The Evergreen-Farmington Sewage Disposal System (EFSDS), operated by the Oakland County Drain Commissioner (OCDC), provides sanitary sewer service to all or parts of sixteen (16) Oakland County communities.  In the 1970s, HRC initiated a comprehensive study of the entire EFSDS to identify and evaluate system problems including excessive infiltration/inflow, combined sewer overflows, separate sewer overflows, and capacity needs for future growth.  Facilities planning reports, completed in the 1970s, presented alternatives for addressing sewer system deficiencies including proposed facilities and locations as well as feasibility and cost evaluations.  These reports were used to obtain federal grant funding.

• Infiltration/Inflow Studies: Each individual community in the EFSDS conducted infiltration/inflow studies of their local collection systems. HRC conducted these studies on behalf of many of the communities. HRC also provided coordination among all sixteen (16) communities to ensure consistency among the individual studies. In addition, HRC worked with MDEQ to ensure that the studies met grant funding requirements.

• Regional Sewer Improvements: HRC planned and designed regional system improvements including interceptor relief sewers in several locations throughout the EFSDS; pump stations; and sanitary retention basins in Farmington Hills and Lathrup Village. Implementation of these projects required coordination among various agencies including MDEQ.

• Combined Sewer Overflow (CSO) Facilities: HRC designed three (3) CSO retention/treatment facilities in the EFSDS. The planning and design of each basin required coordination of multiple agencies. For example, planning and design of the Bloomfield Village CSO retention/treatment facility required coordination with Birmingham, Bloomfield Hills and Bloomfield Township - the three communities tributary to the CSO - as well as Oakland County and MDEQ. To facilitate this coordination, HRC conducted routine technical meetings with all parties throughout project implementation. HRC also assisted the county and communities in obtaining State Revolving Fund (SRF) funding for the CSO facilities.

• 1999 Phase 1 Study: HRC conducted an evaluation of ongoing separate sewer overflows and basement flooding problems in the EFSDS. The study included model evaluation of intense storm events, determination of Town Outlet Flow (TOF), surcharge and capacity evaluations, flood prone manholes, pump station operation, siphon evaluation, and options for protection of flood prone basements. HRC assisted Oakland County in presenting the findings to the sixteen (16) communities and coordinating corrective actions. The Phase 1 study was presented to MDEQ as a first step in negotiating corrective action to address SSOs.

• An update to the Phase 1 study was completed by HRC in 2001 to address specific requests by MDEQ. This update (Supplement No. 2) evaluated intense rainfall events occurring in 2000 and summarized SSOs, TOF, and Segment III sewer capacity.

• HRC assisted Oakland County and the member communities in development of a regional short-term corrective action project to allow for flow transfer, preferential treatment of sanitary sewage and an option for commingling of sanitary and combined sewage.