Multiple means of cellular isolation, dewatering, and PCB sediment removal from a bypassed stream channel.
Large capacity pumping system deployed for complete stream bypass during remediation.

Sediment Removal Project – Ohio

ENTACT has completed a multi–year phased removal of PCB impacted sediments located within a flash flood tributary basin of the Great Miami River. General site activities included: elaborate safety planning; site preparations and storm water and erosion controls setup; installation of separate 50,000 gallons per minute  (GPM) and 9,000 GPM bypass pumping systems to re–route natural stream flow around the work areas; treatment of construction contact water; segregation, stockpiling, and management of PCB impacted floodplain soils and sediment (including those containing free product) prior to load–out and off–site disposal; removal and segregation of PCB impacted sediment, clay, and other native material from an outfall channel; installation of 550 linear feet (LF) of a nested cut–off wall using fiber reinforced plastic sheeting (FRP) with cement bentonite grout injection; vacuum excavation of multiple fiber optic utilities along an active railroad line; directional boring of a new sewer line under a ditch and existing railroad line to connect with an existing public sewer system; and all final site restoration activities. A total of 3,000 LF of ditch line and 5,600 LF of creek channel were remediated, 178,500 tons of impacted soil was transported off–site for disposal, and 4 billion gallons of water were treated in the process. Planning, preparedness, management and protection of work spaces in anticipation of flash flood events was critical to performing the work , protecting key environmental receptors, and the overall safety and ultimate success of the project.

Major earthworks including clearing, excavation, consolidation, and stabilization of 15,000 cubic yards of coal tar impacted soils. 

Former Municipal and Industrial Disposal Site Remediation – Pennsylvania

ENTACT completed remediation of three main areas (A, B, C) at a former municipal and industrial disposal site in Western Pennsylvania. Scope of work included: clearing; excavation and solidification of 15,000 cubic yards of coal tar impacted soil; segregation of impacted and non–impacted soils; on–site consolidation and or disposal of 20,000 cubic yards of impacted soils, coal tar sludge, and greensand; location, excavation and management of drums, tires, scrap metal, etc.; construction of lined and/or armored surface drainage pathways; sediment trap construction; capping of two separate pit areas and an on–site landfill; fencing installation; site restoration grading; and re–vegetation.

 

Cap construction at the Site B area encompassed 4.6 acres and included the installation of a geo–composite clay liner (GCL), 60mil HDPE membrane, drainage net, cover soil, vegetative cover on half of the site. The remaining half of Site B received lightweight cellular concrete, GCL, 60 mil HDPE, drainage net, and lightweight aggregate (Haydite) on the lower half of the site. Cap construction at the Site C area encompassed 3.8 acres and included the installation of a 40 mil HDPE membrane, drainage net, cover soil, and vegetative cover. Security fencing and gates were also installed as part of the site restoration process.

Deep trench excavation under a bentonite slurry to install a soil bentonite groundwater cutoff wall. 

Slurry Wall Installation – Colorado

As one of the leading specialty subsurface cutoff wall contractors in the nation, ENTACT has performed the design and construction of multiple groundwater cutoff slurry walls for an aggregate supplier in Colorado. The work is performed to replace existing cutoff barriers that exceed the Colorado State Engineer Office (SEO) and Division of Minerals and Geology (DMG) allowable seepage requirement for a sealed water storage reservoir. Additionally, the new walls functioned to better facilitate the dewatering efforts necessary to complete dry mining operations at the bottom of the pit. Once the mines are depleted and taken out of service, the upgraded slurry cutoff walls will serve to contain water within the deep mining pits. In an arid region of growing population, public surface water reservoirs are a vital resource and a valuable reuse option for depleted mining excavations.

 

Two typical mining pit recycling projects that ENTACT has completed in Colorado are:

 

Meadows Pit – The scope of work included: conducting a geotechnical investigation for designing a soil–bentonite vertical barrier and the associated backfill mixture materials and concentrations; developing the proposed slurry wall design parameters including engineered plan drawings and specifications; and constructing an approximately 9,080 foot long, 65 feet deep, 30 inch wide (363,200 fascial square foot) soil bentonite slurry wall keyed into the underlying bedrock to a minimum of 4.0 feet to 5.0 feet.

