work and the estimated quantities of daily earthwork contemplated for the site prior to commencement of grading. The Contractor shall inform the owner and the Geotechnical Consultant of changes in work schedules and updates to the work plan at least 24 hours i advance of such changes so that appropriate observations and tests can be planned an accomplished. The Contractor shall not assume that the Geotechnical Consultant is aware of all grading operations.
The Contractor shall have the sole responsibility to provide adequate equipment and methods to accomplish the earthwork in accordance with the applicable grading codes and agency ordinances, these Specifications, and the recommendations in the approved geotechnical report(s) and grading plan(s). If, in the opinion of the Geotechnical Consultant, unsatisfactory conditions, such as unsuitable soil, improper moisture condition, inadequate compaction, insufficient buttress key size, adverse weather, etc., are resulting in a quality of work less than required in these specifications, the Geotechnical Consultant shall reject the work and may recommend to the owner that construction be stopped until the conditions are rectified.
2.0 Preparation of Areas to be Filled
2.1 Clearing; and Grubbing: Vegetation, such as brush, grass, roots, and other deleterious material shall be sufficiently removed and properly disposed of in a method acceptable to the owner, governing agencies, and the Geotechnical Consultant.
The Geotechnical Consultant shall evaluate the extent of these removals depending on specific site conditions. Earth fill material shall not contain more than 1 percent of organic materials (by volume). No fill lift shall contain more than 5 percent of organic matter. t * Nesting of the organic materials shall not be allowed.
If potentially hazardous materials are encountered, the Contractor shall stop work in the affected area, and a hazardous material specialist shall be informed immediately for proper evaluation and handling of these materials prior to continuing to work in that area.
As presently defined by the State of California, most refined petroleum products (gasoline, diesel fuel, motor oil, grease, coolant, etc.) have chemical constituents that are considered to be hazardous waste. As such, the indiscriminate dumping or spillage of these fluids onto the ground may constitute a misdemeanor, punishable by fines andlor imprisonment, and shall not be allowed.
Leighton and Associates, Inc.
GENERAL EARTHWORK AND GRADING SPECIFICATIONS
2.2 Processing: Existing ground that has been declared satisfactory for support of fill by the Geotechnical Consultant shall be scarified to a minimum depth of 6 inches. Existing ground that is not satisfactory shall be overexcavated as specified in the following section.
Scarification shall continue until soils are broken down and eee of large clay lumps or clods and the working surface is reasonably uniform, flat, and free of uneven features that would inhibit uniform compaction.
2.3 Overexcavation: In addition to removals and overexcavations recommended in the approved geotechnical report(s) and the grading plan, soft, loose, dry, saturated, spongy, organic-rich, highly fractured or otherwise unsuitable ground shall be overexcavated to competent ground as evaluated by the Geotechnical Consultant during grading.
2.4 Benching: Where fills are to be placed on ground with slopes steeper than 5:l (horizontal to vertical units), the ground shall be stepped or benched. Please see the Standard Details for a graphic illustration. The lowest bench or key shall be a minimum of 15 feet wide and at least 2 feet deep, into competent material as evaluated by the Geotechcal Consultant.
Other benches shall be excavated a minimum height of 4 feet into competent material or as otherwise recommended by the Geotechnical Consultant. Fill placed on ground sloping flatter than 5: 1 shall also be benched or otherwise overexcavated to provide a flat subgrade for the fill.
2.5 EvaluationlAcce~tance of Fill Areas: All areas to receive fill, including removal and processed areas, key bottoms, and benches, shall be observed, mapped, elevations recorded, andlor tested prior to being accepted by the Geotechnical Consultant as suitable to receive fill. The Contractor shall obtain a written acceptance from the Geotechnical Consultant prior to fill placement. A licensed surveyor shall provide the survey control for determining elevations of processed areas, keys, and benches.
