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Eastern Washington Phase U Municipal Stornni ater Permit <br />generated from PGIS areas. All runoff treatment facilities must be sized for the entire flow that <br />is directed to them. <br />Projects that meet the requirements for dispersal and infiltration (see Chapter 6 of the <br />Stormwater Management Manual for Eastern Washington (2004), particularly BMP T5.30) and <br />do not meet the thresholds for requiring oil treatment are exempt from basic treatment <br />requirements. Discharges to surface water from projects with a total PGIS area <5,000 square <br />feet are exempt from basic treatment requirements unless those areas are subject to the storage <br />or handling of hazardous substances, materials or wastes as defined in 49 CFR 171.8, RCW <br />70.105.010, and/or RCW 70.136.020. <br />Preservation/maintenance projects and some improvement or safety enhancement projects that <br />do not increase motorized vehicular capacities as defined in the sections `Exemptions" and <br />"Partial Exemptions" above are exempt from Basic Treatment Requirements. <br />Certain exemptions may exist for Category 4 wetlands (see the section "Use of Existing <br />Wetlands to Provide Runoff Treatment" at the end of this Core Element). <br />Any of these exemptions may be negated by requirements set forth in a Total Maximum Daily <br />Load (TMDL) or other water cleanup plan. <br />Metals Treatment <br />Metals treatment is required in addition to basic treatment for new development projects with <br />moderate -use sites, high -use sites, and sites that meet any of the following definitions: <br />• Industrial sites as defined by EPA (40 CFR 122.26(b)(14)) with benchmark monitoring <br />requirements for metals; or industrial sites subject to handling, storage, production, or <br />disposal of metallic products or other materials, particularly those containing arsenic, <br />cadmium, chromium, copper, lead, mercury, nickel or zinc. <br />• On -street parking areas of municipal streets in commercial and industrial areas. <br />• Highway rest areas. <br />• Runoff from metal roofs not coated with an inert, non -leachable material. <br />Metals treatment is required in addition to basic treatment for redevelopment projects with <br />high -use sites or high ADT roadways and parking areas and for projects where: <br />• An additional need for stormwater control measures to remove metals has been identified <br />through a TMDL or other water cleanup plan, or <br />• The project takes place at an industrial site that is subject to benchmark monitoring for <br />metals. <br />Exceptions: Unless a specific water quality problem has been identified, the following discharges <br />are exempt from metals treatment requirements: <br />• Discharges to non -fish -bearing streams. <br />Appendix I- Minimum Technical Requirements <br />Eastern Washington Phase II Municipal Stormwater Permit —August 1, 2014 <br />Page 12 <br />