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Matson & Associates, Inc.
331 East Foster Ave.
State College, PA 16801
814 / 231-5253
info@matson-associates.com

Select Consulting Projects

 

Identification and Mitigation of Methane in the Subsurface
A subdivision was developed on a site that had been used as a sand and gravel quarry in the 1940s and then received fill material from nearby road construction in the 1970s. Construction of the subdivision began in the mid-to-late 1990s. After residents moved in, the local fire department responded to the complaint of a strong gas smell emanating from the sump in the basement of one of the homes. Elevated levels of methane were detected in the basements of two additional homes, but not the rest of the subdivision. The homeowners, the County, the developer and builder were all concerned about the presence of methane in the homes.

Our client represented the home builder and retained M&A shortly after the initial methane detection. We were asked to provide consulting expertise concerning the presence of methane in the subsurface and what the builder should do to mitigate the situation and alleviate the homeowners’ concerns. Over a period of two years we consulted with the home builder and its attorney on the appropriate steps necessary to address the methane. The home builder followed our recommendations - installed methane mitigation systems in the homes to route any subsurface gases collected under the foundations to the atmosphere, and replaced cheap gas detectors with robust ones capable of differentiating methane from other volatile gases. After reviewing site data and documents detailing the former uses of the site, we determined that the former quarry had been filled with topsoil containing small amounts of construction debris. We explained to our client that the buried topsoil, rich in organic matter, was being converted to methane by microbial degradation in the subsurface. The company then excavated over 500 tons of organic rich soil from the former quarry and backfilled it with clean fill.

Despite the measures described, the homeowners filed suit against the home builder over the presence of the methane in the subsurface. Our firm was then retained to provide litigation support and expert witnessing services on behalf of the defendants. We provided expert opinions indicating the builder met the standard of care for its handling of the subsurface methane, and that the methane present did not and will not present a hazard to the homeowners. The case settled shortly before going to trial.

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Arsenic Remediation for Groundwater Impacted by Coal Ash Storage
Coal ash impoundments on the banks of the Waccamaw River contaminated the groundwater and the river with arsenic. The unlined ponds stored over one million tons of coal ash from Santee Cooper’s retired Grainger Generating Station. Arsenic levels in the groundwater (up to 2100 ppb) were well above the drinking water standard of 10 ppb. Several local watershed groups had retained the Southern Environmental Law Center (SELC) to assist them with urging the utility to remove the coal ash and remediate the groundwater to prevent arsenic from continuing to leach into the river. SELC retained M&A to review the closure plan alternatives for the coal ash impoundment and to provide a solution for remediating the arsenic contaminated groundwater. Utilizing our expertise on arsenic removal from groundwater, we developed a conceptual design for arsenic remediation that met the criteria for Effectiveness, Cost, Feasibility of Implementation, and Sustainability. We prepared written comments to SELC that included an evaluation of Santee Cooper’s closure plan alternatives, and the conceptual design for remediating the arsenic contaminated groundwater. Ultimately Santee Cooper agreed to remove the coal ash within ten years, and to implement groundwater remediation if the arsenic levels did not subsequently decrease.

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Investigation of the Hydrologic Conditions at a Residential Site
M&A was retained by an attorney to conduct a case evaluation for property damage. Our client represented a landowner alleging water intrusion in his home was caused by installation of a nearby sewer line. Our roles were to assess whether the water intrusion into the basement was potentially related to the nearby construction activities and to assist the attorney in determining whether to file a lawsuit against the construction company for property damage.

The consultation primarily required a site visit as well as a review of engineering reports and other materials on the nearby construction activities and potential hydrologic impacts. From the on-site conditions, it was apparent that upgrades to the home were needed to provide adequate local drainage. We prepared written comments informing our client of the potential difficulties associated with filing a lawsuit at that time against the construction company.

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