3.0 Fill Material
3.1 General: Material to be used as fill shall be essentially free of organic matter and other deleterious substances evaluated and accepted by the Geotechnical Consultant prior to placement. Soils of poor quality, such as those with unacceptable gradation, high expansion potential, or low strength shall be placed in areas acceptable to the Geotechnical Consultant or mixed with other soils to achieve satisfactory fill material.
3.2 Oversize: Oversize material defined as rock, or other irreducible material with a maximum dimension greater than 8 inches, shall not be buried or placed in fill unless location, materials, and placement methods are specifically accepted by the Geotechnical Consultant.
Placement operations shall be such that nesting of oversized material does not occur and such that oversize material is completely surrounded by compacted or densified fill.
Oversize material shall not be placed within 10 vertical feet of finish grade or within 2 feet of future utilities or underground construction.
3.3 Import: If importing of fill material is required for grading, proposed import material shall Leighton and Associates, Inc.
GENERAL EARTHWORK AND GRADING SPECIFICATIONS
meet the requirements of Section 3.1. The potential import source shall be given to the Geotechnical Consultant at least 48 hours (2 working days) before importing begins so that its suitability can be determined and appropriate tests performed.
4.0 Fill Placement and Compaction
4.1 Fill Lavers: Approved fill material shall be placed in areas prepared to receive fill (per Section 3.0) in near-horizontal layers not exceeding 8 inches in loose thickness. The Geotechnical Consultant may accept thicker layers if testing indicates the grading procedures can adequately compact the thicker layers. Each layer shall be spread evenly and mixed thoroughly to attain relative uniformity of material and moisture throughout.
4.2 Fill Moisture Conditioning: Fill soils shall be watered, dried back, blended, andlor mixed, as necessary to attain a relatively uniform moisture content at or slightly over optimum.
Maximum density and optimum soil moisture content tests shall be performed in accordance with the American Society of Testing and Materials (ASTM Test Method D1557-91).
4.3 Compaction of Fill: Mer each layer has been moisture-conditioned, mixed, and evenly spread, it shall be uniformly compacted to not less than 90 percent of maximum dry density (ASTM Test Method D1557-91). Compaction equipment shall be adequately sized and be either specifically designed for soil compaction or of proven reliability to efficiently achieve the specified level of compaction with uniformity.
4.4 Compaction of Fill Slopes: In addition to normal compaction procedures specified above, compaction of slopes shall be accomplished by backrolling of slopes with sheepsfoot rollers at increments of 3 to 4 feet in fill elevation, or by other methods producing satisfactory results acceptable to the Geotechnical Consultant. Upon completion of grading, relative compaction of the fill, out to the slope face, shall be at least 90 percent of maximum density per ASTM Test Method D 1557-9 1.
4.5 Compaction Testing: Field tests for moisture content and relative compaction of the fill soils shall be performed by the Geotechnical Consultant. Location and frequency of tests shall be at the Consultant's discretion based on field conditions encountered. Compaction test locations will not necessarily be selected on a random basis. Test locations shall be selected to verify adequacy of compaction levels in areas that are judged to be prone to inadequate compaction (such as close to slope faces and at the fill/bedrock benches).
4.6 -: Tests shall be taken at intervals not exceeding 2 feet in - vertical rise andlor 1,000 cubic yards of compacted fill soils embankment. In addition, as a guideline, at least one test shall be taken on slope faces for each 5,000 square feet of slope face andlor each 10 feet of vertical height of slope. The Contractor shall assure that fill construction is such that the testing schedule can be accomplished by the Geotechnical Consultant. The Contractor shall stop or slow down the earthwork construction if these minimum standards are not met.
Leighton and Associates, Inc.
GENERAL EARTHWORK AND GRADING SPECIFICATIONS
4.7 Compaction Test Locations: The Geotechnical Consultant shall document the approximate elevation and horizontal coordinates of each test location. The Contractor shall coordinate with the project surveyor to assure that sufficient grade stakes are established so that the Geotechnical Consultant can determine the test locations with sufficient accuracy. At a . -minimum, two grade stakes within a horizontal distance of 100 feet and vertically less than 5 feet apart from potential test locations shall be provided.
