HomeMy WebLinkAbout009.01 - Appendix I.1 - Field Drain Memo
1105 REEVES RD. WEST, SUITE 6
BOZEMAN, MT 59718
406-581-5730
www.headwatersmt.net
Page 1 of 2
June 22, 2026
Engineering Department
City of Bozeman
Re: Diamond 8 MSP & Site Plan 1 – Field Drain Memo
COB # 26161 & 26282
Dear Engineering Staff,
Thank you for the video meeting on June 15th, it was a helpful discussion. This memo is in response to
the field drain & wet pond questions from that meeting.
1. Field drain pipes discharging into wetlands.
As discussed, the pipes that were shown discharging into the wetlands were underground
groundwater dewatering pipes. WET conducted a groundwater analysis for the site and it was
shown that we could not install the groundwater dewatering pipes without lowering
groundwater in the areas of the delineated wetland, therefore these pipes were removed. Sheet
C2.0 as submitted with Site Plan 1 has been updated to remove these pipes.
2. Drain pipes for fields
The fields have perimeter and internal storm pipes proposed to collect surface water that is
collected from storms and transport it to the nearest storm pond. The fields were designed to be
a minimum of 24” above the max groundwater elevation. The proposed 8” storm pipes are to be
placed at around 26” below the field surface so the field drains will be above the high
groundwater for the majority of the site. There are a few places where the high groundwater
will be above the pipe inverts for a short time in the spring. To account for the potential
groundwater that will be captured, we plan to add an outlet pipe to the storm pond with a
control valve. This will allow the groundwater to be passed through the storm pond without
reducing the volume of the pond. This statement has also been added to the Site Plan 1
stormwater design report.
3. Wet Ponds
The groundwater elevations have been measured on this site for over 1 year, with some
additional wells added in January 2026. Using this data, we have designed the retention ponds
to be at least 24” above the high groundwater. The wet ponds have been designed to have a
portion of the bottom at or below the lowest groundwater elevation recorded. The storage
volume will be calculated using the volume above the high groundwater elevation. This
statement has also been added to the Site Plan 1 stormwater design report.
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Let me know if you need anything additional for this request.
Sincerely,
________________
Jeremy May, P.E.
Headwaters Engineering, Inc.
www.headwatersmt.net
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