HomeMy WebLinkAbout3391; CARLSBAD BLVD CANNON RD WIDENING; EVALUATION OF EXISTING CONDITIONS AND RECOMMENDATIONS FOR PROPOSED RETAINING WALL; 2000-03-23U F .760 4 417S E\G INSPECTIONS Ejo_
4B5?1. STING ENGIFEERS SD 543 Pe4 - MAR 23 '00 18:3
Testing Engineerc. Sa n Dugo' Inc Established 1946
- March 231 2000.,
prqjea No 99-519B
Mr, it Ed
City of Carlsbad. Public Works - Engineering
5950ElCa.minoRe3l -
C&lsbad, California 92008
Subject Evaluation of Edsting Conditions and Recommendations for Proposed
Retainmg Wall at SE Corner of Carlsbad BlVdr and Cannon Road,
- Carlsbad Bou1vard/Cannon Road Widerüng,
Carlsbad, California
Dear Mr. Eklur4
In sccordaeee with your request, we have visitI the subjea site to observe and evaluate the m,
isting conftons exposed at the subject site Specifically, we were asked to evaluate whether the
proposed retaining wall and drain system was suitable for use given the observed field conditions
While on site we met with you and Gary Goodman from your office, the residential occupant, a
representative of Lusardi Construction (the homeowner), and Mr Harry Deardorff Structural
Engineer
Based on our review of the plans, end our observations and cliscusona On site, we undstand
that the proposed retammg wall will be constructed in accordance with the City of San Diego Re.
gional Standard Drawings for an eight-foot masonry wall with level baoli1 We understand that
the top of the wall is 'designed to be level with n elevaiion of 56 feet
The soil exposed in the cut was a weakly—cemented silty sandstone The sandstone gralty q3-
-pared to be nnolithic and homogeneous and did not display evidence of fracturing or blocking
that would Indicate tnstththty during its temporary cut condition We understand that the wall is
designed to be bd)led with the excavated mazenal
Lusardi Constiucion and Mr Deardorff raised concenis that the wall bacflh1 slopes up from v-
ticel and that the eloping baikfiB will induce greater than anticipated earth preasures on the walL
Review of the survey drawings provided by SB&O, the design Civil Eriginer, indicate that, the
Tetatg E8iiccrg Sn n 7895 Corvv) Court Su(tc 18 Sio Dico CA 92111 19581 1S 5900 F (855) 713 5910
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19 - FAX 760 417.8 ENG. INSPECTIONS
+858?j55eWESTING ENGINEERS SD P2 Fi 23
..sty of Carlàbed - - March-23, 2000s Carlsbad Boulevard/Cannon Road Widenin Project No 99-SI 9B
- - - ground surface adjacent to the residence and behind the wall is approximately at 59 to 60 feet ele-
I von '.
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SB&O arid our office prepared cros&ccons of the proposed conditions from near the corn& of
the residence to the west towards Carlabad Boulevard, and ta-the north towards Cencrn Road.
The cross-sion to the west indicates approximately' &ghttc ten feet of horizà1 bacll be-
hind the wall, a slight rise at 2:1 rflatterto 60 feet elevation, I and another five feet of hbrizontal
fill to the fitce of the residence. Accordingly, there is an approximate gain of three vtii feet
- -- over 18 to 20 horizontal ft (3:20) from the wall to the residence. The cross-section to the north :
jig simila -nd indicates approximatetyx-feet of horizontal backfill behind the wall, a slight rise at
2:1 or flatter to 60 feet elevation, and another 17 feet of horizontal fill to theface of the residence.
There Is an approximate gain of three feet over 12 horizontal feet (3:12) to the top of the alope
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Based on our site observations, our discussions with your oce and S&O, and our eperlen-ce
with su'nilsr materials it is our opinion that the current wall design Is adequate provided the fol-
lowing revised drain recommendations are followed We recommend thai the gravel and weephole
' drain system indicated in the stindard drawings be supplemented with a two-ded. Mirafi com-
posite drainage fabric and burrito drain system. The Mf&6 drainage fabric should be instfled-
against the out face and eend from th top âf the footing, to -within two feet of the top of the cut
face. The drainage fabric should be contiguous from one end of the wail to the. other end.
A burma drain should be installed at the bottom of the Mlra.ft drain at the beet of the retaining
wall. The burrito drain should consist of four-inch diameter perforated pipe wrapped iñone cubic
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- foot of gravel per linear foot of pipe, wrapped in Nra.fl 140N filter fabric, or gimilar. The pipe
should ,be installed with perforations down. The fabric shouldbe installed with 12-inch overlaps,.
or greater. The pipe should diacliaige toasuitable outlet such as beyond the south end of the wall,
or tie into the area drain outlet that connects to the storm drain along Carlsbad Boulevard
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As an alternative to the gravel and fabric, the filter fabric can be deleted if the' gravel is replaced
- / with permeable material such as Ca.lrran.s Class 2 Permeable MateriI 'or Pervious Baci1 as
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