Related to natural gas development, the most frustrating part of this experience, for me, has been the lack of a fact-based review of the data. That is what you will find here - a fact-based review of the impacts on water wells because of natural gas development with NO SPIN either way. I try not to make any judgments. The main goal of this evaluation is to understand the nature of the regional water quality and to provide a fact-based review of the data. The well water test results of regional wells are compared to the EPA and Pennsylvania Drinking Water Standards. If no standard was available for a particular parameter,, we searched for a standard that has been established by a state or the World Health Organization.
The first problem is that I do not have all the facts for each reviewed well for a number of reasons, which include inadequate or no baseline testing and lack of long-term information for each source. I was not on-site or part of the initial baseline testing or investigation, but I was invited on-site to witness the sampling that was conducted by the EPA. Therefore, the following is a review of this single sampling event.
The following is a summary of the water quality data that was generated by the EPA for a private water well identified as HW-1 in Dimock, Pennsylvania. The well was sampled by the EPA, DEP, and the local natural gas development company in February 2012 after the natural gas drilling wells had been drilled, developed, installed, and some were under production. The primary objective was to determine the presence of any residual impacts at that specific time.
The fact-based review begins with a Well by Well study of the Available Well Water Data, generated by the EPA, for the Dimock Area. I was not involved with the sampling, but I was on-site during the sampling and field evaluation of one home. I was invited by the homeowner. We are still in the process of reviewing the data. The main goal of this evaluation is to understand the nature of the regional water quality and to provide a fact-based review of the data. The results are compared to the EPA and Pennsylvania Drinking Water Standards. If no standard was available, we searched for a standard that has been established by another state or the World Health Organization.
1. Without pre-drilling data, it is not possible to comment on the cause of any water quality problems which has been a very frustrating issue for this area. In many cases, there was no to very little pre-drilling baseline-testing conducted or the testing was inadequate and had "Zero" follow-up.
2. Where possible, I have noted situations where elevated levels of a water quality parameter exist in Pennsylvania.
3. If multiple analyses were available, I used the highest reported value.
4. This evaluation was based on the 2011 EPA Health Advisory (Source). For a more recent version of the EPA Health Advisory Click Here.
5. This is not about cause and effect; it is about a review of the data.
With the exception of the following parameters, the remaining values were reported as NOT Detected (U):
Anionic Surfactants – < 0.01 mg/L – the secondary drinking water standard for foaming agents is 0.5 mg/L. (OK)
Ethane – 0.350 mg/L – No specific drinking water standard (OK)
Methane – 12.0 mg/L – No specific drinking water standard. (OK). The well water is above the new action limit of 7 mg/L and methane gas mitigation measures should be employed. These measures not only include venting the well, but also potentially modifying the well, installing treatment, or taking other action.
There are places in PA where baseline levels of methane gas are at or above 7 mg/L. In general, I would estimate that 1 to 3 % of private wells in this area may have elevated levels of methane. In addition to modifying such wells, it would be advisable to conduct an isotopic analysis. The ratio of methane to ethane is 34 which suggests that the gas is of thermogenic origin and isotopic analysis is critical. There is no specific health concern but action is needed to properly vent gas, it may be necessary to modify the well, and isotopic analysis recommended.
It may be advisable to check the level of other gases, such as propane.
Methane/Ethane Ratio: 34 (Thermogenic)
Biogenic formation of methane: methane produced by biological activity, most typically in anoxic (without oxygen) settings via methanogenic bacteria. Biogenic methane is not normally associated with commercial natural gas drilling.
Thermogenic formation of methane: the formation of methane is caused or associated with a chemical reaction combined with heat and pressure without the need for microbes. This is the form of natural gas produced by commercial natural gas drilling.
As a guide, it may be possible to use a ratio to suggest the source of the gas - “ if the ratio of methane to ethane is 25, the source is thermogenic, but if the ratio is over 2500, then it is microbial" (Mr. Bob Pirkle, President of Microseeps, Inc.). It is when the ratio is between 25 and 2500 that isotopic analysis and gas composition analysis are critical. The isotope analysis refers to the ratio of carbon-13 to carbon-12 isotopes of the methane. Thermogenic methane would have a higher value of that ratio.
Ethylene glycol – the reported value is < 10 mg/L – there is no standard, but the EPA has a guidance limit of < 7 mg/L. Other states have lower and higher standards:
New Jersey 0.300 mg/L (300 ppb)
Arizona 5.5 mg/L (5500 ppb)
New Hampshire 7.0 mg/L (7000 ppb)
Florida, Massachusetts, and Minnesota14.0 mg/L (14,000 ppb)
At a minimum, I would recommend retesting for ethylene glycol and other glycol compounds using a method that is more sensitive or conducting some type of standard additions analysis.
Chloride – 4.36 mg/L (OK) – drinking water standard is < 250 mg/L – this does not suggest any specific impact.
Sulfate – 5.49 mg/L (OK) – drinking water standard is < 250 mg/L – this does not suggest any specific impact.
Barium - 0.304 mg/L (Total) and 0.316 mg/L (D) – drinking water standard is < 2 mg/L – this does not suggest any specific impact and barium is typically detectable in non-saline impacted water at a level less than 1 mg/L. (OK)
Calcium- 7.89 mg/L (Total) and 8.21 mg/L (D) – no specific drinking water standard is available. (OK)
Magnesium- 3.64 mg/L (Total) and 3.76 mg/L (D) – no specific drinking water standard is available. (OK)
Manganese– 0.0022 mg/L (Total) and 0.0019 mg/L (D) – Manganese is regulated as a secondary drinking water standard in Pennsylvania and the action limit is 0.05 mg/L. (OK)
Sodium – 18.1 mg/L (Total) and 19.1 mg/L (D) – – no specific drinking water standard drinking water standard is available, but the EPA has added it to the Candidate List to provide more analysis. The EPA’s initial value of 20 mg/L has been clearly identified as not realistic. When chloride (salt is sodium chloride) is present at a concentration of over 250 mg/L, the water can have an “off” taste. At 400+ mg/L chloride, the water will taste definitely salty. (Source- Dr. Brian Redmond, Professional Geologist). (OK)
Strontium – 0.655 mg/L (Total) and 0.694 mg/L (D) – no specific drinking water standard is available, but it is on the EPA Candidate List. The EPA recommends that drinking water levels of nonradioactive strontium should not be more than 4 mg/L. The report limit is consistent with background levels in Northeastern Pennsylvania. If the background level were above 4 mg/L, it would be advisable to test for radiological parameters, especially alpha/beta. (OK)
Total Dissolved Solids–< 16 mg/L – Total Dissolved Solids is regulated as a secondary drinking water standard by the PADEP in Pennsylvania and the action limit is 500 mg/L. (Question – this value seems inaccurate or a typo – This should be redone or retested.)
1. Heterotrophic bacteria data is not provided.
2. The Methane/Ethane Ratio suggests that the source of the methane is Thermogenic; the level of methane is above the action level of 7 mg/L.
3. The Total Dissolved Solids results are either inaccurate or there is a typo in the draft report.
4. Ethylene Glycol - the testing was not sensitive enough - recommended retesting using a more sensitive method, i.e., a low level of detection, or using a different testing method.
5. Recommend testing the well water for forever chemicals (PFOA and PFOS).
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