U R B A N2 STREETWATER
An application of urban stormwater management in landscape architecture
1)
CONTENT INTRODUCTION Project Background Existing Conditions Application
1 3 13
2)
ECOLOGIES
3)
CONCLUSIONS
Stabilization Treatment Containment
Lessons Learned
17 23 31
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1) McPHERSON PARK
greenville, sc
One of the fastest growing cities in the US, Greenville, SC is constantly changing and evolving in response to its growing population. However amidst this development, the city has lost sight of one of its best and oldest amenities, McPherson Park, Located just north of the bustling town center, McPherson Park is currently used as a dumping ground for grant projects and under-utilized public activities. With its haphazard organization and worn down facilities, the park is far from reaching its potential. With a tributary of Richland Creek day-lighting for the first time within the park and the park’s importance in the city’s historic fabric, there is an opportunity to give McPherson Park relevance in both a historical and ecological context. Through a series of purposeful interventions, the project aimed to give McPherson Park modern purpose through a seamless combination of innovative stormwater infrastructure and historically inspired programmatic spaces. The study that follows will focus primarily on the ecological aspects of the project. 1
UR
CH CH ST
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HIG HW AY 1
INTER STATE 385
2
AIN
NM
ST
EXISTING CONDITIONS Within the city context McPherson Park is located at a northern low point, meaning a large portion of the downtown and several neighborhood districts to the north drain directly into the park. The park itself also features an extreme grade change with the lowest point being 50 ft below the highest point on site.
high point
low point
ma
in
st
high point
low point
3
Through a ridgeline analysis, I was able to determine the contributing runoff area into the park. The total contributing area is 300 acres which include a variety of sources; 30 acres of the cemetery to the south, 60 acres of the downtown business district, 70 acres of local business, and 140 acres of residential.
CONTRIBUTING AREA McPHERSON PARK
4
road network
building context
water 5
on-site structures
pedestrian circulation
vegetation 6
ecological incompetency 7
8
infrastructure issues 9
10
unstable environmental condition 11
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APPLICATION A series of intervention layers were applied to the site using the information garnered from analyzing the existing conditions. Before the stormwater management aspect of the program could be applied, the site had conditions that needed to be improved. A slope stabilization concept was developed in order to create a stable environment and decrease runoff within the site. And then program spaces and stormwater management were added to complete the site.
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program spaces
stormwater management
slope stabilization
14
2)
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E C O LO G I E S Part of the process was to ensure that the ecologies applied were measurable. I concentrated my efforts on three areas; slope stabilization, stormwater treatment, and stormwater containment. The next several pages will break down these three areas and explain the process of applying these concept to the site.
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Slope Stabilization The first step was to perform a slope analysis to determine the areas of intervention = >25% = 10-25% = 5-10% = <5%
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Using the slope analysis I was able to determine to slope subsets in which to propose stabilization.
Areas of high instability
Areas of intermediate instability 18
intermediate instability
high instability
Then a plant palette was proposed with strong root systems that would be beneficial to the stabilizing the slope edge.
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sorghastrum nutans muhlenbergia capillaris ceanothus americanus
rudbeckia hirta coreopsis lanceolata parthenocissus quinquefolia rubus trivialis
Seciton 1
existing
high
intermediate
proposed 20
Seciton 2
existing
high
intermediate
proposed 21
Seciton 3
existing
high
intermediate
proposed 22
Stormwater Treatment The second step was to apply a planting strategy to the creek edge that was informed by the types of contaminants entering through the different outlets from the surrounding area.
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A plant palette was proposed that would elimate or reduce certain contaminents from the creek water.
sediment fertilizers heavy metals
itea virginica lobelia cardinalis iris virginica
cephalanthus occidentalis osumunda cinnamonea illex verticillata
juncus effusus lemna minor
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Then the plants are distributed along the edge by taking cues from where the runoff is coming for and thus making assumptions on what pollutants they will probably contain.
pollutant concentration
high
low
runoff from:
downtown business, neighborhood business, residential
pollutants:
heavy metals, fertilizers, sediment
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pollutant concentration
high
low
runoff from:
neighborhood business,
pollutants:
heavy metals, sediment
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pollutant concentration
high
low
runoff from:
downtown business, neighborhood business
pollutants:
heavy metals, sediment
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pollutant concentration
high
low
runoff from: residential
pollutants:
heavy metals, fertilizer, sediment
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pollutant concentration
high
low
runoff from: residential
pollutants:
heavy metals, fertilizer, sediment
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pollutant concentration
high
low
The idea is that by the time the runoff/creek water has run through the site, the planting strategy will have reduced the contaminant percentage by 90% or more. 30
Stormwater Containment The last step was propose a series of stormwater infrastructure applications along the creek to manage around 90% of stormwater runoff for up to 100 yr storms.
wetland
weir
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Qp = c i A runoff coefficient
rainfall intensity
drainage area
peak discharge
Peak discharge equation was used to determine the quantity of water the infrastructure would need to handle for a 5, 10, 100 year storm. Equations and numbers for coeďŹ&#x192;cients were taken from the Greenville land development design manual.
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peak discharge 5, 10, 100 yr storm
[
normal creek flow rate:
189
normal creek water capacity: cfs
4,500
cf
]
5 yr storm
Q 5 = .63 * 5.1 * 300 = 964 5.1x normal flow rate
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//
cubic ft/sec
18,450 cf of excess water
10 yr storm
Q 5 = .63 * 5.9 * 300 = 1062 5.9x normal flow rate
//
cubic ft/sec
20,790 cf of excess water
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100 yr storm
Q 5 = .63 * 9.4 * 300 = 1776 9.4x normal flow rate
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//
cubic ft/sec
37,790 cf of excess water
stormwater infrastructure
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Weir
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Half-dam
39
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3) LESSONS LEARNED One of the most important things from this kind of project is learning from the process and determining what worked and what did not. The next page acts as a reflection on my project in McPherson Park.
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Stormwater management is not a one-person job
While working on my own allowed me to focus on certain aspects of design that I may not have in a team setting, it also showed me that it is impossible fully realize the details of a site on your own (especially in a single semester).
Stormwater management alone does not make a park
I started the McPherson Park project with such a heavy focus on stormwater management that I lost sight for awhile of making the park a place people wanted to be. I realized its best to make a project a great space first, and then enhance it using green infrastructure.
Just because a park is in an urban area does not make it urban
I thought that by picking a park in an urban area it would become a modern urban amenity type project. What I found instead was the large park wanted to be extremely natural and organic.
Failing can be a success; if youâ&#x20AC;&#x2122;re willing to objectively learn from the mistakes made. 42
ALLY HANGARTNER | 678.920.1225 | AHANGAR@CLEMSON.EDU