 

West Meadows Pit – The scope of work included: design and construction of a 7,438 foot long, 30 inch wide soil–bentonite slurry wall with an average depth of 29.4 feet, and a total facial area of 218,677 square feet. Work also involved protection and excavation around 8 active subsurface utility lines.

ENTACT owned custom reagent blending and batch plants. Hydration of precise reagent dosages delivered via slurry pumped to soil mixing location.
Mechanical stabilization of waste soils using weight to volume dosage blending and backhoe mixing.

MGP Site Remediation – Wisconsin

ENTACT completed remediation work at this former manufactured gas plant (MGP) site located in a downtown city area along Lake Michigan. The scope of work included: protective site preparations; demolition; debris removal; and off–site disposal of extensive subsurface structures including 3 gas holders, 3 purifier boxes, a power house outlet, abandoned MGP piping, and large concrete obstructions at a depth of up to 20 feet below ground surface. Demolition work also included the extraction of over five hundred sixty 35–foot long timber piles that were supporting a former gas holder. Remediation aspects of the project included excavation and off–site disposal of 25,000 tons of MGP–impacted soils and debris, subsurface utilities by–passing and re–routing, abandonment and grouting of existing sewer lines and manholes, in–situ solidification/stabilization (ISS) of 33,361 cubic yards of MGP impacted soils up to 34 feet below ground surface, excess volume (swell material) management, storm and groundwater management and treatment, and site restoration including placement of rooting zone soils and aggregate layers over the site.

 

ISS treatment was performed using a large diameter auger soil mixing technique. Equipped with a 10–foot diameter mixing auger, ENTACT used customized (Company owned) specialty process drilling tools mounted on our DELMAG RH–32 drill rig. Cement–Slag grout admixtures were blended and dose controlled using an on–site batch plant and conveyance system. The quality performance criteria accomplished were: treated material permeability of less than 1x10–7 cm/sec, and a minimum unconfined compressive strength (UCS) of 50 psi within a 28 day period.

Active and Abandoned Oil Production Fields

Active and Abandoned Oil Production Fields – West Coast

ENTACT is currently completing this Superfund remedial action and well abandonment activity over a multi–year period and on numerous individual sites. The work areas include both former and operating oil production fields, and their adjacent support facilities. Representative scopes of work include: completing slope stability improvements at a former mine with hilltop stockpiled mine spoils; remediating a pipe scrap yard area containing iron sulfide impacted soils and piping segments; supporting client investigative and characterization activities; removal of hazardous mercury impacted hot spots; and performing excavation and removal activities at a 270–acre abandoned oil field. Work in the oilfield involves TPH impacted soils excavation, waste management, waste transportation and disposal. Locations for this work are at former production well pads, and along pipeline routes across the property.

 

Excavation depths across this large site are being cycled to accommodate seasonal fluctuations in groundwater and thus minimize water management, shoring, and dewatering. On one portion of the site ENTACT has constructed a single span steel bridge to safely access a removal area.

 

For existing production wells, ENTACT completes preparations for abandonment including: demolition of concrete well cellars and sumps; excavation of impacted soils; restoration grading of the well pad area; and the removal of associated piping. Along pipeline routes, ENTACT performs removal or in–place abandonment of underground piping. Additional site activities include demolition of various support structures and foundations.

 

Aerial photo of large scale remediation activities at a phosphate fertilizer manufacturing site.

Former Phosphate Fertilizer Production and Manufacturing Sites Removal Action Program – Southeast

ENTACT has been a dedicated contractor within this program since 2006. We have performed removal activities to address lead and arsenic impacted soils, sediment, and groundwater at several former phosphate fertilizer production and manufacturing sites throughout the southeast United States. Project sites are located in commercial, residential and industrial zones; tidally influenced areas located adjacent to navigable waterways; marshes and uplands; and adjacent to active railroad lines and major highway rights–of–way. Scopes of work have included: excavation; water management; soil and sediment solidification/stabilization; sediment dredging; residential lot remediation; groundwater remediation; wetlands restoration; and general site restoration efforts. The majority of the projects involve treatment of hazardous soils and sediments prior to off–site disposal. ENTACT has successfully designed numerous bench scale treatability studies at our in–house laboratory to cost–effectively render waste materials as non–hazardous.

