Design-Build WWTF Services for Portland Water District
Weston & Sampson provided the Portland Water District with design/build services for its .2 to.6-mgd wastewater treatment facility on Peaks Island. This variable flow plant servicing mostly summer seasonal residents was in need of a disinfection upgrade. Chemical deliveries to the island had become costly and undesirable. Portland Water District pre-purchased a Trojan PTP3800 disinfection system utilizing two SS troughs in series where each trough was furnished with its own control panel for monitoring and alarm notification.
Our wastewater engineering services consisted of performing a desktop hydraulic model and evaluation of the proposed plant process piping and decant pumps, electrical loading calculations, and structural loading of the proposed upgrades. By project completion, the staff was fully trained on the new system and record drawings stamped by a Maine registered Professional Engineer were provided.
Construction of upgrades began following the preliminary engineering assessments. Upgrades to the WWTF included:
- Re-purposing existing chlorine storage areas for the UV system by removing the wall between the two areas, installing a new door, coring holes for piping, and installing concrete pads to support the new system. Providing a curbed area sloped to drain between the two troughs for lamp cleaning, and providing a hose station to facilitate cleaning.
- Installing dual Trojan PTP3800 UV disinfection systems and control panels.
- Providing new 6-inch and 12-inch stainless steel piping to feed the UV system and discharge treated effluent. Installing new drain piping for UV trough washdown and for the curbed area.
- Providing a new electric unit heater and modifying the existing ventilation system.
- Installing conduit and wire to power new UV system, new single phase transformer, feeder, breaker, distribution box, lighting and receptacles.
- Providing power and instrumentation connections, re-connected I/O, test and demonstrated I/O continuity.
- Providing and demonstrating UV system alarms generated from the control panels and a low water level switch
- Providing programming to utilize available volume in the SBR and skip decanting if a UV system alarm occurs.
- Providing control narratives and code modifications of the system, including tagnames, and screen modifications.