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Eastern Washington Phase HMunicipal Stormwater Permit <br />APPENDIX 6 — Street Waste Disposal <br />Street Waste Liquids <br />General Procedures: <br />Street waste collection should emphasize retention of solids in preference to <br />liquids. Street waste solids are the principal objective in street waste collection and are <br />substantially easier to store and treat than liquids. <br />Street waste liquids require treatment before their discharge. Street waste liquids <br />usually contain high amounts of suspended and total solids and adsorbed metals. <br />Treatment requirements depend on the discharge location. <br />Discharges to sanitary sewer and storm sewer systems must be approved by the <br />entity responsible for operation and maintenance of the system. Ecology will not <br />generally require waste discharge permits for discharge of stormwater decant to <br />sanitary sewers or to stormwater treatment BMPs constructed and maintained in <br />accordance with Ecology's Stormwater Management Manual for Eastern Washington. <br />The following order of preference, for disposal of catch basin decant liquid <br />and water removed from stormwater treatment facilities, is required. <br />1. Discharge of catch basin decant liquids to a municipal sanitary sewer connected <br />to a Public Owned Treatment Works (POTW) is the preferred disposal option. <br />Discharge to a municipal sanitary sewer requires the approval of the sewer authority. <br />Approvals for discharge to a POTW will likely contain pretreatment, quantity and <br />location conditions to protect the POTW. <br />2. Discharge of catch basin decant liquids may be allowed into a Basic or <br />Enhanced Stormwater Treatment BMP, if option 1 is not available. <br />Decant liquid collected from cleaning catch basins and stormwater treatment wet vaults <br />may be discharged back into the storm sewer system under the following conditions: <br />• The preferred disposal option of discharge to sanitary sewer is not reasonably <br />available, and <br />• The discharge is to a Basic or Enhanced Stormwater Treatment Facility. If <br />pretreatment does not remove visible sheen from oils, the treatment facility must be <br />able to prevent the discharge of oils causing a visible sheen, and <br />• The discharge is as near to the treatment facility as is practical, to minimize <br />contamination or recontamination of the collection system, and <br />• The MS4 owner/operator has granted approval and has determined that the <br />treatment facility will accommodate the increased loading. Pretreatment conditions <br />to protect the treatment BMF may be issued as part of the approval process. <br />Following local pretreatment conditions is a requirement of this permit. <br />August 1, 201=1 Appenifix 6 — ,SfMel Waste Disposal Page I qf'2 <br />