Park View Estates Zach Bradley | Riley Jones | Grant Moore | Derek - PowerPoint PPT Presentation

Stormwater Management at Park View Estates Zach Bradley | Riley Jones | Grant Moore | Derek West November 18, 2016

Mission Statement The mission of the Cowboy Stormwater Management team is to design and implement sustainable storm and surface water systems that control erosion damage from stormwater runoff, improve urban development, and enhance quality of life in Stillwater, OK.

Statement of Work • Period of Performance: Aug 15, 2016 – May 12, 2017 • Client: Park View Estates Homeowners Association • Location: Stillwater, Oklahoma

Client Information • Park View Estates Home Owners Association – Incorporated in 1976 – J.C and Evelyn Rogers, from dairy to community – Preside over 230 lots

Project Parameters Client Requirements Client Constraints • Eliminate ponding in streets • Cost/Benefit and yards (top priority) • Safe for residents • Reduce erosion in public space • Natural looking • Stabilize stream bank erosion of creek • Provide three cost options

Project Approach 2 Schools of Thought Low Impact Development (LID) Traditional Using natural methods to Moving the water towards reduce stormwater runoff, streams, rivers, and lakes, increase water infiltration into generally using impermeable soil, and eventually direct surfaces such as concrete water into streams, rivers, and lakes

Problem Sites at a Glance Site A • Ponded water in cul-de-sac 48 hours after storm event • Under designed drain pipe • Erosion at drainpipe outlet & at tree stump

Problem Sites at a Glance Site B • Massive holes forming throughout stream • Streambank erosion • Sediment transport • Sediment deposition

Problem Sites at a Glance

Data Collection Surveying • Cross sections at A, B, and C • Watershed delineation • For use in hydrologic and hydraulic modeling Model Parameters • 𝑢 𝑑 , time of concentration • Q, flowrate • P, precipitation • S, Slope

Development of the Model • Rainfall Data – Stillwater, OK IDF curve 25 = 6.8in P = 𝑆 24 • Estimating Runoff – SCS Curve Number Method (𝑄−𝐽 𝑏 ) 𝑜 Q = 𝑄−𝐽 𝑏 +𝑇 , where Q = runoff (in) P = rainfall (in) S = potential retention after runoff (in) 𝐽 𝑏 = initial abstraction (in)

Development the Model • Time of Concentration – Kirpich Equation 𝑀 0.77 𝑢 𝑑 = 𝑇 00.385 , where L = distance from boundary to outlet (m) 𝑢 𝑑 = mins 𝑇 0 = slope (decimal) • Slope – Slope Equation ℎ 1 −ℎ 2 , where Δ𝑀 ℎ 1 = elevation 1 ℎ 2 = elevation 2 Δ𝑀 = change is distance

Risk Analysis • Flood Frequency Analysis 𝑜 1 𝑔 𝑄 𝑈 , 𝑜 = 1 − 1 − , where 𝑈 P T = Exceedance Probability T = Recurrance Interval n = # years storm event – High Cost 25 1 0.15 = 1 − 1 − , 𝑈 ℎ𝑑 = 154-yr 𝑈 – Medium Cost 25 1 0.50 = 1 − 1 − , 𝑈 𝑛𝑑 = 37-yr 𝑈 – Low Cost 25 1 0.80 = 1 − 1 − , 𝑈 𝑚𝑑 = 16-yr 𝑈

Risk Analysis • Design Life Span – High Cost @ T hc , T D = Y1 year – Medium Cost @ T mc , T D = Y2 year – Low Cost @ T lc , T D = Y3 year http://rpitt.eng.ua.edu/Workshop/WSErorionControl/M odule4/Module4.htm

Problem Site A

Possible Solutions • Regrading Slope • Permeable Pavement • Multiple Bioretention Cells • Enhanced Bioswale

Permeable Pavement Pros Cons • Fast water • High cost • High infiltration • Long life maintenance • Aesthetic • Low strength • Walkway to Greenbelt http://www.vwrrc.vt.edu/swc/Non PBMPSpecsMarch11/VASWMBMPS pec7PERMEABLEPAVEMENT.html Cost Range: $5.30 - $7.10 / sq. ft Average Life: 25 years

Bioretention Cells http://ne.water.usgs.gov/projects/bioremediation/cells.html

Bioretention Cells Pros • Aesthetic • Reduces water to stream • Cleans water contaminants Cons Cost Range: $5.50 - $ 24.00 / sq. ft • High cost • Some maintenance Average Life: 30 years • Small area

Bioswale Pros https://www.columbus.gov/uploadedImages/Public_Utilities/Water_Protection/Wat ershed/Bioswale%20Illustration%201(1).jpg • Aesthetic • Guides water flow • High infiltration • Filters stormwater • Covers large area Cons • High cost • Some maintenance Cost Range: $5.50 - $ 24.00 / sq. ft Average Life: 30 years

Advantages of Turf Bioswales • Directs water • Easily maintained • Decreases water velocity • Less expensive http://chesapeakestormwater.net/wp-content/uploads/2009/11/dry-swale.gif

