DEPARTMENT OF CONSERVATION DIVISION OF MINES AND … · 08/01/1980 · DEPARTMENT OF CONSERVATION DIVISION OF MINES AND GEOLOGY SAN FRANCISCO DISTRICT OFFICE FERRY BUILDING SAN FRANCISCO,

• STATE OF CALIFORNIA- THE RESOURCES AGENCY EDMUND G. BROWN JR., Governor

DEPARTMENT OF CONSERVATION

DIVISION OF MINES AND GEOLOGY SAN FRANCISCO DISTRICT OFFICE FERRY BUILDING

SAN FRANCISCO, CA 9-4111 (Phone .415-557-0633) (415) 557-0413

April 11, 1980

J.W. Cobarrubias Staff Geologist, CEG #35 Grading Division Department of Building and Safety 402, City Hal 1 Los Angeles, CA. 90012

Dear Mr. Cobarrubias:

We are placing on open file the following reports, reviewed by the City of Los Angeles in compli~nce with the Alquist-Priolo Special Studies Zones Act:

[,/ Addendum geotechn ica 1 report for proposed i ndustr i a 1 building, 12340 Montero Ave., (Lots 8-13, Tract 22961), Sylmar, CA.; by Foundation Engineering Co.; Jan. 8, 1980.

Report of seismic investigation, 12968 MacNeil Street (Lot 44, Tract 26569), Sylmar, CA.; by J.D. Merrill; Aug. 29, 1979.

Sincerely yours,

~ EARL W. HART Office of the State Geologist CEG 935

EWH/dew

cc: A-P fi 1 e (2)//

' ' CITY OF Los ANGELES CALIFOR~JIA

C:OMMISSIONERS

DEPARTMENT OF

BUILDING AND SAFETY

MAURICE E. MARTINEZ PRESIDENT

MARCIA MARCUS VICE-PRESIDENT

RACHEL GULLIVER DUNNE

TOSHIKAZU TERASAWA

March 31, 1980

Mr. Earl Hart

TOM BRADLEY MAYOR

Division of Mines & Geology Ferry Building San Francisco, CA 94111

Dear Mr. Hart:

40.2, CITY HALL

LOS ANGELES. CALIF. 90012

JACK M. FRATT GENERAL MANAGER

Transmitted herewith is a copy of the Geologic-Seismic Report dated January 8, 1980 prepared by Carl D. Schrenk of Foundation Engineering Co., Inc. The report has been prepared for Lots 8 - 13 of Tract 22961, pursuant to Chapter 7.5, Division 2 of the Public Resources Code.

The City of Los Angeles has reviewed the report and finds it to be acceptable and in general conformance with the minimum requirements of the Special Studies Zones Act. A copy of the Department letter in review of the report has been enclosed for your files.

&.~:::i::~~:. '35 Grading Division

TDN:mra 485-3435

Attachments: Department letter Report

AN EQUAL EMPLOYMENT OPPORTUNITY-AFFIRMATIVE ACTION EMPLOYER

...

COMMISSIONERS

MAURICE E. MARTINEZ PRESIDENT

MARCIA MARCUS l/ICE·PRE:51DC:NT

CITY OF Los ANGELES CALIFORNIA DEPARTM ENi OF

BUILDING AND SAFETY

402. CITY HALI..

LOS ANGELES. CALIF. 90012

JACK M. FRATT GENERAL MANAGE:l'l!

RACHEL GULLIVER DUNNE TOSHIKAZU TERASAWA

March 20, 1980

Anthony Manufacturing Co. 12354 Gladstone Avenue Pacoima, CA 91342

TRACT: LOT:

22961 8 - 13

TOM BRADLEY MAYOR

LOCATION: 12340 MONTERO AVENUE

Geologtc-Seismtc and Soils Engineering Report dated January 8, 1980 prepared by Foundation Engineering Co., Inc.

REFERENCE: Department letter dated June 25, 1979

The above report concerning the proposed construction of an industrial building has been reviewed by the Grading Division of the Department of .Building and Safety. The property is located within a Fau1t Area identified by the State of California Special Studies Zones (established under Chapter 7.5, Division 2 of the Public Resources Code, i.e., Alquist-Priolo Act.)

According to the report, the proposed industrial building site lies approximately 150 feet south of the nearest mappable fault trace. The report concludes that the site is free from active fau1t rupture or unstable ground. This condition is predicated on 5 test ho1es and approximately 1466 lineal feet of continuous backhoe trenches in areas selected by the project geologist. How~ver, an inspection of the trench logs seems to indicate disruption at about station 5+95 on trench 2 which would coincide with the extension of the break in the cul-de-sac, as shown on the A1quist-Priolo map. In addition, possible offsets occur at about station 1+30 on trench lA and between stations 1+19 and 1+24 on trench 2A, in the area of the property line between lots 8 and 9. No trenching has been done along the northern property line of lot 8 where a possible fault trace is shown on the Alquist-Priolo map.

