2023-10-31_REVISION - M1973021 ‎(7)‎

• Permit No: M1973021
• IBM Index Class Name: Revision
• Doc Date: 10/31/2023
• Doc Name Note: Attachment B - Appendix E - Hydrology
• Doc Name: Request for Technical Revision
• From: Holcim - WCR, Inc.
• To: DRMS
• Type & Sequence: TR9
• Media Type: D
• Archive: No

Summary of Unit Hydrograph Parameters Used By Program and Calculated Results(Version 2.0.11
5-Year Event
Unit Hydrograph Parameters and Results Excess Precip. Storm Hydrograph
W50 W75 Time to Time to Total Runoff per
W50 Before W75 Before Peak Volume Excess Excess Peak Peak Flow Volume Unit Area
Catchment Name/ID User Comment for Catchment CT Cp (min.) Peak (min.) Peak (min.) Peak(cfs) (c.f) (inches) (c.f.) (min.) (cfs) (c.f.) (cfs/acre)
Reclaimed Area.HSG D.Used Recommended depression
storage for Wooded areas and open fields of 0.2 to account
for steep nature of reclaimed slopes.Used%Impervious of
02A 10%due to reclaimed area plan. 0.108 0.067 27.5 2.91 14.3 2.05 4.8 25 1 53,729 0.38 20,463 30.0 7 20,201 0.45
Mined Area.HSG D. Used Recommended depression storage
for Wooded areas and open fields of 0.2 to account for steep
02B mined slopes. Used%Impervious of 50%per Phase 11 Report. 0.089 0.176 8.4 2.63 4.4 1.86 4.4 304 197,171 0.62 121,413 25.0 67 116,051 1.24
natural area+Mined Area.HSG D. Used Recommended
depression storage for Wooded areas and open fields of 0.2
to account for steep mined slopes. Used%Impervious of
3 50%due to haul road. 0.089 0.218 32.2 6.87 16.7 4.86 11.5 127 1 316,083 0.62 194,636 35.0 49 194,627 0.56
100-Year Event
Unit Hydrograph Parameters and Results Excess Precip. Storm Hydrograph
W50 W75 Time to Time to Total Runoff per
W50 Before W75 Before Peak Volume Excess Excess Peak Peak Flow Volume Unit Area
Catchment Name/ID User Comment for Catchment CT Cp (min.) Peak (min.) Peak (min.) Peak(cfs) (c.f) (inches) (c.f.) (min.) (cfs) (c.f.) (cfs/acre)
Reclaimed Area.HSG D.Used Recommended depression
storage for Wooded areas and open fields of 0.2 to account
for steep nature of reclaimed slopes.Used%Impervious of
02A 10%due to reclaimed area plan. 0.106 0.067 27.1 2.89 14.1 2.04 4.8 26 53,729 1.60 85,929 40.0 25 84,825 1.71
Mined Area.HSG D. Used Recommended depression storage
for Wooded areas and open fields of 0.2 to account for steep
02B mined slopes. Used%Impervious of 50%per Phase 11 Report. 0.089 0.178 8.2 2.62 4.3 1.85 4.4 309 197,171 1.86 366,331 30.0 202 349,320 3.72
natural area+Mined Area.HSG D. Used Recommended
depression storage for Wooded areas and open fields of 0.2
to account for steep mined slopes. Used%Impervious of
3 50%due to haul road. 0.089 0.220 31.7 6.85 16.5 4.84 11.4 129 316,083 1.86 587,261 45.0 151 587,273 1.74