Managing Construction Stormwater: SWRO Contaminated Site Experiences Carol Serdar, LG Contaminated Construction SW and Hydroelectric WQ Compliance Manager (Water Quality Program SWRO) Managing Stormwater in Washington Conference, 8 March 2017 Session: Construction Stormwater Management Fundamentals 1
Construction Stormwater General Permit (CSWGP): Steps in permitting & management of sites with known contamination: Submit NOI and supporting documents with application Review data on site contamination & proposed stormwater management Visit Site site conditions, acreage, previous small slope failures, & adjacent surface water Issuance of CSWGP Compliance inspection Graduated enforcement Notice of Termination
How will contaminated construction stormwater be managed? SW Management typically described in: Stormwater Pollution Prevention Plan (SWPPP); and Temporary Erosion and Sediment Control (TESC) drawings These may be found in CSWGP condition S9. CONTAMINATED SITES REQUIRE ASSURANCE THAT CONTAMINATED STORMWATER/GROUNDWATER DOES NOT DISCHARGE FROM THE SITE. (ask about options later ) DOCUMENTS NEEDED FOR REVIEW: SITE SPECIFIC INFORMATION contamination (lab and other reports, maps with data locations, etc.) TABLE or list of known contaminants present within the footprint of ground disturbing activities, depth found, and concentrations; associated map showing data location. CONTINGENCY PLAN description for additional contamination found or suspected contamination present; dewatering plan SWPPP - Relevant portions include: site conditions, narrative on specific SW management, dewatering plan (if known and needed), etc. (? Opportunity for contractor to develop remaining portions?)
Contamination data review: Tacoma Smelter Plume: soils polluted by ~100 years of lead & copper smelting. Lava, slag, or beauty rock
Contamination data review: Complex sites require a lot of planning, including contingencies some sites have known contamination as well as unexpected
Site visit to understand site conditions and stormwater management Site conditions are unique Depend on lithology, slope angle, groundwater, contaminants (known and unknown), space for baker tanks and/or treatment system, neighbors, previous use of land, area of disturbance (correct on NOI?) Proximity to waters of the state Discharge locations (sanitary vs storm systems)
BMPs gone wrong; (unfortunately, just before compliance inspection) INLET PROTECTION BERM constructed with contaminated material
BMPs gone wrong (cont.) PLASTIC SHEETING CHECK DAMS
Check dams over filled with sediment, carried turbid stormwater to treatment system which eventually couldn t keep up and was flooded out; ultimately discharge a lot of turbid water occurred into the Puget Sound.
BMPs gone wrong (cont.) SILT FENCES (1 of 2)
SILT FENCES (2 of 2)
Need to apply adaptive management and use AKART (all known and reasonable technology). This site uses a TESC drawing to track and document adaptive management and AKART throughout their site.
CSWGP COMPLIANCE and ENFORCEMENT: ADAPTIVE MANAGEMENT and AKART INSPECTIONS to monitor for compliance GRADUATED ENFORCEMENT: CORRECTIONS REQUIRED NOTICE OF PENTALTY NOTICE OF VIOLATION
List of WQP Regional Contacts and Headquarters for contaminated CSWGP: Take home messages for sites with known contamination: 1.Provide contamination data, site conditions, and stormwater management plans early in the application process for prompt CSWGP coverage. 2.Ongoing: provide lab results call your regional contact with any question about stormwater management. CRO ERO NWRO SWRO HQ Lloyd Steven, Jr. (509.329.3610) Shannon Petrisor (509.329.3610) Greg Stegman (425.649.7019) Carol Serdar (360.407.6269) Amy Moon (360.407.6467) 14