5.0 Subdrain Installation
Subdrain systems shall be installed in accordance with the approved geotechnical report(s), the grading plan, and the Standard Details. The Geotechnical Consultant may recommend additional subdrains andlor changes in subdrain extent, location, grade, or material depending on conditions encountered during grading. All subdrains shall be surveyed by a land surveyor/civil engineer for line and grade aRer installation and prior to burial. Sufficient time should be allowed by the Contractor for these surveys.
6.0 Excavation
Excavations, as well as over-excavation for remedial purposes, shall be evaluated by the Geotechnical Consultant during grading. Remedial removal depths shown on geotechnical plans are estimates only. The actual extent of removal shall be determined by the Geotechnical Consultant based on the field evaluation of exposed conditions during grading. Where fill-over-cut slopes are to be graded, the cut portion of the slope shall be made, evaluated, and accepted by the Geotechnical Consultant prior to placement of materials for construction of the fill portion of the slope, unless otherwise recommended by the Geotechnical Consultant.
7.0 Trench Backfills
7.1 The Contractor shall follow all OHSA and CaVOSHA requirements for safety of trench excavations.
7.2 All bedding and backfill of utility trenches shall be done in accordance with the applicable provisions of Standard Specifications of Public Works Construction. Bedding material shall have a Sand Equivalent greater than 30 (SE>30). The bedding shall be placed to 1 foot over the top of the conduit and densified by jetting. Bacldill shall be placed and densified to a minimum of 90 percent of maximum from 1 foot above the top of the conduit to the surface.
7.3 The jetting of the bedding-around the conduits shall be observed by the Geotechnical Consultant.
7.4 The Geotechnical Consultant shall test the trench backfill for relative compaction. At least one test should be made for every 300 feet of trench and 2 feet of fill.
Leighton and Associates, Inc.
GENERAL EARTHWORK AND GRADING SPECIFICATIONS
7.5 Lift thickness of trench backfill shall not exceed those allowed in the Standard Specifications of Public Works Construction unless the Contractor can demonstrate to the Geotechnical Consultant that the fill lift can be compacted to the minimum relative compaction by his alternative equipment and method.
SLOPE FACE ---------- --- ----- -
----------
--- - - - -7c_. - - - - - - - - - - - - - - - ----WINDROW--------- - - ' - -j-- - - -- - --- - --- - JEFTED OR FLOODED
APPROVED SOIL
---
A ----
----
- -
Oversize rock is larger than 8 inhes - -
in largest dimension.
0 Backfill with approved soil jetted or
flooded in place to fill all the voids.
Do not bury rock within 10 feet of
finish grade.
----
Windrow of buried rock shall be
parallel to the finished dope face.
SECTION A-A'
J
PROFIlE ALONG WINDROW
----------------- ----------------- ------------------
-----
JElTED OR FLOODED
APPROVED SOIL
GENERAL EARTHWORK AND GRADING
OVERSIZE ROCK DISPOSAL SPECIFICATIONS
STANDARD DETAILS B
NATURAL
-
I-%.-- ------------- - ---- - -COMPACED FILL
TYPICAL --------
BENCHING
SUB DRAIN ALTERNATE A P"FoRATED 'IPE Dm FILTER MATERIAL WITH FILTER MATWW FILTER MATERIAL SHALL BE CLASS 2 PWMWBLEMATERLALPWSTATEOF CALIFORNIA SANDARD SPECIFIC4lION, OR AWROMDALTWNATE.
FILTER MATERIAL (9FT jm CWSS 2 GRADING AS WUOWS:
S~eve 9ze Peraent Pass~rg
1" 100
314" 90-100
318" 40-100
No. 4 2540
No. 8 18-33
No. 30 5-15
NO. 50 0-7
No. 200 0-3
SUBDRAIN ALTERNATE A-2
6" 0 MIN.
