Combined Sewer Separation Program - New Haven, CT

Cardinal Engineering Associates was commissioned to prepare a Facility Plan for the City’s wastewater collection system in 1979. The objective was to evaluate the existing combined sewer system in the City of New Haven and develop a facility plan that eliminates the discharge of untreated combined sewage overflows and optimizes the use of existing collection and treatment systems in a feasible and environmentally acceptable manner. After economic analysis of four alternatives, Complete Separation was selected. The Facility Plan developed by Cardinal which included preliminary design of 120 miles of storm sewers was approved by the State DEP in 1980.

Sewer Separation Design and Construction

Cardinal has completed design and provided construction engineering services for eight major combined sewer separation projects in New Haven between 1986 and 2003. These projects included approximately 8,500 linear feet of interceptor stormwater interceptors ranging in size from 48" diameter to 102" diameter as well as 25,000 linear feet of collector storm sewers. These projects included many difficult conditions. Maintenance of traffic and minimization of impacts on businesses on busy city streets in downtown New Haven required pipe jacking, nighttime work and bridging of jacking pits during the day.

Completed Projects:

Combined Sewer Overflow Correction Project, Orange Street, Phase I and II

This project was located in the East Rock area of the City of New Haven. Phase I included construction of 2,800 linear feet of 72" to 84" storm sewer interceptors and 2,800 linear feet of 15" to 36" collector storm sewers and inlets on Orange Street, a major urban collector. Due to the extreme depth of the interceptor - 25' deep and below existing combined sewers, the interceptor was constructed by pipe jacking. 11 Jacking pits were required. Deep wells were used for dewatering in the sandy soils. Phase II included the installation of 12,500 LF. of 15" to 24" and 5,000 LF. of 36" to 48" storm sewer collectors, and 450 storm laterals for private inflow separation. Construction of Phase II was completed in the Spring of 2003.

Combined Sewer Overflow Correction Project: Elm Street Storm Sewer Interceptor

One of the first CSO projects Cardinal Engineering Associates was commissioned to design for the City of New Haven. Elm Street is located in Downtown New Haven. The area serviced was between Church Street and Broadway. The project consisted of the installation of a total of 1900 linear feet of RCP pipe. The pipe sizes ranged from 15" to 72". Seven jacking pits were necessary to install 760 feet of 54" Reinforced Concrete Jacking Pipe and 475 feet of 60" Reinforced Concrete Jacking Pipe. Due to the location of the project, it was necessary for night construction with bridging of jacking pits for daytime traffic.

Combined Sewer Overflow Correction: Goffe Street Interceptor Sewers

This project entailed the separation of combined sewers in the area of Goffe Street and included survey, design, plans and specifications, contract administration and resident inspection services of 5,400 linear feet of storm sewer interceptor ranging in size from 18" to 102" and 1400 linear feet of sanitary sewers.

Combined Sewer Overflow Correction Project: Church Street and Grove Street

The project area is Church Street, Wall Street, Grove Street and Whitney Avenue in downtown New Haven. It involved the installation of 2300 linear feet of 8" to 42" RCP storm drainage with two jacking pits for 300 linear feet of 30" and 42" Reinforced Concrete Jacking Pipe.

Combined Sewer Overflow Correction: Sherman Parkway Area

This project entailed the separation of combined sewers in the area of Sherman Parkway and included survey, design, plans and specifications, contract administration and resident inspection services for 5,000 linear feet of storm sewer ranging in size from 15" to 18" and 2,500 linear feet of 24" to 36" storm sewers.

Combined Sewer Overflow Correction Project: Haven Street

Cardinal Engineering was retained by the City of New Haven to perform a drainage study of the Haven Street area and to design improvements to eliminate flooding in the neighborhood. The solution was the construction of approximately 1000 linear feet of 4' x 8' Concrete Box culverts to relieve flooding. Work included survey, design, preparation of contract documents, contract administration and construction inspection services.

Long Wharf Drive Extension and Storm Sewer Interceptor

The project entailed the extension of Long Wharf Drive a distance of one mile along New Haven Harbor. This project included the design of roadway drainage and also the design of 1,000 linear feet of 60 Inch Diameter Storm Sewer Interceptor and outfall to New Haven Harbor. The interceptor sewer and end wall were supported by a pile foundation.