Wastewater Engineering & Control
Supervisory Control and Data Acquisition / Process Control
LRWWU engineers have an important role in managing the operations of the Duck Island WWTF through the Supervisory Control and Data Acquisition (SCADA) System. Most of the processes in the Duck Island facility are controlled remotely through SCADA, which is a state-of-the-art distributed control system. SCADA's maintenance and troubleshooting is overseen by the Engineering Supervisor. In addition to overseeing the SCADA system, LRWWU engineers also work closely with the Operations Division to ensure that the treatment processes are operating smoothly and providing effective treatment. A particularly important aspect of process control is the monitoring and troubleshooting of odors that may be generated throughout the wastewater treatment process.
Miscellaneous Engineering Activities
Miscellaneous, small-scale construction projects are implemented by LRWWU engineers, who also execute the design of collection system and treatment plant improvements and oversee the construction of these projects. In addition, numerous technical and administrative projects and programs are managed by LRWWU engineers, such as website maintenance, sewer abatements, collection system characterization, spill response, and various plans and records.
Capital Improvement Planning & Implementation
LRWWU manages a large Capital Improvement Program (CIP) that is responsible for the reinvestment of more than $100M in the past decade. The CIP has focused on upgrading failing or inadequate equipment and infrastructure in the sewerage/drainage collection systems, as well as at the Duck Island and satellite facilities. Priority is given to making wastewater transport and treatment systems reliable and effective. The design and construction of these improvements is typically performed by outside contractors who are supervised by LRWWU.
An important aspect of LRWWU's CIP is its Long Term Control Plan (LTCP) for the reduction of Combined Sewer Overflows (CSOs) and Sanitary Sewer Overflows (SSOs). CSOs result from the discharge of combined wastewater and stormwater to a local waterway during a storm event; these CSO discharges relieve overloaded transport and treatment systems. SSOs are caused by surcharging of impaired and/or overloaded sewers, which then spills wastewater onto streets or private property, including basements. While both of these overflow types are undesirable, SSOs are considered more serious because of their impact on human health and property.
LRWWU has developed a multi-phase LTCP program that is reviewed and approved by the Massachusetts Department of Environmental Protection (MassDEP) and the United States Environmental Protection Agency (USEPA). The LTCP began in 2003 with a ten year Phase one program with two primary components:
- A sewer separation program that reduced SSOs by eliminating local sewer surcharging.
- A wet-weather treatment / storage project that optimized the capacity and operations of existing infrastructure at the Duck Island WWTF and LRWWU's sewer interceptor system.
To date, these improvements have greatly reduced the volume and frequency of CSOs and SSOs in LRWWU's service area. Ten years ago, LRWWU typically discharged upwards of one billion gallons of CSOs into the local waterways. In the past four years, the average annual CSO discharge volume has been slightly more than 200 million gallons - almost an 80% reduction. Similar gains have been made with SSO reduction. As importantly, several pieces of critical equipment at Duck Island have been replaced and many miles of sewerage pipes have been rehabilitated.
LRWWU has plans to continue its CIP/LTCP program with additional improvements aimed at further reductions to CSOs/SSOs and increased reliability of the wastewater transport and treatment systems. The proactive approach taken with this capital reinvestment program will ensure the long-term effectiveness of LRWWU's facilities.