Inflow & Infiltration Study - Middletown, CT

The existing sewage collection system in the City's Central Business District consists of combined sewers with an average age of 100 years. Due to the deteriorated condition of the existing sewers, groundwater infiltration into the system was excessive. In addition, the combined sewers also carried runoff from both roadway and roof drainage systems. The purpose of these projects is to eliminate the combined sewer overflows by designing a separate storm sewer system and by replacing or rehabilitating the existing combined sewers.

Cardinal Engineering has been retained by the City of Middletown, Connecticut, since 1987, to prepare final construction plans and specifications and to provide contract administration and resident engineering services during construction for 10 combined sewer separation and sanitary sewer rehabilitation projects.

Sewer System Evaluation Survey

The Sewer System Evaluation Study consisted of closed circuit television inspection and condition assessment of 12 Miles of combined sewers and over 200 manholes, smoke testing, dye testing of roof leaders, and exterior and interior inspection of over 500 buildings to identify sources of inflow such as roof leaders, yard drains, and sump pumps.

Cost Effective Analysis

After completion of the SSES, a cost analysis of various rehabilitation methods was done to determine the most effective method to eliminate infiltration from the combined sewer system.

Sanitary Sewer and Manhole Rehabilitation

Upon completion of the Sewer System Evaluation Survey, Cardinal Engineering proceeded with the design of rehabilitation measures to reduce infiltration into the system.

The following rehabilitation measures were considered:

• Total replacement
• Spot repairs or partial replacement
• Cured-in-Place lining
• Pipe bursting
• Chemical grouting of joints
• Fold-N-Form lining

A cost effective analysis was performed to determine the most cost-effective method of rehabilitation.

The final design included 8 miles of sanitary sewer replacement, spot repairs, 3 miles of cured-in place lining, 1 mile of chemical grouting and manhole rehabilitation.

Contract 19A included cured-in-place lining of 2000 linear feet of trunk sewer along Laurel Brook and the repair and lining of manholes. Manhole frames and covers were raised to prevent inflow replaced with watertight frames and covers. Contract 12 involved lining 1000 linear feet of sewers in a wetland area with deformed PVC.

Spot repairs were grouped into three categories:

1. less than 10 feet
2. 10-20 feet
3. 0-50 feet

Manhole rehabilitation will consist of joint sealing, repointing of brickwork, chemical grouting to seal leaks, rubber or pollyethylene sealing of brick collar, replacement of frames and covers, rebuilding of inverts, etc.

Cardinal Engineering also provided Resident Engineering Services and Contract Administration for ten (10) construction projects. Construction will be completed in 2007.

Cardinal Engineering assisted the City in obtaining funding from the state of Connecticut DEP under the Federal Lean Water Fund, and attended Public Information, WPCA and City Council Meetings to gain public support for these projects which were constructed over a 17 year period.