Engineering And Remediation
Walsh understands the challenges inherent in reclamation and remediation of environmental sites. Our primary goal is achieving closure in an environmentally responsible and cost-effective manner. Walsh's team of engineers and environmental scientists have remediated and achieved closure on dozens of sites, from landfills and underground storage tanks to industrial smelters high in the Colorado Rockies. Our team has completed Environmental Site Assessments (ESAs), Engineering Evaluation/Cost Analysis (EE/CAs), Remedial Investigation/ Feasibility Studies (RI/FSs), remedial designs, and remedial actions throughout the western United States, including Arizona, California, Colorado, New Mexico, and Utah. We have remediated sites in North and South America, Europe, and Asia.
Our staff is experienced in the full range of remediation technologies for soil, water and air contaminated with petroleum, radioactive, and hazardous waste regulated under RCRA, TSCA, CERCLA, CWA, SDWA, and AHERA. We have extensive experience with both solid waste and hazardous waste permitting, management, treatment, and disposal. We also have prepared and certified Spill Prevention, Control, and Countermeasures (SPCC) Plans for several clients in a broad range of industries.
We have remediated a wide variety of contaminants, from hydrocarbons and PCBs to radionuclides, metals, and pesticides. Our work has required the use of a broad variety of remediation technologies and approaches, including capping and containment remedies, pump-and-treat remediation systems, and in situ air sparge and soil vapor extraction systems. We have assisted clients with risk-based closures, helped secure State Voluntary Cleanup (VCUP) funds, and guided clients through various corrective action processes. We are also highly experienced in the application of treatment in wetlands, and are leaders in addressing asbestos in soils and building materials.
Domestic Case Studies
Relocation of St. Anthony West Hospital to Denver Federal Center. Walsh assisted St. Anthony Hospital in relocating from Northwest Denver to the Denver Federal Center. The hospital purchased two properties from the Denver Federal Center, one of which included a 26-acre historic landfill that contained asbestos, building material, boiler ash, and other miscellaneous debris. Walsh removed waste from several areas and designed and constructed a protective cap over the remaining areas. The cap consisted of a compacted clay liner and vegetative layer. An asphalt parking lot was also constructed over a portion of the cap.
Captain Jack Mine Site RI/FS, Colorado. Walsh conducted a site assessment for the CDPHE of the widely publicized Superfund project at the Captain Jack and Big Five mine and mill sites near Ward, Colorado. This involved the assessment and remediation of acid mine drainage emanating from a 10,000 foot tunnel and closure of several shafts and adits. The project also involved preparation of the Record of Decision for reclamation/remediation of 10 large waste rock and tailings dumps.
Dry Cleaner Chlorinated Solvent Remediation, Denver, CO. At a former dry cleaner in the Denver Metro Area, tetrachloroethylene (PCE) and other volatile organic compounds (VOCs) were detected in soil vapor at levels exceeding applicable indoor air vapor intrusion regulatory standards. In addition, groundwater PCE concentrations were detected above applicable groundwater cleanup levels. In response, Walsh completed a Phase II ESA and an Integrated Corrective Action Plan (ICAP) describing proposed remedial actions. Following approval of the ICAP by the CDPHE, Walsh prepared the engineering design and oversaw implementation of the remedial actions described in the ICAP, including the injection of RegenOx, a proprietary chemical oxidant, into the vadose zone to treat PCE in soil; the injection of HRC, a proprietary compound, to stimulate reductive dechlorination of PCE in groundwater; and the installation of a sub-slab depressurization system to help mitigate the potential for vapor intrusion of VOCs and help ensure protectiveness to future tenants. Walsh is now conducting ongoing maintenance and monitoring at the site.
Anvil Points Remediation, Rifle, CO. At the former Naval Oil Shale Reserve #3 at Anvil Points, Walsh conducted a site investigation and completed an EE/CA to address the impacts of hydrocarbons and heavy metals from spent shale on drinking water and aquatic life in the downstream Colorado River. Walsh prepared a remedial design incorporating a repository for the shale and is now conducting ongoing maintenance and monitoring of the site to evaluate any remaining environmental issues.
Oxy Natural Gas Production Facilities SPCC Plans, Parachute, CO. Walsh has prepared over SPCC plans for over 140 natural gas production facilities in western Colorado. Walsh performed initial site inspections, evaluated existing versus required secondary containment requirements, generated site diagrams and information forms documenting site conditions at each facility, and performs periodic inspections and updates to the SPCC Plans.
Saginaw Hills Abandoned Mine Reclamation, AZ. For the Bureau of Land Management, Walsh prepared an EE/CA for the Saginaw Hills abandoned mine land site on the outskirts of Tucson, AZ. Walsh conducted site sampling and installed and sampled two onsite groundwater monitoring wells. Walsh also investigated six alternatives for soil remediation and incorporated the findings into a remedial design. As the site was approximately 0.5 miles from a school, public concern over the waste material was a significant issue. Walsh personnel provided extensive community relations support.
