A Primer on Stormwater Management, your Facility and the Chesapeake Bay. Tom Schueler Chesapeake Stormwater Network June

Transcription

1 A Primer on Stormwater Management, your Facility and the Chesapeake Bay Tom Schueler Chesapeake Stormwater Network June

2 Key Themes Why do we need to be concerned about Stormwater? What are all these letters about? (MS4, TMDL, BMP etc) What are stormwater practices and what do they actually do? What is the Full-Cycle approach to managing stormwater practices? What can I do at my facility to prevent stormwater pollution?

3 Urban Stormwater Basics Center for Watershed Protection, 2001

4 10% IC

5 30% IC

6 60% IC

7 Impervious Cover

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9 Runoff Coefficient (Rv) Relationship Between Watershed Imperviousness (I) and the Storm Runoff Coefficient (Rv) (Source: Schueler, 1987) Watershed Imperviousness (%)

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15 IC and Stream Habitat 8-10% < 5% 20% > 65% 30%

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18 What are all these letters about? Bay TMDL MS4 Permit Federal Facilities

19 The Chesapeake Bay Watershed, by the numbers 64,000 square miles in area Forest is about 58% of the area Row Crops are about 10% About 10% is turf and 5% is paved The rest is pasture, meadow, wetlands and open land About 3.2 million animal units (chicken/hogs) and 40 million tons of manure ~ 500 wastewater plants that discharge 3 billion gallons per day 19

20 Chesapeake Bay Total Maximum Daily Load (TMDL) The Bay Pollution Diet Chesapeake Bay TMDL was finalized by EPA and Chesapeake Bay partners in 2010 Bay Pollution Diet set goals to install all practices needed to clean up the Bay by 2025, with 60% of the practices in place by end of 2017 Final reduction targets for nutrients and sediments by 2025 or beyond Federal facilities lead by example under the Executive Order 20

21 Key Sectors Involved in the Bay Pollution Diet Agriculture: Farms and Feedlots Wastewater Treatment Forest (60% of CBW) Air Deposition Urban and Suburban Runoff 21

22 Chesapeake Bay TMDL: Pollution Diet for All Sectors and Sources Nitrogen Simulated Pollution Loads Delivered to the Bay (million pounds/year) Phosphorus ,000 10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1, Interim target 2025 Planning Target (amt. allowed in Bay) Sediment

23 Indicators of improving ecosystem health: We are making progress Blue Crabs Bay Grasses Water Clarity WQ Standards Attainment Reducing Pollution 23

24 MS4 PERMITS A municipal separate storm sewer system (MS4) is a conveyance or system of conveyances owned by a state, city, town, or public entity that discharges to waters of the U.S. and is designed or used for collecting or conveying stormwater but is not a combined sewer Federal facilities may require MS4 permits

25 Municipal Stormwater Permits Required Minimum Management Measures 1. Public Education and Outreach * 2. Public Involvement and Participation 3. Illicit Discharge Detection and Elimination * 4. Construction Site Runoff Control * 5. Post Construction Stormwater Management * 6. Municipal Pollution Prevention and Good Housekeeping * Annual compliance reporting 25

26 The Link Between Ms4 Permits and the Bay TMDL: Nutrient Accounting Numerical load reduction or impervious cover treatment requirements are now included in many new Ms4 permits Existing MS4 permit requirements for BMP maintenance, inspection and reporting are used to comply with Bay BMP verification Most of the MS4 minimum management measures are eligible for pollutant reduction credit 26

27 Federal MS4 Permit Requirements Measurable and enforceable measures Budget for stormwater controls, including permit requirement Reduce turf grass fertilizers Consistent with Chesapeake and local TMDLs Include estimated dates for meeting them Clear tracking, reporting and verification requirements 27

28 MDE Restoration Targets for Federal Facilities MDE estimates nutrient targets for federal facilities that are equivalent to a 20% retrofit of any untreated impervious area at a facility. The target only applies to the urban stormwater loads from federal facilities. Don t worry about agriculture or forests on federal lands

