Category Archives: Water/Wastewater

Washington Township Water Storage Tank

Washington Township, Michigan

Washington Township constructed a new 100-foot diameter, 1.5 million gallon water storage tank to help meet the needs of this rapidly growing township. In addition, new asphalt driveways, a pump house, and detention basins were constructed for the $4.3 million project. The tank walls were constructed with layers of shotcrete and pre-stressed steel wire wrapped around the tank, with an overall pre-stressed steel wire wrapped length of 22.5 miles.

Fast Facts

Project Owner

Washington Township, MI

Scope

G2 Consulting assisted Giffels Webster and Washington Township during design and construction.

G2 Services Provided

Geotechnical Engineering
Special Inspections/Materials Testing

Challenges/Solutions
    • Unsuitable fill soils and unstable granular soils were present at the foundation bearing elevation. G2 provided undercut and subgrade stabilization recommendations to support the tank foundations.
    • Shallow perched groundwater challenged construction. G2 provided dewatering recommendations so undercuts and subgrade stabilization could be performed in dry conditions.

Smart. Results. Fast. G2’s geotechnical solutions minimized costly subgrade undercuts and kept the project on schedule.

Lavergne Avenue Sewer Project , Tunnel and Reservoir Plan

Chicago, Illinois

Chicago Department of Water Management constructed a relief sewer, including a series of drop shafts, drain connections, catch basins and inlets along North Lavergne Avenue. This $20 million project replaced a 100-year-old sewer, preventing flooding in neighborhood homes. Jay Dee Contractors performed this work, which included installation of over 2,600 feet of reinforced concrete pipe sewer in a shallow tunnel (about 60 feet below the ground), five drop shafts connecting to the shallow sewer tunnel or to the existing deep tunnel (over 200 feet below grade), and connection structures to join the two tunnels. G2 Consulting Group assisted Jay Dee by evaluating subsurface conditions to guide construction techniques.

Fast Facts

Project Owner

Chicago Department of Water Management

Scope

G2 identified dewatering requirements for construction of the drop shafts, providing shaft designs through both soft ground and underlying rock leading to the deep tunnel, and evaluating design alternatives to meet requirements for constructing the shallow tunnel under an existing railroad line. In addition, G2 assisted Jay Dee Contractors during tunnel construction when the tunnel boring machine unexpectedly encountered saturated soils.

G2 Services Provided

Geotechnical Investigation and Design

Challenges/Solutions
    • Tunnel shafts were drilled through soft soils which overlay a deeper rock layer. Limited data was available to define the interface of these two layers. G2 conducted a geotechnical investigation to characterize existing conditions and evaluate dewatering techniques for construction of the shafts.
    • One of the shafts extends over 230 feet, connecting the new shallow collector tunnel to the existing deep tunnel. G2 developed shaft construction designs to provide stability in the soft soil conditions and in the rock.
    • As the tunnel was being constructed, saturated soils halted work.  G2 assisted Jay Dee by designing an approach using grouting and dewatering techniques to enable work to continue.
    • An existing railroad line crosses over the alignment of the new tunnel.  G2 assisted Jay Dee Contractors as they analyzed design alternatives to meet the railroad’s requirements.

Smart. Results. Fast. G2’s geotechnical solutions facilitated an expedited construction schedule for this highly visible project by simplifying excavation of the tunnel drop shafts and addressing construction challenges during tunnel boring.

Dugway Tunnel Project

Cleveland, Ohio


Part of Cleveland’s long term plan to control sewage discharges into Lake Erie, the $179 million Dugway Storage Tunnel intercepts high water flow and directs it to proper treatment before discharge to Lake Erie. This project included the installation of a 24-foot diameter, 15,000-foot long storage tunnel at depths approaching 200 feet below ground level. Several consolidation sewers, diversion structures, and drop shafts were constructed to capture and store combined sewer overflow from the service area.

Fast Facts

Project Owner

Northeast Ohio Regional Sewer District

Scope

G2 Consulting Group designed shafts ranging in configuration from circular with concrete ring beams to trapezoidal with steel bracing to facilitate construction of both tunnels and junction chambers.

