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 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 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.
First question is why? Because I do not have all the facts for each 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-17 in Dimock, Pennsylvania. The well was sampled by the EPA, DEP, and the local natural gas development company in 2012 after the natural gas drilling wells had been drilled, developed, installed, and some under production. The primary objective was to determine the presence of any residual impacts at that specific time.
A fact based review - Well by Well of the Available Well Water Data for the Dimock Area that was generated by the EPA. 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 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 predrilling data, it is not possible to comment on the cause for any water quality problems. This has been a very frustrating issue for this area. In many cases, there was no to very little predrilling 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 duplicate analysis provided, I attempted to use the highest reported value.
4. This evaluation was based on using 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)
Barium – 0.239 mg/L – the primary drinking water standard for barium is 2.0 mg/L –– this does not suggest any specific impact and barium is typically detectable in non-saline impacted water at a level of less than 1 mg/L. (OK)
Calcium- 33.1 mg/L (Total) – no specific drinking water standard, drinking water standard is available. (OK)
Chloride – 7.12 mg/L (OK) – drinking water standard is < 250 mg/L – this does not suggest any specific impact.
Copper – 0.0035 mg/L (OK) - the secondary drinking water standard is 1.0 mg/L and the primary drinking water standard is 1.3 mg/L. (OK)
Ethane **–**0.040mg/L – No specific drinking water standard (OK)
Methane – 3.3 mg/L – No specific drinking water standard. (OK).
The well water is not above the new action limit of 7 mg/L, but the well should be fitted with a basic vented well cap, but the level of methane is at a level were passive venting is recommended.
The methane/ethane ratio is (2.0/ 0.011) – 82.5
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.), but between 25 and 2500 this is where isotopic analysis and gas composition analysis is critical.
Magnesium- 6.64 mg/L (Total) - no specific drinking water standard, drinking water standard is available. (OK)
Manganese – 0.040 mg/L (Total) – Manganese is regulated as a secondary drinking water standard in Pennsylvania and the action limit is 0.05 mg/L. Therefore, the total manganese content does not exceed the secondary drinking water standard. (OK)
Nickel - 0.0012 mg/L (Total) – no specific drinking water standard, drinking water standard is available, but the EPA has suggest a MCL of 0.1 mg/L. (OK)
Nitrate+Nitrite- N – 0.707 mg/L, this is well below the EPA / PADEP drinking water limit of10mg N/L for nitrate-N and would also be below the limit of 1.0 mg N/L for nitrite-N. (OK)
Sodium – 12.1 (Total) – 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 definitely taste salty. (Source- Dr. Brian Redmond, Professional Geologist). (OK)
Strontium – 0.835 mg/L (Total) – no specific drinking water standard, 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 was above 4 mg/L, it would be advisable to test for radiological parameters, especially alpha/beta.(OK)
Sulfate – 10.4 mg/L (OK) – drinking water standard is < 250 mg/L – this does not suggest any specific impact.
Total Dissolved Solids – 52 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.
Uranium – 0.0037 mg/L (Total) – Uranium is regulated as a primary drinking water standard by the EPA and PADEP in Pennsylvania and the action limit is 0.030 mg/L. (OK)
Zinc – 0.0065 mg/L (Total) – Zinc is regulated as a secondary drinking water standard by the PADEP in Pennsylvania and the action limit is 5.0 mg/L. (OK)
Arsenic – 0.0027 mg/L (Total) – drinking water standard is < 0.010 mg/L – this does not suggest any specific impact and arsenic is a common problem in NEPA – about 6 % of private wells have arsenic above 0.010 mg/L. It would be advisable to monitor the arsenic level of the well on an annual basis.
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 Minnesota 14.0 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.
1. No major problem.
2. Arsenic was detected, but not above a drinking water standard, but annual monitoring is recommended.
3. Methane/Ethane Ratio could suggest the source of the methane is of thermogenic origin and the level of methane is well below the action level of 7 mg/L, but at the action level of 2 mg/L where passive venting is recommended.
There are two main types of methane found in rock formations and groundwater. The types are based on a difference in origin, not composition:
a. Thermogenic methane, which is formed from buried organic matter at considerable depths where the rocks are compressed and heated; this includes the methane found in coal, gas from some Devonian sandstones/shales, and gas from the Marcellus and Utica Formations. Methane is produced by the inorganic breakdown of organic matter (heat and pressure).
b. Microbial (previous term biogenic or bacterial methane) forms closer to the surface by the action of bacteria (**methanogens** - bacteria that produce methane and cannot live in an environment with oxygen). This would include methane generated in landfills, lake sediments, wetlands/swamps, organic-rich glacial deposits, other recently buried organic deposits, and other carbon rich environments that are without oxygen. Microbial methane gas typically contains 20 percent to 30 percent less methane than is found in thermogenic natural gas.
4. Retesting for glycols using a more sensitive technique is recommended.
5. Recommend testing the well water for forever chemicals (PFOA and PFOS).
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