Ar-{ EQUAL EMPLOYMENT OPPORTUNITY-AFFIRMATIVE ACTION EMPLOYER

12340 MONTERO AVENUE Anthony Manufacturing Co. March 20, 1980 Page 2

On the basis of the findings presented in the report and the subsurface exploration conducted on the site, the report is acceptable with the following conditions:

1. No habitable structure shall be erected on lot 8.

2. Prior to issuance of any permits, plans for the project shall be approved by the soils engineer and geologist.

3. No dangerous or flammable substance shall be stored on the property.

4. Allowable foundation pressure and frictional and lateral soil bearing values shall be limited to a maximum one-third in- . crease when considering earthquake and other temporary forces.

5. A grading per~it shall be obtained, for all structural fill, and retaining wali backfill.

6. Prior tc the p1acing of compacted fill, a representative of the cons~1ting Foundation Engineer shall inspect and approve the bottom excavat•ons. He shall post a notice on the job site for the :~:y Srading Inspector and the Contractor stating that the soi1 inspected meets the conditions of the report, cut that nc f;11 shall be placed until the City Grading Inspector ha~ a1so inspected and approved the bottom excavations. A written certification to this effect shall be filed with the De~artment upon completion of the work. The fill shall be piaced under the inspection and approval of the Foundation Engineer. A compaction report shall be submitted to the Department upon completion of the compaction.

7. A11 graded slopes shall be no steeper than 2:1.

8. All man-made fill shall be compacted to a minimum of 90 per cent relative compaction as required by Code Section gl.3006(d).

9. If import soils are used, no footings shall be poured until the Foundation Engineer has submitted a compaction report containing in-place shear test data and settlement data, to the Department, and obtained approval.

10. A supplemental report shall be submitted to the Grading Division containing recommendations for shoring, underpinning and sequence of construction if any excavation would remove the lateral


support of the public way or adjacent structures. A plot plan showing the type, number of stories, and location of any structures (or absence of any structures) adjacent to the excavation shall be provided with the excav~tion plans:

11. Suitable arrangements shall be made with the Department of Public Works for the proposed removal of support and/or retaining of slopes adjoining the public way.

12. If the actual foundation design loads do not conform to the foundation Toads assumed in the report, the Foundation Engineer shall submit a supplementary report containing specific design recommendations for the heavier loads to the Department for review and approval prior to issuance of a permit.

13. The applicant is advised that the approval of this report does not waive the requirements for excavations contained in the State Construction Safety Orders enforced by the State Division of Industrial Safety.

14. A copy of the subject and appropriate referenced reports end this. a::::'"?va1 letter shall be attached to the District Office and· ~ie1d set of plans. Submit one copy of the anove ra~crts to the Building Department Plan Checker prior to issuance o+ the permits.

15. Prior to the ~ouring of concrete, a representative of the consult:ng Foundation Engineer shall inspect and approve the footing excavations. He shall post a notice on the job site for the City Building Inspector and the Contractor stating that the-work so inspected meets the conditions of the report, but that no concrete sha11 be poured unti1 the City Suiidfng Inspector has also inspected and approved the footing excavations. A written certification to this effect shall be filed with the Department upon completion of the work.

16. The owner shall record a sworn affidavit with the Office of the County Recorder which attests to his knowledge that the site is located within an area subject to surface fault rupture and/or severe ground shaking.

'. -...


17. To best inform future owners of possible damage to structures on the site, the geologic-seismic and soil engineering report shall be recorded with the office of the County Recorder.

APPROVED: r

~W.· COBARRUBIAS q{a~f Geologist, Building and Safety

TDN/MRW:rnra 485-3435

cc: Foundation Engineering Co., Inc. ST Inspection VN Ir.specti:1n ST Plan Chae;; VN P1an Cne::k LA P1c.:I Che::k Board Fn e

A /.1 ~/n--ed:f / p ~ 0. ROBB ~~er

Chief of Grading Division

.. • • ADDENDUM

GEOTECHNICAL REPORT

for

PROPOSED INDUSTRIAL BUILDING

at

12340 Montero Avenue Sylmar, California

OWNER

ANTHONY MANUFACTURING COMPANY 12364 Gladstone Avenue

Pacoima, California 91342

ENGINEERS

MACKINTOSH & MACKINTOSH, INC. 3838 Oakwood Avenue Los Angeles, California

90004

January 8, 1980

F 0 U N D A T· I 0 .N ENGINEERING c 0 .. I N C.

