HomeMy WebLinkAbout3307; CARLSBAD BLVD SHORE PROTECTION; WALL HEIGHT LETTER; 1991-10-231550 Hotel Circle North
San Diego, CA 92108
(619) 294-9400
Fax: (619) 293-7920
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Woodwartlyde Consultants
October 23, 1991
Project No. 9051144E-0005
Mr. Bill Ponder
California Coastal Commission
3111 Camino del Rio North, Suite 200
San Diego, CA 92108-1725
COASTAL PERMIT APPLICATION #691-60
CARLSBAD BOULEVARD SHORE PROTECTION
CARLSBAD, CA LIFORNIA
Dear Mr. Ponder:
In accordance with your letter dated October 18, 1991, we are providing the requested
information in regard to the staffs recommendation to limit the height of the subject seawall
to 2-feet above the sidewalk. It is our understanding that the purpose of this limitation is to
maintain public views.
The proposed wall, as designed extends 3.5-feet above the sidewalk. This design limits
overtopping of the wall during the design storm to several localized low points and is
intended to mitigate any significant damage to Carlsbad Boulevard and the existing and
proposed associated facilities. If the wall is lowered by 1.5-feet as recommended by the
Coastal Commission staff, the entire wall would be subject to overtopping during the design
storm as well as during lesser storms. This would subject Carlsbad Boulevard and the
associated facilities to flooding and damage and would increase the hazards to the public.
It is our opinion that the 2-foot high wall would be subject to significant overtopping during
storms similar to those in 1982-83 and this would not comply with Special Condition No. 2
of the staff report. It is expected that such overtopping could occur 10 to 15 times during
the 75 year design life and that the magnitude of overtopping (volume of water) would be
3 to 4 times that of the 3.5-feet high wall.
The wall is designed such that significant overtopping of the wall should occur only 1 or
2 times during the life of the structure and that this overtopping would be limited to small
localized areas.
As previously noted, it is our opinion that the safety of the public during storm conditions
is directly related to the frequency and magnitude of overtopping of the wall. Thus, it is
Consulting Engineers, Geologists
and Environmental Scientists
Offices in Other Principal Cities o
Mr. Bill Ponder Woodward-Clyde
California Coastal Commission Consultants
October 23, 1991
Page
further our opinion that the lower (2-foot high) wall would significantly increase this hazard
during storm conditions and that it would increase the frequency of the hazard.
If you have any questions or need additional information, please call at your convenience.
Very truly yours, -
WOODWARD-CLYDE CONSULTANTS
FE
R.C.E. 43782 No. 43782
49
MA/LIL/jea
cc: City of Carlsbad, Mr. John Cahill
ODI
A1905114424005