Proposed - Massachusetts Water Resources Authority

S. 141 Wastewater Process Optimization
Project Purpose and Benefits
Contributes to improved public health
Provides environmental benefits
Extends current asset life
Improves system operability and reliability
To optimize wastewater system operating procedures and make system improvements and modifications to ensure
maximum wastewater treatment, minimum operating and maintenance costs, and extension of the useful life of
system assets.
Project History and Background
This project was established to support MWRA Business Plan strategies, which recommend the development of a
wastewater process optimization plan, central monitoring facilities for the sewerage system, rehabilitation of
wastewater interceptors, and the utilization of automation and new technology to increase efficiency.
The completed planning phase included the development of an updated hydrologic and hydraulic model (InfoWorks
CS) and the evaluation of optimization alternatives under typical and extreme storm events. MWRA has evaluated
several of the alternatives and has using hydraulic information gained during this phase to develop facility control
logic under the Wastewater Transport SCADA Implementation Project. Two alternatives, which include pipeline
modifications, will be taken further as defined below. The model developed under this project continues to be used
by MWRA staff for in-house system evaluation and NPDES reporting requirements and by outside consultants to
support CSO-related and collection system improvement projects.
Scope
Sub-phase
Planning
Somerville Sewer
Siphon Planning
Manhole Structure
Flood Protection
Design and
Construction
North System
Hydraulic Study
Hydraulic Flood
Engineering
Analysis – North
System
Scope
Evaluate collection system and facility modification alternatives to maximize wastewater
treatment and minimize operating and maintenance costs.
Design and construct a connection between the upstream end of the Somerville Medford
Branch Sewer and the North Metropolitan Relief Sewer to reduce surcharge and divert
flow away from the Cambridge Branch Sewer and Delauri Pump Station.
Further evaluate the benefits of constructing a redundant siphon crossing the Mystic River
from the Cambridge Branch Sewer to the Delauri Pump Station.
Evaluate, design and construct modifications to manholes and backflows preventers at
some CSO locations to prevent elevated rivers, streams and flood zones from back-flowing
into the MWRA’s regional collection system. During the recent March 2010 storm events,
flood waters were documented well above the rim elevation of many MWRA structures
that was suspected to contribute to system capacity limitations and extended periods of
high flows.
Review the frequency and extent of sanitary sewer overflows (SSOs) in the area tributary
to Chelsea Creek Headworks and to evaluate and recommend alternatives to optimize the
performance of the collection system and to eliminate or reduce SSOs or relocate them in
the least potential of human health risks or environmental impacts.
Opportunities for implementation of system optimization measures or more significant
system modifications which will be identified during the initial study. Additional followup
analysis or project implementation may be done under this phase.
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