•

' • FouNDATION ENGINEERING GEOTECl-!NICAL ENGINEERING

18344 OXNARD STREET

704 SOUTH SPRING STREET

TARZANA, CALIFORNIA 91356

LOS ANGELES, CALIFORNIA 90014

996-1600

873-5032

ADDENDUM GEOTECHNICAL REPORT

General

An addendum geotechnical study has been conducted for an industrial

building to be located at 12340 Montero Avenue, Sylmar, California.

The sites are situated on a. portion of Montero Avenue. The legal

description of the property is Tr.act 22961, Lots 8-13.

Reference is made

1977. In addition

to our original Geotechnical

to the four test holes and

Report dated May 19,

seismic trench which

were originally excavated during 1977 to ascertain site conditions, an

additional fault trench study was initiated per the City review letter

dated June 25, 1979. A new grading plan and plot plan has also been

prepared. This addendum report addresses these items. The addendum

report supercedes the May 19, 1977 report, however applicable

information from that report is incorpo.rated into this addendum.

Surface Conditions

Surficial soils consist of disced clayey sand and silty sand. The

absence of shrinkage cracks indicates nonexpansive surface soils.

Streets and nearby buildings were observed for settlement and effects

of unstable, soils. No significant distr_ess from these causes was

observed. However, patched irregular street cracks and replaced

sidewalks indicate severe ground motion has .occurred in the area.

•

' • Addendum Geotechnical Report


• 2

Presence of fill was noted in our trenching and is also evidenced by

the general raised condition of the ground in the southerly portion of

the build ing site. The site is currently vacant and has been recent

ly disced for weed abatement purposes.

Foundation Conditions

Test holes and seismic trenches were excavated with a backhoe. A

Geologic and Location of Test Hole Map derived from plans prepared by

MacKintosh & MacKintosh, and Logs of Test Holes and Seismic Trenches

are attached. The natural soils consist of silty and gravelly sands

in a dense condition. Boulders up to 24 inches were also encountered.

Loose fill up to 5 feet in depth was encountered both in the test

holes and the 1977 seismic trench. Localized deeper areas of fill

should be anticipated elsewhere on the site.

Seismic and Geologic Conditions

An additional continuous fault trench was excavated, inspected and

logged. This fault trench is labeled Seismic Trench Profile /12. The

resultant Seismic Trench Profile graphically portrays the results of

geologic trench inspection. Information was also obtained from review

of published data relating to the February 9, 1971 earthquake.

F 0 -U . N D _A T I 0 _ N ENGINEERING c 0.' I N C,

•



• 3

The site is underlain by up to 5 feet of existing fill as described in

the Foundation Conditions of this report. Underlying fill, Recent

alluvial lenses of sand and gravel along with stratified layers of

silty sand were observed and inspected. No evidence of displacement

was observed within the horizontal lenticular sand layers exposed by

the trench.

Subject site is located in an area between two en-echelon faults; the

Sylmar, and the Tujunga Fault segments. The general displacemnt from

the 1971 earthquake was that of the northern block thrusting south

westward over the southern block, with approximately equal amounts of

vertical uplift, exhibiting north-south compressions and left lateral

slip (see Attached Block Diagram). The zone in which subject property

lies was subject to intense compression from the en-echelon E-W fault

ing. Studies conducted by the staff of the U. S. Geological Survey

and California Institute of Technology after the earthquake indicated

that the surface breaks between the main fault zones are, " .•• in an

area of apparent discontinuity between the Sylmar and Tujunga segments

and • • • • instead of a single clear break, there is a maze of

small ruptures," (Bonilla, M. G., et al; and Kamb B., et al, U.S.G.S.

Professional Paper 733).

An apparent fault trace has been mapped through the middle of the cul

de-sac of Montero Avenue. However, it appears that this trace was

drawn based upon crescent shaped openings between the street and the

curb that were caused by the compression of the pavement. (See Figure

No. 11 U.S.G.S. Professional Paper 233 pg. 66; and Photo., Calif.

FOU.ND.6.TION ENGINEERING c o .. I N C.

•



• 4

Division of Mines Bulletin 196, page 147). Again, based upon close

inspection of the trench there is no evidence offault rupture within

the property.

It is our opinion that the surface ruptures previously observed were

the result of longitudinal shortening that occurred during the

northeast-southwest compression of the region between the two main

fault traces. Future ground shaking within the area would produce

additional surface ruptures which would not necessarily follow the

same pattern. Therefore, it is our opinion that restricted usage of

Lots B through 13 is not warranted due to close observation of the

seismic trenches, review of photographic data on subject site, and

information published in the aforementioned Professional Papers.

