Salem Wastewater Treatment Plant Reed Bed Expansion
The City of Salem currently owns and operates a wastewater treatment plant. The design capacity of the plant is 0.741 mgd. Currently, wastewater is treated in an oxidation ditch followed by settling in three clarifiers. There is an existing peak flow holding basin to store excess flows during peak flow conditions and two sludge storage basins for storing sludge. In the past, the city utilized sludge drying beds for treating solids before final disposal.
In 1999, the City of Salem concstucted reed beds to treat biosolids generated at the wastewater treatment plant.
Reed beds are constructed wetlands that provide sufficient storage, treatment and volume reduction of biosolids prior to final disposal. Currently the city has four small beds and two large beds with the total area of the beds being 19,021 SF.
In the year 2005, 807,563 gallons of sludge at solids concentration of 2% was applied to the reed beds. The average loading rate for the sludge was 43 ga/SF/yr. But based on 2005 flow data the average flow rate for the plant was 0.58 mgd. At a 2% solids concentration, the total sludge produced was 1.24 MG. The amount produced exceeds the existing reed bed capacity by 36.2%.
Archer was hired to analyze and design improvements to the reed beds that would accommodate current flows and allow for future expansion.
An Engineering Report was written to review existing conditions pertaining to and affecting the desired improvements as required by MDNR. Archer submitted applications and reports necessary to obtain construction permits.
Plans and specifications were compiled so the city could seek competitive bids for the construction of two additional reed beds identical in size and capacity to the city's two largest existing reed beds.
Archer provided construction staking and construction administration to ensure that work is being done in accordance with the Contract Documents.