Polk3-planprofile.pdf

USDA FOREST SERVICE - TONGASS NATIONAL FOREST SH. ofR-10 -

DESIGNED: DATE:

DATE:DRAWN:

REVIEWED: DATE:

DATE: REVISION: BY:

PLOT ON 11"X17" PAPER

TONGASS

ENGINEERING & RECREATION TNFTYP:09/04

POLK BRIDGE EMERGENCY INSTALLATION PLAN & PROFILE

THORNE BAY RANGER DISTRICT

M.DORGAN 10/00/11

M.DORGAN 10/00/11

Q. SMITH 10/00/11

ACAD.DWG

3 5

BEAVER DAM - ELEV 97.6

FL

O

W

EXISTING ROAD

EXISTING ROAD

NEW SILL, TYP.

POLK

IN

LE

T

KL

AW

OCK

R.P.: SPIKE IN BASE

OF TREE, ELEV. 100.0

53 FT.

NEW 70FT MODULAR BRIDGE DECK

U.S. CL D.S.

SEE NOTE 2

2. THE PROFILES SHOWN ARE THE OBSERVED ERODED BANKS AT

UPSTREAM EDGE, DOWNSTREAM EDGE, AND CENTERLINE OF ROAD.

LEFT BANK ONLY WAS MEASURED. STREAM BED AND RIGHT BANK

ARE ASSUMED ONLY. "BR" REPRESENTS BEDROCK ENCOUNTERED,

IN APPEARS SIMILARLY ON RIGHT BANK.

U.S. CL D.S.110

E

LE

V A

TI

O

N

BR

BACKWALL & SILL

ROAD BACKFILL

ABUTMENT SPREAD

FOOTING (NOTE 3)

GEOTEXTILE

RIPRAP, CLASS

5 OR 6 (NOTE 4)

1. THE ORIGINAL 8 FT DIA. C.M.P. CULVERT AT THIS SITE HAS

WASHED OUT, LEAVING THE EXPOSED BANKS ABOVE BEDROCK.

SURVEY DATA IS LIMITED. PLACE MODULAR 70 FT BRIDGE TO BEST

FIT THE SITE, MAINTAINING ROAD GRADE ON EITHER END OF BRIDGE.

3. BUILD ABUTMENT SPREAD FOOTING TO A MINIMUM THICKNESS OF

4 FT. RIPRAP MAY BE USED BELOW FOOTING DOWN TO BEDROCK.

PLACE GEOTEXTILE BETWEEN RIPRAP AND FOOTING.

0 50 100 150

4. MACHINE PLACE RIPRAP STONES INDIVIDUALLY TO FORM AN

INTERLOCK STONE WALL.