7800 EVERGREEN WAY HYUNDAI Drainage Report 2025-04-28

From: Robert Metcalfe<rmetcalfe@geoengineers.com> Sent: Wednesday, March 2, 2022 7:19 PM To: Tim Prusa Cc: Michael Langston;Jonathan S. Owen; Kyle Carrick; Ricky Kennedy Subject: RE: Lee Johnson Dealership Improvements-7800 Evergreen Way- Infiltration Considerations Attachments: PIT Site plan.pdf Follow Up Flag: Follow up Flag Status: Completed Hi Tim, Yes, as discussed,the pilot infiltration test(PIT) results confirmed what we thought would likely be low long-term design infiltration rates. I attached a drawing with the approximate PIT locations. Here is a brief summary: PIT-1 (northern PIT) was completed at a depth of 4 feet. Very dense glacial soils were encountered at about 4 feet deep, or at the PIT elevation.The soils consisted of very dense silty sand with gravel (glacial till).The field testing resulted in a long-term design infiltration rate for PIT-1 of 0.15 inches per hour. PIT-2 (southern PIT). During excavation, moderate perched groundwater seepage was encountered at a depth of 3 feet and approximately 5 to 8 inches of water filled the excavation over a 3-hour period. Very dense silty sand with gravel (glacial till) was encountered at a depth of about 5 feet. The soils above this were relatively loose fine to coarse sand with silt and gravel. Due to the observed perched groundwater seepage, we could not perform a pilot infiltration test at a depth of 4 feet and infiltration at depths below 3 feet is not considered feasible in this area. We plan to wrap the PIT results into our geotechnical report for the project. I will check tomorrow to see when we can get you the updated report. Please let us know if you have any questions/comments. Thanks, Bob Robert C. Metcalfe, PE, LEG Principal Geotechnical Engineer I GeoEngineers, Inc. Telephone: 425.861.6099 Fax: 425.861.6050 Mobile: 425.422.3806 Email: rmetcalfe(@,qeoenqineers.com