Cosmopolitan Engineering Group has extensive experience in providing both public and private clients with water resource analysis and design for both naturally occurring and artificially created storm drainage basins. These studies and projects have included comprehensive stormwater planning, regional detention facility analysis and design, flood plain analysis, and stormwater system design.

Hydrologic Studies / Hydraulic Design

Comprehensive stormwater and watershed planning consists of developing strategies for managing storm runoff within a defined project area. Our staff is experienced with all of the hydrologic models currently available, including HSPF, SWMM, HEC-1, and the SBUH methodology. Additionally, we are experienced with both local and state design standards and criteria.

Thea Foss Waterway Source Control - City of Tacoma, WA Clear Creed Drainage Basin Feasibility Study - Pierce County SWM, WA T Street Gulch Erosion Control - City of Tacoma, WA

Culverts, Outfalls, and Pipelines in Sensitive Areas

Our staff has prepared planning documents, engineering plans, and specifications for stormwater culverts and pipelines on numerous projects, many crossing environmentally sensitive areas. These projects range in complexity from culvert replacements to providing fish passage to sanitary sewer force mains crossing wetland environments. In addition, the members of Cosmopolitan Engineering Group have been involved in the planning of numerous stormwater and sanitary sewer outfalls, with several of them resulting in the preparation of plans and specifications.

Diru and Flett Creek Culvert Replacements - Pierce County SWM, WA Salmon Creek Culvert Replacement - Sumner, WA South Magnolia Outfall Replacement - King County, WA Willapa River TMDL - Raymond, WA

Stormwater Detention Facilities

Members of our staff have been responsible for the evaluation and design of stormwater detention facilities, some of which incorporated natural and/or constructed wetlands. The facilities have ranged in size from a1/2-acre-foot local drainage facilities to a 350-acre-foot regional facility that utilizes an existing 70-acre natural wetland for detention and a facility with an embankment over 40 feet high. Additionally, several of the large detention facilities we have designed required a Dam Safety Evaluation and Permit to satisfy the Department of Ecology regulations. We have a thorough understanding of Ecology's requirements and have established a positive working relationship with their staff members. We have provided the required experience and expertise to address these detention facility and dam safety issues on many projects, including:

T Street Sedimentation Facility - City of Tacoma, WA Rody Creek Regional Detention Facility - Pierce County SWM, WA