WATER QUALITY IMPROVEMENTS WITH PERMEABLE PAVEMENTS

Transcription

1 IMPROVEMENTS WITH PERMEABLE PAVEMENTS VUSP PA STORM SYMPOSIUM

2 The removal efficiency of pollutants, both particulate and dissolved, from stormwater is a difficult and inefficient process simply put, the evaluation process is largely a work in progress. PA SWBMP MANUAL

3 Published values provide a wide range of results because the testing methodologies are highly variable and the various treatment mechanisms are not considered. PUBLISHED VALUES

4 POLUTION REMOVAL PATHWAYS

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6 Sandy clay soil (HSG C) UNH STORM CENTER

7 Two years of monitoring 26 storms and 18 water sampling events. UNH STORM CENTER

8 Effluent concentrations (when present) typically higher likely due to washout of accumulations in the system. Interesting note the medium particle diameter in the effluent was microns. UNH STORM CENTER

9 Provides a spreadsheet model to evaluate stormwater runoff nutrient loads and treatment efficiencies of BMPs base on studies within the State of Florida. Compares pre to post development nutrient loadings, and factors in the benefits derived from the BMP. FLORIDA STATE BMPTRAINS

10 Contaminant Loading for different pre development conditions, Proportional to runoff volume FLORIDA STATE BMPTRAINS

11 POST DEVELOPMENT Total site = ac Landscape = ac Bldg/Asphalt = ac PICP = ac Non DCIA CN from TR-55 - C Soil, good grass cover - CN = 74 DCIA % = ( )* = 85.8%

12 Average annual contaminant loading is proportional to EMC and annual runoff volume FLORIDA STATE BMPTRAINS

13 PRE and POST P & N loadings Required treatment efficiency FLORIDA STATE BMPTRAINS

14 Input PICP profile to calculate available storage Input PICP area to get treatment efficiency (iterative process) FLORIDA STATE BMPTRAINS

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16 Two main objectives: 1. Investigated the TSS removal efficiency of different jointing material 2. Determine the frequency of remedial maintenance based on typical sediment loadings. FGCU STUDY

17 TEST SETUP

18 TEST SETUP

19 Two contaminant types: 1. NJCAT (NJ Corp of Advanced Technology) 2. Winter Sand Three concentrations: mg/l mg/l mg/l Two scenarios year progressive loading 2. Equivalent mass loading TEST SETUP

20 Post-testing Pre-testing TEST RESULTS

21 TEST RESULTS

22 1. There is an increase in removal efficiency, and a reduction in infiltration, as more TSS materials are trapped in the jointing material. 2. TSS removal efficiency was 60 to 100% in the jointing material based on grain size. 3. Remedial maintenance required between 9-20 years. TEST RESULTS

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25 Phosphorus is highly adsorbed by soil particles. Research in agriculture has indicated that P holding and leaching capacity of medium is directly related to the content of amorphous aluminum and iron oxides. PHOSPHORUS

26 Hydrocarbon removal can occur through: 1. Adsorption to sediment / aggregates 2. Volatilization 3. Microbial action 4. Photochemistry Expect that Adsorption required to retain hydrocarbons and provide retention time for volatilization and microbial action HYDROCARBONS

27 Although the N forms may change, total N does not (outside of Absorption). Hunt and Davis looked at creation of an Anoxic Denitrification Zone at the bottom of the system. Found: If zone remains saturated long enough, anaerobic conditions are created which promote denitrification. This is contrary to maximum retention time for subgrade stability NITROGEN

28 More research required on how these processes apply to Hydrocarbons, Nitrogen, Phosphorus and Metals Where to go from here 1. Determining the P & metal removal efficiencies / limits of different aggregates. 2. Using P deficient supplements. 3. Adding sorptive / organoclays / sponge materials to jointing aggregates (so it can be extracted when saturated). 4. Treatment train with vegetative uptake or mulch medium (bioretention). 5. Looking at fate of different metals 6. OTHER?

29 This concludes the presentation! What questions do you have? For more information contact: Glenn Herold at