IWS was awarded a Design-Build contract by the Sundown Sanitary Sewer District (SSSD) in Astoria, Oregon in January 2008 to replace their existing wastewater plant to meet new Oregon DEQ discharge requirements for the facility under their National Pollutant Discharge Elimination System (NPDES) permit. SSSD was operating under a Notice of Violation by the ODEQ for discharge issues and needed to meet a tight deadline for upgrading the plant. IWS was contracted by SSSD to meet the deadline
under a Design-Build contract.
Project History
The original SSSD facility was constructed during World War II in the mid 1940’s to service a hospital and related housing units being built to house anticipated casualties from the US invasion of Japan. The site was later developed in the 1970’s by a private owner into a subdivision which includes 85 residential and 39 apartment
units. The average daily flow from the development is 22,000 gallons per day. The existing plant had a digester building, an aeration basin, a clarifier, sludge drying beds, and a chlorine contact chamber. In addition, the client addressed collection system infiltration issues to minimize impact to the treatment system.
The IWS Solution
IWS developed a cost effective design by utilizing existing components wherever
possible. Operating the existing system while making modifications to the structures proved to be a bit of a challenge, however, with careful planning and execution, IWS was able to incorporate all modifications to the new system without taking the existing system off-line. The design includes the following components
and approach:
- IWS utilized the existing clarifier and aeration tank as primary treatment tanks. The tanks were inspected and deemed to be in operable condition. Reusing the existing concrete basins allowed the client a substantial cost savings.
- IWS installed the following new treatment system components:
a. 30,000 gallon recirculation tank
b. 6,000 gallon dosing tank
c. Cover for concrete aeration basin
d. 12 - AX-100 Advantex Recirculation Pods along with auxiliary equipment
e. UV Disinfection System
f. 60kw standby generator - Discharge remained the same under the NPDES permit with the treated effluent being discharged into Young’s River.
Current Status
IWS will complete construction of the system in the fall 2009 and make the switch over to the newly configured plant. IWS is projected to complete the permitting, engineering, and construction of the project from start to finish within nine months of the signed design-build contract. The design-build contracting vehicle enabled the project to proceed quickly and meet the compliance schedule required by the ODEQ.
