December 19, 2011 lrerracan MulvannyG2 Architecture 18200 Von Karman Avenue Suite 910 Irvine, California 92612

Attn: Mr. Terry W. Odle, AIA

SUBJECT: Addendum to Fault-Rupture Hazard Study and Response to City of San Diego Geotechnical and Geological Review Costco Wholesale Store Addition, 4605 Morena Boulevard, San Diego, California, City of San Diego Project No. 259618

REFERENCES: Fault-Rupture Hazard Study, Costco Wholesale Store Addition, 4605 Morena Boulevard, San Diego, California, prepared by Terracon Consultants Inc., dated November 14, 2011 (their project no 60115239).

Dear Mr. Odle,

Geotechnical Engineering Report, Costco Wholesale Store Addition, 4605 Morena Boulevard, San Diego, California, prepared by Terracon Consultants, Inc., dated September 29, 2011 (their project no. 60115239).

This report has been prepared in response to the City of San Diego, Cycle Issues, BDR­Geology Review, Project No. 259618, dated December 8, 2011. This report serves as an addendum to the above referenced geotechnical report and fault-rupture hazard study. In order to provide continuity of discussion, we are responding to the City's review comments in the numerical order of their comments in a question and answer format.

7. Fault-Rupture Hazard Study, Costco Wholesale Store Addition, 4605 Morena Boulevard, San Diego, California, prepared by Terracon Consultants Inc., dated November 14, 2011 (their project no 60115239).

This is the referenced report for which the review letter was issued.

8. The geotechnical consultant must clarify whether or not the proposed project is located in a City of San Diego Fault Hazard Zone or a State of California Fault-Rupture Hazard Zone

The subject proposed addition site is not located within a State of California Fault­Rupture Hazard Zone for "active faults." However, the site does lie within a City of San

Terracon Consultants, Inc. 16662 Millikan Avenue Irvine, California 92606 P [949] 660 9718 F [949] 660 9732 terracon.com

Geotechnical • Environmental • Construction Materials • Facilities

Diego Fault Hazard Zone for "potentially active faults" as shown on the Fault Zones

Location Map (Figure No. 2).

9. The geotechnical consultant must provide appropriately scaled maps that show the relation of the proposed project to the Fault Hazard Zones, mapped faults, and illustrate the fault trench location (Leighton & Associates dated September 20, 1990) with respect to the proposed project.

Figure Nos. 1A, 18, and 2 show the location of the proposed project site in relation to the Fault Hazard Zones and mapped faults according to the City of San Diego (2008). The estimated location of fault trench by Leighton & Associates (1990) is shown on Figure No. 1A. The proposed project site and fault trench are located just outside of the Fault Hazard Zone designated as potentially active by the City of San Diego (2008).

10. The geotechnical consultant must state that the data from that investigation is sufficient to characterize the project site currently under review (OTS 259618) with respect to the presence of faulting (i.e. subsurface exploration located to intercept faults with 30-degrees of the expected trend).

The fault investigation performed by Leighton and Associates was located within and intercept ratio of 30-degree from the mapped fault trends shown on Figure Nos. 18 and 2. Their investigation is, therefore, considered satisfactory to characterize the lack of active or potentially active faults crossing the project site.

11. Provide perpendicular cross sections through the proposed project that illustrate the geologic conditions.

Figure Nos. 3A (Geologic Cross-Section A-A') and 38 (Geologic Cross-Section 8-8') are

included in this report and illustrate the geologic conditions according to our exploratory borings and the fault trench log by Leighton & Associates (1990).

12. Provide an explicit opinion whether or not an "active" or ''potentially active" fault trace passes beneath the proposed project.

The fault trenching by Leighton & Associates (1990) was performed adjacent to the current proposed building addition. Accordingly, based on our review of the their fault investigation report and of the Fault-Rupture hazard map by the City of San Diego (2008), it is our professional opinion that "active" or "potentially active" fault traces likely

do not pass beneath the proposed warehouse addition.

13. The geotechnical consultant must address the proposed foundation setback from the nearby descending slope in accordance with the 2010 CBC Section 1808. 7.2.