SUBDRAIN ALTERNATE B DETAIL OF CANYON SUBDRAIN TERMINAL J
314" GRAVEL WRAPPED IN FILTER FABRIC
12" MIN. OVERLAP
DESIGN
FINISHED WE FUTERFABRBC
(MIRAFI IQN CR
314" MAX. GRAML OR AL-NATE B-2 NU4 ER~W
ALTERNATE APPROVED EQuIVAlEFn.
--
(9FT jlrn
I_-
\3 PERFORATED PIPE IS 0Pn.N PER
GOVERNING AGENCY'S REQUIREMENTS
CANYON
SUBDRAIN
GENERAL EARTHWORK AND GRADING
SPECIFICATIONS
STANDARD DETAILS C
-----
0mET PIPES
44 NON-PERFORATED PIPE,
100' MAX. O.C. HORIZONTALLY
30' MAX. O.C. VERTICALLY
----------
SUBDRAIN ALTERNATE B
1, MIN. .* . 12" OVERVIP FROM ME TOP
KEY WIDM
SUBDRAIN ALTERNATE A POSITIVE SEAL WU) BE FILTER FABRIC
PROVIMD AT THE JOINT
TCCNNErnON FRCM
COUEClION PIPE TO CUTLtT PIPE
SUBDRAIN INSTALLATION - Subdrain collector pipe shall be installed with perforations down or, unless othenvise designated by the geotechnical consultant Outlet pipes shall be non-perforated pipe. The subdrain pipe shall have at least 8 perforations uniformly spaced per foot Perforation shall be I/$' to 1/2" if drilled holes are used. All subdrain pipes shall have a gradient at least 2% towards the SUBDRAIN PIPE - Subdrain pipe shall be ASTM D2751, ASTM Dl527 (Schedule 40) or SDR 23.5 ABS pipe or ASTM D3034 (Schedule 40) or SDR 23.5 PVC pipe.
GENERAL EARTHWORK AND GRADING
SPECIFICATIONS
STANDARD DETAILS D
CUT-FILL TRANSTION LOT OVEREXCAVATION
OMREXC4VATE
AND RECOMPACT
UNWEATHERED BEDW)Q< OR MATERIAL APPRDMD
BY THE GEOTKHNIW CCNSULTANT
SIDE HILL FILL FOR CUT PAD
GENERAL EARTHWORK AND GRADING
TRANSITION LOT FILLS SPEQRCATIONS
AND SIDE HILL FILLS STANDARD DETAILS E
NATURAL
\
/
I
0 I I
0 I
I I 11 Rev. 7/00
t--------- RESTRICTED USE AREA
i
C
OMREXC4VATE
0 I
/ I
0 I
0 / FINISHED CW PAD
AND RECCMPACT
(REPMEMENTFIU)
OVERBURDEN
PAD OVEREXCAVATION AND RECOMPAOICN
SHALL BE PERFCRMED IF SPECKED
BY THE GEOECHNICAL CCNSULTANT
~N~~ERED BEDW)O( OR MA1ERIALAPPRDMD
BY THE GEOTECHNICPL CCN9JLTANT
SUBDRAIN OPTIONS AND BACKFILL WHEN NAlIVE MATERIAL HAS EXPANSION INDEX OF 40 OPTION 1: PIPE SURROUNDED WKH
CLASS 2 PERMEABLE MATERIAL OPTION 2: GRAVEL WRAPPED
IN FILTER FABRIC
WTTH PROPER WllH PROPER
WATERPROORNG
(SEE GENERAL NOTES) WATERPROOFING
(SEE GENERAL NOTES) FILTER FABRIC
CLASS 2 PERMEABLE
FILTER MATERIAL V4 m 1% INCH SIZE
4 INCH DIAMETER
PERFORATED PIPE
Class 2 Filter Petmeable Material Gradation
Per Caltrans Specifications
sieve S~E Percent Passing
1" 100
314" 90-100
318" 40-100
NO. 4 25-40
NO. 8 18-33
NO. 30 5-15
NO. 50 0-7
No. 200 0-3
* Waterproofing should be provided where moisture nuisance p/oblem through the wall is undesirable. * Water proofing of the walls is not under purview of the geotechnical engineer * All drains should have a gradient of 1 percent minimum *Outlet portion of the subdtain should have a 4inch diameter solid pipe discharged into a suitable disposal area designed by the project engineer. The subdrain pipe should be accessible for maintenance (rodding) *Other subdrain backfill options are subject to the review by the geotechnical engineer and modification of design pammetefs. 