29 What are stormwater practices and how do they actually work? The goal of stormwater practices is to design the post-development landscape so that it functions as if the hard surfaces were actually forest or meadow cover thereby reducing flooding, bank erosion and pollutant loads to predevelopment levels

30 Bioretention: How it Works Runoff flows into a bioretention facility and temporarily ponds. Water then slowly filters through the filter bed and either is collected by the underdrain and sent to the storm sewer system or infiltrates into the surrounding area. 30

31 Key Parts of Bioretention Ponding area Filter media Pea gravel Overflow Vegetation Optional: Underdrain + stone Infiltration sump 31

32 Infiltration

33 How It Works Infiltration 33

34 How It Works Surface Sand Filter

35 Permeable Pavement

36 How It Works Permeable Pavement Photo credit:

37 Grass Channels

38 How It Works Grass Channels 38

39 Wet Stormwater Pond

40 Dry Stormwater Pond

41 Non-structural Stormwater Practices Street Sweeping Storm Drain Cleanouts BMP Maintenance Municipal Housekeeping Pollution Prevention Plans Control of Illicit Discharges

42 What is the Full-Cycle management approach?

43 Full Cycle Management 1.Monitoring 7. Makeover 2.Assessment 6.Maintenance 3.BMP Design 5.Inspection 4.Construction

44 What is the Full Cycle Approach? 1. Establish minimum performance objectives for the practice 2. Ensure the practice is feasible for the site 3. Meet design criteria to maintain performance over entire cycle 4. Be properly constructed and established 5. Regularly inspect using visual indicators 6. Use landscape contractors to maintain BMP function over time 7. Perform a make-over when functions diminish

45 What can I do at my facility to prevent stormwater pollution? Be the eyes and ears at your facility Coach your co-workers on pollution prevention practices Look for illicit discharges in your storm drain system Make your landscaping greener Know when and how to maintain your stormwater BMPs

46 6 Common Hotspot Operations Vehicle Operations Outdoor Material Waste Management Physical Plant Turf / Landscaping Areas Unique Operations

47 Coach Your Co-workers Involve employees to increase their stormwater pollution prevention IQ Use the CSN Stormwater Benchmarking Tool to assess your site:

48 Prevent Parking Lot Pollution Evaluate the condition, drainage and maintenance of the parking lot to reduce runoff and reduce pollutants

49 Prevent Spills at Fueling Areas Inspect Fueling Areas at the Site Cover Fueling Islands Dry Spill Response Kits Redesign Flows to Prevent Storm Drain Entry

50 Seasonal Operations/Outdoor Wash-water Assess seasonal operations at the facility with the potential to produce polluted runoff or wash-water out of the storm drain system

51 Spill Control and Response Walk the site to find areas of greatest spill risk, and critically evaluate how to improve spill response Provide spill kits at high risk areas of site Update emergency contact numbers Create an unannounced fake spill

52 Prevent Runoff From Outdoor Storage Walk the site to look for materials stored outside on a temporary or permanent basis that could come into contact with rainfall Place materials on pallets Temporary cover Secondary containment and berms No streak or stain lines on way to storm drain

53 Exterior Dumpster Management Walk the site to look for dumpster juice and spillage Dumpster covered, have lids and are water tight Schedule pickups with solid waste contractors frequently Disconnect dumpsters from storm drain

54 More on Dumpsters

55 Adopt Green Landscaping Practices Modify landscaping contracts to reduce inputs of fertilizer, pesticides and water Avoid herbicides on fence lines Use native species in landscaping

56 Check for Dry Weather Flows in Drain Follow the storm drain system until it outfalls to a ditch or stream and look for evidence of illicit discharges or dry weather flow Do outfall investigation Trace the source and fix it

57 Questions and Comments 57