Location of a major Chromium Ore Processing Residue (COPR) remediation within a dense urban area in the northeastern US.

Chromium Impacted Site Remediation Projects – Northeast

ENTACT has performed numerous site cleanups as part of an area–wide Chromium Ore Processing Residue (COPR) remediation effort. General scopes of work have included: remedial designs, permitting, regulatory notifications and approvals from the City, Regional Water Authorities, and State regulators; above grade and subsurface demolition; small and large–scale excavation and load–out of COPR impacted materials; soil segregation and amendment; dewatering and water treatment; sheet pile and shoring systems installation; capillary break installation; cap construction; backfill placement; and site restoration. The volume of work has included placement of over 400,000 cubic yards of surcharge materials in a rolling fashion over seven designated areas; installation of over 180,000 square feet of epoxy coated sheet pile with grouted or sealed interlocks; excavation and segregation of 230,000 cubic yards of multiple types of impacted material to a maximum depth of 20 feet bgs; import, placement and compaction of 285,000 cubic yards of backfill; construction of two 10–acre composite cap systems; and installation of a groundwater extraction system within capped areas. Total materials management exceeds 1.4M cubic yards.

Large scale soil stabilization and ground improvement project using an owned large diameter auger (LDA) soil mixing drill rig.

Integrated Energy Supplier Program – Multi–State

ENTACT performs remedial construction, geotechnical construction, and civil construction activities throughout the U.S. and select international locations for a major integrated energy company with core businesses in Exploration and Production, Manufacturing Products, Transportation, Chemical Production, Mining, Power Operations, and Technology. Work is performed at operating and former refineries, terminals, retail sites, oil field production sites, and Superfund sites in which activities include: large–scale management of organic and inorganic impacted soils, sediments and sludge; Corrective Action Management Unit (CAMU), cell, and cap construction; on–site material consolidation; sheet pile installation; waste soils stabilization/solidification; bioremediation; chemical oxidation; demolition of tanks, buildings, and structures; wetlands restoration; aboveground and below ground pipe removal or in–place abandonment; coordination of transportation and disposal; and various type site restorations.

 

In the planning and performance of a wide range of remedial actions within the program, ENTACT serves as an integrated team partner for our client for preliminary design evaluations, site engineering, remedy selection, and cost budgeting.

ENTACT performing the excavation of PCB impacted materials on a residential property.

Residential Interim Removal Action – Alabama

ENTACT performed a multi–year project of residential remediation and restoration activities at this high profile Superfund site. Scope of work included: remediation and restoration of 676 PCB impacted residential properties; transportation and placement of removed materials to various on–site staging areas, or an off–site TSCA approved disposal facility; construction of a 6–acre landfill repository and installation of an earthen vegetated cap with associated surface drainage features; phased construction of a 20–acre landfill repository (geosynthetic cover installed annually over partially completed areas with full earthen cover system installed on areas that reached  design grades); remediation of a PCB impacted city park; and expedited removal of PCB impacts on a school property, as well as decontamination of the school's interior surfaces. On approximately sixty homes, ENTACT installed marker barrier systems in crawl spaces below the houses as part of a remedy to prevent direct contact with underlying impacted soils. Additionally, ENTACT performed residential interior surfaces cleaning and hepa–vacuuming on dwellings of severely impacted by historic dust migration.

 

During project performance, the ENTACT team was also responsible for participating in and conducting public meetings; conducting post–completion surveys to ensure each individual home owner's expectations were met; and interacting daily with residents to communicate the project schedule and goals. ENTACT additionally worked with the client and oversight consultant to create an instructional video for residents that described the anticipated work elements and processes.

