HomeMy WebLinkAboutGroundwater Certification 2018_02_12
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MEMO
32 Discovery Drive Bozeman, MT 59718 (406) 582‐0221 Fax (406) 582‐5770
Project Name: West Winds SW –Phase 2
Project Number: 16-003
Date and Time: February 12, 2018
Re: Groundwater Conditions
To: City of Bozeman
From: Mark Fasting, PE - Allied Engineering Services, Inc.
MEMO DETAILS:
Groundwater monitoring was performed in the spring of 2016 in order to develop a groundwater
surface. Monitor wells were installed February 2, 2016 and depths were recorded roughly every 2
weeks starting March and continuing through May. The peak groundwater elevations for all 8
monitoring wells were observed on April 8. A groundwater surface based on the highest observed
groundwater elevations was generated and can be seen with finished grading on attached Exhibit 1. It
should be noted that monitoring was ended in May due to the start of construction and construction
dewatering; as a result a groundwater peak outside the duration of monitoring would not have been
observed. Also, monitoring performed in 2016 may not represent the highest typical groundwater
condition when compared to other years.
A finished grade surface has been developed for the entire site to ensure drainage is provided from the
lots to adjacent roads. In general, the depth to groundwater compared to the finished grade surface
ranges from 6 to 8 feet within the lots. The top of foundation wall for the proposed structures will be
at least 0.5 feet to 1.0 foot above the adjacent finished grade to maintain positive drainage away from
the structure. Crawl spaces are anticipated to be 4 to 5 feet below top of foundation wall. Based on
the assumptions above, groundwater is expected to be a minimum of 2-ft below crawl spaces during
seasonally high groundwater.