Based upon information derived from the Los Angeles Flood Control Dis

trict groundwater in the area is greater than 50 feet below the ground

surf ace. Therefore, considering the depth of groundwater, liquef ac

tion is not considered a significant hazard to the proposed develop

ment.

The closest mappable fault lies approximately 150 feet as shown on the

attached Fault Vicinity Map. Since severe tensional and compressional

movement occurred within the area during the 1971 earthquake resulting

in considerable distress to several industrial buildings nearby, it is

suggested that the structure be designed for 0.3g and that long ex

panses of glass and nonstructural walls and isolated piers not be

utilized in the design of the proposed building.

F 0 U N DA T I 0 .N ENGINEERING c a .. I N C.

• Addendum Geotechnical Report

12340 Montero Avenue Sy !mar, Ca Ii forn i a

Testing

• 5

Testing consisted of field exploration and laboratory tests at various

locations throughout the site. The trench and test pits were exca

vated by a backhoe. The approximate locations of the trenches and

test pits are shown on the attached plan.

Logs of the test holes are attached, which tabulate data, classifica

tion tests and visual inspection by the engineer in the field. A

legend precedes the logs describing the various tests made. The test

holes represent the condition at the particular location, changes in

soil type and variations in the thickness of various layers of soil

can be expected between the test holes.

Classification tests consisting of grading analysis and moisture con

tent indicate that the soils on which the building will be supported

are mostly silty and gravelly sands. The undisturbed natural soils

are considered to be in a medium dense condition, which will minimize

settlement of footings. Density tests show the undisturbed soils to

have uniform densities (D.D. ); thus settlements of similar footings

will be uniform.

Consolidation and shear tests were conducted on representative samples

of the foundation soils. The samples that were selected were consid

ered to be the most compressible and to have the least strength for

each of the types of soil. In general, these were the samples with

the lowest density, the lowest relative density, the highest degree

F 0 U N DA T I 0 .N ENGINEERING c o .. I N C.


12340 Montero Avenue Sy !mar, California

• 6

of plasticity and the highest percentage of fines passing no. 200

sieve. The results of the consolidation and shear tests appear to be

consistent with the conditions found in the field and with results of

tests on similar soils.

attached.

The test methods and the test results are

An expansion test was conducted in accordance with UBC Standard 29-2.

The test results indicate that the soil less an expansion index of 17.

This soil is nonexpansive.

Description of Proposed Structure and Grading

It is proposed to construct a one story steel frame building with pre

cast walls. Loads on conventional spread footings are expected to be

on the order of 100 kips for isolated columns and 3000 pounds per

linear foot for continuous footings.

Grading is expected to provide for a level building pad and proper

drainage.

A variable height retaining wall up to 6 feet in height is anticipated

along the easterly property line.

This report is intended for construction similar to the proposed

building and grading described above. Changes should be reviewed for

additional recommendations.

FOUNDATIO.N ENGINEERING c a .. I N C.



Design Calculations

• 7

The allowable bearing capacity for spread footings was computed by the

simplified method of determining bearing capacity presented in Soil

Mechanics in Engineering Practice by Terzaghi and Peck, page 222. The

allowable bearing value incorporating a safety factor of 3 is tabu

lated below for typical footings:

BEARING CAPACITY CALCULATIONS

Continuous footings

Square footings

Width, Ft.

1

3

Depth, Allowable Foundation Ft. Pressure, psf

1 2250

1 3000

The above calculations are based on shear strength only and must be

modified according to the settlement potential.

Settlement calculations are based upon the consolidation test results

in accordance with the method set forth in Fundamentals of Soil

Mechanics by D. W. Taylor, page 258. The amount of settlement is a

function of the size of the loaded area as well as of the load. The

size of the loaded area is represented by the influence factor, which

is a dimensionless quantity that depends on the area and Poisson's

ratio. Settlement calculations are based on the maximum stress. When

the applied stress becomes less than ten percent of the applied load,

it is assumed that consolidation would be 'negligible.

F 0 -U N D _A T I 0. N ENGINEERING c o .. I N C.



• 8

The settlement analyses indicate that the maximum settlement under the

heaviest expected load will be about 3/4 of an inch. Maximum differ

ential settlement between two adjacent footings will be about 1/4 of

an inch. In fact, the settlement will be less than calculated as

these calculations are based on tests in which the soils are complete

ly saturated. This condition is unlikely to occur at the proposed

building site. Thus, the actual bearing capacity will be higher than

that indicated, and the amount of consolidation would be considerably

less. Calculations for settlement are based on the total live load

plus dead loads. The settlement will be less than the calculations

indicate, as the dead load is about 80 percent of the total load. It

is estimated that 60 percent to 80 percent of the settlement due to

footing loads will take place during construction.

