Interconnection

Block Island Wind Interconnection Substations

gzadan — Thu, 07 Oct 2021 12:57:09 +0000

Block Island Wind Interconnection Substations gzadan Thu, 10/07/2021 - 08:57

Challenge

Alleviating Block Island’s dependence on expensive oil-fired electricity generation required interconnection to the Rhode Island mainland and to the 30 MW offshore Block Island Wind Farm located approximately 3 miles southeast of the Island.

Solution

Energy generated by the turbines is transmitted to the Block Island Substation, and then to the Rhode Island mainland to the Dillon’s Corner Substation, via 34.5 kV submarine cables. These substations not only support the Block Island Wind Farm, but also connect to the bulk electric grid and telecommunications services on the mainland, increasing reliability and decreasing cost of utilities to the island residents. The Block Island and Dillon’s Corner substations both included: 1) new control houses; 2) 35 kV terminal transmission line structures or underground feeder lines; 3) transformers; and 4) ancillary equipment and bus structures. GZA completed the geotechnical borings, laboratory testing, and evaluation of subsurface conditions, and provided the project team with geotechnical and civil consulting support throughout the design development and construction phases. GZA was on site to assess the need for and extent of removal of weak and organic existing site soils, to be replaced with controlled structural fill. Several foundation support systems were used at the substations, including drilled shafts, mat foundations with integrated oil containment systems, and shallow foundations following subgrade improvement. GZA also worked with the project team during construction of a neighboring 5,600 square-foot underground infiltration basin.

Benefit

Expediting the design construction of these interconnection substations was vital to enhancing the Island’s critical infrastructure, as well as connecting the first utility-scale U.S. offshore wind farm to the bulk electric grid.

Geotechnical services for design and construction
Civil engineering services during construction
Construction control services for: drilled shaft (caisson) foundations, mat foundations with integrated oil containment systems, removal of unsuitable soils, 5,600 square foot underground infiltration basin, 150-long retaining wall, and temporary support of excavation

Rhode Island

Energy

Onshore Geotechnical for Offshore Wind

gzadan — Tue, 14 Sep 2021 20:23:40 +0000

Onshore Geotechnical for Offshore Wind gzadan Tue, 09/14/2021 - 16:23

Challenge

The projects involved the design of three onshore interconnection substations, three export cable landings, and over 20 miles of underground transmission cable tasked with bringing power generated from three offshore wind farms to land and connecting to the onshore grid. GZA was the geotechnical engineer responsible for collecting subsurface information along the cable routes and at the substations and providing engineering recommendations for the project. Challenges included permitting though local, state, and federal agencies, and working on state and local public roads, private property, railroad rights-of-way, and beaches.

Solution

GZA worked with the project design team to plan and execute the subsurface exploration programs. GZA’s methods balanced the technical needs of the project with the budget and schedule, while minimizing the disturbance to abutting properties and other stakeholders. GZA coordinated all geotechnical laboratory testing, including thermal resistivity of soils for each site that was utilized in the development of ground models by the underground cable designers. GZA also provided recommendations for site development and foundation design for substation equipment. One of the substations is located on a closed landfill with development issued related to future settlement of the landfill material and organic soils below the landfill layer. Furthermore, GZA evaluated the soils below the landfill and organics for liquefaction potential and found that the soils were susceptible to seismic liquefaction. GZA recommended low-capacity piles and provided pile design criteria to address these issues.

Benefit

Resources from multiple GZA offices local to each project site were utilized for each project. That local knowledge, GZA’s geotechnical engineering experience, and extensive work within the offshore wind industry, were all integral to the successful execution of the subsurface exploration programs.

Geotechnical services for export cable landings, onshore cable routes, and onshore electrical substations associated with 3 offshore wind developments in the Northeast U.S.
Planning the explorations programs, permitting, subcontractor management, and geotechnical reporting in support of design of horizontal directional drilling, underground duct banks, and substation equipment foundations
Geotechnical field and lab testing, thermal resistivity sampling, 4-point ��Ϸ��nner field resistivity testing, and environmental characterization of soil and groundwater, including for PFAS
Unexploded ordinance (UXO) survey and UXO Avoidance Plan
Construction over landfill and liquefiable soils

Energy

Geotechnical Engineering Services

Hudson High Voltage Direct Current (HVDC) Converter Station

gzadan — ��Ϸ��d, 01 Sep 2021 12:46:40 +0000

Hudson High Voltage Direct Current (HVDC) Converter Station gzadan ��Ϸ��d, 09/01/2021 - 08:46

Challenge

GZA was asked to provide geotechnical services and environmental studies for Siemens Energy, Inc. for its proposed Hudson High Voltage Direct Current (HVDC) Converter Station in the New Jersey Meadowlands, part of a transmission project intended to convert the power between New Jersey’s Public Service Electrical & Gas (PSEG) 230 kV grid and New York’s Con Edison 345 kV grid. The site includes active trucking and warehouse operations as well as wetlands.

Solution

Geotechnical: GZA performed a geotechnical subsurface exploration program and provided geotechnical and foundation recommendations for the project. The major structures for the proposed station include four transformer pads, one spare transformer pad, two valve halls, a control building, six AC filter banks consisting of a total of 18 foundation pads, and various other necessary support facilities including valve hall cooling fans, smoothing reactors, fire protection water storages and pump house, and a heavy transport access road.