1808A.7.2 Foundation setback from descending slope surface. Foundations on or

adjacent to slope surfaces sha ll be founded in firm materia l with an embedment and

set back from the slope surface sufficient to provide vertica l and lateral support for the

foundat ion without detrimental settlement. Except as provided for in Section

1808A.7.5 and Figure 1808A. 7.1, the fo llowing setback is deemed adequate to meet the

criteria. Where the slope is steeper than 1 unit vertica l in 1 un it horizonta l (1 00-

percent slope), the requ ired setback sha ll be measured from an imaginary plane 45

degrees (0.79 rad) to the horizontal, projected upward from the toe of the slope .

14. The copy of the investigation by Leighton & Associates dated September 20, 1990 included as Appendix C in the report by Terracon dated November 14, 2001 [sic 2011] contains dissected copies of the figures entitled "Trench Location Map 11 and "Fault Trench Log. 11 Non-segmented and complete copies of those figures must be provided.

Complete copies of the "Trench Location Map" and "Fault Trench Log" are included with

th is report.

We appreciate the opportun ity to be of service to you on this project. If you have any questions concerning this report, or if we may be of further service, please contact us.

Sincerely, Terracon Consultants, Inc.

~1flw ~-@=~ Stephen E. Jacobs

Engineering Geologist

PG 3978, CEG 1307

Department Manager

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LEGEND

+ B-1

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SOIL BORl'NG APPROXiMATE LOCATION

ESTIMATED LOCATION OF FAULT TRENCH (LEIGHTON, 1990)

APPROXIMATE LOCATION OF GEOLOGIC CROSS SECTION 11;.( ;it.'•'.1 I!- ''.1 < : ; i" ' i1 I{,; :1: .:.. I. IN ·:u " ;,'. J . ~,

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BORING LOCATION mAGRAM

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Costco Wholesa le Store Addition 4605 Morena BoulevaPd

San Diego . Californ ia

P'roj l!lt ~ No... ire a n S. c: .<a l ~ :

601152 39

n = 140' ~CE-62 t,M,;..1::ff• l~-.·t:ri u!:

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LEGEND

INFERRED POTENTIALLY ACTIVE FAULT

FAULT ZONE (CITY OF SAN DIEGO)

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E.'S Til'.1 ~TED LOC .S,ilON DF F.!-1.IL' TREIVC!-1 t LEGHTO N. I 9:tl))

.=,p, OF GEOL051G CRIJSS 'S E•::.T lat~

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FEET

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SITE LOCATION MAP Costco Wholesale Store Addition

4605 Morena Boulevard San Diego, California

FIGURE 1 B

- -••••••••

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200 400 600 800 IOOOFeet

DATUM IS ME4N SEA LEVEL CONTOUR INTERVAL 5 FEET f',··· • -· .

ONE i~~~~N~.lfEOblG~~LJfO~~l~R~DE~i~~~R~L:~E GoRJR-r~50NE 6) NOTE • Tll! RECTAN$1JLAR COORDltfll.T[ VALUU ARE SHOWN OH TKE $0UTH AHO WEST MARGINS

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LEGEND

Inferred Fault

Concealed Fault Shear Zone

Active, Alquist-Priolo Earthquake Fault Zone

Potentially Active, Fault Zone, inactive, presumed inactive or activity unknown

Hazards and Faults, Map Sheet 25, dated 2008. Base Map: County of San Diego Topographic Map Sheets

238-1 695 and 238-1701, dated 1963, scale 1 :2400.

CITY OF SAN DIEGO FAULT ZONES MAP Costco Wholesale Store Addition

4605 Morena Boulevard San Diego, California

TERRACON Figure 2.