Regrading Slope • The poor slope is the main cause of flooding in cul-de-sac • Regrading will eliminate future flooding • Average cost of grading: $0.59 / sq. ft

Site A - Low Cost Solution • Curb and Pathway – Regrade slope – Seal or remove pipe – Widen curb inlet • Greenbelt Area – Remove eroded sites – Regrade existing swale – Keep existing soil

Site A - Low Cost Solution Problem Site A - Low Cost Solution Unit Low Rate (per unit) High Rate (per unit) Curb Inlet (ft) 5 $ 13.00 $ 29.50 Regrading (ft 2 ) 5100 $ 0.50 $ 0.68 Turf (ft 2 ) 5100 $ 0.01 $ 1.09 Calculated Costs - $ 2,666.00 $ 9,174.50 Average Cost $ 5,920.25

Site A - Medium Cost Solution • Curb and Pathway • Greenbelt Area – Redo slope grading – Construct complete bioswale – Remove broken pipe – Replace subsoil with – Implement sand permeable walkway http://docplayer.net/docs-images/14/42740/images/34-1.jpg

Site A - Medium Cost Solution • Small bioswale • No permeable pavers Problem Site A - Med Cost Solution Unit Low Rate (per unit) High Rate (per unit) Curb Inlet (ft) 5 $ 13.00 $ 29.50 Regrading (ft 2 ) 800 $ 0.50 $ 0.68 Turf (ft 2 ) 800 $ 0.01 $ 1.09 Permeable Pavers (ft 2 ) 0 $ 7.10 $ 12.00 Bioswale 2775 $ 5.50 $ 24.00 Calculated Costs - $ 15,735.50 $ 68,163.50 Average Cost $ 41,949.50

Site A - Medium Cost Solution • Large bioswale • Including permeable pavers Problem Site A - Med Cost Solution Unit Low Rate (per unit) High Rate (per unit) Curb Inlet (ft) 5 $ 13.00 $ 29.50 Regrading (ft 2 ) 800 $ 0.50 $ 0.68 Turf (ft 2 ) 800 $ 0.01 $ 1.09 Permeable Pavers (ft 2 ) 500 $ 7.10 $ 12.00 Bioswale 4200 $ 5.50 $ 24.00 Calculated Costs - $ 27,123.00 $ 108,363.50 Average Cost $ 67,743.25

Site A - High Cost Solution • Curb and Pathway – Redo slope grading – Remove pipe – Implement permeable walkway – Install multiple small bioretention cells • Greenbelt Area – Construct complete bioswale – Add check dams – Input aesthetic vegetation along swale

http://www.cleanwateriowa.org/filesimages/ResidentialUrban/bioswale1.jpg Example of High Cost Residential Bioswale

Site A - Cost Analysis • Low Cost solution – Cost range: $2615.00 – $3615.50 • Medium Cost solution – Small swale cost range: $15,727.50 – $67,291.50 – Large swale cost range: $27,115.00 – $107,491.50 • High Cost solution – Cost > $110,000 Sources: • http://www.homewyse.com/services/cost_to_grade_landscaping.html • http://greenvalues.cnt.org/national/cost_detail.php

Problem Site B - Stream • Streambank erosion • Vertical banks • Large pooling • Sediment build up

Possible Solutions • Riparian buffer zone • Riprap • Streambank slope restoration • Implement native vegetation

Riparian Zone http://www.waiautrust.org.nz/general/you-and-trust • Roots from vegetation provide an anchor for the stream bank soil • Provides an ecosystem for small animals and insects that help stream stability • Inexpensive way to help prevent stream bank erosion

Riprap • Riprap prevents erosion by providing armor for the streambank soil • Vegetation can grow in between the stones, benefiting the riparian zone • Natural appearance

Native Vegetation http://www.srwc.org/projects/stream-restoration/ • “Live stakes” are small woody cuttings of indigenous trees or shrubs that can easily be replanted into the stream bank • Implementing vegetation that is indigenous to the area provides stability, biofiltration, and natural aesthetics

Site B - Low Cost Solutions http://www.waiautrust.org.nz/general/you-and-trust • Implement “No Mow” riparian buffer zone • Regrade high priority sites • After regrading apply turf and coir matting

Site B – Medium Cost Solution • Build on low cost solutions • Regrade the medium priority sites along with the high priority sites • After regrading, apply turf and coir matting

Site B Long Term – High Cost http://www.biohabitats.com/newsletters/ecological-construction-planting- https://www.dubois-king.com/projects/oak-hill-stream-channel-restoration/ and-management/ • Build on low and medium cost solutions • Plant live stakes and other native vegetation • Incorporate all possible solutions into one total stream reconstruction design

Surveying • Cross section surveys were conducted • Survey data will allow us to determine priority sites, stream profiles, and bank slopes ratios • These parameters will be used to assess stream bank erosion and the best restoration practice to be applied

Surveying Example of surveyed stream cross sections • This data will be utilized in future work to create a model of the stream using river and stream morphology software