RK&K’s Environmental Water/Wastewater Group is partnering with Harford County, Maryland Department of Public Works on designing upgrades to various processes at the county’s Sod Run Wastewater Treatment Plant (WWTP). The facility had undergone significant improvements under the Enhanced Nutrient Removal (ENR) that was completed in 2014, but several of the unit processes have not undergone upgrades for over forty years.
The county originally intended to complete each of three upgrades as independent construction projects with a phased approach. To attract more qualified bidders, in 2022, county officials combined the three major project designs into a larger, single design and construction project. The three tasks included:
- Converting the gas chlorination system to UV disinfection to address safety considerations and cost/availability of chlorine.
- Upgrading the anaerobic digesters to improve performance, gas capture and utilization.
- Design upgrades to two of four primary clarifiers constructed in the late 1960’s including new mechanisms, drain system, scum vaults and scum pumps.
The project is challenging because it requires a thorough knowledge and understand of all parts of the WWTP, and how each unit process our team is working on affects the others and the plant’s treated effluent quality. Our team has experience working both for this client and designing similar upgrades to the three-unit processes that make up this project at other sites. Additionally, we have all the necessary disciplines to complete the project holistically.
During the preliminary engineering and design phases of the project our team did extensive field verification through photos, measurements, and annotations to the record drawings. Additionally, we put together a very detailed sequence of construction which includes constraints that the contractor must follow regarding which tanks and unit processes can be out of service at the same time and for how long. Maintenance of plant operations is at the forefront of the design documents to allow the wastewater treatment plant to retain the capacity it needs at each stage of the process during construction. For example, we designed a temporary chlorination system to be utilized during the conversion of the disinfection system from chlorination to ultraviolet radiation.
Combining the three projects into one larger project will benefit the client in several ways. First, a larger project with a higher construction value will attract more qualified bidders which will provide the plant a better product. Secondly, having one general contractor responsible for the entire project eliminates the headaches associated with several contractors working at a wastewater treatment plant at the same time. Lastly, it reduces the client’s management burden by only having one construction job to manage and coordinate with plant operations rather than three. In this case, Harford County was able to retain a construction manager.
Note: Maia will be discussing this project at the 2023 Chesapeake Tri-Association Conference from August 29th – September 1st in Ocean City, Maryland.
About the author:
Ms. Tatinclaux is a Project Manager with RK&K specializing in wastewater treatment design. Ms. Tatinclaux has worked on a variety of treatment projects in the mid-Atlantic area with a focus on rehabilitation projects. She has an extensive background in biosolids treatment having previously worked as the Process Engineer for the anaerobic digestion system at the Back River WWTP. Ms. Tatinclaux also serves on the Short-Course Committee and teaches biosolids related coursework.