Washtenaw County Storm Water Asset Management Plan

Spicer Group was hired by Washtenaw County to do an asset management inventory of 297 miles of the county’s open drain systems, all 324 of the county’s storm water ponds and associated structures, and 6 MDEQ-regulated dams as part of an awarded grant through the MDEQ’s Storm water, Asset Management and Wastewater (SAW) program.  This also included six miles of large-diameter confined-space-entry inspections. A GIS-based PACP collection application was also developed for inspection of large diameter pipes in the system. Watershed-level water quality samplings were done utilizing grab samples and automated samplers. The team then utilized ArcGIS and CityWorks to build a digital, mobile GIS database of the entire system for reference and analysis.

Using all that information, the team developed a township-level SWMM model to identify capacity issues, as well as pollutant loadings from multiple future development scenarios. The team also developed a condition rating system for inspected assets to determine future maintenance schedules. Once all this data was received, a storm water management plan was created for Washtenaw County with an emphasis on Pittsfield Township, which has the most potential for future development.