1. Professor Art McGarity, Zach Eichenwald Assisted by Markia Collins, Sophia Richardson, Richard Scott, Pete Cosfol

2. The Team (minus Sophie)

3. Little Crum Creek Watershed – the area from which surface water drains into a particular body of water after an event (rainfall)

4. 1. Monitor Collect and test water samples to represent stream quality with data 2. Model Simulate stream flow and pollutant transport to help pinpoint locations for stormwater management technology 3. Low Impact Development Stormwater management technology and practices to reduce runoff volume and nonpoint pollution

5. Collecting Samples

6. ISCO Sampler Triggered by rain or stream depth, samples at certain intervals throughout an event Stores flow data Velocity Depth Rainfall Flow Captures up to 24 samples

8. Gathering Data

9. Testing for Pollutants Nitrates (NO3) and phosphates (PO4) Excess plant nutrients cause algae blooms (eutrophication) whose decay depletes oxygen TSS (Total Suspended Solids) Sediments can clog creek beds Carry other pollutants, including heavy metals, along with it

10. The Tests Hach colorimeters quantify pollutant levels by the amount of absorbance of light In the TSS test solids are filtered from a 100 mL sample and weighed to calculate concentration

11. Other Tests and Calculations Standard Additions Turbidity Turbidity vs. TSS Pollutant Load- an estimation of the total PO4, NO3, and solids flowing throughout a specific interval during an event L = CQ∆t Event Mean Concentration Σ(C t Q t ) Σ(Q i )

12. SampleTurbidity (fau)TSS (mg/L)NO3 (mg/L)Abs %PO4 (mg/L)Abs% A118172.146.280.3479.7 A212-762.146.31.5735.24 A31695330.3890.3976.93 A45068530.389.080.4275.87 A52804900.486.260.4773.1 A61422100.972.470.2883.18 A71121470.970.870.2982.62

13. The Sonde Remotely and continuously monitors: pH/ORP Dissolved oxygen Nitrate Conductivity Temperature Turbidity Depth

16. Why Model? We can’t observe the entire watershed We aren’t able to observe all possible weather events The model allows us to see the response of the watershed to any possible input, including large storm events that occur infrequently We can experiment with different development and storm water reduction scenarios

17. Modeling the (Big) Watershed Previous work: StormWISE (StormWater Investment Strategy Evaluator) Optimization program developed by Professor Arthur McGarity Uses RUNQUAL (Penn State) to develop water quality parameters Placement of Best Management Practices (BMPs) optimized using linear programming techniques. Locations for BMPs are not site specific

18. Zooming in Summer work involves developing a more site specific version of StormWISE Water quality and quality are modeled using EPA’s SWMM (StormWater Management Model) Model will be able to identify site specific locations for BMPs and model the effects of implementation

19. SWMM Dynamic rainfall-runoff simulation Can be used for single event or long term simulation of storm water runoff quantity and quality Is used to develop a simulated hydrograph and pollutograph given rainfall input Can model the transport of Nitrate, Phosphate, and TSS

20. The SWMM Model Subcatchments Conduits Nodes

21. SWMM Parameters SWMM requires (a few) basic parameters about each subcatchment, node, and conduit SubcatchmentsSCS CN, amount of impervious surface (%), slope (%), hydraulic length NodesInvert elevation, initial depth, maximum depth ConduitsLength, roughness, size, type

22. Basic Hydrology (SWMM uses this!) Source: Louisiana DEQ - http://www.deq.louisiana.gov/portal/Default.aspx?tabid=1979

23. Infiltration Not all precipitation enters the stream Must calculate effective precipitation (precipitation that is converted to runoff) using an infiltration model Many infiltration models have been developed One common model is the SCS Method (USDA’s Soil Conservation Service, now Natural Resource Conservation Service [NRCS]) Assigns a curve number (CN) to many different land use categories CN range from 0 – 100 (completely pervious to completely impervious). Pavement is 98.

24. SCS Method Develops an empirical relationship between effective precipitation and actual precipitation: I a = initial abstraction (in) P = the observed precipitation (in) S = maximum potential retention (in) Q = effective precipitation (in)

25. SCS Method The CN describes the maximum possible retention, where We assume I a = 0.2S, determined from a study of many small watersheds by SCS

26. SCS Curve Number Source: USDA NRCS TR-55

27. SCS Curve Number Adjustments are made for antecedent moisture conditions CN(II) is for average moisture conditions CN(I) and CN(III) are for dry and moist conditions, respectively

28. SCS Curve Number An analysis of rainfall-runoff relationships for Little Crum Creek has found a strong correlation between antecedent moisture and effective precipitation

29. SCS Curve Number Source: USDA NRCS TR-55

30. Problems with SCS Developed by USDA for use on agricultural land types Attempts to apply the SCS CN method to the Little Crum Creek watershed result in underestimates of the effective precipitation Not terribly useful for envisioning the effects of numerous parking lots, storm sewer drainage systems, etc.

31. Problems with SCS We calculated the theoretical CN(II) for one section of the watershed to be 88.8 Underestimates total runoff Analysis of observed rain events shows that the actual CN is closer to 96 Solutions (Easy and Hard): Account for roads (Easy) Find a new relationship between S and I a (Hard)

32. Other Parameters Average impervious percentage, slope, conduit length, and elevations are determined from GIS analysis Elevations are from a Digital Elevation Map (DEM) Impervious percent is from a raster dataset that classifies land use into 5 categories

33. Land Use and Impervious Percent

34. Putting it all together Model currently built for a section of the watershed Little Crum Creek Park Girard

35. Close…

36. Still close…

37. Preliminary Results Simulated results either underestimate or overestimate the amount of flow This difference is sometimes quite pronounced, depending on the nature of the storm event Simulation results typically exhibit a time lag

38. What’s Next Adjust parameters to get a better fit to actual data Add capability to model Nitrate, Phosphate, and TSS to the model Model the implementation of BMPs and LID within the watershed

40. Modeling Low Impact Development and BMPs A completed model allows BMP and LID alternatives to be compared A benefit-cost analysis can be performed to determine the most economically efficient method of reducing runoff

41. Types of BMPs/LIDs Many ways to reduce runoff, including: Green roof (we have one on the roof of Alice Paul and David Kemp) Constructed Wetland Cisterns and rain barrels Permeable pavement surfaces

42. Preliminary BMP Recommendations SiteBMP Springfield Square, Springfield, PAGreen Roof Farmhouse Circle, Springfield, PAConstructed Wetland See http://watershed.swarthmore.edu/littlecrum for ongoing recommendations for all four municipalities: Springfield, Swarthmore, Ridley Township, Ridley Park

43. Springfield Square Green Roof on Swarthmore’s Alice Paul Hall (image: Meghan Whalen)

44. Farmhouse Circle Constructed Wetland at Ridley High School

45. http://watershed.swarthmore.edu