Brief Project Description
Frederick Winchester Service Authority owns and the Frederick County Sanitation Authority operates the Parkin’s Mill Wastewater Treatment Plant which has an existing hydraulic capacity of 2.0 MGD. As a result of increasing flow and service demands, the facility was approaching its rated capacity in late 2003; thereby, requiring an Action Plan for the facility.
The first components of this Action Plan were a Process Capacity Study along with a Comprehensive Plan Review to identify possible expansion options and process performance. Upon concluding the Comprehensive Plan Review and based on forecasted growth rates within the service area the Authorities committed to the expansion of the facility to a 5 MGD facility.
In proceeding with this plan, new Bay Regulations and waste load allocations for nutrients adopted by the State Water Control Board were incorporated into the design and expansion of the facility. To maintain capacity needs and meet waste load allocations, the design of the facility has included Enhanced Nutrient Removal technology to achieve discharge concentrations not to exceed 0.3 mg/l total phosphorus and 4.0 mg/l total nitrogen, along with annual loadings under the WQMP Regulation assigned to the Parkin’s Mill facility.
The Preliminary Engineering Report presented a project scope that would require an extensive upgrade to the 2 MGD facility, in order to provide for: nutrient removal and expansion for future capacity needs.
The 5.0 MGD Expansion and ENR Upgrade Project will consist of the following:
- Headwork’s facilities that would include a second influent pumping station and associated grit removal and screening facilities (non-eligible component)
- Construction of primary clarification and primary sludge pumping facility (considered to be 20% eligible)
- Construction of 2 new bio-reactors (each rated at 0.7565 MG) with 54% of the volume and 25% of the aeration components eligible for cost share.
- Conversion of four existing oxidation ditches to plug flow bio-reactors with necessary baffles and selector zones to provide for nutrient removal along with upstream primary anoxic tank volume. The total volume of the existing ditches equates to 2.0 MGD; the volume resulting from conversion and new construction is 3.93 MG. Converting the existing ditches was considered 100% eligible for cost share.
- Construction of 2 new secondary clarifiers (0.0878 MG each and considered to be 50% eligible) with associated waste and return pumping facilities (considered to be 46% eligible).
- Construction of effluent traveling bridge sand filters, effluent filter pumping station, and supplemental carbon and ferric chloride chemical storage and delivery equipment.
- Construction of a sludge stabilization building with polymer addition and mechanical thickening of WAS.
- Expansion of solids handling to include: sludge storage, and installation of second centrifuge for sludge dewatering.
- 85% of the design flow was felt to be reasonable/necessary