Superfund remedial action at an industrial waste site in Texas involving 95,000 tons of impacted soils, and treatment of over 11M gal. of water.

Petrochemical and Industrial Waste Site – Texas

ENTACT completed the Remedial Action of Operable Unit 1 (OU1), and related construction activities at a petrochemical and industrial waste Superfund Site listed on the National Priorities List (NPL). The scope of work included: the design and operation of a waste water treatment plant to pump and treat over 11 million gallons of impacted water from a former process/storage lagoon; and the in–situ solidification/stabilization (ISS) of 95,000 tons of hydrocarbon and PCB impacted sludge to increase the bearing capacity, while reducing the leachability of the treated materials. Resulting unconfined compressive strengths (UCS) for the treated material averaged 40 psi, while successful SPLP leachate testing was achieved for: metals; VOC/SVOC; and PCBs. Additional scope of work items included management of stored liquids and demolition of tanks and incinerators; management of over 500,000 cubic yards of material to construct a vault to contain stabilized sludge, impacted soils, demolition debris, drums, and barrels; construction of a 33–acre RCRA Subtitle C capping system; creation of a 12–acre waterfowl habitat lake from the on–site borrow area; installation of monitoring wells; and site restoration.

 

Remedial and Geotechnical Construction Services

ENTACT hIGHLIGHTS

 

Sediment Removal Project

MGP Site Remediation

Industrial Complex Remediation

Former MGP Site ISS

Integrated Energy Supplier Program

Former Disposal Site Remediation

Active and Abandoned Oil Production Fields

Ash Remediation Program

 

Residential Interim Removal Action

Slurry Wall Installation

Former Phosphate Fertilizer Production ...

Chromium Impacted Site Remediation

Active Refinery RCRA Corrective Action ...

Petrochemical and Industrial Waste Site

Applied Technologies

Soil Compaction / Ground Improvement

Storm Water, Erosion, and Sediment Controls

Surface Water Retention and Diversion

Excavation Support

Waste Soil Excavation and Removal

Construction Surface Restoration

Building and Structures Demolition

Remedial Construction Services

Health and Safety Zone Setup and Maintenance

Mechanical Excavation, Backfill and Compaction

Waste Material Transportation and Disposal

Clay and Earthen Cap Construction

Surface Paving, Seeding and Landscaping

Mechanical Demolition (Shear and Thumb)

Hot Torch and Cold Cut Metals Demolition

Debris Decontamination and Disposal

Featured Projects

 

ENTACT’s experience includes work on projects throughout the United States, Canada, Mexico, Puerto Rico, and select international locations. Our field and technical capabilities enable us to create and deliver solutions for many environmental challenges. This section highlights select recent projects demonstrating some of our service capabilities.

ENTACT owns a large fleet of heavy equipment for remediation, earthworks, and geotechnical construction.

SERVICES

Overlapped soil mixed columns provide excavation support, water cutoff, and solidification of impacted soils at a former MGP site.

Former MGP Site – In–Situ Solidification– Northeast

ENTACT safely and successfully completed a multi–year MGP site remediation for a major power utility company in the northeastern US. Site obstructions included gas holders, concrete footings, foundations and subsurface utilities that required abandonment and removal prior to the in–situ solidification (ISS) remedy deployed for the MGP waste impacted soils. An additional site condition that required attention in terms of safety was the presence of permanent overhead power lines which required shielding in compliance with OSHA clearance standards. Scope of work for the project included: excavation, transportation and disposal of 52,000 tons of MGP impacted soils; in–situ solidification/stabilization of approximately 168,000 cubic yards of impacted material using cement–bentonite–slag grout to a maximum of 30 feet deep using 8–foot diameter vertical augers (DSM); management, transportation and disposal of 15,750 tons of DSM derived spoils; excavation, stockpiling, and re–use of 30,000 tons of lesser impacted on–site material; installation of a soil–crete retaining wall (overlapping DSM columns); construction, demolition, and reconstruction of a parking facility; utility removal, relocation and replacement; and final site restoration. Excavation and spoils management activities were performed under a temporary containment building equipped with a vapor management system.

