2023-01-10_PERMIT FILE - M2023001 ‎(12)‎

• Permit No: M2023001
• IBM Index Class Name: Permit File
• Doc Date: 1/10/2023
• Doc Name Note: Exhibit G - Water Information
• Doc Name: Application
• From: J-2 Contracting Company
• To: DRMS
• Email Name: PSH
• Email Name: JLE
• Media Type: D
• Archive: No

Fair Meadows Pit Groundwater Evaluation
November 19, 2022 Page 5 of 28
walls; and iii) seasonal fluctuations in the water table due to agricultural pumping and irrigation
return flows.
Hydrogeology
The hydrogeology of the SPR alluvial aquifer is described by Lindsay and Others(1998 and 2005),
CDM (2006 and 2013) and CSU (2013). Figure A2 shows the site surficial geology (Tweto,
1979). The alluvium within the model areas consists of alluvial sand and gravel(Qa) adjacent to
the modern SPR flood plain, and older terrace alluvium (Qg) outside the floodplain. Bedrock
consist of the Laramie Formation(Kl), which is primarily a black shale that is exposed beyond the
northeastern corner of the model.
Figure A2 also shows the well data permits and reported well depths. Wells with a less than (<)
sign represent wells that did not encounter bedrock based on their driller's logs. The deepest
portion of the surficial sand and gravel is over 100 feet deep and extends north from the Fair
Meadows and other existing pits (pink triangles). This suggests that the modern alluvium (Qa)
mapped by Tweto likely extends further north than what is shown on the Figure A2.
Bedrock Elevation Contours
Figure A3 shows the calculated bedrock elevation based on the ground elevation minus the
reported depth to bedrock from a"driller's"log. The data was used to update the bedrock elevation
contours(aka. structure map)published by the USGS (Hurr and Schneider, 1972). The map shows
a deep (over 100 foot deep) erosional "paleochannel" extending from the northwest to southeast
across the study area. The depression was eroded into the bedrock by the Poudre River thousands
of years ago before the river established its current depositional channel and modern floodplain.
The bedrock elevation within the paleochannel drops from approximately 4600 ft in the west to
approximately 4530 feet in the east. The Fair Meadows pit is located where the elevation of
bedrock drops steeply from 40 ft deep in the southwest corner to over 90 ft deep in the east.
Water Level Contours
We created a water table map (Figure A4) using available data from registered SEO wells (Table
Al), Fair Meadows monitoring wells (Table A2), and the September 2022 measurement from the
monitored registered wells (Table A3). The water table elevation data from SEO wells was
determined by subtracting the reported depth to water when drilled from well site elevations
interpreted from US Geological Survey 10m Digital Elevation Model (DEM) data sets. The
ground elevations for wells in Tables A2 and A3 were surveyed. The 10 ft elevation contour lines
shown on Figure A4 are a manual interpolation of the well data and river elevations. The water
table on the western portion of the model is at an elevation of approximately 4630 ft and the water
table gradient falls approximately 25 feet to approximately 4605 ft on the east end of the model.
Groundwater flows perpendicular to the contours and generally towards the river. The Poudre
River gains in the western side of the map between the 4630 ft and 4620 ft contours and loses
between the 4620 ft and eastern edge of the model area. The location of the 4610 ft contour is
heavily influenced by the Fair Meadows monitoring wells which appear to have water
levels several feet below other nearby wells, which likely is the result of late season
irrigation and stock well pumping.
McGrane Water Engineering,LLC
1669 Apple Valley Rd. •Lyons,CO 80540•Phone:[phone]
E-Mail:[e-mail] Web:ttp://www.mcgranewaterengineering.com