A A'

120-

m ~ ~- 100-0 ::::i (/)

::::i

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. Existing r Proposed Building Addition ) I Bldg. B2 B3 I (proj.) ~ I

I< Leighton Fault Trench (projected) )I

""-. , Fence Wall

Soil - l- Soil-Af- -___: ------- -_____ .... Ta Ta

Property Line

1-120

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I- 80 <D -60 60

0 20 40

FEET

LEGEND

At Artificial Fill

Soil Weathered Ardath Shale

Ta Bedrock: Ardath Shale (Eocene age)

Geologic Contact (dashed where interred)

B3 Approximate Location of Soil Boring

Note: all locations are approximate

GEOLOGIC CROSS-SECTION A-A' Costco Wholesale Store Addition

4605 Morena Boulevard San Diego, California

TERRACON Figure 3A

m CD < ~-0 :::::i en :::::i ,, CD CD .-+

8 B' f\.I Af"\O \A

Existing Building ""' Proposed Buildinq Addition ~120 ~

120-

100-

so-

60-

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~ I Leig~ton FaultTrench •I

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LEGEND

Af Artificial Fill

Soil Weathered Ardath Shale

Ta Bedrock: Ardath Shale (Eocene age)

Geologic Contact (dashed where inferred)

83 Approximate Location of Soil Boring

Note: all locations are approximate

FEET

GEOLOGIC CROSS-SECTION B-B' Costco Wholesale Store Addition

4605 Morena Boulevard San Diego, California

TERRA CON Figure 38

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TRENCH LOCATION MAP

PRICE CO./FAUL T

SAN DIEGO, CALIFORNIA

Base map provide j by client Proiect No. 4901244-01

.............. _ --- --- --·---- - -·-- - -- - --~~

· _~., )t: In

Scale No Scale

EngrjGeol. -=G"'C"'"/'-'R'-'H __ _

Dratted By --'D=L:G'----­Date September 20, 1990

[][I] 1044 889

Figure No. 2

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N49°E ~-4" thick uo· oonc:ret•

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LEGEND

fill Approxlutely 10·-12• of yellow-brown duop, dense, gravelly sand; very silty; Bue ll&ter1al

Yellow-gray, brown, and dart gray, mist, stiff to Mdfia dense, sandy clay and clayey sand; scattered to abundant rounded cobbles to 10• di-tar

ARQATH Sl!AL E

Orange and gray, dup, stiff to very stiff, siltstone and locally very silty, very fine sandstone; locally ussive to fissile

I 21' -23': Two-foot-wide zone with high­ang 1 e fau 1 ts and fractures , •I nor apparent offset; 1/16°-1/4° layers of soft clay-lined fau 1 t and fracture surfaces

t 44': High-angle fault lined with 1/2" thick soft reioolded clay

I 70' : Grades to less oxidized, mre aass ive mterlal; groy , d111p, hard siltstone with thin (1/4") sandstone layers; well lndurated, scattered very tight fractures

t 75' -154' : Continuous dart gray to black, mi st, soft, reioolded chy so•; locally abundant crystals of gypsta along sen, sea111 fs continuous and not offset along ent I re southeast trench

'°' ·'.·r ~'"-'f ' '~~ ~~::\!~~,..., • "-1l.'- ·::. ;~ .. ;:,:; .. 1v!&·~~·· · · ·~

Beddlng{b), F ault(F) and FractureCf) Attitudes

b:W25E/65E 18

f : ll4711/68SW 19

f : lllOll/!O 20

f : Nl3E/80SE 21

b:NlOE/lZJIW 22

b: NSOW/llllE 23

F: ll60lf/90 24

F:NllOE/52SE 25

b:ll47V/26SW 26

10 f :NeV/90 27

II b:ll40E/11NV 28

12 f:E-V/66S 29

13 F:H7BE/96NV 30

14 b: ft44V/7NE 31

15 F:N68V/B2NE 32

16 f :N47E/90 33

17 b : tfZSEflNll 34

f : NZOW/77SW

b:N68E/ 17NW

f:Nl6V/76SV

F( ?) : N75E/80NE

f :N75W/8 5SW

b:N75W/10SW

f :N60W/85SW

f:N78W/7SNE

b: N60E/9SE

b:N84V/6NE

b:E-W/ SN

f :NSSW/87SV

f :N70E/78NV

f:ft39E / 82SE

b:N60E/ 8NW

b:HSOV/SNE

b:N75W/4NE FAULT °TRENCH LOG PRICE CO.IF AULT

SAN DIEGO, CALIFORNIA

[1][8 1044 889

Project No. 4901244-0l

Scale -'1'-~;...s~· ___ _

Engr./Geol. ..-G;...;C"'-/:..:.R:..:.H __ _

Dratted By _::.D::.LG=----Date September 20, 1990

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