ENTACT owns a fleet of off-road earth moving dump trucks of different sizes with carrying capacities of 40 tons, 30 tons, and 25 tons.

Active Refinery RCRA Corrective Action, Capital Expansion, and Facility Maintenance Projects – Gulf Coast

ENTACT has been performing remediation, geotechnical construction, and facility maintenance at this active refinery since 2005. Highlighted scopes of work include: solidification/stabilization of storm water surge ponds and canal sediments; flowline restoration; ground improvement work for above ground storage tanks (AST) and process unit construction; hurricane damage repair; maintenance dredging and dredge spoils management; impacted effluent water treatment; plant and structures demolition; aeration basin removal; installation of a groundwater cut–off wall, permeable reactive barrier and interceptor trench construction; bio–cell construction; storm water canal cleaning, maintenance and repairs; firewater pond excavation; ditch sediment removal; and miscellaneous work such as pipe removals, exploratory excavations, vegetation removal, and other small projects.

 

As an integral part of the refinery’s corrective action team, ENTACT participates in the remedy selection process. Our role includes: draft remedial design preparation; design reviews; peer reviews; waste treatability studies; final design preparation; field project execution; and participation with the oversight and client representative team during regulatory agency project reviews and inspections. Throughout the duration of this complex project, ENTACT has played a key role interacting with multiple stakeholders, regulators, local authorities, consultants, engineers, and owner oversight representatives.

Construction of a large CAMU on a 2200 acre site to help manage 3.8 million cubic yards of earthworks and waste soil remediation.

Industrial Complex Remediation – Nevada

ENTACT performed several integrated remedial actions at this 2,200 acre brownfields site in Nevada which contained 16 process ponds, waste disposal ponds, and associated conveyance ditches. Due to the excessively high moisture contents of the materials to be excavated from the ponds, ENTACT conducted months of treatability evaluations to determine the most cost effective way to reduce the moisture levels of the targeted waste materials to a specified density of 80% solids. The treatability process involved geotechnical evaluations, laboratory mixing, free–draining, dewatering, and reagent dosage evaluations from dozens of material sources.

 

Major scope of work items included: the systematic blending, drying, solidification and removal of 3.8M cubic yards of waste soil, sediment and sludge; construction of an on–site 53–acre Corrective Action Management Unit (CAMU); concurrent placement of the amended on–site waste materials within the CAMU; design and installation a 50 foot deep steel sheet pile retaining system to enable excavation of pyrophoric wastes, blended VOC's and PCB's; installation of a RCRA Subtitle C quality cover system over the CAMU; and installation of all associated storm water management and erosion control features.

 

Precise excavation, removal and backfill of incinerator waste soils on a Superfund Site in a major suburban community in Florida. 

Ash Remediation Program – Florida

ENTACT has been working as a design/build remediation contractor in this Superfund cleanup program since 2009. Ash generated historically from municipal incinerator waste was comingled with backfill to create a source area for several designated CERCLA Operable Units (OU) throughout a major southern city. Impacted use areas included schools, residences, parks, and industrial properties. ENTACT has successfully executed remedial and civil construction activities at various OU sites throughout the City. Highlighted scopes of work include: excavation and backfill of 460 residential parcels; transportation and disposal of impacted materials; direct contact barrier installations in residential home crawl spaces; removal of lead–ash impacted soils from in and around city storm water ponds; backfilling with clean soils to support city storm water infrastructure improvement projects; select demolition; and site restoration activities.

 

Residential remediation projects require a skill set uncommon to most other large scale environmental cleanups. Over our long history, ENTACT has made the investment of time and energy needed to specialize and excel in this type of work. Interacting with homeowners while working in and around their domain requires extensive communication and sensitivity to individual needs. A heightened degree of health and safety planning, environmental controls including dust and fugitive emissions, traffic safety and control procedures, and daily flexibility of work plans are some of the other key elements vital to working in residential neighborhoods.

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