St. Louis Lemay Sanitary Sewer Improvements

St. Louis Lemay Sanitary Sewer Improvements

Location: St. Louis, Mo.

Client: Metropolitan St. Louis Sewer District

The Metropolitan St. Louis Sewer District (MSD) is expediting project delivery throughout its service area by contracting with watershed consultants for design of various infrastructure improvement projects. This approach is being used to comply with the requirements of a consent agreement with the U.S. Environmental Protection Agency, which requires elimination of all combined sewer overflows (CSOs) and sanitary sewer overflows (SSOs) over a 23-year period. Burns & McDonnell has been selected as the watershed consultant for the Lemay Watershed and will provide design and engineering services during construction to implement MSD's CSO Long Term Control Plan (LTCP) and SSO control plan. Approximately 70 projects will be designed over a 5- to 10-year period.

  • Preliminary studies
  • Field investigations
  • Public and private inflow removal
  • Sanitary and storm sewer design
  • Hydraulic modeling

The Lemay Service Area covers approximately 119 square miles in the City of St. Louis and a portion of St. Louis County west and south of the City. The program comprises four watersheds within the Lemay Service Area, including Gravois Creek, Mackenzie Creek, Martigney Creek and University City. Some areas are served by combined sewers while others are served by separate sanitary and storm sewers. Wastewater treatment is provided at the Lemay Wastewater Treatment Facility (WWTF).

In general, the project scope includes review and evaluation of sewer sizes, recommended alignments and lengths, including hydraulic analysis and design assumptions, as well as private inflow reduction (PIR), and preparation of preliminary studies for some projects. Wet weather storage facilities and pump stations will be constructed to handle peak flows during storm events. The storage facilities may be above or below ground and will be designed to blend in with the surrounding area. The storage facilities will be equipped with automatic controls for filling, emptying and flushing, as well as remote operation via MSD's SCADA system.

Sanitary replacement and relief sewers will be designed to augment existing sewers or replace undersized/deteriorated sewers. Because of the highly developed nature of the project area, alignments must be carefully selected to avoid disruption of existing homes, commercial buildings, roadways and utilities. Coordination with utilities will be critical since proposed corridors are shared by multiple facilities. Public infiltration/inflow (I/I) reduction, consisting largely of CIPP (cured-in-place pipe) sewer lining, will be performed. Private I/I sources such as downspouts and area drains will be disconnected throughout the service area to reduce the load on the sewer system.

The Burns & McDonnell team includes 15 firms providing specialty services related to surveying, geotechnical, hydraulic modeling, storage facility design, and public and private I/I removal. Coordination and management of such a large program with numerous stakeholders will involve the use of web-based collaboration tools and a suite of project management and scheduling software. Regular reporting and communication with EPA and the Missouri Department of Natural Resources will be performed to keep the program on track and meeting the consent decree requirements. A community-wide public involvement program is included to keep residents informed and obtain buy-in and feedback.

  • Consent decree driven
  • Multi-year program
  • Sanitary and combined sewer overflow removal
  • Sewer separation
  • Wet weather storage facilities
  • Public involvement program