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4.0 EXISTING GROUNDWATER CONDITIONS <br /> Groundwater was measured in seven (7) piezometers, and typically occurs at depths usually ranging from 17'to 25'feet <br /> below surface with shallower groundwater to the north of the Site.The prevailing groundwater flow direction at the Site is <br /> to the north reflecting the Site topography. Groundwater in the area is tributary to the South Platte River located <br /> northwest of the Site. Depth to groundwater is shallower, as little as 5 feet, underlying the Town of Gilcrest likely due to <br /> the deep bedrock and low topography relative to the surrounding area. Locally the groundwater levels and flow directions <br /> are influenced by: <br /> ➢ The South Platte River is northwest of the Site. For most of the year,the river likely acts as a drainage <br /> way, or gaining river reach, maintaining groundwater levels at elevations greater than water elevations <br /> in the river. In shorter periods of high run off, usually in the spring, river water levels will locally <br /> recharge the groundwater table. <br /> ➢ The Western Mutual Ditch passes southeast of the Site under the intersection of Weld County Road 42 <br /> and Weld County Road 29. North of Weld County Road 36, the ditch joins with a wetland drain which <br /> likely provides water year-round. During the irrigation season, the ditch diverts water from the South <br /> Platte River as well raising the water level of the ditch. <br /> ➢ The Farmers Independent Ditch traverses the southeast comer of the Site and bisects Cell 5a and 5b. <br /> The ditch flows most of the year based on diversion records for the ditch headgate located southwest <br /> of Platteville. <br /> ➢ The Evans#2 Ditch passes southeast of the Town of Gilcrest on the eastern side of Highway 85. The <br /> ditch did not have discharge during the months of November and December but did have flow during <br /> the remainder of the year. <br /> ➢ The Platte Valley Ditch branches off from the Evans#2 Ditch south of the Town of Gilcrest. The Platte <br /> Valley Ditch does not have a stream gage, so it was assumed that it was flowing at the same time as <br /> the Evans#2 Ditch. <br /> ➢ There is a pond south of Weld County Road 42. This pond likely causes elevated groundwater levels <br /> at the south of the Site during the irrigation season. <br /> ➢ There is a pond north of Weld County Road 44.This pond likely causes elevated groundwater levels at <br /> the south of the Site during the irrigation season. <br /> ➢ There are two unnamed sloughs approximately'/2 a mile to the west and another a '/<mile to the north <br /> of the Site respectively. These sloughs receive groundwater flowing out from the higher terrace and act <br /> as drains moving water to the river. <br /> ➢ There are multiple recharge ponds it the area of interest which provide groundwater recharge (refer <br /> Figure 2). <br /> ➢ Irrigation: The Site is located in an area of irrigated cropland. Applied irrigation that is not lost to <br /> evaporation and transpiration recharges the groundwater. <br /> Groundwater Model Report—Section 20 Gravel Mine Site -2- August 2022 <br />