Maunakea Hydrology and TMT
Tom Nance, President of Tom Nance Water Resource Engineering, provided testimony for the TMT Conservation District Use Permit (CDUP) Contested Case hearing that was not refuted by any experts. Tom's company specializes in water resource development, well and water system design and hydrologic analyses, and Tom has been qualified as an expert in hydrology and water resource engineering on a number of occasions, including reviewing the sections on water, wastewater, and drainage of the TMT Final Environmental Impact Study (FEIS).
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Conclusion: In light of the foregoing, the TMT Project will not have a significant or adverse impact on water resources, including Lake Waiau and the underlying groundwater.
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Excerpts from Tom Nance's testimony are below.
Wastewater
As stated in the FEIS and CDUP, TMT will install a zero-discharge wastewater system at the observatory, which means there will be no discharge of any wastewater from the observatory, including domestic wastewater, and mirror washing wastewater. Wastewater will not be an environmental issue for the TMT project.
Lake Waiau
The TMT observatory will be on the opposite flank of Maunakea from Lake Waiau and will not be in the lake's tributary watershed. In the event that surface runoff during an extreme storm event were to flow off the TMT site, it would move in an opposite direction from the lake. It is not physically possible for such surface runoff to flow to and over the Pu'u Waiau crater rim to enter the lake.
The TMT project's Batch Plant Staging Area, roughly 3,000 feet upslope of Lake Waiau, is also not located in the lake's watershed. There is no possibility of such contamination from runoff at the Batch Plant. Given the physical terrain, there would be no effect on Lake Waiau from surface runoff from the TMT observatory site or the TMT Batch Plant.
Groundwater Occurrence
 The occurrence of groundwater beneath the summit area is what is referred to in Hawaii as "high-level," which means that the groundwater is impounded by subsurface geologic structures such as intrusive dikes, which compartmentalize the groundwater. Although groundwater is the primary source of drinking water in Hawaii, there are no wells extracting groundwater near the summit. The nearest wells are approximately 12 miles away.
Furthermore, the composition of Maunakea consists of very porous lavas that naturally treat and filter water percolating downward. Any discharge on the summit would be naturally treated and filtered through thousands of feet of the porous lavas, thereby removing any contamination in that discharge by the time it reaches groundwater.
There is no reasonable prospect of the TMT project adversely impacting groundwater.
Surface Runoff
Paved areas and buildings are impervious surfaces that prevent rainwater from directly percolating into the subsurface. The TMT project will have approximately 1.3 acres of impervious surfaces at the observatory and paved portions of Access Way. The impact due to new impervious surfaces will be limited by the high permeability of the surrounding ground surface and the area down slope.... The impact associated with localized runoff from new impervious surfaces created by the project will not be significant. Runoff will dissipate via percolation into surrounding permeable areas.
Conclusion: In light of the foregoing, the TMT Project will not have a significant or adverse impact on water resources, including Lake Waiau and the underlying groundwater.
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