Helen Mercury Mine Removal Site Investigation


The US Department of the Interior Bureau of Land Management (BLM) hired Burleson to prepare a removal site investigation (RSI) report to evaluate the need for a removal action at the Helen Mine.

Helen Mine was discovered in 1871, and several hundred flasks of mercury were produced from 1873 to 1876.
The mine operated intermittently from 1900 to 1956 and produced about 7,000 flasks of mercury. BLM needed to know if the contamination from the site created the need for a removal action.

Data Compilation

Burleson compiled site and watershed wide analytical data for soils, sediment, water, and biota to support development of a conceptual site model (CSM) and risk screening. Burleson also identified data gaps.

Preliminary Conceptual Site Model

Burleson prepared a preliminary CSM to identify complete exposure pathways for human and ecological receptors.

Risk Screening

Site risks to humans, biota and water quality were evaluated for completed pathways shown in the CSM. Burleson evaluated:

  • Potential risks to human health by comparing mercury concentrations in sediment and mine waste at the Helen Mine to screening benchmarks.
  • Potential risks to ecological receptors by comparing mercury concentrations reported in sediment at the mine to the median risk management criteria for ecological receptors and by comparing the results of fauna sampling for mercury near Helen Mine to mercury in fauna downstream from the mine and in regional data sets.
  • Potential water quality impacts by comparing detected concentrations to water quality criteria.


Based on consideration of NCP removal factors and consideration of the risk screening, Burleson found that a removal action was not necessary at the Helen Mine. Burleson recommended that BLM conduct sampling and analysis to determine the mercury content of waste rock at the site. Burleson also recommended sampling and analysis of sediment in Dry Creek upstream and downstream of the tributary from the Helen Mine to evaluate impacts of this feature on the watershed.

Client Satisfaction

"Burleson Consulting was excellent to work with and very professional. They assembled a top-notch team of experts to study and propose solutions to the water supply challenges at Sutter National Wildlife Refuge. The communication was excellent throughout the project. This included project staff, contracting personnel, and interested stakeholders. As a result, the project was completed on time and on budget. I would not hesitate to use or recommend Burleson Consulting in the future."Kevin Clancy, Project Manager – United States Bureau of Reclamation

"Burleson provided exceptional services under this contract. Because of their successful work, they were awarded a $7M follow-on IDIQ contract in 2014, that also encompasses biological monitoring at former Fort Ord. They have consistently improved their plant material collection and propagation techniques and pass the savings onto the federal government. Burleson is a valuable team member on Fort Ord and I feel that they are true stewards of the environment." William K. Collins, BRAC Environmental Coordinator, US Army Corps of Engineers

"Burleson has been able to work with several government agencies (to include tribal groups and natural resource trustees) and several responsible parties to assist in progressing this site to a stage where technical and agency concerns can be identified and resolved. Strengths – overall and in depth understanding of mine site and CERCLA dynamics. Deficiencies – none. I would not hesitate to use Burleson." Daniel McMindes, USACE Liaison to EPA, US Army Corps of Engineers

"Burleson helped to manage the Sacramento Area Voltage Support Environmental Impact Statement. They came through and were always available during an ‘energy crisis’ in California. I will continue to work with them."Loreen McMahon, Project Manager - California Public Utilities Commission

"We appreciated Burleson’s great work, re: completing the draft EIR on the scheduled date (it was a tremendous task, but they completed it). All of them put a lot of work into it (it was a true team effort). They should all be proud of this accomplishment given the changes and obstacles encountered along the way, and I cannot thank them enough."Glenn M. Shuder, AIA, CFM, Chief Architect - Project Director, SMUD

"We chose Burleson Consulting because of their experience with the specific project matter in technical and regulatory issues and for their record of excellent communication skills in complex, multiparty projects. They were responsive to the matter and were sensitive to all relationships between the parties involved."Kevin Mayer, PE, Project Manager - USEPA