HomeMy WebLinkAboutCDP 00-50; Quirk Residence; Geotechnical Response Letter; 2000-10-19I WM American Geotechnical
Protecting Your Future
October 19, 2000 File No. 22366.01
Mr. Luis Quintanar
THORYK ARCHITECTURE
1235 Shafter Street
San Diego, Califomia 92106
Subject: RESPONSE TO AGENCY REVIEW
Quirk Residence
3075 Ocean Street
Carlsbad, Califomia
CDP 00-50
Reference: "Preliminary Investigation, Quirk Residence, 3075 Ocean Street, Carlsbad, Califomia," prepared
by American Geotechnical, dated September 21, 2000
"Memorandum, CDP 00-50, Quirk Residence, Completeness and Issues Review," prepared by
City ofCarlsbad Engineering Department, dated October 7, 2000.
Dear Mr. Quintanar:
As requested, American Geotechnical has reviewed the agency review sheet provided. This letter is intended to
address the concems presented in this letter. The primary area of concem for this office would appear to be item
3 of the review sheet which states, "Provide two copies of a preliminary soils report. At a minimum, the report
shall analyze 1) whether grading/development impacts are mitigatable for at least 75 years or the life of the
stmcture and 2) potential impacts from ocean waves and 3) potential impacts (slope failure) from placing
boulders at the top of the slope." The following discussion is intended to address each ofthe concems
mentioned.
1) "whether grading/development impacts are mitigatable for at least 75 years or the life of the stmcture"
Proposed grading at the site is minimal and would primarily include restoring the lot once demolition of the
existing residence is complete. Additional grading might include removing and recompacting any loose near-
surface material. This amount of grading would have little to no impact on changing present site conditions. The
development planned should likewise have little to no impact on changing present site conditions as it is our
understanding that the proposed residence will encompass areas which are now covered with the existing
residence or other site improvements such as retaining walls, concrete patios, etc..
2) "potential impacts from ocean waves"
Given the recommendations in our report are followed to deepen the foundation to competent formational soil,
impacts from ocean waves would be considered to have relatively little impact on the residence. If significant'
erosion to the beach were to occur the primary concem as a result of this erosion would be to appurtenances at
the rear of the residence. If erosion were to occur up to this area these improvements would not have a
foundation system deepened to competent formational soil and could be subject to undermining and damage from
wave action. If a deepened foundations system is utilized for the residence, damage should be limited to site
improvements and possibly to undermining the rear portion of the proposed residence. Even if a portion of the
residence is undermined the deepened foundation system proposed should minimize damage to the residence.
22725 Old Canal Road, Yorba Linda, CA 92887 (714) 685-3900 (800) 275-4436 FAX (714) 685-3909
5764 Pacific Center Boulevard, Suite 112, San Diego, CA 92121 (858) 450-4040 FAX (858) 457-0814
File No. 22366.01
October 19, 2000
Page 2
American Geotechnical
Given the past performance ofthe residence now existing on this lot and those on adjacent lots, future
performance would be anticipated to be similar assuming conditions at the site remain relatively similar (i.e. the
beach is maintained and not allowed to experience a continual or significant loss ofthe sand along the beach).
3) "potential impacts (slope failure) from placing boulders at the top of the slope"
It is our understanding that the boulders in question will be false boulders made of concrete and fiberglass.
Based on our current understanding of the placement and constmction of these boulders stability ofthe slope
should not be compromised. The soil at the site, in the area where the boulders are to be placed, is considered to
be a relatively competent terrace sand formational material that would not typically be susceptible to stability
problems. Additionally, the height and inclination of the slope would not suggest instability of the slope to be of
concem.
Finally, two additional copies of our preliminary report have been included to forward to those parties requesting
such.
We appreciate the opportunity to be of service. If you should have any questions or require additional
information, please contact this office.
Sincerely,
AMERICAN GEOTECHNICAL
Richard K. Walsh '
Senior Engineer
G.E. 2498
RKW:lm
Distribution: Mr. Luis Quintanar - (2) Via Fax & Mail