Proposed Annexation Highlights Dexter’s Need For Water And Sewer Improvements

Last spring, the City of Dexter was approached by Baker Road Land LLC, Dexter Land Holdings LLC, and Dick and Maureen Sloan with the request to annex all or a portion of six parcels of land along Baker Road, currently in Scio Township, into the City of Dexter.

The parcels are located just south of the Dexter Business and Research Park and consist of approximately 242 acres. On the east side of Baker Road are 222 acres with the remaining 20 on the west side with access to Mill Creek.

The proposed development of the land would be residential or mixed use (residential and industrial) with a Residential Equivalency Unit value of 405. The proposal also included the request for the City to provide water and sewer to the parcels. The City of Dexter requested the developers contract the engineering firms of OHM to analyze the City’s water supply and Fleis & VandenBrink (F&V) to study the Dexter’s sewer system and consult the City on the impact such a development would have on the existing infrastructure.

Both firms recently submitted their findings to the Dexter City Council. In addition to current city use, the following commitments and future developments were taken into consideration:

Future City Developments:

  • Grandview Commons
  • 3045 Broad St
  • Victoria Condos
  • 150 Jeffords St
  • New Elementary School
  • Business Park Development
  • Projected 20-year city growth

Supply for Outlying Areas

  • Island Lake Road
  • Huron River Drive
  • Mast Road

OHM introduced their report with the statement, “While the City of Dexter has experienced robust growth in the past 20 years, there remain certain areas of the City that have either not been developed, are still under construction, or are underdeveloped when compared against underlying zoning.”

The biggest and immediate challenge to Dexter’s water supply is the need for an additional water source. Currently the City is supplied by five wells drawing on two aquifers Both of these water sources have what is considered a “high drawndown” which determines the rate at which water can be extracted.

OHM calculated that Dexter’s current water system as a whole is already operating at capacity and recommends improvements in the form of a new well, modifications to the treatment system, a new water tower and increases in the distribution system to better serve immediate needs as well as future developments. Projected cost for the stated improvements is estimated just under $7 million.

In summary, the report emphasized that any future improvements should begin with a new well. “Based on our knowledge of the existing treatment plant, wellfield, and raw water lines, there is limited expansion potential at the existing sites. Due to the production limitations of the City’s two aquifers, it is recommended that the City explore a new well site in order to find an aquifer capable of providing adequate supply to meet existing and future demands. The specific location and capacity of wells will largely dictate subsequent infrastructure discussions.”

The City of Dexter retained Fleis & VandenBrink (F&V) to evaluate the impact the proposed Baker Road Properties development would have on the City’s Wastewater Treatment Plant (WWTP). The original WWTP was constructed in 1979. The 1999/2000 improvements project converted the original Rotating Biological Contactor (RBC) process to a conventional activated sludge process. An equalization basin was constructed in 2009 to store high flows during wet weather events. Most recently, the existing anaerobic digester was upgraded for better biosolids treatment.

In their report, F & V states, “the existing influent pumps are in need of replacement, the current screening and grit removal systems are inadequate, and the existing sand filters must also be replaced.”

F & V describes that Dexter’s current WWTP “is a conventional activated sludge plant. This means that organic matter and ammonia is biologically removed in aerated tanks by microorganisms present in the wastewater. These microorganisms (bacteria, protozoa, etc) have been carefully managed by returning a portion of the concentrated microorganisms (called return activated sludge, or RAS) and blending it with the wastewater needing treatment.”

“This process brings the food source (biochemical oxygen demand, BOD, a measurement of the biologically degradable organic material, and ammonia) into contact with the microorganisms so that it can be reduced. Eventually a portion of the microorganisms must be removed from the process stream as they die out or become too concentrated in the aeration tank; therefore a portion of the concentrated biomass (called waste activated sludge, or WAS) is consistently removed from the secondary clarifier and routed to the anaerobic digester as part of the solids management process.”

When taking into consideration all current and projected demand on Dexter’s sewer system, F & V summarized their report saying, “annexation of the proposed Baker Road Properties development into the City would require improvements to be made at the Dexter WWTP. The capital cost for the secondary treatment process improvements alone ranges from $3.1 – $5.7 million. When considering required screening, grit removal, influent pump replacement and tertiary treatment, the capital cost for a complete treatment plant improvements project increases to $8.0 – $8.9 million.”

Improvements to Dexter’s water and sewer systems remain a high priority for City Council members and will continue to report the progress as it is made available.

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