General Recommendations

All existing fill deposits are non-uniform and loose, and should be

removed from the bu ii ding area. This area will cover most of the

easterly l/3rd of the building site. In order to provide a more

nearly uniform foundation system, the upper 24 inches of natural soils

should be removed from the remainder of the building site and be re

compacted. After the recommended grading, the structure may be sup

ported on conventional spread footings founded in the compacted fill

soils. Footings may be designed in accordance with the "Recommenda

tions for Design" section which follows.

The "Recommendations for Construction and Grading" section includes

recommendations that should be included in the plans and specifica-

tions. In addition, grading specifications are appended to the re-




• 9

port. The grading specifications should be revised by the architect

and applicable portions that are not in conflict with the design

should be incorporated in the plans and specifications.

It is recommended that the completed plans and specifications be

submitted to us for review of the geotechnical aspects. The reiew

would not include checking calculations by the structural engineer.

Recommendations for Design

Exterior footings should be placed at a minimum depth of 12 inches be

low the lowest adjacent finished grade. The minimum depth of interior

footings should be at 12 inches below the top of the concrete slab.

The minimum width of both the exterior and interior footings should be

12 inches.

Continuous footings may be designed for a foundation pressure of 2200

pounds per square foot. Isolated pad footings may

foundation pressure of 3000 pounds per square foot.

be designed for a

The weight of the

footing below the lowest adjacent grade can be neglected. The allow

able foundation pressure may be increased up to twice the given value

for earthquakes or other temporary forces.

Continuous footings should be reinforced with at least one no. 4 bar

near the top of the foundation wall and at least one no. 4 bar near

the bottom of the footing.

Spread footings may be tied together with properly reinforced floor

slabs and the tilt-up walls. The reinforced floor may be used to




• 10

resist horizontal forces with a coefficient of sliding of 0.4. Hori

zontal forces may be resisted by the footing itself with the sliding

coefficient given above. Horizontal forces also may be resisted by a

passive pressure of 200 pounds per cubic foot, equivalent fluid pres

sure. The allowable horizontal forces may be increased 50 percent for

earthquakes and other temporary forces.

The retaining wall at the east property line should be founded in firm

natural soils and its footing may be designed similar to a continuous

footing. The retained backslope will be approximately 1-1/2:1, there

fore the wall should be designed for 55 p.c.f., equivalent fluid pres

sure. A lined gutter should be provided behind the wall and provision

should be made to allow cleanout of debris, which will erode from

above. The wall should be drained at its base by a gravel backed

weephole system.

Recommendations for Construction

All existing fill deposits are non-uniform and loose, and should be

removed during site preparation. To provide uniform footing support

and to assure stability of floor slabs, driveways, and other apper

taining structures founded on or near the existing ground surface,

compaction of the loose surface soils is also recommended. A minimum

of 2 feet of upper soils should be removed and recompacted in the

building area. The excavation and replacement with compacted fill

should extend beyond the edge of the footing for at least 3 feet or a

distance at least equal to the depth of compacted fill below the foot

ing, whichever is greater.

FOUNDATION ENGINEERING c o .. I N C.



• 11

All fill should be compacted according to prevailing codes. Prior to

placing any fill the prepared subgrade should be inspected by the soil

engineer. During placement of the fill it should be tested by the

soil engineer.

Import fill shall be silty sand, clayey sand or sand and shall have an

expansion index of 20 or less.

On completion of the work, the site should be graded to slope away

from the building. Areas such as poorly graded planter areas or where

walks and drives would create depressed areas which could pond water

adjacent to buildings, should be eliminated.

Conclusions

We conclude that the site will be suitable for the proposed grading

and construction. Our recommendations are based on site conditions

during exploration, laboratory tests, geologic reconnaissance and

experience with similar sites; and are in accordance with generally

accepted procedures of soil mechanics and foundation engineering.

The recommendations in the report are based on random sampling. Soil

deposits may vary in type, consistency and many other important pro

perties between the test holes. Therefore, this report should be con

sidered only preliminary in nature;· its purpose is to determine the

general foundation system for the structure described in the report.

Foundation Engineering Co. should continue to be retained for the pro

ject in order that continued observation of the subsurface conditions

FCUNDATIC.N ENGINEERING c a., I N C.


12340 Montero Avenue Sy !mar , California

• 12

can be made and additional recommendations made for changes in design

if needed. Provision should be made for possible changes in quanti-

January B, 1979

Attachments: 1 set - Grading Specifications 1 - Fault Vicinity Map 1 - Block Diagram 1 - Location of Test Hole Map 4 pgs - Seismic Trench Profiles 1 - Legend for Logs 3 pgs - Log of Test Holes 2 pgs - Direct Shear Tests 1 pg - Consolidation Test 1 - Description of Test

FOUNDATION ENGINEERING c 0 .. I N C.