1) Sand should have a sand equivalent of 30 or greater and may be densified by water jetting. 2) 1 Cu. ft. per ft. of 114- to 1 112-inch size gravel wrapped in filter fabric 3) Pipe type should be ASTM Dl527 Acrylonitrile Butadiene Styrene (ABS) SDR35 or ASTM Dl785 Polyvinyl Chloride plastic (PVC), Schedule 40, Armco A2000 PVC, or approved equivalent. Pipe should be installed with perforations down. Perforations should be 318 inch in diameter placed at the ends of a 120-degree arc in two rows at 3-inch on center (staggered) 4) Filter fabric should be Mitafi 140NC or approved equivalent. 5) Weephole should be 3-inch minimum diameter and provided at 10-foot maximum intmls. If scposure is permitted, weepholes should be located 12 inches above finished grade. If exposure is not permitted such as for a wall adjacent to a sidewalWcurb, a pipe under the sidewalk to be discharged through the curb face or equivalent should be pmided. Fwa basement-type wall, a proper subdrain outlet system should be provided.
FOR WALLS 6 FEET OR LESS IN HEIGHT
WHEN NATIVE MATERIAL HAS EXPANSION INDEX OF 550
Leighton and Associates, Inc.
A LEIGHTON GROUP COMPANY
TRANSMITTAL
To: Woodside Homes of California
23 12 1 Antonio Parkway, Suite 120
Rancho Santa Margarita, California 92688
Date: January 30,2004
Project No. 1 10712-002
Attention: Mr. Peter Evans
Transmitted:
X Herewith -
- Via Courier
- Client Pick Up
- Fed Ex
- Other
The Following:
Draft Report -
X Final Report -
- Extra Report
- Proposal
For:
- Your Use
X As Requested -
Subject: Geotechnical Review of Rough Grading Plans, Tract 3 1 194, Menifee, County of Riverside, California.
LEIGHTON AND ASSOCIATES, INC.
By: Scot Mathis
Distribution: (3) Addressee
(3) Hunsaker & Associates; Attention: Mr. Doug Snyder
41715 Enterprise Circle N., Suite 103 Temecula, CA 92590-5661 909.296.0530 rn Fax 909.296.0534 www.leig htongeo.com
July 1, 2021
Project No. 11813.003
Richland Communities Inc.
4100 Newport Place Drive
Newport Beach, CA 92672
Attention: Mr. Brian Hardy, VP – Land Development
Subject: Geotechnical Plan Review / Addendum
Golden Meadows, Tract 31194, Phase IV (PLN21-0199)
Menifee, California
In accordance with your request and authorization, we are pleased to present this addendum report providing geotechnical plan review and updated seismic coefficients for the subject project. This report also discusses current site conditions as observed during our recent geologic reconnaissance and confirm s our previous findings and recommendations.
PURPOSE AND SCOPE OF WORK
As indicated above, this addendum report is to provide a plan review and updated seismic coefficients per the 2019 California Building Code (CBC). More specifically, the scope of our work included the following:
Review of available site-specific geologic information, including our 2004 geotechnical report performed for this site.
Preparation of this addendum/ plan review report confirming our findings and providing updated recommendations pertaining to the proposed residential development.
