 8am ‐ 12pm

$9,680.00 ($4,840)

Task 4. Coordinate and hold (2) four 5‐day camps at rec. centers (action / field trips)

$9,600.00 ($4,800)

Task 5. Meet with recreation center directors to evaluate program

$300.00

Task 1. K‐2 Pond/wetland study

$1,425.00

Task 2. 3rd grade field experience

$425.00

Task 3. 4th grade field experience

$1,500.00

Task 4. 5th grade field experience

$1,500.00

Task 5. Teacher planning, training and curriculum writing

$1,000.00

Task 1. Parks Ambassadors (Reduce to $5,000)

$8,000 ($5,000)

Task 2. Program evaluation

$8,000.00 ($5,000)

Task 1. Wetland edge restoration

$10,000.00

Task 2. Service learning hands‐on restoration

$1,500.00

$15,000 ($15,000)

Task 3. Adopt a Drain awareness building

$1,000.00

Task 4. Youth intern alum staffing

$2,500.00

$5,850 ($5,850)

2

Medium

District 11 Planning Council ‐ Hamline Midway Coalition

Building Community Through Clean Water Education

Medium

Frogtown Farm

Cultivating Water Ambassadors at Frogtown Farm

Medium

In Progress (10 youth, 4 poster exhibits, 2 public events)

Our Sacred Water

Medium

Public Art Saint Paul

Task 1. Tool Purchase for Adopt a Drain

$560.00 ($200) Task 2. Community engagement event for Adopt a $925.00 Drain Task 3. Community engagement events for Pierce $3,515.00 Butler Meadows (Recommend reducing to ($2,000) $2,110)

Task 1. Bioswale management $6,000.00 ($4,000) Task 2. Rain garden maintenance $6,000.00 ($0) Task 3. Berm and swale system education at $3,000.00 Market Saturdays

$5,000 ($3,125)

Task 1. Recruitment / partner engagement

$20,000 ($13,190)

Task 5. Reflection and future goal setting

$2,200.00 ($1,190) $6,500.00 ($4,500) $6,500.00 ($4,500) $3,800.00 ($2,000) $1,000.00

Task 1. eARTh lab workshop planning

Task 2. eARTh lab workshop production (Recommend funding $8,000) Task 3. Raised garden beds

$10,000.00 ($8,000)

$10,000 ($8,000)

Task 4. Evaluation

Task 2. Youth training (recommend reducing to $4,500) Task 3. Digital message creation (Recommend reducing to $4,500) Task 4. Public messaging and advocacy

eARTh Lab Summer Youth Workshops

TOTAL

$15,000 ($7,000)

$102,040

3

December 5, 2018 Board Meeting V. Action Items â&#x20AC;&#x201C; C. Appoint Cheryl Braun to the Citizen Advisory Committee

DATE: TO: FROM: RE:

November 29, 2018 CRWD Board of Managers Mark Doneux Appointment of Cheryl Braun to the Citizen Advisory Committee

Background On November 28, 2018 CRWD received an application from Cheryl Braun with a request to become a member of the Citizen Advisory Committee.

Issues Ms. Braun is a new resident to St Paul, although she was born here. In her first year and a half in the West 7th neighborhood, she grew to love this city. She has attended Fort Road Federation meetings and she follows the neighborhood community groups on Facebook. In her former position, she conducted focus groups on Employee Engagement. She also developed and implemented a Continuous Process Improvement Program, training 250 employees. She was an active member of The Minnesota Speech and Hearing Association during her professional career. She is concerned about water quality and availability and would like to contribute in any way that she can towards this cause at a local level.

Requested Action Appoint Cheryl Braun to the Citizens Advisory Committee.

enc.: Citizen Advisory Committee Membership Application form for Ms. Cheryl Braun

W:\05 Citizen Advisory Committee\Application Materials\Board Memo Appointed\Bd Memo appointment of CArol Zierman to the CAC 9-1918.docx

CRWD Citizen Advisory Committee Membership Application Form Submission Timestamp:

2018-11-27 15:55:24

Headshot Image URL Name: Mailing Address: Phone (home): Phone(Work): Email: Occupation:

Cheryl Braun 1144 Pleasant Ave Saint Paul, Minnesota 55102 (612) 554-9430 (612) 554-9430 ctbraun55@gmail.com Speech Language Pathologist

Availability:

Would you be able to attend regular meetings and take an active role working with the Capitol Region Watershed District Board of Managers? Meetings are at 7pm on the second Wednesday of each month.

I would be able to attend meeting regularly. I work part time and my schedule is very ďŹ&#x201A;exible.

I would look forward to participating in projects!

Experience/Background:

Describe experiences advising government bodies or participating in community groups, neighborhood associations, nonproďŹ t organizations, cooperative societies, clubs, or any other group.

I am a relatively new resident to St Paul, although I was born here. In my

Citizen Advisory Committee Membership Application Form

1

ďŹ rst year and a half in the West 7th neighborhood, I have grown to love this city. I have attended Fort Road Federation meetings and follow the neighborhood community groups on Facebook.

In my former position, I conducted focus groups on Employee Engagement. I also developed and implemented a Continuous Process Improvement Program, training 250 employees. I was an active member of The Minnesota Speech and Hearing Association during my professional career.

Motivation:

I am concerned about water quality and availability and would like to contribute in any way that I can towards this cause at a local level.

Citizen Advisory Committee Membership Application Form

2

December 5, 2018 Board Meeting VI. Unfinished Business E). H2O to Go – Innovative, Participatory Display Update (Frisvold) DATE: TO: FROM: RE:

December 5, 2018 CRWD Board of Managers Megan Frisvold H2O to Go – Innovative, Participatory Display Update

Background This fall, the Communication and Engagement Division identified the need for a new education display to be showcased at community events, and in CRWD’s office. With help from our Watershed Artist in Residence, Christine Baeumler, the team came up with a competition-based process for developing an education display in partnership with local artists. The purpose of this display will be to better engage a wide range of community members at events, including engaging more diverse audiences through more accessible and visually-appealing material, relating to the Diversity Strategic Plan (with potential for translation where necessary).

Updates The Communication and Engagement Division, along with Christine Baeumler, completed a draft “Call to Artists” early last week, and Christine shared it with several university colleagues, who will provide feedback on the initial draft call and consider incorporating it into their spring semester classes. A broader call will be shared with the general public on January 7, 2019 and a kick off workshop will be tentatively held on February 5, 2019 in order to provide more background information and answer questions. Final proposals will be due March 25, 2019 and a selection committee (TBD) will choose 2-3 finalists to move on with developing prototypes. $250 will be provided to each of the three finalists to facilitate this process. Prototypes will be showcased at the 595 Aldine Grand Opening in June 2019, and a winner will be selected via public input and committee vote. In July 2019, the winner will be announced and awarded $5,000 to complete final fabrication of the display by August 30, 2019.

Requested Action Information only.

"W:\07 Programs\Edu-Outreach\Communication\Display\2018 CRWD Display Competition\Board Memo_H2O to Go Display.docx"