Connectivity or conductivity?
USGS counters MCWD press release regarding monitoring well findings.
On Monday, Nov. 2, Mammoth Community Water District (MCWD) distributed a press release alleging that “preliminary results from two shallow monitoring wells drilled by the United States Geological Survey (USGS) … indicat[ed] that Ormat Technologies’ Casa Diablo IV Geothermal Development Project could have impacts on local water availability and environmental resources.”
Two USGS scientists disagreed.
The two recently drilled USGS monitoring wells are part of a program funded by the California Energy Commission (CEC). “Ormat is paying for 50 percent and the CEC is paying for 50 percent on a grant,” explained MCWD General Manager Pat Hayes.
The MCWD press release stated that the new wells “have revealed hot water in the shallow aquifer, suggesting potential connectivity between the region’s groundwater basin and the geothermal zone below.” The press release noted that the wells closest to Ormat’s current geothermal production have recorded temperatures as high as 210 degrees Fahrenheit.
The press release also stated that “at least one MCWD production well has shown traces of chemicals associated with geothermal water, suggesting potential water quality impacts due to geothermal pumping.”
But retired USGS Chemist Bill Evans, and current USGS Hydrologist Jim Howle, argued that the claims made by MCWD in its press release were disingenuous.
Evans explained that the USGS “drilled the [two shallow monitoring] wells, and about a month ago, we mounted an attempt to collect water from the wells and had a problem with the pump. As far as I know, other than samples we grabbed during the drilling itself, which aren’t very good, there isn’t any chemistry that’s been run on those wells. That’s certainly the plan, but without that water chemistry in hand, it’s going to be very difficult to assess connectivity.”
Although Evans said that the fact that there is hot water at a shallow depth “would be of concern to the Water District, I think that this [the press release] is correctly written: ‘suggesting potential connectivity.’ In my opinion, there’s still a lot of work to be done before you remove that ‘suggesting potential connectivity.’”
Jim Howle went further. “That’s some unfortunate wording, and I was actually going to talk to the Mammoth Community Water District about it,” he said. “Just because the water is warm doesn’t mean there’s connectivity. What they’ve said in that press release is misleading at the least, and until there’s chemistry data from the water, which we’re still trying to acquire, whether there is a connection is yet to be determined.”
Howle said that because of the temperature of the water in the two wells, the USGS requires special equipment to test the wells’ water chemistry. Likely that equipment won’t arrive until January. Then it will be several more months before “the labs have done their analysis and we have a data set that we can start making interpretations from.”
Howle said there are other explanations for warm water found in a shallow monitoring well. “It could be that the shallow aquifer in that area is simply heated by the hot rock below it, overlying the geothermal reservoir,” he said. This effect is called conductivity.
Howle say the press release as “part of their [the Water District’s] ongoing media blitz,” which began when MCWD sued Great Basin Unified Air Pollution Control District (GBUAPCD) over its approval of the Casa Diablo IV Final Environmental Impact Report. MCWD felt that the FEIR did not require an adequate monitoring and mitigation plan, should Ormat’s geothermal expansion affect Mammoth’s groundwater supply.
The MCWD lawsuit came to an end with a ruling from Judge Stan Eller in GBUAPCD’s favor, but the MCWD Board made the decision in September to pursue an appeal of the decision. MCWD continues to argue that the FEIR violated the California Environmental Quality Act; that the Casa Diablo IV project would jeopardize surrounding groundwater; and that the project’s current mitigation measures are “woefully inadequate.”
In MCWD’s media campaign against Ormat and GBUAPCD, the Water District has often alluded to a MCWD production well that has already shown traces of chemicals associated with geothermal water. MCWD argues that those traces suggest potential water quality impacts due to geothermal pumping.
Howle took issue with this assertion, too. He said that while the well has shown traces of chemicals associated with geothermal water, “that that was caused by geothermal pumping is absolutely not true,” he said. “The two systems obviously intermingle.”
Howle said the USGS has seen more evidence of this intermingling on the north and west side of town, where the MCWD well with slight geothermal chemical traces is located. “That has nothing to do with the ongoing pumping … it is a natural mixing.”
In support of that is the fact that, “There are samples that predate any geothermal pumping over near Shady Rest, which started in 2006, and those [geothermal chemical] constituents were in those wells long before any geothermal pumping began. So their statement that this is caused by geothermal pumping is totally untrue, and deceitful, I might add.”
In a follow up interview with The Sheet, MCWD General Manager Pat Hayes called Howle a “very solid scientist,” but argued that the very fact that there could be intermingling between geothermal and warm water is enough reason for MCWD to continue pursuing more stringent monitoring and mitigation measures from Ormat before it builds Casa Diablo IV.
“If what Jim is suggesting is that this [geothermal constituents] was there [in one of MCWD’s wells] before Ormat was pumping, we’ll see if the level of constituents increases,” said MCWD District Engineer John Pederson. “That’s the kind of science that we think is needed to ensure that our water won’t be affected.”
Moreover, “The very fact that there is water in the shallow USGS wells is significant,” Hayes said. He said that Ormat didn’t believe the USGS would find any water when in the new wells. (Ormat did not respond with a comment to the MCWD press release before deadline).
“The fact that the water was also of some temperature … and that that water is at the same elevation as our groundwater wells, is significant new information,” Hayes said. “I think Jim Howle would agree with all of that.”
Pederson explained that “One of the main reasons that we’re familiar with Jim and his work is that we initiated a contract with him and the USGS to continue sampling our wells for geothermal water constituents.”
Hayes added that MCWD has paid for that sampling for approximately a year. “We look to the USGS as an independent expert and third party; that’s why we hired them to do the water quality testing,” he said. “We have a great deal of respect for what they’re doing. The identification with these two wells that there’s water, and there’s hot water, causes the District some concern. There are various theories out there, and what we’re interested in is, what are the facts? We look forward to their ongoing analysis to bring that information forward.”