G2 Services Provided

Geotechnical engineering
Geotechnical instrumentation monitoring

Challenges/Solutions

      • Work was performed in populated areas, and the construction approach minimized impact on this population. G2 designed remote geotechnical instrumentation to monitor construction activities, including vibration, providing the team access to this important data on a real time basis.
      • This project was on a fast-paced schedule. In cooperation with Walsh, G2 submitted plans and specifications for all 6 Phase I shafts within 30 days of Notice to Proceed.

Smart. Results. Fast. G2 completed design of 6 shafts within 30 days to meet critical project milestones.

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Ann Arbor Wastewater Treatment Plant Upgrade

Ann Arbor, Michigan

Rehabilitation of the Ann Arbor Wastewater Treatment Plant was the largest capital project undertaken in the city’s recent history. The project included rebuilding half of the wastewater treatment plant and renovating the other half while remaining in continuous service. The City hired Walsh Construction Company to lead the work, and Walsh in turn tapped G2 Consulting Group to oversee the challenging underground work portion of the project.

Fast Facts

Project Owner

City of Ann Arbor

Scope

Because most of the work occurred underground, several geotechnical engineering firms were retained by subcontractors to perform work. G2 coordinated these technical efforts for consistency among the various disciplines on site and managed Walsh’s geotechnical risk.

G2 Services Provided

Geotechnical engineering
Geotechnical instrumentation monitoring
Retention wall design

Challenges/Solutions

      • One of the great challenges at this project site was the hydrogeological characteristics. The complicated artesian conditions coupled with the depths of required excavations and the presence of the Huron River along the perimeter of the project site required careful consideration and coordination among all the trades involved.  G2 provided an independent evaluation of site dewatering to help expedite the subcontractor submittal approval process and to evaluate the proposed phased dewatering across the site.
      • G2 constructed a mathematical model of the hydrogeological conditions and calibrated the model based on actual pumping and drawdown response on the project site. G2 used existing geotechnical data along with the geotechnical instrumentation data being collected during the course of the project to evaluate how much dewatering to perform during specific underground tasks across the site. This reduced the amount of energy consumed during construction by only pumping the amount required at specific locations.
      • Several small braced excavations were required during construction.  G2 designed earth support systems using the materials and equipment available on site allowing Walsh to self-perform work and expedite the schedule.

Smart. Results. Fast. G2 provided geotechnical solutions to address challenging conditions for this highly visible project, expediting the schedule, reducing costs and managing risk.

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Clintondale Pump Station

Clinton Township, Michigan


After nearly four decades of service, the Clintondale Pump Station was experiencing serious problems: its three, 500 horse power pumps had outlived their life, its operations were outdated, maintenance had to be done in confined space, and the lines leading to the facility were severely inadequate to feed the pumps. The Macomb County Public Works Office retained a construction team led by Walsh Construction to construct a facility to meet current and future needs.  Walsh turned to G2 Consulting Group to solve the challenging geotechnical conditions that were threatening construction.

Fast Facts

Project Owner

Macomb County Public Works Office

Scope

G2 Consulting Group provided geotechnical engineering consulting to the construction team to address artesian conditions on the project site.

G2 Services Provided

Geotechnical Design
Remote Geotechnical Instrumentation
Construction Engineering

Challenges/Solutions

  •  Extensive underground construction was required to construct the new pump station design, and the team knew that artesian groundwater conditions existed on site.
  • Instead of proceeding with the expensive jet grouting originally recommended to address this, G2 designed a depressurization plan to manage artesian groundwater conditions that included temporary earth retention systems and a geotechnical instrumentation monitoring plan to proceed with construction safely.
  • Key to this approach was a remote geotechnical instrumentation plan to continuously monitor groundwater pressures within the aquifer around the shafts and settlement within the cohesive soils at different depths to verify anticipated conditions. The use of continuous monitoring proved to be especially beneficial when structural questions arose during demolition and when the site lost power during dewatering.

Smart. Results. Fast. G2 developed a more conventional construction approach that ultimately saved the owner nearly $2 million, while enabling the construction team to better manage owner risk while maintaining the project schedule.

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Bay Area Water Treatment Plant

Bay County, Michigan

A project that was four decades in the making – construction on a new $59.6 million, 40,893-square-foot Bay Area Water Treatment Plant was completed in July 2015. The facility provides water to nearly 38,000 customers from a state-of-the-art membrane water treatment plant. Result: increased capacity, dual transmission lines, best in class technology.

