Location Map Ocean Avenue Dune Grading · Ocean Avenue Dune Grading . NWP-2014-398 . Within the Pacific Ocean, adjacent to Ocean Avenue between Jackson and Jefferson Streets, Section

Location Map Ocean Avenue Dune Grading NWP-2014-398

Within the Pacific Ocean, adjacent to Ocean Avenue between Jackson and Jefferson Streets, Section 30, Township 5 North, Range 10 West, Cannon Beach, Clatsop County, Oregon (45.89294, -123.96477).

NWP-2014-398 Page 1 of 7 Enclosure 1

Horning Geosciences 808 26th Avenue, Seaside, Oregon 97138 503-738-3738

Hagrenes/Dune Grading Plan/Jackson to Jefferson Streets Page 5 August 25, 2014

Figure 2: Summary plan for grading and disposal of dune sand from Jackson to Jefferson Streets. The range of sand disposal in the surf zone represents assumptions of whether the 1-ft layer of beach grass-tainted sand is pushed to the beach or disposed of partly or entirely offsite. Sand calculations assume that grading will be to 32 ft NAVD, or to FEMA V-Zone elevation (28 ft NAVD + 4 ft), although at the north end of the area, it could be graded to 29 ft NAVD.




Figure 3: Dune grading plan showing area to be graded (blue), the profiles AA’ to OO’ and elevation contours at 2-ft intervals. Summary of volume calculations are posted on left side, obtained from cross sectional profiles in Figures 4 and 5. Brown blocks along east ends of profiles mark the approximate edge of the Presidential Streets silty-clay terrace.


1JB: 3000 Clljl (111 Cll yd}

CO: / 0900 C/1 fl (-10-1 C/1 yd)

D

DE: 1 71 75 C/1 fl (636 C/1 ytl)

G

H

HI: r.li -1 Cllfl (6./J C/1 )'d)

KL: 138 7S C/1 fl (8/N Cll ytl)

L

LM: zso-s "" fl (929 c 11 yll)

0

JEFFERSO'i

0

~IAO ISON

Nortlt

100 ft t sralr : 70 ft - 1 inch

9156 c11 yd excat,ated to 32ft NA VD (FEMA + 4 /1)



Figure 4: The northern third of the grading profiles. Panel cross sectional areas are shown in boxes above each profile. Panel cross sec-tional volumes are posted between the relevant profiles. Red triangles mark the minimal cross sectional areas of dune sand that must re-main after grading is completed, in all cases met satisfactorily. The base of the beach is regarded conservatively as at 10 ft NAVD.




Figure 5: The southern two-thirds of the grading profiles. Panel cross sectional areas are shown in boxes above each profile. Panel cross sectional volumes are posted between the relevant profiles. Red triangles mark the minimal cross sectional areas of dune sand that must remain after grading is completed, in all cases met satisfactorily. The base of the beach is regarded conservatively as at 10 ft NAVD.


VE28'

H

I

K

L

N

GH: 25500 cuft (944 cuyd) 0

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HI: 17374 cuft (643 cuyd)

3·-~·u•z:wl , ig] ,: ' ·;~ • ----lf---1~ IJ: 19400 cuft (718 cuyd)

30

KL: 23875 cuft (884 cuyd)

30

LM: 25075 cu ft (929 cuyd)

NO: 26625 cuft (986 cuyd)

30



Figure 6: Dune grading plan showing finished dune platform at 32 ft NAVD, plus several 2-ft-high landscaping dunes to provide a more natural appearance to the graded area, also serving as modified baffle dunes to entrap windblown sand more effectively in the first two years of vegetation recovery.


CD: 10900 Cit fl (.10./ Cit yd)

De: 1 i 1-J cu fl (636 cu ydJ

EF: 19110 Cit fl ( -ll cu yd)

FG: 20-100 cu fl r - JJ c11 ydJ

G

H

HT: I ir-1 Cit fl (6-1.1 Cit yd)

KL: 238iJ Ctl fl (88-1 Cll )'d)

L

LM: l50i J Clift (919 C/1 Jd)

0

TO BE GRADED TO 32 (I NAVD

JEFFERSO:\

0

:\10/\ROE

100ft sralr: 70 ft - I lnrh

North

t



Figure 7: Map showing disposal area for dune sand with dense dune and beach grass. The disposal site is locally known as the Rippet Quarry.


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Sand/G rass

Documents

Location Map Ocean Avenue Dune Grading · Ocean Avenue Dune Grading . NWP-2014-398 . Within the Pacific Ocean, adjacent to Ocean Avenue between Jackson and Jefferson Streets, Section