Client: Former Petroleum Refinery
Location: Casper, Wyoming
Project Overview: Trihydro has been involved with all aspects of a refinery decommissioning, environmental compliance, and remediation system design and construction since 1996. In 2001, Trihydro designed and permitted a 580,000 cubic yard Corrective Action Management Unit (CAMU) for the facility in Central Wyoming . Key elements of the liner system design included a 60-mile, high-density polyethylene (HDPE) geomembrane, geosynthetic clay liner (GCL), and leachate collection system. Key elements of the cap system design include a gas collection system, gas collection layers, 40 mil low-density polyethylene (LDPE) geomembrane, geocomposite drainage layer, protective soil cover, and animal intrusion barrier.

In addition to permitting and design of the CAMU, Trihydro was responsible for generation of Bid Documents, project coordination with the contractor and regulatory agencies, construction management, QA/QC program implementation and documentation, and budget management and projections. Trihydro was responsible for oversight of all QA/QC inspection, testing and adherence to design specifications during construction.

Construction of the engineered subgrade, composite liner system and leachate collection system began in March of 2002 and was completed in May 2002. The first phase of the landfill construction was completed on time and under budget. The CAMU is currently in operation; to date, approximately 365,000 cubic yards of remediation wastes have been placed and compacted in the waste containment cell. Approximately 10% of the material managed in the CAMU is material not suitable for direct placement and compaction. This material is stabilized with fly ash prior to compaction.

During construction and operation of the CAMU, Trihydro has been responsible for overseeing air monitoring in the work areas and at the facility boundary to ensure that fugitive emissions from the construction/operation activities were not adversely impacting site workers or the adjacent community. As part of the approved CAMU permit application and implementation, Trihydro was also responsible for design and construction management of an air sparge/biovent system installed underneath the landfill. Construction included installation of 70 air sparge wells and a passive venting system. In addition, Trihydro has designed, managed the construction of and operated two other soil vapor extraction systems at the facility. These systems collectively account for 160 vertical extraction wells and four horizontal extraction trenches. The combined systems have a flow capacity of 1400 scfm and utilize thermal oxidation for treatment of extracted vapors. These systems have been effective in mitigating migration of contaminated groundwater and free phase hydrocarbons to the adjacent river, and capturing and controlling fugitive volatile organic vapors in the subsurface.

Client: City of Cheyenne
Location: Cheyenne, Wyoming
Project Overview: . Trihydro currently provides a variety of environmental services at the City of Cheyenne landfill, a large portion of which is related to the environmental monitoring and compliance associated with the landfill.

Activities associated with environmental monitoring at the landfill involve monthly gauging of fluid levels, quarterly monitoring of methane concentrations, collecting groundwater samples under detection and compliance monitoring programs, statistically analyzing groundwater monitoring results, and recommending changes to the monitoring program.

The statistical analyses are completed using the statistical program SANITAS®, designed for the statistical analysis of contaminant data collected from sanitary and industrial landfills. The detailed results generated during the statistical analysis are used to modify/enhance the environmental monitoring program at the landfill.