Deep in the ground, thousands of feet below the Earth’s surface, geothermal fluids pose no threat to human health or the environment. Raise them to the surface, though, and shielding the public from their toxic qualities becomes a problem.
To avoid having to deal with the fluids as hazardous waste, the design of the Puna Geothermal Venture operation calls for reinjecting them deep into the Earth. The state’s experimental geothermal plant in Puna, HGP-A, diverted fluids to a pond where they were allowed to soak back into the ground. Because of concerns over groundwater pollution and violations of Environmental Protection Agency requirements, the ponding of geothermal fluids has been abandoned as a satisfactory, long-term means of dealing with the problem of their disposal.
The reinjection of geothermal fluids has been described as critical to the overall success of any effort to develop geothermal resources in Hawai`i. Wilson Goddard, one of the independent consultants retained to study the June 1991 blow-out of PGV’s well KS-8, said on one occasion that “if injection fails, the project fails.”
Past Problems
Reinjection is not a tried and true technique. One of the few places it has been attempted has been the Coso Hot Springs geothermal field in California. According to Subir K. Sanyal, vice president of GeothermEx, Inc., a consulting engineering firm retained by the state, at Coso, “the injected gases have broken through at several production wells. This has caused the following problems:
“The power generation level has declined due to the increase in the gas content of the steam;
“The capital cost has increased because of the need to install an H2S abatement system not originally planned for;
“The operations and maintenance costs have increased due to the need for H2S abatement;
“A gas discharge permit had to be obtained … which was not originally planned for.
“It is possible that these problems would occur at the KERZ [Kilauea East Rift Zone, on which the PGV plant sits] given the new injection plan.”
In a memo to the state Department of Business, Economic Development and Tourism dated October 23, 1991, Sanyal went on to describe the complex task of forecasting the way in which cooling and gas break-through might occur at PGV. Given the lack of data at the site, such modeling was impossible at the time of his memo, he said. However, he added, GeothermEx would be developing such a model on behalf of Credit Suisse (one of the principal investors in PGV) “after the PGV’s drilling and well-testing activities are completed.”1
High Hurdles
Injection wells are little more than holes in the ground, cased to a certain depth. In the case of geothermal injection wells, the wells are supposed to carry fluids safely past the stratum of potable water and down to the same depth from which they were originally drawn (a mile or more below the Earth’s surface).
But the nature of the fluids in the Kilauea East Rift Zone makes what may appear to be a straightforward task into something quite complex. One problem is the high silica content of the fluids in this area. As Goddard described it, “if you take too much heat out of the silicas or you take too much water out of the silicas, they will precipitate,” causing silica build-up on the well casing. As a general rule, he continued, injection wells “have to be reamed every six months,” which means that drilling rigs have to be brought back to the site, the well has to be reopened, the liner pulled out and cleaned, and the whole system reassembled.2
In the memo quoted earlier, Saynal of GeothermEx weighed the pros and cons of siting injection wells in the same field as production wells. This approach, he said, eliminates possible contamination of ground water aquifers — a claim that many people dispute, given the fact that the PGV plant, unlike most plants developed elsewhere, sits above a potable water resource — and provides “some pressure support” to production wells. On the other hand, it might cause cooling of production wells “due to the breakthrough of cooler, injected water.” Also of concern is the “possible breakthrough of the injected non-condensible gases at the production wells.”
(The non-condensible gases include, in addition to hydrogen sulfide, carbon dioxide, ammonia, argon, nitrogen, methane, helium, and hydrogen as well as more toxic gases: mercury vapor, radon 222, and arsenic among them. To avoid the emission of these into the atmosphere, the plant design calls for these gases to be run through a compressor and pumped back into the Earth along with the rest of the geothermal fluids. If they enter the production wells, they displace steam and can reduce plant efficiency.)
Groundwater Concerns
In Hawai`i, the state Department of Health is responsible for protecting underground sources of drinking water, but it the federal Environmental Protection Agency has not yet delegated to the DOH authority to enforce federal safe-drinking water laws. And the EPA, as primary enforcement authority, has taken a keen interest in the state’s permitting of PGV’s injection wells.
In July of this year, the DOH issued a “final” underground injection control permit for two PGV wells, KS-3 and KS-1A. Within a month, however, the EPA received a 35-page letter detailing the various ways in which this permit fell short of the standards of protection set by federal law. Signing the letter were 10 individuals representing diverse interests. The permit did not impose upon PGV conditions that would prevent contamination of underground sources of drinking water by geothermal fluids, the letter stated.3
The letter pointed out that the state had virtually written off the need for ground water protection in the Puna area by establishing, in revisions to its rules made in 1991, a special exemption for aquifers in designated geothermal resources subzones. This, the letter stated, “appears to be the result of increased pressure from geothermal developers.” It continued: “That surrender to pressure from geothermal developers … adds to the problems of DOH’s ongoing effort to achieve the delegated authority of the federal UIC program.” Problems that the state has had regulating UIC wells both in Puna and elsewhere in the state4 were listed, as were concerns over ground water protection raised by past use of unlined pits to hold spent geothermal fluids.
