Stormwater Management

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Stormwater Management

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Stormwater Management

  1. 1. Stormwater Management Wali Memon1 Wali Memon
  2. 2. Presentation Outline Water Quantity and Quality Issues Rules Today and Tomorrow Structural and Non-Structural Controls Metrics and Measures2 Wali Memon
  3. 3. Hydrologic Cycle3 Wali Memon http://www.mde.state.md.us/environment/wma/stormwatermanual/
  4. 4. Inland Natural Systems4 Wali Memon
  5. 5. Water Quantity Effects Increased flooding potential Changes to streambed morphologyhttp://www.forester.net, 2002 5 Wali Memon
  6. 6. Water Quantity Effects Decrease in base flows6 Wali Memon
  7. 7. Water Quality Effects Increased pollutant load – Habitat degradation – Public health and recreation impacts7 Wali Memon Sean Chamberlain, 2002
  8. 8. Water Quality Effects Nutrient and Sediment Transport8 Wali Memon
  9. 9. Stormwater Pollution Sources Urban runoff Construction Agriculture Forestry Grazing Septic systems Recreational boating Habitat degradation http://www.sierraclub.org/sprawl, 2002 Physical changes to stream channels9 Wali Memon
  10. 10. Flood Control /Conveyancehttp://www.nae.usace.army.mil/recreati/lvl, 2002 10 http://www.lawrenceks.org, 2002 Wali Memon
  11. 11. Water Quality – Stormwater Constituents Sediment Nutrients: nitrogen and phosphorous Oil, grease, and organic chemicals Bacteria and viruses Salt Metalshttp://www.txnpsbook.org, 2002 11 Wali Memon
  12. 12. Stormwater ConstituentsMedian Concentrations Constituent Units Urban Non-Urban Total Suspended Solids (TSS) mg/l 67-101 70 Chemical Oxygen Demand (COD) mg/l 57-73 40 Total Phosphorous (P) µg/l 201-383 121 Total Kjeldahl Nitrogen µg/l 1179-1900 965 Nitrate + Nitrite µg/l 558-736 543 Lead µg/l 104-144 30 Copper µg/l 27-33 -- Zinc µg/l 135-226 195 Source: U.S. EPA, Nationwide Urban Runoff Program, 1983.
  13. 13. Stormwater Management Challenges Variability of Flows (Duration, Frequency, Intensity) Difference between peak control and treatment objectives Different water quality constituents require different treatment mechanisms Site-to-site variability of quantity and quality Maintenance of non-centralized treatment units Monitoring and measurement13 Wali Memon
  14. 14. Treatment Events Criteria for Storm Events Boston Logan Rainfall Record 1920 - 1999 Cumulative Rainfall Depth Percentage 100 90 Percent of Total Cumultive Depth 80 70 60 50 40 30 20 10 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 Rainfall Depth (in) Cumulative Rainfall record for Boston Logan 1920 - 1999.
  15. 15. Sizing Systems Intensity / Duration Frequency Relation
  16. 16. Calculating Peak Runoff Rates Rainfall Runoff Analysis /Rational Method Qp = CiA C = constant runoff coefficient i = rainfall intensity 1 A = drainage area 0.8 (tc = time of concentration < rainfall duration) 0.6 Q / Qp 0.4 0.2 0 0 1 2 3 4 5 616 Wali Memon t / Tp
  17. 17. Federal Regulations 1987 Clean Water Act Amendments (U.S. EPA) 1990 Phase I National Pollutant Discharge Elimination System (NPDES) Storm Water Program 1999 Phase II NPDES Storm Water Program 1990 Costal Zone Act Reauthorization Amendments, Section 6217 (U.S. EPA / NOAA) Costal Zone Management Program17 Wali Memon
  18. 18. NPDES Permit Program Goal: reduce negative impacts to water quality and aquatic habitat Requirement: develop storm water pollution prevention plans (SWPPPs) or storm water management programs with minimum control measures Implementation: use best management practices (BMPs)18 Wali Memon
  19. 19. NPDES Applicability Phase I "Medium" and "large" Phase II municipal separate storm Certain regulated small sewer systems (MS4s) municipal separate storm located in incorporated sewer systems (MS4s) places or counties with populations of 100,000 Construction activity or more disturbing between 1 and 5 acres of land (i.e., Eleven categories of small construction industrial activity, one of activities) which is construction activity that disturbs five or more acres of land19 Wali Memon
