Santana Park Water Conservation

Santana Park

Water Conservation Analysis

City of Corona 400 SouthVicentia Avenue | Corona, Ca 92882 T: 951.736.2400 www.ci.corona.ca.us

2-20-09

310 North Joy Street | Corona, Ca 92879 T: 951.737.1124 | F: 951.737.6551 www.bmla.net

Contents Executive Summary………………………………………………….. 1 Problem Statement…………………………………………………… 2 Soil Analysis…………………………………………………………… 2-3 Irrigation Analysis…………………………………………………….. 4-6 Conclusions……………………………………………………………. 7 Recommendations……………………………………………………. 8 Resources……………………………………………………………...

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Appendices…………………………………………………………….. 10 A. Controller water use August 08 (provided by Tim Brown at Corona Parks and Community Services Department) B. CALSENSE controller schedule August 06 (provided by Chris Baldino at Corona Parks and Community Services Department) C. Total Area Method for precipitation rate D. Area B Irricalc 3 scheduling model (performed by BMLA) E. Manufacturer specifications for spray heads and rotors

Executive Summary

The City of Corona has asked for an evaluation of the irrigation system at Santana Park in order to convert to a recycled system. BMLA Inc. has evaluated the irrigation design and existing field conditions and has determined the following: x x x x

The irrigation system will work within the peak demand of 1000 GPM. The irrigation system, as designed, can be converted to a recycled system.

The existing irrigation controllers are adequate for the conversion.

The watering window can be accomplished in 7.1hours per day at peak demand in July.

The following recommendations will improve the irrigation efficiency and ensure the irrigation system will function within the designed parameters: x x x x

Coordinate with CALSENSE to optimize the timing of the valves Use the FLOWSENSE option on the controllers.

Make use of the soak and cycle function on the controllers.

Adjust the watering window using the CALSENSE controller based on historic ET.

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Problem Statement The goal of this report is to determine if the irrigation system at Santana Park will function as designed, without exceeding its limits; particularly in the extreme heat of the summer months. It also looks at the possibility of using recycled water for irrigation, and the feasibility of irrigating within the watering window required by city regulation. The questions below have guided this discussion: 1) Does the irrigation system as designed exceed the peak irrigation demand?

2) What is the watering window for the designed system?

3) What is the optimal water schedule for the park, considering climate, soils and plant material?

4) What are the existing site conditions?

Soil Analysis Soil Texture From initial soil probes, the soil appeared to either be very rocky or compacted; or irrigation is only wetting the upper 2-3 inches of soil.

Visit to Santana Park x Soil probed with 10” screwdriver to determine soil wetting and permeability x General observation Area

probe depth

North baseball fields -very thatched, easy to lift Slopes

2-3” 2-3”

Soccer field (next to tot lot) -top dressed and reseeded, looks completely reworked -Rain Bird 7005 rotor

10”

Soccer field (south of tot lot) -wear around goal; sprouting but very matted Bermuda -looks like sections may have been repaired with sod -Rain Bird rotors

2-3”

Upper field -bare compacted dirt in goal areas, high wear areas -whole field looks yellowish; dormant grass

0-6”

NW Baseball field -some thatch, can pull up, little wear

2-4”

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Core Samples Two core samples were taken in the lower soccer and baseball fields to gain a better understanding of soil conditions. As the probe measurements were consistent throughout the park, fewer core samples were taken. In taking these samples, the depth reached was about the same, with the coring tool stopping at a hard material or scraping on rocks. The soil retrieved was loose and moist, with roots only down to the first one or two inches. Soil textures for the two samples were estimated using the ‘Texture by Feel Analysis’, described by the Natural Resources Conservation Service. http://soils.usda.gov/education/resources/k_12/lessons/texture/

Soil Sample 1:

sandy loam, 2.25” deep, core limited by hard surface that felt like a large rock

Soil Sample 2:

sandy loam, 3.5” deep, core limited by protruding rocks (one pulled out was 1.75” long

Additional soil study, perhaps a full profile test, would be beneficial for a better understanding of the water holding properties below the 4 inch depth in order to determine opportunities for deeper rooting.