• • STANDARD GRADING SPECIFICATIONS

Scope

These specifications ore for all earthwork where slope of natural ground is flatter than 5 horizontal to I vertical.

These specifications do not include pavement or preparation of the s uhg rode for pavement.

The specifications ore not intended to supercede any controcturol agreement between the owner oncl the contractor.

The specifications ore of general nature and mov refer to work not required. ·

The extent of the work required is shown on the plans oncl supercedes dimensions given in the specifications.

General

All necessary grading permits shall be obtoinecl by the architect or owner prior to. construction.

Grading should be in accordance with the project grading specifications, the applicable portion of the Building Code, the regulations of the Deportment of Building and Safety, and the State Division of Industrial Safety.

The governmental agencies having jurisdiction over the project shall be notified by the contractor that grading is to commence and he is to make all arrangements for timely inspections.

The soil engineer will be retained by the owner, however, the contractor must notify the soil engineer in advance to permit proper observance of excovoti on and testing of fi 11.


' • • Grading Specifications 2

The contractor shall provide supervision to properly execute the project and to provide assurance that the work is in accordance with the plans and the specifications. The soil engineer will notify the contractor when tests foil so that the contractor may direct the work to achieve compliance with the specifications.

The soil engineer is not authorized to modify the contract between the contractor and the owner. If work requested by the soil engineer is not included in the contract the work must cease and the owner notified.

If changed conditions are encountered the owner, architect anrl soil engineer should be notified.

If a well, seepage pit or cesspool is encountererl it shall not be filled until approval to do so is obtained from the qovernmental inspector and Foundation Engineering Co.

A soil engineering report was prepared for the design of the project. The report may not be sufficient for the contractor to net ermine the subsurface conditions over the entire site. He should anticipate variation in soil properties throughout the site or make arrangements for further exploration before commencing work.

A copy of the soil report is available for the contractor's inspection at the architect's office or Foundation Engineering Co.

The property limits and elevation benchmarks at the property line will be provided for the contractors use. The contractor shall provide or shall request the owner to provide, at timely intervals, a II necessary surveying within the project. The soil engineer cannot verify dimensions, grades, or slope angles. The soil engineer can only indicate the location of the natural qrounrl, designate various soil strata and identify the various soil as disclosed by the grading operation.

Representatives of Foundation Engineering Co., Inc., will observe the work in progress, make tests of the soil, anrl examine the excavations and trenches. It should be understood that the contractor shall supervise and direct the work and he shall be responsible for all construction means, methods, techniques, sequences, and procerlures. The contractor will be solely and completely responsible for conditions at the job site, including safety of all persons anrl property during the performance of the work. Intermittent or continuous inspection by Foundation Engineering Co. is not intended to include review of the adequacy of the contractor's safety measures in, on, or near the construction site.


• • Grading Specifications 3

Test Methods and Specifications

The following standard test methods and standard specifications shall be considered a part of these specifications.

American Society for Testing Materials (ASTM) 1916 Race Street Philadephia, PA 19903

D 1557 Test for Moisture-Density Relations of Soil and Subgrade Mixtures Usinq a 10 lb. Hammer and 18 Inch Drop

D 2419 Test for Sand Equivalent Value of Soils and Fine Aggregates

D 2487 Classification of Soils for Engineering Purposes

Uniform Building Code (UBC) International Conference of Building Officials 5360 S. Workman Mill Rood Whittier, CA 90601

29-2 Expansion Index Test

Standard Specifi cations for Pub Ii c Works Construction, (SSPWC) American. Public Works Assn and Associated General Contractors Building News, Inc. 3055 Over I and Avenue Los Angeles, California 90034

Certification

Contractor will be required to provide certification from the manufacturer that materials conform to materials specified in the above specifications.

FOUNDATION ENGINEERING c c .. I N C,


Site Preparation

The soil engineer shall be notified of commencement of work when demolition and clearing starts.

The method of clearing and stripping should be reviewed by the contractor and the so ii engineer.

All surface vegetation, debris and structures to be demolished shall be removed from the site prior to commencing site preparation, excavation or placement of fill.

Where no excavation or filling is required in a building area the ground should be scarified to a depth of at least 8 inches, moistened to near optimum moisture and compacted to a density of at least 90 percent.

Excavation

All existing fill in the building areas or areas where compacted fill is to be placed for future structures shall be removed. Removal should extend beyond a proposed building or structural fill a distance equal to the depth of fill below the building, structural fill, or 5 feet, whichever is greater.

Reference is made to the soil report for information relating to the approximate location and character of existing fill.