Fast Facts

Project Owner

Bay County Department of Water & Sewer

Scope

New water treatment plant, two finished above ground water tanks, yard piping and equalization basin, plus two miles of new dual transmission lines.

G2 Services Provided

Geotechnical Recommendations and Construction Engineering

Challenges/Solutions

  • The compacted, three-month project design schedule hinged on completion of the geotechnical investigation and design. G2 expedited all aspects of work to maintain the overall schedule.
  • The overall site was raised five feet to elevate new buildings and tanks above the floodplain. Approximately three to four feet of undocumented fill existed below building and tank locations.  G2 recommended removal/replacement of undocumented fill with engineered fill to enable use of shallow foundations, instead of an expensive deep foundation system.
  • G2 assisted the design team in developing drawings and specifications for the proposed geotechnical instrumentation, dewatering and drainage, backfill and compaction, excavation support and compaction, and granular materials to address the project challenges.
  • Groundwater was as shallow as three feet below existing grades. G2 performed extensive analyses to evaluate site dewatering to lower the groundwater table and allow undercutting/ backfilling, trenching and deep excavations in dry conditions.
  • Existing structures and utilities were vulnerable to damage during construction of new facilities.  G2 recommended hydro-excavating at existing utilities to determine their as-built location, avoiding damage to existing structures.

Smart. Results. Fast. G2 expedited the geotechnical investigation, design and recommendations addressing subsurface construction hurdles while avoiding expensive deep foundation systems – keeping the schedule on track.

Connor Creek CSO Control Improvements

Detroit, Michigan

G2 provided geotechnical engineering services for Connor Creek CSO (PC-739), a Detroit Water and Sewer Department Wastewater Collection System construction project in Detroit, Michigan. The project provided for an 80-foot wide by 300-foot long retention basin to provide storage capacity of sewerage overflow. The overflow is stored in the basin until the wastewater collection system is able to receive the overflow, thereby stopping direct discharge into the Detroit River.

Fast Facts

Project Owner

Detroit Water and Sewer Department

Scope

80-foot wide by 300-foot long retention basin

G2 Services Provided

Geotechnical Engineering, Geotechnical Instrumentation and Monitoring, Temporary Earth Support Design and Slope Stability Evaluations

Challenges/Solutions

  • Extensive excavation into soft clay deposits resulted in potentially unstable excavation bottom.
  • G2 provided instrumentation that allowed for early warning detection of basal instability.
  • G2 provided instrumentation to monitor structural loads in the earth retention system to monitor actual loads and compare to the design loads anticipated.

 

Belle Isle CSO Control Improvements

Detroit, Michigan

G2 provided engineering services during construction of a new 90 foot by 45 foot retention basin for the control of sewer overflow conditions on Belle Isle in Detroit, Michigan. In addition, a new wet well was constructed adjacent to the existing pump station that required approximately 20-foot deep excavation in a 20 feet by 26 feet footprint.

Fast Facts

Project Owner

Detroit Water and Sewer Department

Scope

90-foot wide by 45-foot long retention basin

G2 Services Provided

Geotechnical Engineering, Vibration Monitoring, Pile Load Testing, Temporary Earth Retention Designs and Geotechnical Instrumentation

Challenges/Solutions

  • The primary concern was the deep excavation into soft clays resulting in excavation bottom instability.
  • G2 performed extensive geotechnical investigation to capture in-situ soil strengths, and implemented staged excavation techniques to provide a stable and efficient excavation system.
  • G2 provided geotechnical instrumentation including inclinometers, vibration monitoring and settlement markers to provide for early warning systems for any bottom instability hazards.
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Oakland County Stream Bank Protection

Oakland County, Michigan

G2 provided geotechnical investigation services for several Oakland County Stream Bank Projects in the Village of Bingham Farms, Michigan to construct erosion protection systems.  Water mains and sanitary sewer lines near many of the sites are threatened by on-going erosion. G2 identified  subsoil conditions and assisted in development of corrective systems that are compatible with the soil conditions and the restricted access to the construction sites.

Fast Facts

Project Scope

Construction of erosion protection systems

G2 Services Provided

Geotechnical Engineering
Construction Engineering

Challenges/Solutions

  • Difficult access to the construction sites limited the choices for erosion protection.
  • G2 selected erosion protection systems to achieve the desired flow improvement characteristics.
  • G2 designed temporary earth support systems to provide protection to nearby utilities during stream bank improvement construction.