REV106218

• Permit No: M1980244
• IBM Index Class Name: Revision
• Doc Date: 7/11/2001
• Doc Name: HYDROLOGICAL ANALYSIS FOR PORTIONS OF THE BATEMAN CREEK WATERSHED
• Type & Sequence: TR39
• Media Type: D
• Archive: No

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1.0 INTRODUCTION
003-2142.6
A hydrological analysis was conducted by Golder Associates Inc. (Golder) to evaluate the
surface water flow routing for the following ponds at the Cresson Mine:
- Bateman Creek detention pond;
- Arequa Gulch sedimentation pond;
- Crusher sedimentation pond; and
- BMP sump.
Contained herein are the hydrologic calculations for routing surface water flows into the
ponds and diversion ditches. The hydrologic calculations were conducted using the HEC-1
(Hydrologic Engineering Center, 1990) model using watershed delineations and curve
numbers developed for the mine site.
2.0 HYDROLOGIC ANALYSIS SUMMARY
The hydrologic model was run to simulate the stormwater run-off from the 100-year,
24-hour; and the 10-year, 24-hour storm events. The Bateman Creek detention pond is
designed to attenuate the 100-year peak flow. The Crusher and Arequa Gulch sedimentation
ponds and the BMP sump are designed to contain two times the runoff volume of the
10-yeaz, 24-hour storm event. The hydrological analysis for the 100-year, 24-hour storm
event, that includes the Bateman Creek detention pond, and Arequa Gulch and Crusher
sedimentation ponds, and BMP sump is presented in Appendix A. The hydrologic analysis
for the ]0-year, 24-hour storm event to size the Crusher and Arequa Gulch sedimentation
ponds and the BMP sump is also presented in Appendix A.
Drawing 1 presents the sub-basin delineations used for the hydrological analyses. Flow
arrows presented on Drawing 1 show the general direction of routing of surface water. The
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