Sunday, October 7, 2012

CSU Tests Huerfano County Residential Wells

CSU PUEBLOFaculty and students from Colorado State University-Pueblo Department of Chemistry, in collaboration with the Colorado Water Institute conducted their sampling program for private wells in Huerfano County between May 12 and June 21 of this year.

Dr. Perry Cabot, Prof. Dave Lehmpuhl and Prof. David Dillon supervised the program. A total of 31 wells were sampled for subsequent water quality analysis by ACZ Laboratories in Steamboat Springs, Colorado. To the right is a gross-scale map showing the spatial range of the sample locations.

Citizens for Huerfano County (CHC) proposed the baseline water testing project to the Colorado Water Institute due to the pending exploratory oil and gas drilling in Huerfano County and served as a local contact during the project. Dr. Cabot provided updates regularly via the public Shell-Huerfano Community Forum held monthly at the Community Center in Walsenburg.

The sampling protocol adhered rigorously to a peer-reviewed quality assurance project plan (QAPP) that was developed using the Voluntary Baseline Groundwater Quality Sampling Program document prepared by the Colorado Oil & Gas Association (COGA). Participants in the program were asked to select from three tiers of analysis for their water samples, with 42%, 35%, and 23% of well-owners opting for Tier 1, Tier 2, and Tier 3, respectively. Samples were collected by teams of three, each led by a CSU-Pueblo faculty member and assisted by two students, who helped to maintain records, prepare sample bottles and preserve chain of custody. After collection, samples were preserved in coolers at temperatures below 4°C (on ice or refrigerated) and driven overnight to the analytical laboratory in order to adhere to the 48 hour analysis window suggested by the Colorado Oil & Gas Association (COGA).

The results of the analyses are the sole property of the well owners, but the basic results can be generalized. Total Dissolved Solids (TDS) concentrations averaged 383 mg/L. The EPA secondary standard for TDS is 500 mg/L and 3 of the 31 samples exceeded this standard. The TDS level is basically the sum of all minerals, metals, and salts dissolved in the water. It is a good general indicator of water quality.

Another analysis of interest in the area is arsenic, which was undetected in all but one sample, which also did not exceed the maximum contaminant level (MCL) of 0.010 mg/L. Iron was not detected in 18 of the 31 samples, averaged 0.118 mg/L in detectable samples, and exceeded the secondary standard of 0.3 mg/L in one sample. Samples for methane were collected at each of the 31 wells using zero-headspace guidelines. Methane was undetected in 24 samples, averaged 2.45 mg/L in the remainder of samples, and exceeded 10 mg/L in one sample, for which the well owner was notified.

Although dissolved methane in drinking water is not currently classified as a health hazard for ingestion, the defined action level for hazard mitigation recommended by the US Office of the Interior is 10 mg/L.

Each well was also sampled for the presence of benzene, toluene, ethylbenzene, and xylenes (BTEX). With the exception of one sample which found toluene, BTEX concentrations were below the method detection limit (MDL) of 0.2 micrograms per liter (μg/L) in any of wells. The single toluene sample was only just slightly above this MDL and is considered satisfactory because it is less than the primary standard of 1000 μg/L.

Lastly, gross alpha emitters in the samples averaged 4.02 pCi/L with 2 samples slightly exceeding the primary standard of 15 pCi/L.

The Colorado Water Institute (CWI), an affiliate of Colorado State University, exists for the express purpose of focusing the water expertise of higher education on the evolving water concerns and problems being faced by Colorado citizens.

Eltschlager KK, Hawkins JW, Ehler WC, Baldassare F. 2001. Technical Measures for the Investigation and Mitigation of Fugitive Methane Hazards in Areas of Coal Mining. Pittsburgh: US Dept of the Interior, Office of Surface Mining Reclamation and Enforcement.

1 comment:

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