  20. 20. Phase II Minimum Control Measures Public education and outreach on storm water impacts Public involvement/participation Illicit discharge detection and elimination Construction site storm water runoff control Post-construction storm water management in new development and redevelopment Pollution prevention/good housekeeping for municipal operations20 Wali Memon Website for EPA NPDES Phase II Fact Sheets: http://cfpub.epa.gov/npdes/stormwater/swfinal.cfm
  21. 21. Stormwater Management Standards 1. No new untreated storm water discharges allowed 2. Post-development peak flow discharge rates < pre-development peak rates 3. Minimize loss of recharge to groundwater 4. Remove 80% of average annual total suspended solids (TSS) load (post development) 5. Discharges from areas with higher potential pollutant loads require use of specific BMPs21 Wali Memon
  22. 22. Stormwater Management Standards 6. Storm water discharges to critical area require use of approved BMPs designed to treat 1 inch runoff volume (post development) 7. Redevelopment sites must meet the Standards 8. Construction sites must utilize sediment and erosion controls 9. Storm water systems must have an operation and management plan22 Wali Memon
  23. 23. Non-Structural BMPs Pollution prevention/source control Street sweeping Storm water collection system cleaning and maintenancehttp://www.tennatoco.com/stormwater, 2002 Low impact development and land use planning Snow and snowmelt management Public Education
  24. 24. Better Design Green roofs High Density Grassed/Porous Pavement http://www.lrcusace.army.ml, 2002
  25. 25. Structural BMPs Detention/Retention and Vegetated Treatment: Infiltration: infiltration detention basins, wet retention trenches, infiltration ponds, constructed wetlands, basins, dry wells water quality swales (rooftop infiltration) Filtration: sand and organic filters Pretreatment: water quality inlets, hooded and deep sump catch Advanced basins, sediment traps Sedimentation/Separation: (forebays), and hydrodynamic separators, oil drainage channels and grit chamber25 Wali Memon Source: MADEP/MACZM Massachusetts Stormwater Management, Volume 2: Stormwater Technical Handbook, March 1997
  26. 26. Detention Basins TSS Removal Efficiency: 60-80% average 70% design Key Features: Large area Peak flow control Maintenance: low Cost: low to moderate
  27. 27. Wet (Retention) Ponds Removal Efficiency: 60-80% average 70% design Key Features: Large area Peak flow control Maintenance: low tohttp://www.txnpsbook.org, 2002 moderate Cost: low to high 27 Wali Memon Source: MADEP/MACZM Massachusetts Stormwater Management, Volume 2: Stormwater Technical Handbook, March 1997
  28. 28. Constructed Wetlands Removal Efficiency: 65-80% average 70% design Key Features: Large area Peak flow control Biological treatment http://www.txnpsbook.org, 2002 Maintenance: low to moderate Cost: marginally higher than wet ponds28 Wali Memon Source: MADEP/MACZM Massachusetts Stormwater Management, Volume 2: Stormwater Technical Handbook, March 1997
  29. 29. Water Quality Swales Removal Efficiency: 60-80% average 70% design Key Features: Higher pollutant removal rates than drainage channels Transport peak runoff and provide some infiltration Maintenance: low to moderate http://www.txnpsbook.org, 2002 Cost: low to moderate29 Wali Memon Source: MADEP/MACZM Massachusetts Stormwater Management, Volume 2: Stormwater Technical Handbook, March 1997
  30. 30. Infiltration Trenches/Basins Removal Efficiency: 75-80% average 80% design Features: Preserves natural water balance on site Susceptible to clogging Reduces downstream impacts Maintenance: high Cost: moderate to high StormTech, subsidiary to Infiltrator Systems, Inc, 200230 Source: MADEP/MACZM Massachusetts Stormwater Management, Volume 2: Stormwater Technical Handbook, March 1997 Wali Memon
  31. 31. Dry Wells Removal Efficiency: 80% average 80% design On-site infiltration For untreated storm water from roofs only (copper excluded) Source: MADEP/MACZM Massachusetts Stormwater Management, Volume 2: Stormwater Technical Handbook, March 1997
  32. 32. Sand and Organic Filters Removal Efficiency: 80% average 80% design Design Features: Large area Peak flow control Maintenance: high http://www.txnpsbook.org, 2002 Cost: high32 Wali Memon Source: MADEP/MACZM Massachusetts Stormwater Management, Volume 2: Stormwater Technical Handbook, March 1997
