Pilot Study

Conclusions and Recommendations of the 2015 Pilot Study Report


The EHC and local partnering NGO the Asociación Nuevavelica conducted a pilot study in June and July 2015 to assess the efficacy of encapsulation of contaminated walls and floors in six mercury-contaminated earthen homes in Huancavelica, Peru. The results of this study are presented in this report and support completion of a focused Feasibility Study that will identify the most cost effective and protective remedial action for Hg-contaminated homes in Huancavelica. In addition, analysis of soil, adobe and rock for other heavy metals were further evaluated during the pilot study and have also been included in this report. The results of the pilot study are summarized below:

• Mercury vapor was analyzed in ambient outdoor air for determination of a background concentration (21 ng/m3). This is twenty time above global background levels.

• Mercury vapor in six homes was analyzed before the home was treated using the encapsulation method of installing a concrete floor and plaster or cement walls. Follow up analysis indicated that final Hg vapor concentrations in each of the treated homes was below the WHO screening value of 200 ng/m3 for chronic exposure.

• Mercury vapor was analyzed with the Lumex in six other homes that were not treated during the pilot study, with readings ranging from 50 to 656 ng/m3.

• Samples of tailings, travertine, soil and adobe (common building materials in Huancavelica) had elevated concentrations of As, Hg, and Pb, all of which were above screening levels for residential use. Arsenic and Pb were not included in the Risk Assessment, however additional analysis and evaluation is warranted, based on these findings.

Based on the results presented above and supported in more detail in this report, the following conclusions and recommendations are made:

• Treatment of floors and walls with encapsulation such as concrete and plaster is an effective treatment method to reduce or eliminate indoor sources of incidental ingestion exposure to particulate-bound Hg as well as other heavy metals that may be co-located with Hg. It is also, on the whole, effective in reducing inhalation exposure to indoor Hg vapor. Exposure to particle-bound Hg in floors and walls was found to be the higher risk driver in the Risk Assessment. The encapsulation method of installing a concrete floor and plastering walls should be compared to other remedial action alternatives in the FS. This alternative preliminarily appears to be the most cost effective and protective remedy.