Regional Water Quality and Protective Standards
The project-area groundwater consists of three aquifer systems: the unconfined surficial aquifer system, the intermediate aquifer system, and Floridan aquifer system. The surficial aquifer, closest to the surface of the earth andcomprised of sands and limestone, is primarily recharged with rainfall. A barrier of dense clay and stone separates the surficial aquifer from the intermediate aquifer, slowing or preventing seepage from one to the other. Another similar barrier further protects the Floridan aquifer throughout most of the mine site. HPS’s excavation will occur in the surficial aquifer, above the clay and limestone barriers protecting the intermediate and Floridan aquifers, outside the sensitive area of the aquifer, which will prevent any impact on the aquifer water quality.
The groundwater within this site is classified as G-II for potable water. The surficial aquifer presently meets applicable groundwater standards, except for slightly elevated levels of aluminum and iron (which are naturally occurring in the areaand possibly the result of aluminophosphate weathering). Florida Department of Environmental Protection (FDEP)regulates groundwater quality by setting limits on substances commonly found in groundwater and enforcing those limits through the Industrial Wastewater permitting program. In accordance with state regulations, groundwater on the site will be at least evaluated semi-annually prior to and during miningfor a variety of constituents, including nutrient levels, temperature, and pH, to confirm that groundwater leaving the site is not being adversely affected by mining activities. No existing groundwater uses in the area will be impacted by the HPS mine.
The project-area surface waters consist of 4,331.28 acres of wetlands, 132.27 acres of streams (natural and ditched), ditches, cattle ponds, and upland cut lakes, and the New River bisecting Union and Bradford Counties. The New River, about 3,000 acres of wetlands, and 79 percent of streams on site will be avoided in the mining plan, and the quality of these surface waters will be protected during mining. Surface water quality for on-site waters is typical of an agricultural site in the region, generally meeting all surface water quality standards, except for naturally occurring elevations of aluminum and iron due to weathering.
Per FDEP regulation, HPS will monitor the surface water quality on site at least quarterly by analyzing samples from various places around the property to examine nutrient content, turbidity, and other characteristics, to ensure the off-site and avoided surface waters are not being affected by mining operations.
To prevent impacts on water quality around the mining site, HPS will adhere to setbacks around undisturbed waters, and implement erosion control measures and other best management practices known to be effecting in protecting water quality. During mining, those measures will be coupled with a ditch and berm system and stormwater treatment system that will filter sediments from stormwater before they reach offsite or avoided waterbodies. Within the mining area, the ditch and berm will prevent any release of material from the HSTS, and where it passes outside of the mining area, a swale and catchment will be constructed to retain any escaped material. Over the New Riverand its protected corridor, the double-layer HSTS will be enclosed.
After mining, HPS will continue to protect water quality with enhancement projects. A new forested buffer and reverse swale on the banks of the New River, as well as the elimination of agricultural ditches, will slow the velocity of runoff to the river and enhance filtration of stormwater. Further, the New River corridor running through the property will be fenced and kept free of cattle, which will reduce the amount of nutrients draining to the river.