GZA’s subsurface exploration consisted of eight soil borings, three observation wells, and five cone penetration soundings (CPT). Geotechnical laboratory testing was performed on soil samples and field “slug�� tests to determine in-situ permeability. GZA determined that the site, located within the Hackensack Meadowlands, was underlain by man-made fill over a layer of organic peat, over glacially deposited silt, sand, and clay, over glacial till and bedrock. Groundwater was approximately five feet below ground surface.

To optimize foundation designs, GZA provided recommendations for four different types and sizes of deep foundations for the most heavily loaded structures, and recommendations for shallow foundations for lighter and less settlement-sensitive structures. A small amount of general filling of the site was required which posed the potential for additional settlement. Another portion of the site required the filling of virgin wetlands; slope stability and settlement of that area were addressed.

Environmental: GZA’s environmental studies included a Phase I Environmental Site Assessment (ESA), a Phase II Site Investigation, and additional site investigations as warranted. The Phase I ESA provided an opinion on the presence of Recognized Environmental conditions which may result in hazardous substances or petroleum products in the soil and groundwater at the site.

GZA’s Phase II Site Investigation evaluated soil and groundwater conditions at potential Areas of Concern (AOCs) identified in previous environmental reports completed by others and made available to GZA, as well as AOCs identified during GZA’s Phase I ESA. Potential AOCs on the site include former locations of underground storage tanks, an on-site septic system, transformers, a railroad spur, building floor drains and sumps, and portions of the site downgradient of off-site groundwater plumes. An additional site investigation was completed to further delineate impacted areas of soil and groundwater contamination confirmed in the initial Phase II Site Investigation.

Hazardous Materials: A pre-demolition Hazardous Materials Survey of the site building included testing and assessments for asbestos-containing materials (ACM) and a visual survey for residual solid and hazardous wastes, universal wastes, and potential poly-chlorinated bi-phenyl (PCB)-containing components. Given the age of the facility and strong likelihood that detectable levels of lead are present in the paint, lead safe work practices will be required during demolition. Construction Management: GZA completed a Construction Contaminant Management Plan to present the extent and magnitude of contaminated soils and groundwater, in light of proposed construction activities that may encounter these contaminated media. In addition, the plan evaluated the impact of regulatory requirements on planned construction and development plans. Ecological: GZA also evaluated a ��Ϸ��tlands Mitigation Plan for the site prepared by others. GZA’s evaluation included a cost estimate to implement the plan.

Benefit

This project successfully harnessed the breadth of GZA’s in-house, multidisciplinary services, facilitating a fast-tracked project schedule that met the client’s needs.

Site Encompasses Areas of Industrial Use and ��Ϸ��tlands
Multiple Services Provided: Geotechnical, Environmental, Hazardous Materials, Construction Management, Ecological
Fast Track Schedule

Energy

Geotechnical Engineering Services

Demolition and Clean-up of Fire-Damaged Battery Storage Building

Anonymous — ��Ϸ��d, 25 Sep 2019 17:10:56 +0000

Demolition and Clean-up of Fire-Damaged Battery Storage Building Anonymous ��Ϸ��d, 09/25/2019 - 13:10

Challenge

When a fire severely damaged a 10,800 square-foot Battery Equipment Storage Systems (BESS) building on a Hawaiian wind farm, the demolition and lead release clean-up from the batteries required a skilled team. GZA was retained as Construction Manager for the demolition and clean-up.

Solution

Within two days of the client’s request, GZA arrived in Hawaii, developed a scope of work, specifications and bid package; GZA also conducted site visits with demolition contractors and scrap dealers. The fire caused severe damage to the steel-framed building and caused lead from the “environmentally friendly�� lead acid batteries and inverter systems to be released to the floor slab and surrounding components. Lead debris was present in the form of hazardous ash, molten lead, and burnt lead batteries plates still remaining in the battery racks. GZA conducted a pre-demolition asbestos survey; developed and received regulatory approval and permits for a Demolition and Clean-Up Work Plan; coordinated with utilities, subcontractors, and recycling/disposal facilities; characterized waste streams; and established work areas and site controls. Recycling and salvage of materials was maximized by meticulous waste segregation. Following demolition of the structure, the surface of the slab and surrounding soils was remediated to below applicable clean-up standards. GZA documented construction activities, interfaced with regulatory agencies, conducted perimeter lead (Pb) air monitoring, and collected and analyzed clean-up confirmation samples of concrete slabs and surrounding soils. GZA’s detailed closeout documentation report, prepared on the client’s behalf, was accepted by the Hawaiian regulatory authorities.

Benefit

GZA provided this wind energy client with the construction management and environmental expertise required for complex demolition and site close-out �� meeting an aggressive schedule and on budget �� allowing reconstruction to occur.

Insights

Conducted Pre-Demolition Hazardous Material Survey
Obtained Regulatory Approval for Demolition and Clean-up Work Plan
Characterized Waste Streams and Coordinated Recycling and Disposal Facilities
Conducted Perimeter Air Monitoring
Segregated, Removed, and Containerized Hazardous Materials and Non-Hazardous Materials Remaining in Building
Maximized Salvageable Materials through Intensive Waste Segregation
Achieved Regulatory Closeout
Met Aggressive Schedule and Completed on Budget

Industrial

Energy

Environmental Site Investigation & Remediation

EHS Regulatory Compliance

Construction Management