| Maury Island, like any island, relies on a natural balance to sustain life. Water, the very essence of life, falls as rain. Island soils the acts as a large underground storage facility, working as a filter and holding tank -- ensuring continuous recharge of our aquifer throughout the year. This aquifer is not a "lake or pond" of water lying below the island -- it is a layer of permeable rock that holds the water that we then tap with our wells.
Mining a 235 acre site at the narrowest part of Maury Island will have a very deep impacts on the recharge of our water supply. The island will lose 64 million cubic yards of its underground water filtration and storage facility.
Ground water flow will also be altered. The new profile of the island will allow rainwater, formerly used to recharge the aquifer, to run into the Sound. The ground water will no longer be filtered through hundreds of feet of soil, but through a mere 15 feet of soil. The quality of water in the wells on Maury will change if the mining occurs. |
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| The proposed Glacier NW mine on Maury Island will certainly have many impacts, but one that has the potential for catastrophic results is the effect the operation might have on the island's only water source. Totally rain fed, this aquifer sits just above sea level. The exact size, shape, and location of the aquifers of Vashon/Maury Islands are not completely understood. There is a good deal of common belief that most or all of the water sources beneath Vashon / Maury are interconnected. All are supplied exclusively by groundwater recharge, and accessed by deep drilled water wells, supplying the drinking water to the many residents of the islands via a combination of private wells and neighborhood water districts. While the communities nearest the proposed mine are exposed to the greatest risk of water supply disruption or contamination, there is real concern that the unknown interconnections of what may be a single aquifer beneath Vashon / Maury very credibly extends this risk to a much wider area. Water is a precious resource on the island, as any islander can tell you. Disruption or contamination of this resource is intolerable, as there is no alternative source.
The extent of the mining operation has serious implications on the recharge ability of the immediate aquifer. The site, located at one of Maury's narrower stretches, cuts nearly halfway through the island at this point. The effect this may have on the flow and recharge characteristics of the aquifer can only be surmised.
The depth of the mining cut will come to within 15 feet of the aquifer. This narrow margin gives rise to serious concerns of direct contamination, particular considering the levels of arsenic and other heavy metals found at this location, which presently have remained out of the deep water aquifer.
The aquifer rests just above sea level, contained within a network of porous earth and vacuous pockets beneath the land. Breaching this barrier could potentially contaminate the water with the salinity of the Puget Sound waters, should they begin to intermix freely. Direct drainage of the freshwater supply into the Sound is another concern, as this could work to deplete the supply, or divert the natural flow.
More complete studies of the morphology of the underlying contact of the ground beneath the islands and the effects this has on groundwater flow must be performed before these questions can be set aside. Glacier NW's hypothesis of groundwater breaks and subsurface flows 'isolating' the site from having adverse effects on the surrounding water supplies offers little security in the way of thorough science. With the neighboring communities vitally dependent upon the security of their only water supply, these answers must be absolute, not simply the best guesses from paid consultants of Glacier NW.
A related concern relates to the fact that Glacier has not been specific about where it intends to get the water needed for servicing the mining operation itself. A large amount of water is used in gravel extraction (an estimated 5,000 gallons per day will be used by the proposed operation). Tapping into the local water supply would create serious "draw down" on the current water supplies of the surrounding communities. |
Geological Impacts
Steep slopes, erosion, and slides are a major issue for adjacent property owners. Hydrologic pressure from the alteration of the recharge area could contribute to the problems. There are concerns about reduced seismic stability as well. The effects of even a small quake may be greatly exacerbated by the compromised stability of the earth surrounding the site.
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