MWWTP Headworks Upgrade

The County Commissioners of Charles County are seeking proposals from qualified engineering firms for services on the Headworks Upgrade Project at the Mattawoman Wastewater Treatment Plant. This project is a comprehensive initiative aimed at enhancing the capacity, reliability, and efficiency of the plant's preliminary treatment processes. This project involves significant upgrades to the existing headworks facility, which is integral to the initial phase of wastewater treatment. The primary objectives of this project are to increase screening capacity, enhance grit removal capacity, implement screenings washer/compactors, prevent freezing, and mitigate flooding.

The current headworks facility operates with two mechanical bar screens and two vortex grit removal units, all located in a below-grade concrete structure connected to the influent pumping station. These systems are critical for removing large debris and grit from incoming wastewater to prevent damage and wear to downstream equipment.

Current Issues and Challenges

Several issues have been identified in the existing headworks facility:
I. Insufficient Capacity:
The current bar screens and grit removal units do not have the capacity to handle peak flow conditions effectively. During peak flows, the plant struggles to manage the volume of incoming wastewater, leading to potential overflows and operational inefficiencies.
II. Lack of Redundancy:
The existing setup lacks redundancy. If one of the bar screens or grit removal units fails or requires maintenance, the plant's capacity is significantly compromised, increasing the risk of untreated wastewater passing through the system.
III. Screenings Management:
The plant currently discharges wet screenings directly into dumpsters without the benefit of screenings washer/compactors. This practice results in high water content, weight, volume, and odor in the screenings, which causes landfill disposal concerns.
IV. Freezing Issues:
Exposed portions of the bar screens are susceptible to freezing during cold weather. This has necessitated the use of temporary propane heaters, which are not only inefficient but also pose a risk of damage to the equipment.
V. Flooding and Equipment Submergence:
High operational levels in the influent wet well during peak flows have caused flooding in the lower levels of the headworks. This results in the submergence and subsequent damage of electrical and mechanical equipment, leading to frequent repairs and replacements.