The MDC’s Clean Water Project: South Hartford Conveyance and Storage Tunnel (SHCST)
Hartford - West Hartford, Connecticut
Owner: The Metropolitan District Commission
Client: AECOM; Camputaro & Son; Kenny/Obayashi IV, A Joint Venture
The Metropolitan District Commission’s Clean Water project is a 15-year plan designed to control and reduce the overflow of untreated sewage into natural waterways. The largest construction component of the CWP is the construction of the South Hartford Conveyance and Storage Tunnel (SHCST). This 18 foot in diameter by 4 miles long structure will handle sewage from West Hartford, Newington and Hartford and will be able to store 41.5 million gallons of sewage until such time as this stored sewage can be treated at the Hartford Treatment Plant. The SHCST is being constructed by tunneling within bedrock 200 to 250 feet below ground surface. The MDC intends to accomplish this work under five separate contracts: Contract #1: Preparatory Utility Relocation; Contract (Awarded) #2: Tunnel and Shaft Construction; Contract #3: Tunnel Pump Station; Contract #4: Franklin Avenue and Maple Avenue Consolidation Conduits; and Contract #5: Flatbush, Arlington, New Britain and Newington Consolidation Conduits. The SHCST is expected to be completed no later than 2023. Freeman Companies has been providing on-call professional services since 2012.
Construction Contract 1: Preparatory Utility Relocation: Freeman Companies is currently providing Land Surveying and Geotechnical Engineering services to the Prime Contractor for Contract 1. The Preparatory Utility Relocation includes a new 23kV concrete primary duct bank and manholes at the Tunnel Pump Station site as well as construction of a new concrete switchgear pad for both permanent and temporary power. Once completed, Eversource (formerly CL&P) will pull and terminate the conductors along with installing new switchgear. Freeman Companies is providing comprehensive monitoring services, including but not limited to: coordination with utilities and railroad, deep benchmarks, deformation monitoring points, monthly monitoring, and additional monitoring.
Geotechnical Engineering Support to AECOM: For this project Freeman Companies is providing preliminary subsurface exploration/technical monitoring of test borings and detailed logging of bedrock structural features observed in bedrock core samples recovered from the test borings. Freeman Companies has also provided geotechnical and environmental services to MDC including a geotechnical peer review of the Geotechnical Data Report (GDR) for the Tunnel (involving review of the GDR and technical memorandum summarizing comments and recommendations regarding the GDR). Freeman Companies, LLC has also assisted the MDC in developing a GIS database of existing and new subsurface information, standard QA/QC protocol for the project, developing strategies for reuse of excavated materials, and addressing potential contamination issues; coordinated preliminary geotechnical design studies for eleven different sewer separation projects within Hartford and West Hartford, and final geotechnical and environmental design studies for the Tower Avenue and Airport Road sewer separation projects, and assisted in the team review of a portion of the Homestead Avenue Interceptor Extension project consisting of a curved microtunnel, the first curved tunnel constructed in the United States.
CSO Conduit 3D Basemapping: The firm was selected as one of four professional land surveyors to provide three-dimensional survey basemapping for the project. Freeman Companies’ scope included: Flatbush Avenue CSO Conduit (approximately 3,200 LF) and New Britain Avenue SCO Conduit (approximately 6,200 LF), providing complete Civil 3D AutoCAD Basemap from face-of-building to face-of- building (survey corridor 100’ wide in non-street areas); 3D basemap which included topography, property lines, all structures and all buried utilities; and four (4) and six (6), respectively, microtunnel shafts, each of which included a 1 acre off-street (or side street) area as part of the 3D survey basemap.
Construction Contract 2: Freeman Companies’ Land Surveyors, Geotechnical and Civil Engineers are providing Geotechnical Instrumentation and Monitoring and Weekly Stormwater General Permit Services to the Prime Contractor, Kenny/Obayashi. The firm has also provided a “Tunnel Geologist” to the Contractor. These services began in 2016 and will continue until the Tunnel’s completion in 2023.
In The News:
‘Chris Tonzi: Tunneling to Success’
‘MDC Awards $ 279.4 Million Tunnel Project’
'NEREJ: Freeman Companies, LLC'
Freeman Companies is providing the following services:
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