Where required, the natural soil in buildinq areas should be removed to the depth as shown on the pl ans. The removal of natural soil should extend at least 5 feet beyond the edge of the proposed buildings.

Temporary vertical cuts may not exceed a maximum height of 5 feet unless shown otherwise on the plans.

The site should be excavated to provide 3/4 horizontal to I vertical slopes at the property line before commencing cut at any property line.

Slot cuts or shoring shall be made in accordance with the sequence shown on the plans.

F 0 U N D A T -1 0 N ENGINEERING c o .. I N C.

• • Grading Specifications s

Compacted Fil I

Compacted fill should not be placed until the subgrade has been examined by the soil engineer,

The soil engineer may require the contractor to excavate test pits to a depth not exceeding 3 feet at I or more locations on the subgrade to examine the soil. The pits shall be backfilled with compacted fill.

The subgrade or surface for the fill should be scarified, moistened to near optimum moisture, and compacted.

Fill material shall be placed in level, uniform layers not exceeding 8 inches in thickness when compacted. Each layer shall be thoroughly mixed during the spreading to insure uniformity of material and moisture in each layer.

The moisture content during compaction shall not be less ti-Ian 2 percent below optimum moisture except clay and sandy clay which shall he placed at a moisture content of 3 percent or more above optimum moisture.

If the soil has moisture content that exceeds S percent ahove optimum, the soil must be aerated to reduce the moisture content as specified by the soil engineer and compaction shall not commence until approval to do so has been given by the soil engineer.

All fill shall be compacted to a density of not less than 90 percent of maximum density.

The soil engineer shall be notified to test the fill at regular intervals. If the tests have not been made, after 3 feet of compacted fill has been placed, the contractor shall stop work on the fil I until tests ore mode,

Fill that does not have sufficient moisture shall be removed, moistened to proper moisture and recompacted even if the proper density has been achieved without proper moisture.

F D U _N D A T i D N ENGINEERING c o .. I N C.


During winter or inclement weather all fill that has been stockpiled in the area where fi II is to be compacted or has been spread ready for compaction shall be compacted before stopping work for the day or stopping because of inclement weather. The compacted fill surface shall be sloped to drain.

Work shall not recommence after a rainy period unless the site has been examined by the soil engineer and he has authorized resumption of work.

Loose fill that was not compacted prior to rain and has a moisture 5 percent above optimum or more, shall be removed and aerated before placement and compaction.

The compacted fill surface will not require scarification for bonding new fill or for aeration after a period of rain. All ponded water on the surface must be removed before placement of fi II.

Any existing fi II on the site is suitable for use as compacted fi II after combustible debris has been removed. Inorganic debris such as concrete, asphalt paving, bricks, etc. may be included in the fill if it is dispersed through the fi II and i ndi vi duo I pieces do not exceen 6 inches.

Import fi II sha II be si I ty sand, sandy si It, clayey sand, grave II y sand, or sand and shall have an expansion index of less than SO.

Import will be approved only at the site. The contractor shall inform the soil engineer at least 36 hours in advance of the source of import soil. If the source is from a site for which a soil report was prepared, a copy of the report should be provinen the soil engineer.

FOU-NDA-TlON ENGINEERING c 0 .. I N C.


Fill for Floor Slabs

Fill for floor slabs shall consist of native soil, sand and gravel or import as required on the plans.

Native soil placed for slab support shall be placed in layers not exceeding 4 inches when compacted, moistened to near optimum moisture content, and compacted.

Import for floor slab support shall consist of sand, gravelly sand or silty sand and shall have an expansion index of less than 30.

Base material un<ler floor slabs sha II consist of gravel or crushed aggregate base, crushed slag base or crushed miscellaneous base in accordance with Section 200-2 (SSPWCl.

All native soil end import soil shall be compacted to a density of at least 90 percent of maximum density.

Soil within 18 inches of the base of the floor slab that has an expansion index of 50 or more shall be soaked to saturate the soil to a depth of at I east 24 inches.

The moisture content of any expansive soil must be tested by the soil engineer within 36 hours of placement of the vapor seal or the concrete floor. The concrete should not be placed without approval by the soil engineer.

F 0 U-N D A- T r a N ENGINEERING c o .. I N C.


Wall Backfill

The area to receive fill must he inspected by the soil enqineer within 24 hours of commencement of hackfillinq operations or placement of drainage facilities.

Drainage facilities shall consist of weepholes in the wolf with a pocket of rock or a perforated pipe surrounded with rock. Rock shall consist of gravel or coarse concrete aggregate conforming to Section 200-1 • ( SSPWC)

Weepholes shall he 1-1/2 inches in diameter spaced at or unmortared joints not exceedinq 3 foot intervals. shall be 6 inches above the finished grade. At least rock shall be placed behind each weephole.

