Comprehensive Environmental Inc. (CEI) is the geotechnical engineer working as a sub-consultant on behalf of the Massachusetts Department of Transportation (MassDOT) to provide subsurface exploration, geotechnical evaluation and foundation design for a bridge in Taunton Massachusetts. MassDOT is proposing to replace a single span 30-foot-long bridge that carries Scadding Street over the Snake River in Taunton, MA.
This project is being implemented to widen the bridge, to improve resiliency against scour and to improve safety / roadway geometry for the crossing. The design includes the construction of a new 40-foot single span bridge that is 44’ feet wide and provides accessible sidewalks for pedestrian access and fishing.
CEI design services included a geotechnical investigation consisting of drilling test borings and evaluating blow counts at several locations which included borings completed on land and underwater using a boring rig mounted on an offshore barge. The evaluation also included preparing logs for each test borings in accordance with MassDOT standards; developing soil profiles and subsurface condition summaries; monitoring ground water levels; locating bedrock and completing rock cores; and preparation of a laboratory testing plan of subsurface soil samples for gradation, classification and of soil/rock strength characteristics.
Subsurface data was used in the identification of soil parameters for foundation design and to identify potential impacts of subsurface conditions on the design and construction of the proposed bridge replacement. CEI completed geotechnical analysis to evaluate the encountered soils and identify general soil properties to be used to geotechnical design parameters. Several assumptions were made to determine the soil properties and parameters based on SPT analysis and laboratory testing results.
Based on the completed geotechnical analysis, CEI completed design of foundation elements, including support for the abutments, cantilever wingwalls and retaining walls to support the relocated roadway through the adjacent lake, river and floodplain. The foundation designs were completed in accordance with LRFD and included end bearing steel H-piles driven to bedrock, battered piles to resist uplift forces and mechanically stabilized earth retaining wall components.
Foundation design and recommendations were provided to structural designers for bearing capacity, settlement predictions, earth pressures, soil / rock strength moduli and potential stresses. The design includes the selection of materials, sizing of foundation elements and spacing layout of those elements. CEI also completed a lateral load analysis and seismic assessment including calculations for potential lateral seismic earth pressures, pile resistance to lateral pressures and potential bridge deflection from lateral forces. CEI also provided recommendations for foundation element construction including bedding and compaction requirements; potential settlement concerns; excavation support and anticipated dewatering needs.