Permeability A soil permeability test was performed in the hole left by soil sample 1. The method described by the Food and Agriculture Organization (FAO) was used (ftp://ftp.fao.org/FI/CDrom/FAO_Training/FAO_Training/General/x6706e/x6706e09.htm).

After measuring infiltration rates of water in the soil, the coefficient of permeability was measured to 1.58 x10-3, falling in the range for permeability.

This suggests that there is not a hard pan layer restricting infiltration to the lower layers of soil.

Field Capacity Field capacity is defined as the depth of water that can be held against the force of gravity; or the water that remains after full saturation and the following subsurface draining of excess water. Irrigation should be applied after 50 percent of available water is depleted. Most irrigation scheduling software assumes the area is at field capacity prior to irrigation. Each irrigation event replaces the 50 percent lost.

Determination of field capacity based on additional soil study will improve the ability to schedule irrigation events.

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Irrigation Analysis Irrigation Equipment Existing static water pressure: 136 PSI Type of water: currently potable, recycled in the future Designed peak irrigation demand: 1000 GPM System design pressure: 85 PSI Number of controllers: 7 Type of turf: sports field mix of Bermuda hybrid and perennial rye grass Type of controllers: A through F = Calsense ET1, G and H = Calsense ET 2000

Function in Peak Irrigation Demand A worst case was calculated to determine if the irrigation system would still function at times of peak demand. Operating under the assumption that only one station at any one controller would be on at a time, the scenario of highest demand was developed. The stations with the highest flow rates for each controller were added together to see if they exceeded the maximum design flow of 1000 gpm.

The total is 999 gpm, so the system will function within the worst case scenario at peak irrigation demand as long as the controllers are programmed so that only one station is on at a time.

Irrigation Schedule (August 2006) The schedule data from August 2006 provided by the city shows a range of daily watering times between 2.7 and 8.4 minutes (see Appendix B). The total time each controller required to complete irrigation cycles varied between 2.3 and 7.52 hours per day in August 2008 (see Appendix A). The watering window target, to comply with recycled water regulations, was determined by the city to be 6.5 hours. At least two controllers exceeded this limit in August. The scheduling question is compounded by the fact that the shallow moisture depths sometimes required a second irrigation to overcome afternoon heat stress.

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Schedule Modeling Irrigation schedule modeling was performed using Irricalc 3 software to determine what irrigation schedule and watering window is optimal for turf health.

Controller B was chosen for modeling because it was the highest water user in August 2008, based on the historic irrigation data provided by the city (see Appendix A). If it is able to irrigate within the watering window, the rest of the areas will be able to as well. Information regarding watering days and historic evapotranspiration data was selected. The CALSENSE controller in place at the park is not inventoried in Irricalc, so a controller with similar station numbers and features was selected (Rain Bird ESP 24MC). Next, information regarding each station was entered, including soil type, plant factor, precipitation rate, and root depth. The soil type was determined through site visit and soil texture feel tests.

The plant factor was used from the Water Use Classification of Landscape Species (WUCOLS) document, using an average (0.7) of the factor for cool season turf (0.8) and that of warm season turf (0.6). The precipitation rate was determined by sourcing the data from manufacturer spray head and rotor performance charts (see Appendix E). In situations where the precipitation rate is not matched, the Total Area Method was used for that station (see appendix C). Root depth was selected based on information on Bermuda from the Texas Cooperative Extension (Duble), that 80% of the roots are located in the top 6� of soil. It is worth noting that Bermuda has the potential to root to a depth of 6’.

Turf grass that is more deeply rooted and watered with less frequent but deeper irrigation events will be more tolerant of drought conditions.

