2021-04-20_REVISION - M1983033 ‎(20)‎

• Permit No: M1983033
• IBM Index Class Name: Revision
• Doc Date: 4/20/2021
• Doc Name: Request For Amendment To Permit
• From: Albert Frei & Sons, Inc.
• To: DRMS
• Type & Sequence: AM9
• Email Name: PSH
• Email Name: JLE
• Email Name: AWA
• Media Type: D
• Archive: No

Walstrum Spur Amendment, Exhibit G- Water Information
January
February
March
April
May
June
July
August
September
October
November
36.4
37.8
42.7
50.6
60.9
72.1
77.9
75.2
68.6
57.8
44.9
15.6
15.9
19.6
26.4
34.6
42.1
48.7
46.8
39.7
31.5
22.6
0.63
0.68
1.15
1.97
1.81
1.46
2.43
2.19
1.50
1.10
0.75
9.9
10.0
14.5
18.2
6.4
1.0
0.0
0.0
1.9
8.5
10.7
�r
2
1
0
0
0
0
0
0
1
April 2021
December 36.6 16.3 0.78 11.7 2
_ Yearly _ _ _ _
(Avg/Total) 55.1 30.0 16.45 92.8 1
Vegetation patterns commonly provide indications of soil moisture and/or groundwater in arid climates. Figure G-5
shows a false color infrared image of the Spur Amendment and surrounding terrain. Woody vegetation such as
conifers, woody shrubs, and other water demanding vegetation, show up as dark red on the false color image.
Notice the relative lack of dark red in the Spur Amendment. This image demonstrates that the vast majority of
precipitation runs off the Spur Amendment and is not available for groundwater recharge. This explains why the
Existing Quarry has been a"dry mine".
7.0 STORMWATER
The steep slopes shown in Figure G-4 and the relatively impermeable nature of the gneiss indicate why the vast
majority of precipitation runs off the Spur Amendment and is not available for groundwater recharge. Mining of the
Spur Amendment will entail grading such that precipitation that falls in disturbed areas is directed west to the
Existing Quarry for water quality treatment prior to discharge or onsite re-use.
As demonstrated by compliance with the CDPHE Discharge permit, the Existing Quarry has little to no impact on
water quality in Clear Creek. Wthin the Existing Quarry, stormwater is captured in several natural pond areas to
prevent erosion and sediment transfer. AFS has developed stormwater runoff controls within the plant area by
paving five (5) acres of the quarry entrance, level 1, and level 2 ramp areas and diverting stormwater into
detention basins. Furthermore, tracking pads are installed during storm events to reduce sediment tracking on to
external surfaces. Stormwater Best Management Practices (BMPs), such as sweeping and watering roads to
reduce dust and sediments from accumulating on these surfaces, are followed daily.
Since the 2002 amendment, AFS has significantly improved the heavily used Texaco Placer area (south of
Highway 6). The Texaco Placer is also referred to as Stage Y and Parcel C2. Approximately 60 percent of the
Texaco Placer is now paved to facilitate sweeping and sediment control by AFS. Landscaped berms were
installed by AFS to separate the area from Clear Creek and an earthen/gravel detention basin was installed to
prevent discharge from the Highway 6 area to Clear Creek. To further reduce potential impacts to water quality,
AFS is planning to install an engineered, concrete detention basin along with additional paving for the area
� TETRA TECH P a g e 4 � 7
Table G-1: Climate Data - Georgetown Station