2021-06-01_HYDROLOGY - M1977436

• Permit No: M1977436
• IBM Index Class Name: Hydrology
• Doc Date: 6/1/2021
• Doc Name: Substitute Water Supply Plan
• From: DWR
• To: DRMS
• Email Name: ECS
• Media Type: D
• Archive: No

Aggregate Industries South Platte Combined SWSP June 1, 2021
Plan IDs 3614, 4773, 3624, 4772, 4616, 3437, 3376, 3650, 3668, 5475, 5829, 8t 6090 Page 4 of 23
Platte Valley Pit Status: Mining operations at the Platte Valley Pit are not anticipated to occur in
(South Platte 2021, though reclamation activity consisting of backfilling portions of the site
Mainstem) will continue in 2021. Aggregate intends to import 912,940 tons of material
mined at other sites to the Platte Valley Pit site for processing. The imported
material will be washed with water withdrawn from exposed groundwater ponds
on the site, therefore 2% of the weight of the imported material will be charged
as a depletion. The initial moisture content of the material will be charged as
depletions at the originating source, which may include sources operated by
other entities. Depletions covered by this SWSP include water lost due to
evaporation, aggregate processing, dust control, and concrete batching. Water
for concrete batching will come from Well Permit No. 13410-F-R (WDID
0207073). Note that the water right for this well was on the division engineer's
2010 Decennial Abandonment List, but the well may still be used in accordance
with its permit as long as all depletions are treated as junior to all other vested
water rights in accordance to this SWSP and the well complies with the South
Platte Well Measurement Rules. The applicant submitted the attached "Figure
1— Platte Valley Pit 2021 Exposed Area" for verification of the area that has
been exposed starting in 2019.
Exposed Groundwater Surface: 63.8 acres
Active Dewatering: No
Distel Pit Status: Mining operations at the Distel Pit were completed in 2011 and
(St. Vrain River) reclamation is in progress. In 2017, Aggregate used water from the Distel site as
a water supply for a portable ready-mixed plant located at the site for a
short-term job. Depletions covered by this SWSP include water used for dust
control, and lagged depletions from past concrete batching and past aggregate
production, and post-pumping depletions from past dewatering. Dewatering at
the site ceased due to flooding in September 2013, and Aggregate currently has
no plans to reactivate dewatering. The City of Longmont has assumed the
augmentation responsibilities for lagged and future depletions from evaporation
and consumptive use by wetlands vegetation at the site under their plan for
augmentation decreed in case no. 2009CW271.
Exposed Groundwater Surface: N/A (augmented under case no. 2009CW271)
Active Dewatering: No
Tull Pit Status: Mining operations are anticipated to continue at the Tull Pit in 2021.
(St. Wain River) Depletions covered by this SWSP include water lost due to evaporation, dust
control, aggregate production, and dewatering. The site will be dewatered
continuously throughout 2021.
Exposed Groundwater Surface: 4.0 acres
Active Dewatering: Yes
Irwin-Thomas Status: Mining operations are anticipated to commence at the Irwin-Thomas Pit
Pit in 2021. Water use at this site will consist of dewatering, evaporation from
(St. Vrain River) exposed groundwater, aggregate production, and dust control.
Exposed Groundwater Surface: 2.5 acres
Active Dewatering: Proposed to start in 2021