1 foot intervals Tfie weephol es

I cubic foot of

Pipe shall have a minimum diameter of 4 inches and shall conform to Section 207-15 or 207-16 (SSPWC) or rubber modified styrene conforming to ASTM D 2321, or equal. The pipe shall be perforated with not less than 4 holes per foot not exceeding 1/2 inches in diameter and shall be laid with holes down. The pipe shall be lower than the top of the adjacent finished grade or top of concrete paving.

Pipe shall be surrounded with rock with a minimum thickness between the pipe and soil of 6 inches.

The drainage facilities must be inspected by the soil engineer before placement of any backfill.

Wall backfi II shall consist of sand, gravely sanrl, si I ty sand, sandy silt or clayey sand and shall have an expansion index of 30.

All wall backfill shall be placed in layers not exceeding 4 inches when compacted, moistened to not less than 2 percent below optimum moisture and compacted to at least 90 percent of maximum density.

Flooding and jetting of backfill shall not be permittd.

F · 0 U N . D A· T I 0 .N ENGINEERING c 0 .. I N C.

• • • Grading Specifications 9

Uti I ity Trench Backfi 11

Pipes smaller tlian 8 inches in diameter shall be laid on a 4 inch thick layer of bedding material. Pipes larger tlian 8 inches sliall be laid on a 6 inch layer of bedding material.

All pipes shall be backfilled around the pipe and to 12 inches above the pipe with bedding material. Filling shall he made simultaneously on each side of the pipe.

The remainder of the trench shall not be filled until the bedding is observed in place by the soil engineer.

In the remainder of the trench, within huilcfinq areas, backfill shall consist of bedding or Base material as specified for floor slabs. After the backfill has f-ieen completed to witliin 12 inches of the top of the trench, it shall be flooded with sufficient water to preclune settlement after completing backfill.

In the remainder of the trench, outside of the building, backfill may consist of native soil. The backfill shall be flooded or compacted to preclude settlement and to provide a density equivalent to the adjacent natural soil. The upper 2 feet shall be compacted to 90 percent of maximum density except in parking and driveways where the upper 2 feet shall be compacted to 95 percent of maximum density.

Flooding and jetting of backfill during placement of fill is not permitted; it may be done when the fill is within 12 inches or 2 feet of finished grade.

Bedding material should consist of sancl having a minimum sand equivalent of 30.

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Continuous disturbed samples were taken for classification tests to identify the various soils, and 2-1/2 inch diameter undisturbed samples were taken at frequent intervals for detailed laboratory tests.

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M.C. Moisture content in percent of dry weight.

D.D. Dry Density in pounds per·cubic foot

4 The percent of material that will pass a no. 4 (3/16") sieve. The materials larger than the no. 4 sieve and smaller than 3 inches would be designated as a gravel, and the material smaller than the no. 4 and larger than th.e no. 200 would be termed a sand.

200 The percent of the material that will pass a no. 200 sieve (the largest particle that will pass a no. 200 sieve is about the smallest that can be seen with the unaided eye). If more than half of the sample passes this sieve, it would be classed as a silt or clay.

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• • • • •

U\BORA'IDRY TEST METHODS

EXPANSIOO TEST

The expansion index test is in accordance with the Uniform Building Code Standard No. 29-2. A moistened sample was compacted in a four inch diameter ring with 15 blows of a 5.5 pound hammer having a fall of 12 inches per inch of compacted sample. If the degree of saturation ranged between 49 and 51 percent for an assumed specific gravity of 2.7, the specimen was loaded with 144 pounds per square foot and flooded. After 24 hours the expansion was noted and the expansion indices calculated.

CONSOLIDATION TESTS

The consolidation tests were conducted on saturated specimens 2-1/2 inches in diameter. The specimens were loaded with an initial load of 200 pounds

• per square foot, saturated and allowed to remain for 24 hours. Increment loads were added and allowed to remain until primary consolidation had been completed. The final load was 20,000 pounds per square foot. The amount of settlement was recorded for each increment before applying additional loads.

DIRECT SHEAR TESTS

The direct shear tests were conducted on 2-1/2 inch diameter saturated specimens. Specimens were allowed to consolidate under the normal load for 24 hours. The normal loads ranged from 500 to 4000 pounds per square foot. Shear loads were applied at the rate of 0.001 inch per minute in accordance with the generally accepted test procedure for the consolidatedundrained shear test (R).


Documents

DEPARTMENT OF CONSERVATION DIVISION OF MINES AND … · 08/01/1980 · DEPARTMENT OF CONSERVATION DIVISION OF MINES AND GEOLOGY SAN FRANCISCO DISTRICT OFFICE FERRY BUILDING SAN FRANCISCO,