Atch 10 bridge boring summary.pdf
PDF 471 KB Posted
- Solicitation number
- 127EAX26Q0070
- Issued by
-
Department of Agriculture Forest Service
About this file
This is an internal communication email chain from the U.S. Forest Service regarding subsurface investigation findings for the Sand Pond Bridge project. Jonathan Berry, PE, Public Services Staff Officer at Plumas National Forest, reports on auger hole testing conducted on September 12, 2025, to assess soil conditions for helical pile foundation design.
The key findings indicate that helical piles must reach a minimum depth of 7.5 feet below ground surface (BGS) and then rely on torque capacity requirements per helical pile design manuals. Soil composition above 6.5-7 feet consists of fine sands with minor layers of organic soils and silts, with saturated, liquefiable sands present between 2 and 7 feet BGS that must be avoided. At approximately 7 feet depth, the investigation encountered hard material potentially consisting of glacial till, weathered rock, or other coarse deposits that could not be penetrated with hand tools. One auger hole (Hole 2) had to be abandoned due to caving within the saturated sand layer and was relocated 8 feet back from the bank to achieve the 7-foot depth. Berry notes that drive probe blow count testing was not conducted during this site visit but recommends that the minimum depth specification be modified to 7.5 feet with subsequent reliance on torque requirements from helical pile design standards to move forward with the structural design.
View the file
Other files
Show all 20
On GovTribe
Work with this file
- Download the original file
- Contacts named in this file
- Similar government files
- Ask GovTribe AI about this file
Text version
Shields, Christopher (CTR) - FS, CA
From: Berry, Jonathan - FS, CA Sent: Friday, September 12, 2025 3:04 PM To: Shields, Christopher (CTR) - FS, CA Cc: Mack, Ryan - FS, CA; Rios, Temoc - FS, CA; Villa, Cesar - FS, CA Subject: FW: Scanned image from MX-M264N Attachments: Sand Pond Bridge Subnsurface investigation 9-12-2025.pdf
Chris, AƩached are the auger hole notes from today's site visit.
I did not bring the drive probe to get blow counts, but based on the auger results, the helical piles will need to be a min of 7.5 ' below ground surface (BGS), and then should rely on reaching the required torque capacity aŌer that. Above 6.5- 7 Ō, there are fine sands (with some minor layers of organic soils and silts) with saturated, liquifiable sands between 2' and 7' below ground surface. The helical piles need to get below that elevaƟon.
If appears we are hiƫng something hard. It could be glacial Ɵll, weathered rock or some other course deposit at around 7 Ō. It was hard to tell since I was not able to auger past that elevaƟon on either side of the bridge with hand tools.
Hole 2 kept caving in within the saturated sand layer zone, so I had to abandon it and move about 8 Ō back from the bank to get to 7' depth.
I am glad I went back out there. Min depth should be modified to 7.5 Ō, and then rely on the on the torque requirements provided by the helical pile design manuals.
Hope this provides you with the data you need to move forward with the design.
Jonathan
Jonathan Berry, PE Public Services Staff Officer Forest Service Plumas NaƟonal Forest p: 530-283-7853 c: 530-616-5770 jonathan.berry@usda.gov 159 Lawrence Street Quincy, CA 95971 hƩps://gcc02.safelinks.protecƟon.outlook.com/?url=hƩp%3A%2F%2Fwww.fs.usda.gov%2F&data=05%7C02%7CChristop her.Shields%40usda.gov%7C8e40c6775a5f45fdd76a08ddf24857c9%7Ced5b36e701ee4ebc867ee03cfa0d4697%7C1%7C0 %7C638933115016612274%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOi JXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=ODa5AzfcYudKGx5uSPy1oZOcEdrkDNXXucW1 TI80sps%3D&reserved=0
Caring for the land and serving people
-----Original Message----- From: pnfengineeringcopier@usda.gov <pnfengineeringcopier@usda.gov> Sent: Thursday, September 11, 2025 9:21 AM To: Berry, Jonathan - FS, CA <jonathan.berry@usda.gov> Subject: Scanned image from MX-M264N
Reply to: pnfengineeringcopier@usda.gov <pnfengineeringcopier@usda.gov> Device Name: Not Set Device Model: MX- M264N LocaƟon: Not Set
File Format: PDF (Medium) ResoluƟon: 200dpi x 200dpi
AƩached file is scanned image in PDF format.
Use Acrobat(R)Reader(R) or Adobe(R)Reader(R) of Adobe Systems Incorporated to view the document.
Adobe(R)Reader(R) can be downloaded from the following URL:
Adobe, the Adobe logo, Acrobat, the Adobe PDF logo, and Reader are registered trademarks or trademarks of Adobe Systems Incorporated in the United States and other countries.
hƩps://gcc02.safelinks.protecƟon.outlook.com/?url=hƩp%3A%2F%2Fwww.adobe.com%2F&data=05%7C02%7C Christopher.Shields%40usda.gov%7C8e40c6775a5f45fdd76a08ddf24857c9%7Ced5b36e701ee4ebc867ee03cfa0d4697% 7C1%7C0%7C638933115016637848%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAw MCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=7H838h06R5ZpeyQZwDUfozYKBqc MjL%2Bj1zbDO43oYEY%3D&reserved=0
File details come from the government source that posted it. Updated .