Over our tenure in the Environmental Consulting Field, Four Corners Environmental, Inc. has been privileged to serve our Clients on many and varied projects. Four Corners Environmental, Inc. enjoys challenges and utilizes innovative technologies and approaches to meet Environmental Challenges in the least burdensome way. Summarized in the following text are four Projects on our very favorite list. Enjoy!

Abandoned Mine Reclamation Projects

Spotlight Cave Creek Regional Park and San Tan Park, Arizona

Four Corners Environmental, Inc. provided professional consulting and construction contracting services associated with the evaluation and closure of abandoned mines within two Maricopa County Regional Parks in Arizona. Four Corners understanding of project goals; health and safety issues; long time mining laws; and liabilities associated with abandoned mine sites provided Maricopa County with a cost effective plan to protect the safety and welfare of Park staff and patrons while preserving biological and cultural diversity of the parks for the public.

Four Corners developed an evaluative process for the abandoned mines within each park property with the goal of mitigating the hazard associated with open mines while preserving the cultural, biological and the scenic beauty resources of the Park. Four Corners heuristic approach to the mitigation of hazards while preserving resources and considering budgetary restrictions was a first of it’s kind in Arizona.

The process included numerous hazard and cost criteria that enabled Four Corners to present a hazard based plan of action to Maricopa County Risk Management. The plan allowed Maricopa County to attack the facilities that presented the highest hazard within the limited budgets while reducing overall liabilities for the Parks. The plan also presented National Environmental Protection Act (NEPA) issues associated with cultural resources and biological diversity inherent to each Park. Further, Four Corners was able to integrate learning opportunities for Park Patrons within the abandoned mine closure plans.

Multiple stakeholders had an interest in the outcome of the reclamation activities including federal, state, and local agencies. Stakeholder issues were each addressed by Four Corners in our plan and were accepted by the stakeholders.

Four Corners also conducted actual closure activities for the mines at both Parks. Although some the mine locations were known and the mine dimensions were well documented, access to most of the mines was limited. Mine sites were located on relatively steep slopes with deteriorated preexisting roads or located along existing foot trails with no access for heavy construction equipment. Numerous biological habitat features, including bats, and cultural resources were present within the Park that required special consideration to minimize adverse impacts. Four Corners closure activities ranged from establishing entrance barriers to the development and installation of bat gates and educational facilities.

Four Corners and Maricopa County were successful in mitigating the immediate hazards associated with the abandoned mines within the Parks while enriching the Park experience through the protection of wildlife, vegetation, and cultural resources while providing educational components for Park Patrons.

City of Gallup Water Resources Investigations

A regional groundwater numerical simulation model for thePermian San Andres/Glorieta aquifer system of northwestern New Mexico has been prepared in support of the Application by the City of Gallup for Permit to Appropriate Groundwater. The numerical simulation model was mandated by the New Mexico Office of the State Engineer Hearing Examiner to support the City of Gallup’s Application. The model framework stipulated by the Hearing Examiner included the need for a three-dimensional numerical model capable of simulating aquifer stresses to the Permian San Andres/Glorieta aquifer system, the Sonsela sandstone of the Petrified Forest Member of the Triassic Chinle Formation, and leakance through theTriassic Chinle Formation.

Four Corners completed exploratory borehole drilling activities near the geologic structure known as the “hogback” section near Gallup, New Mexico. The boreholes were completed as exploration wells with the goal of defining potential aquifers within the geologic materials penetrated, to enable the completion of aquifer testing, and provide groundwater monitoring capabilities within the aquifers penetrated.

Rio De Flagg Remedial Investigation/Feasibility Study (RI/FS)


A significant amount of environmental work has previously been completed along the proposed flood control improvement corridor. On behalf of the City of Flagstaff, Four Corners has historically conducted several subsurface investigations to assist in identifying locations of historic environmental concern, and the US Corps of Engineers and others have completed additional work.

The result(s) of these environmental investigations suggested that there were numerous locations along the alignment that had environmental concerns. Eight specific locations required additional investigation. Four Corners conducted additional work at these locations to identify and characterize the extent of contamination, determine the most feasible remedial approach, and implement remedial activities to satisfy the needs of multiple agencies.

