GSI’s stormwater services include comprehensive support for underground injection control permitting and program development; contaminant source evaluation and control; and MS4 permits.
Underground injection control (UIC) facilities are important stormwater management tools in Washington and Oregon. They are subsurface structures that collect stormwater and allow it to seep into the soil above the water table (called the vadose or unsaturated zone), rather than to surface water or to a collection system. GSI’s staff is experienced with planning and implementing UIC assessments. Assessments can range from collecting on-the-ground information at individual UICs, to GIS support, to evaluating multiple UICs with one complex modeling effort. More about GSI’s UIC Expertise.
Contaminant source evaluation and control can be a critical component for municipalities managing their stormwater system and meeting permit requirements. GSI has experience investigating and documenting historic and current contaminant release to stormwater and combined sewer overflow systems; reconstructing historic system configuration; and identifying potential upland source of contamination.
GSI also provides Municipal Separate Storm Sewer System Permit (MS4) support. Our work focuses on developing Stormwater Pollution Prevention Plans (SWPPP) and conducting public outreach efforts related to the elements required by the SWPPP and MS4.