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With these parameters, the major variables being precipitation rate of the spray heads or rotors and GPM per valve, the schedule was modeled (see Appendix D).

Figure 1: Area B Irricalc 3 scheduling output extracted from Appendix D

Month of July: 427 min x Day

1 hour_ = 7.1 hours 60 min

Two important conclusions were found: 1) Longer watering events are required for summer months.

2) Even with longer watering periods, Area B will only slightly exceed the 6.5 watering window, but falls well within an 8 hour window at 7.1 hours per day.

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Conclusions Examination of soil condition suggests that permeability is adequate though there are some barriers very near the surface limiting root development. These may be due to dry soil, compacted soil, very rocky soil depending on the area. High use areas on soccer fields have clear compaction; other areas have good topsoil that is rocky and hard to penetrate beyond 3-4 inches. Analysis by a soil scientist may clarify this question and also determine field capacity for park areas. Irrigating in a cycle and soak manner for a longer duration will make sure that excess water does not remain on the surface and drain off, while encouraging root development deeper in the soil.

The irrigation system will be able to function within the designed maximum flow of 1000 gpm as long as controllers are coordinated, and only one valve per controller is on at any one time. The peak irrigation demand of 1000 GPM, as designed, includes all of Phase 2. This includes the new field and parking area, and the parking lot and slopes that have yet to be installed. Programming longer irrigation times will only slightly exceed the existing 6.5 hour watering window by 0.6 hours, but the practice will ensure that the turf will not need additional irrigation through the day in hot summer months.

The recommendations on the following page respond to these conclusions.

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Recommendations I. Change watering window parameters to allow for sufficient watering during the summer months.

II. Reconfigure scheduling program. x

x

x

x x

Utilize FLOWSENSE option if available. This option on ET2000 minimizes the watering window by managing when valves are turned on or off based on the flow capacities of the system. The FLOWSENSE option should be programmed so as not to exceed the 1000 gpm design limit.

Program the controller to turn on only one valve at a time. This will make sure that the system will irrigate within safe limits of the system as designed.

Work with CALSENSE to reconfigure the irrigation schedule.

Based on the model schedule the watering times need to be extended. This will encourage optimal turf growth.

Make use of cycle and soak functions where longer irrigation periods are required.

Contact Bob Moxley from CALSENSE at 760-580-9428 to obtain training.

III. A soils test and profile by a qualified soil laboratory is recommended. This would help for fine tuning of the irrigation system, however it is not a priority item.

IV. Consult with turf management expert to optimize management practices such as turf aeration.

V. Reduce irrigated area. x

x

Reduce turf areas where not necessary, such as parkways and other non-field areas. This will reduce watering requirements throughout the year. These areas may be changed to drought tolerant shrubs or a no-water alternative such as mulch or gravel.

This is not a priority as it may take many years to recoup the cost of conversion in water savings. The recommendation is to reprogram the irrigation controllers and follow the recommendations of the soil analysis.

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Appendices A: Controller water use August 08 (Provided by Tim Brown at Corona Parks and Community Services Department) B: CALSENSE controller schedule August 06 (Provided by Chris Baldino at Corona Parks and Community Services Department) C: Total Area Method for calculating precipitation rate D: Area B Irricalc 3 scheduling model (Prepared by BMLA) E: Manufacturer specifications for spray heads and rotors

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Appendix A: Controller water use Aug 08 (Provided by Tim Brown at Corona Parks and Community Services Department)

Appendix B CALSENSE controller schedule Aug 06 (Provided by Chris Baldino at Corona Parks and Community Services Department)

Appendix C Total Area Method for calculating precipitation rate: P.R. (in/hr) = Total GPM x 96.25 Total Area (sqft) Calculated as described in Hunter Industries’ Tech Guide.

Appendix D Area B Irricalc 3 scheduling model (Performed by BMLA)

Appendix E Manufacturer specifications for spray heads and rotors