Recommendations for the Implementation of the Environmental Program

A framework currently exists to investigate multiple contaminated sites with the goal of developing remedial options. The Remedial Investigation/Feasibility Study (RI/FS) framework was part of the Comprehensive Environmental Response, Cleanup and Liability Act (CERCLA), and provided guidance for the determination of the nature and extent of contamination (remedial investigation), and the screening of remedial options (feasibility study).

The remedial investigation typically requires the development of several documents to succinctly state the project goals, method(s) of achieving those goals, and the level of data review necessary to confirm the accuracy of the results. The documents included: a Work Plan (WP) to provide the history of the site(s) and clearly delineated the project rationale, goals and regulatory involvement requirements; a Sampling Plan (SP) that stipulated the methods to be used to undertake the remedial investigation(s); and a Quality Assurance Project Plan (QAPP) that provided data quality objectives and methods of achieving those objectives.

The WP, SP and QAPP are valuable tools to assist with determining and negotiating the Scope of Work, regulatory involvement, applicable laws and regulations, and remedial standards. Once negotiated and agreed upon, the WP, SP and QAPP provide a valuable tool for the identification of roles and responsibilities, limitations of work activities, and reliability of the information obtained.

Four Corners prepared for the City an WP, SP and QAPP for the project to facilitate the involvement of the Corps, Arizona Department of Environmental Quality (ADEQ) and other interested parties in developing the project goals and determining the methods to be used to adequately characterize each site. The WP, SP and QAPP was provided to each interested party for review and comment, and negotiated to reach an agreement over the scope of the remedial investigations and information necessary to analyze the feasibility of remedial options.

Buckeye Hills and Surprise Shooting Range Closure Activities

To facilitate better training of Sherriff Officers, Maricopa County closed two main County shooting ranges and re-constructed a regional training and public use shooting facility in Buckeye, Arizona. Four Corners completed the closures of the Buckeye Hills and Surprise shooting facilities for Maricopa County to allow for the construction of the new facilities without long term monitoring requirements associated with most hazardous waste sites. Four Corners conducted initial investigations into lead and other contaminants in soil and developed a strategy for Maricopa County to remediate and close the facilities under the Arizona Department of Environmental Quality (ADEQ) Voluntary Remediation Program (VRP).

Four Corners worked closely with the ADEQ to facilitate the project goals as agreed upon by Maricopa County, ADEQ and the public. Four Corners strategy that was implemented included the following elements.

  • Full characterization of the project sites for lead, arsenic, and other heavy metals.
  • Evaluation of site aspects for biological, archeological, historical and cultural significance and impacts.
  • Development of an ADEQ accepted, cost effective remedial action plan that integrated all project aspects from the decommissioning of the facilities; demolition and disposal of existing buildings; treatment and excavation of impacted soil; re-use of excess soil at other facilities; appropriate transportation and disposition of contaminated soils; and post-remediation verification sampling and re-grading.
  • Implementation of cost effective remedial technologies that reduced the leachability of lead in soil to reduce overall disposal costs, potential hazards to the environment, and to allow re-sue of certain soils for other shooting range facilities.
  • Remediation of the Shooting Ranges to soil contaminant levels below the ADEQ residential soil remediation levels (SRL’s).

Four Corners coordinated all aspects of these projects and received verification from ADEQ that closure was complete under the VRP. Without Four Corners’ project plan and implementation of the plan, the shooting ranges may have been subject to hazardous waste closure requirements under the Resource Conservation and Recovery Act (RCRA) that would have generated hazardous wastes that would have cost the taxpayers millions because of required out-of-state disposal, extended the remedial activities by at least two years, and a required 30 years of continuous post remediation monitoring.

The new Buckeye Hills Shooting Facilities currently includes both City and County Law Enforcement and public areas, including pistol and long ranges; tactical practice yards; bomb detonation areas; and archery, trap and skeet ranges. The facility is the only facility in Arizona that is completely run my solar power facilities and is used by Federal, State, County and City Law Enforcement Officers as well as private shooting clubs.

Four Corners was pleased to be of assistance to the Maricopa County taxpayers and our Law Enforcement Officers on this project.

Have questions about how we can help? We’d be glad to talk!