Burlington Mine Remediation and Reclamation, Jamestown, CO. The remediation of the Burlington Mine Site, an inactive fluorspar mine, incorporated many innovative techniques. Our engineering team worked closely with our in-house ecological team to develop a remedial design intended to imitate natural form and function, enhance wildlife habitat, and protect waterfowl. The resulting design exceeded basic closure requirements, provided long-term closure protection, and prevented future collapse within the mine workings. At the Colorado Mining Association’s 108th National Western Mining Conference & Exhibition, Honeywell International Inc. was presented with the Hard Rock Reclamation Award for Walsh’s outstanding remediation and reclamation work at the Burlington Mine. In addition, the project was featured in the July 2008 edition of EPA’s Technology News and Trends.
Sheridan Redevelopment Area, Sheridan, CO. Walsh partnered with Miller Weingarten to complete a Phase I and Phase II ESA and VCUP for this former municipal solid waste landfill and industrial area. The $150MM redevelopment consisted of nearly 700,000 square feet of redevelopment and included installation of methane control systems to protect buildings and occupants from gases from the former landfill.
Landfill Design and Monitoring for West Garco Landfill, Garfield County, Colorado. Walsh performed various tasks at this solid waste disposal facility near Rifle, Colorado. Tasks involved groundwater and methane monitoring, including installing methane monitoring wells at and around the landfill; complete design and construction quality assurance; water quality analysis and reporting; and generating special waste disposal requests.
RI/FS at Nacimiento Mine Site, Cuba, NM. At the Forest Service’s Nacimiento Copper Mine site, Walsh completed a large RI/FS to determine surface and groundwater impacts from past in-situ leachate mining activities and to develop alternatives for meeting remedial action objectives.
Horizontal Well Soil Vapor Extraction (SVE) Systems, Weld County, CO. At four natural gas compression facilities, Walsh designed and installed horizontal well SVE systems for each site and conducted long-term O&M, sampling, and monitoring of these two systems and two additional systems in the area.
Industrial Wastewater Treatment Evaluation, Brush, CO. Walsh is evaluating wastewater management options for a hydroponic tomato greenhouse, including on-site treatment and disposal to surface water in accordance with State Permissible Effluent Limitations and disposal to a publicly owned treatment works. Part of the evaluation involves cost associated with replacement of surface water.
Northside Aztlan Community Center Project in Fort Collins, Colorado. Walsh and its partnered companies are proud to announce that they were granted the Phoenix Award – Region 8 and Nationwide 1st Runner-Up - for their work on the Northside Aztlan Community Center Project in Fort Collins, Colorado. The Downtown River Corridor Redevelopment Program used EPA Targeted Brownfields Assessment to remediate a former municipal landfill into a community asset with Gold LEED-certified community building and public access to nearby river and walking trails. Walsh assisted the City of Fort Collins during the planning, construction, and post-construction phases of the redevelopment project.
Department of Oil and Public Safety - Petroleum Contamination Remediation, Grand Partnership, 654 Main Street, Grand Junction, Colorado - Walsh defined the extent of contamination and prepared a Corrective Action Plan (CAP) for the owners of the site.
Clifton SVE Deep Vapor Extraction System-Lowe Development - Walsh implemented a CAP prepared by others. Walsh performed a pilot test to determine the spacing of the SVE wells, installed over 50 SVE wells connected to a high-displacement vacuum pump and thermal oxidizer, and operated the system coupled with manual and automatic free-phase recovery to remove over 60,000 gallons of gasoline. The system successfully removed over 95% of the gasoline and over 99.99% of the benzene. Walsh assisted the client with reimbursement applications, allowing them to retrieve all remediation costs.
International Case Studies
Bioremediation Pilot Test, Japan. Walsh conducted a field pilot test of in-situ bioremediation of soils contaminated with TCE, a chlorinated solvent. The site was an electronics manufacturing plant located in Chiba Prefecture, Japan.
Remediation System Design for Industrial Site, Japan. Walsh conducted process design and site layout design for a TCE- and PCE-contaminated industrial site in Japan.
Review of Remediation Designs for Oil Storage Caverns, Sweden. For the Swedish National Oil Stockpile Agency, Walsh reviewed site assessment reports by other consultants for quality and technical feasibility related to bioremediation.
Hydrologic Assessment of Rubber Plant Sites - Philippines. For the Goodyear Tire and Rubber Co., Walsh provided ground water resources and well field operations investigation for two rubber plant sites at Marikina, Philippines.