  33. 33. Inlets and Catch Basins Removal Efficiency: 15-35% average 25% design Design Features: Debris removal Pretreatment Maintenance: moderate to high Cost: low to high33 Wali Memon Source: MADEP/MACZM Massachusetts Stormwater Management, Volume 2: Stormwater Technical Handbook, March 1997
  34. 34. Sediment Traps/Forebays Removal Efficiency: 25% average 25% design Design Features: Pretreatment Retrofit expansion Larger space requirement than inlet. Maintenance: moderate Cost: low to moderate34 Wali Memon Source: MADEP/MACZM Massachusetts Stormwater Management, Volume 2: Stormwater Technical Handbook, March 1997
  35. 35. Innovative BMPs - AdvancedSedimentation Removal Efficiency: 50-80% average 80% design Design Features: small area Oil and Grease control Maintenance: moderate Cost: moderate Rinker Inc, 2002
  36. 36. Innovative BMPs - Sand Filtration Removal Efficiency: 50-80% average 80% design Design Features: small area Nutrient and pathogen (potential) Maintenance: moderate Cost: moderate Stormtreat Inc, 2002
  37. 37. Innovative BMPs - Hydrodynamic Removal Efficiency: 50-80% average 80% design Design Features: small area Oil and Grease control Maintenance: moderate Cost: moderate Vortechs Inc, 2002
  38. 38. Innovative BMPs – Media Filtration Removal Efficiency: 50-80% average 80% design Design Features: small area Oil and Grease control Maintenance: moderate Cost: moderate Stormwater Management Inc, 2002
  39. 39. Innovative BMPs – Inlet Inserts Removal Efficiency: To be determined Design Features: Retrofit Construction Oil and Grease control Maintenance: moderate http://www.stormdrainsfilters.com, 2002 Cost: moderate
  40. 40. Water Quality MonitoringTARP- Technology Acceptance Reciprocity Program Address technology review and approval barriers in policy and regulations; CA IL Accept the performance tests and data MA from partner’s review to reduce MD subsequent review and approval time; NJ NY Use the Protocol for state-led initiatives, PA grants, and verification or certification VA programs; and TX Share technology information with potential users in the public and private sectors using existing state supported programs
  41. 41. Performance Verification - TARP Storm Event Criteria to Sample 2 More than 0.1 inch of total rainfall. 2 A minimum inter-event period of 6 hours, where cessation of flow from the system begins the inter-event period. 2 Obtain flow-weighted composite samples covering a minimum of 70 % of the total storm flow, including as much of the first 20 % of the storm as possible. 2 A minimum of 10 water quality samples (i.e., 10 influent and 10 effluent samples) should be collected per storm event. Determining a Representative Data Set 2 At least 50 % of the total annual rainfall must be sampled, for a minimum of 15 inches of precipitation and at least 15, but preferably 20, storms.
  42. 42. Performance Verification - TARP Stormwater Sampling Locations Sampling locations for stormwater BMPs should be taken at inlet and outlet. Sampling Methods Programmable automatic flow samplers with continuous flow measurements should be used – Grab samples used for: pH, temperature, cyanide, total phenols, residual chlorine, oil and grease, total petroleum hydrocarbons (TPH), E coli, total coliform, fecal coliform and streptococci, and enterococci. Stormwater Flow Measurement Methods – Primary and secondary flow measurement devices are required.
  43. 43. Performance Verification - TARP Sample Data Quality Assurance and Control − Equipment decontamination, − Preservation, − Holding time, − Volume, − QC samples (spikes, blanks, splits, and field and lab duplicates), - QA on sampling equipment − Packaging and shipping, − Identification and labeling, and − Chain-of-custody.
  44. 44. Performance Verification - TARP Calculating BMP Efficiencies (ASCE BMP Efficiencies Task 3.1) Process efficiencies or removal rates should be determined from influent and effluent contaminant concentration and flow data. Efficiency Ratio, Summation of Loads, Regression of Loads, Mean Concentration, and Efficiency of Individual Storm Loads. Note: The Efficiency Ratio method is preferred.
  45. 45. Questions45 Wali Memon

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