Jefferson County Stormwater Engineering Services

As the primary Municipal Separate Storm Sewer Systems (MS4s) permit holder with several communities as co-permittees, Jefferson County is required to have a Stormwater Management Plan (SWMP) for pollution prevention. The SWMP must address the following six minimum control measures (MCMs) through stormwater engineering services:

• Public education and outreach
• Public involvement and participation
• Illicit discharge detection and elimination (outfall mapping)
• Construction site runoff control
• Post-construction site runoff control
• Pollution prevention and good housekeeping in County/municipal operations

HR Green’s on-call stormwater engineering services were retained to address item #3 (from the above-mentioned MCM) by completing an Illicit Discharge Detection and Elimination (IDDE) system inventory of outfalls into waters of the US within the urbanized areas of unincorporated Jefferson County. The inventory included approximately 55 miles of streams within the Big River Watershed (BIG), Grand Glaize Creek – Meramec River Watershed (GDG), Hamilton Creek – Meramec River Watershed (HMM), and Heads Creek Watershed (HDC).

HR Green’s stormwater engineering services used a high-accuracy mobile GIS approach for collecting IDDE System Points and Concern Points along the stream lengths identified for this project. HR Green’s on-call stormwater engineering services prepared mobile data collection applications for updating the County’s GIS database by making data additions and changes from the field. To promote efficiency and protect data integrity, data collectors were equipped with custom pick-lists to standardize the recording of asset information. Photos of outfalls and points of concern were captured by the field staff and linked directly to their corresponding asset records in the database.

To assist Jefferson County with future compliance activities, HR Green provided a value-added GIS-based map book and a comprehensive database report and photo log detailing all IDDE System Points and Concern Points along the 55 stream miles investigated.