2020-04-06_PERMIT FILE - M2019054 (2)

Home Browse Search

�TF/Y1 Consulting Jocelyn F. Mullen, PE,CWP 970-210-8366 2027 Charis Court, Grand Junction, CO 81507 Ms. Lori Lazarus Skull Creek Homeowners 1665 E.4500 S. Vernal, UT 84078 Dear Ms. Lazuras, At your request, I reviewed several environmental issues of concern surrounding the application for a sand and gravel mining operation in NW Colorado based out of Lot 50 of the Skull Creek Estates Subdivision, accessing State land to the east. The first issue I evaluated is the adequacy of a 15 gpm/1 ac-ft per year well permit from Colorado DNR to supply water for dust suppression of mining and transportation activities. At 15 gal x 60 min x 12 hrs x 5 days x 50 weeks =2,700,000 gal/yr min hr day week year If the well were pumped during all operating hours, 2.7 Mgal of water could be pumped from the well per year. With a 1 ac-ft annual limit, equal to 325,829 gal/yr, clearly this cannot be allowed for the mine to remain in compliance. So the question arises of how the mine would be required to accurately measure its withdrawal from the well,to ensure the surrounding well owners were not damaged by excessive withdrawals. Conversely,the mine owners should be required to conduct a pump test to demonstrate that withdrawal at the rate and amount allowed will not damage surrounding residential well owners. Based on these calculations,the mine would only be able to pump during 12%of their operating hours without exceeding their permitted rate or volume of withdrawal. Reviewing the literature for application rates for dust suppression, one gleans that application rates are site, climate,and soil type specific. However, several studies considered application rates in the 1.9 mm/ft2-100 mm/ft2 range, calling 1.9 to 2mm/ft2 the low end, and 100 mm/ft2 the high end of application rates (Water Application for Dust Control in the Central Plateau: Impacts, Alternatives, and Work Strategies; September 2018, by Yonkofski, CMR et al., Prepared for the U.S. Department of Energy, under Contract DE-ACOS-76RL01830, Pacific Northwest National Laboratory). The actual application rate needed to provide adequate dust suppression in the Skull Creek area will be best determined empirically, as a revisable Best Management Practice (BMP). However,the climatological and ecological setting for Skull Creek is similar to that of the Hanford Site. The Central