“There is a very real potential that underground injection will not work properly or at all,” the writers said. Corrosion, potential release of non-condensible gases, inadequate oversight of all aspects of PGV operations by county and state officials, and a host of other concerns were cited in this connection.
The EPA Intervenes
In what appears to be an attempt to take up these matters with the state, Harry Seraydarian, water management division director of EPA Region IX in San Francisco, wrote to DOH Deputy Director Bruce Anderson on September 18, 1992.
“Due to the fact that Hawai`i has not been delegated the UIC program, we believe that it is necessary to review these [UIC] permits carefully… After reviewing this permit, we have some concerns that need to be addressed before injection commences,” he wrote. Seraydarian appended to his letter a summary of the EPA’s several concerns.
The integrity of the wells was an issue in four separate points. Well KS-1A lacked tubing, and therefore could not be used for geothermal fluid injection. The operation of well KS-3 was questionable: “during the August 1992 flow test,” Seraydarian wrote, KS-3 “did not take the volume of injectate that it was designed for.” Ponds for temporary storage of brine must be lined, “have sufficient capacity for an upset condition, and piping must be set up to reroute the brine from the ponds back to the injection wells so that the ponds do not overflow.”
At virtually the same time the EPA was listing its concerns, Thomas G. Kizis, environmental manager for Puna Geothermal Venture, was writing the Department of Health, elaborating on some of the very issues Seraydarian had touched upon.
In Kizis’ letter, dated September 21, he mentioned that “severe localized corrosion damage” had been discovered in the 9-5/8-inch casing of well KS-3 at a depth of 2,500 feet. “This resulted from external corrosion by acidic geothermal fluid in a low-permeability fracture zone at that depth. Pressure testing confirmed a small leak in the corroded casing.”
PGV attempted to seal the leak “with an acid-resistant latex polymer modified cement,” after which it installed a 7-inch liner. When tested at 860 pounds per square inch, however, a small leak was still found. “It was concluded that it would not be practical to achieve a gas-tight repair of the leak by squeeze cementing,” Kizis wrote, so the liner was pulled out, “pending further evaluation of the alternatives. Operations on KS-3 were temporarily suspended on September 8 and the rig was moved to begin drilling KS-4.” Kizis was writing to seek Department of Health approval for PGV’s plan to repair KS-3 for use as a “standby injector,” with possible conversion to regular injection service “at a later date.”
The Final Final Permit
On October 14, 1992, DOH Director John Lewin wrote Seraydarian, attempting to address his concerns. Well KS-1A would be lined before being permitted, Lewin stated. And Seraydarian’s concern over the potential capacities of the wells was a non-issue, Lewin stated. The reinjection capacities would be “the limiting factor” determining power output, he stated. If more fluids were being produced than could be taken in by injection wells, “it is within PGV’s control to throttle down the production volumes to match the reinjection capacities. Because PGV has this control, the issue of substantiating reinjection capacities to match production well capacities is not a regulatory issue of the reinjection well permit.”
In other words, the Department of Health would be relying on PGV to cut production to match injection capacity, even when that might run counter to PGV’s economic interests.
On October 21, 1992, the final UIC permit was issued to Puna Geothermal Venture, authorizing the use of KS-1A as a primary injector and KS-3 as a “standby injector.” Chauncey Hew of the Department of Health Safe Drinking Water Branch told Environment Hawai`i that since issuance of the permit, repairs have been made to well KS-3 so that it, too, may be used by PGV as a primary injector.
In late November, PGV announced that well KS-4 — whose purpose had changed from injection to production and back to injection again — would be used as an injector after all. If the necessary permit is issued, this would give PGV a total of three injection wells — enough, it claims, to meet all of its injection needs at full, 25 megawatt production.
1 The state apparently had no objections to GeothermEx providing services to a PGV investor. Earlier, however, DBEDT had asked that so long as GeothermEx was under contract with the state, it not provide consulting services to Kilauea Energy Partners, the consortium selected by Hawaiian Electric, Inc., to develop the plan to export 500 megawatts of electricity via undersea cable from the Big Island to O`ahu. See the memo from Murray C. Gardner, GeothermEx executive vice president, to Murray Towill, DBEDT director, of July 5, 1991.
2 Wilson Goddard, comments made March 25, 1992, at a Hawai`i County Energy Advisory Commission workshop on geothermal health and safety.
3 The Department of Health later claimed that the July 27 permit never took effect. It had been “held in abeyance by the DLNR” – Department of Land and Natural Resources – “pending final reinjection well construction and their conformance to the specifications as described in the UIC permit. Therefore, at the present time PGV does not have a UIC permit to operate reinjection wells for power production.” The quote is taken from a letter dated October 14, 1992, to Harry Seraydarian, director of EPA Region IX Water Management Division, from DOH Director John Lewin.
4 Including West Maui, where wells used to dispose of sewage effluent are suspected to be linked to algae blooms. For more on this, see the October 1992 edition of Environment Hawai`i.
Volume 3, Number 6 December 1992