Golder_Associates_Field_Report_-_April_2016.pdf

18300 NE Union Hill Road, Suite 200 Redmond, WA USA 98052-3333 Tel: (425) 883-0777 Fax: (425) 882-5498

TO: File

FHWA, attn.: Mike Niemi

ON SITE: 13:00 OFF SITE: 16:00

DATE: JOB NO:

4/19/2016 14-0391.001

PROJECT:

Middle Fork Snoqualmie River Road

LOCATION:

Snoqualmie Middle Fork Road, Site #4

CONTRACTOR: OWNER:

ACI FHWA

WEATHER: TEMP: ~75 °F at 1300 PM Clear and Sunny

PRESENT AT SITE:

Kyle Obermiller – Golder Terry Hager - FHWA

THE FOLLOWING WAS NOTED:

Golder was onsite to review the limits of the staked mesh at blast zone 4, STA 280+00 to STA 281+90.

The following occurred while on site:

1. Terry summarized to Golder the comments and questions the contractor (ACI) had with regards to the blast zone 4 preliminary drawing. These comments and questions were also provided to Golder as ACI Contractor Comments and Questions (CC&Q) dated April 15, 2015.

2. K. Obermiller (Golder) traversed along the soil cut slope crest from STA 280+00 to STA 281+90 and made visual observations of the current site conditions. A long the traverse several small excavations were made with a shovel to characterize the near-surface soil conditions. (Reference photographs 1 through 3)

Observations:

1. As mentioned in ACI’s letter there are several large stumps in line with the soil cut slope crest and 2:1 soil cut slope (Contractor Comments and Questions [CC&Q] #5); and an escarpment between STA 280+00 and STA 280+70 upslope of the upper mesh boundary(CC&Q #4).

2. The small excavations along the soil cut slope crest showed similar near surface soil conditions all along the traverse;

dominantly consisting of a silty sand with gravel/cobbles interpreted to be alpine glacial outwash or alpine till.

Golder Recommendations:

1. (CC&Q #1) An equivalent all-thread anchor is an acceptable anchor in lieu of the specified hollow core anchor.

2. (CC&Q #2) Excavations will need to be increased to 26 inches or larger to accommodate the P66 plate.

3. (CC&Q #3) Question/comment is for FHWA/RPA.

4. (CC&Q #4) Where there is exposed soil along the scarp, located roughly STA 280+00 to STA 280+40, the cable mesh and turf reinforcement mat should be extended to cover the exposed soil. Anchors should be placed along the top of the scarp and along the toe so the mat and wire are up against the native ground surface. Note the recommended additional slope coverage on the attached Rockfall Mitigation Plan.

5. (CC&Q #5) Extra care should be taken when removing the large stumps that are in line with the soil cut slope crest so that disturbance to the native ground upslope of the catch, due to the root mass, is minimized.

6. (CC&Q #6) Question/comment is for FHWA/RPA.

7. (CC&Q #7) Question/comment is for FHWA/RPA.

8. (CC&Q #8) The construction sequence for the anchored mesh should be from the top down and in lifts. The depth of the excavation lifts should be roughly 6 feet in height, slightly below the elevation where anchors will be installed. The anchored mesh slope stabilization system needs to be in place prior to the blast.

COPIES TO: Robert Peccia & Associates, atn.: Brian Wacker

DOCUMENT1

FIELD REPORT

SIGNED:

Kyle Obermiller

April 2016 3 14-0391.001 photo.docx

Project Title: Middle Fork Snoqualmie River Road

PHOTOGRAPH 1

Southern end of project looking up station. Dashed lines show the soil cut slope catch.

PHOTOGRAPH 2

STA 280+00 Looking up station along the soil cut slope crest.

Dashed lines show the soil cut slope catch.

Outwash

April 2016 4 14-0391.001 photo.docx

PHOTOGRAPH 3

Exposed soil along escarpment located in the vicinity of 280+10 and above the current cable mesh boundary

Alpine till

Outwash