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Standards that must be met <br /> The law(C.R.S. 37-92-602) is quite clear that 97% of the storm water detained in the <br /> sediment basin from a 5-year or smaller storm must be released or infiltrated in 72 hours after the <br /> storm. For larger storms than 5-year, release and infiltration should be as quickly as practicable, <br /> but 99% of the volume must be released within 120 hours of the storm. <br /> That sounds well and good, except there does not seem to be any facilities installed on <br /> Turkey Creek to determine the size of various storms. What amount of rainfall in the watershed is <br /> needed over the 24 hour period to produce a particular size storm? <br /> The 72 and 120 hour time limits are easily achieved in most instances. As for the volume <br /> that is released it is as stated before -pump out as much water from the pond as feasible without <br /> pumping mud into Turkey Creek. Not pumping the pond dry(discharging mud) will help prevent <br /> fine sediment accumulating in basins in the stream bed where important biological resources may <br /> be surviving when the stream is not actively flowing during dry spells. <br /> Turkey Creek formerly was almost a perennial stream, but as the climate has dried in <br /> recent years the stream has become more and more intermittent. Also, with dry soils on the slopes <br /> of the watershed more and more of the total storm water is retained in soils than was previously <br /> the case. This means that to produce a given flow as well as maintain a more perennial character, <br /> storms need to be a bit larger than previously to produce the same flow volume. In that respect a <br /> slower release of water from the pond could maintain a bit more flow in the stream, but the <br /> volume collected in the pond is not likely to be enough to make much difference in maintaining <br /> historical flow volumes from Turkey Creek. The basin is simply not large enough even without <br /> sediment. <br /> Water quality in the discharge is also of concern, but visual tests of pumping water out of <br /> the pond and filtering it through a fine filter sock appears to produce quite clean water with little <br /> sediment. Most of the sediment in the water is retained in the sock and can be removed and <br /> discarded when the sock is cleaned. Furthermore, the volume of water discharged at any one time <br /> is not great so this method appears to work well at keeping the water quite clean. <br /> Technical Revision Menzer Quarry M-1973-009-HR June 2021 Page 4 of 7 <br />