SITE AND PROJECT DESCRIPTION
The proposed residential development (overall Tract 31194) is located southeast of Evans Road and Garbani Road in the City of Menifee, California (see Figure 1). Based on our recent site visit, the subject property is in generally the same geologic conditions as those described in our previous report (Leighton, 2004) . The proposed Phase IV development (subject of this review/addendum) generally constitutes the eastern portion of the overall site (Tract 31194) and encompasses approximately 43.7 acres. Based on provided site conceptual plan (Figure 2), Phase IV will be developed into 262 homesites Geotechnical Plan Review / Addendum July 1, 2021
Golden Meadows, Tract 31194, Phase IV (PLN21-0199)- Menifee, California Project No. 11813.003
- 2 -
with associated streets, utilities, a retention basin, and a park site. In addition, 2:1 c ut slopes up to a height of 110-feet are proposed along the northern/eastern site boundaries.
SUMMARY OF CONCLUSIONS & RECOMM ENDATIONS
Based on our review of the provided conceptual grading plan (Figure 2) , we confirm herewith that our recommendations contained in the referenced report (Leighton, 2004) remain valid except as superseded below.
General Earthwork Considerations
Due to anticipated shallow rock conditions and proposed site grading, deep excavations on this site are expected to require heavy ripping, blasting or other rock reduction techniques and will likely generate oversize rock materials (rock fragments greater than 12 inches). Based on County standards, oversize rock should not be placed in the upper ten (10) feet below finish pad grades.
2019 CBC Seismic Coefficients
The 2019 CBC site-specific seismic coefficients provided in table below are based on an interactive tools/programs currently available on USGS website and OSHPD seismic maps. These seismic coefficients were based on Site Class C since this site is generally underlain by relatively shallow bedrock.
Site Seismic Coefficients / Coordinates Site
Latitude 33.65155
Longitude -117.18727
Site Class C
Spectral Response (short), SS 1.41g
Spectral Response (1 sec), S1 0.52g
Site Modified Peak Ground Acceleration, PGAM 0.72
Short Period Site Coefficient at 0.2s Period, Fa 1.20
Long Period Site Coefficient at 1s Period, Fv 1.48
Max. Considered Earthquake Spectral Response Acceleration (short), SMS 1.69g Max. Considered Earthquake Spectral Response Acceleration – (1 sec), SM1 0.77g 5% Damped Design Spectral Response Acceleration (short), SDS 1.12g 5% Damped Design Spectral Response Acceleration (1 sec), SD1 0.51g Site-Specific Peak Ground Acceleration, PGA 0.60
g = Gravity Acceleration
Geotechnical Plan Review / Addendum July 1, 2021
Golden Meadows, Tract 31194, Phase IV (PLN21-0199)- Menifee, California Project No. 11813.003 - 3
-
CLOSURE
We appreciate the opportunity to work with you on this project. If you have any questions regarding this report, please call us at your convenience at (866) LEIGHTON, direct at the phone extensions or e-mail addresses listed below.
Respectfully submitted,
LEIGHTON AND ASSOCIATES, INC.
Simon I. Saiid, GE 2641
Principal Engineer
Ext. 8013; [email protected]
Robert F. Riha, CEG 1921
Senior Principal Geologist
Ext. 8914; [email protected]
At
tachment: References
Figure 1 – Site Location Concept Plan
Figure 2 – Proposed Phase IV Concept Plan
Di
stribution: (1) a ddressee (pdf via email)
Geotechnical Plan Review / Addendum July 1, 2021
Golden Meadows, Tract 31194, Phase IV (PLN21-0199)- Menifee, California Project No. 11813.003 References
Leighton and Associates, Inc., 2004a, Geotechnical Review of Rough Grading Plans, Tract 31194, Menifee, County of Riverside, California, PN. 110712 -002, dated January
30. Leighton and Associates, Inc., 2004b, Geotechnical Review Update, Tentative Tract No. 31194, Menifee Area, County of Riverside, California, PN. 110712.004, dated November 2.
Leighton and Associates, Inc., 2017, Results of Onsite Percolation/Infiltration Testing, Proposed Storm Water Infiltration Basins, Golden Meadows, Tract 31194-1, -2, &- 3, City of Menifee, Riverside County, California, PN 11813.001, dated October 9.
Leighton and Associates, Inc., 2021, Geotechnical Exploration , Proposed Water Tank, Golden Meadows – Tract 31194, Menifee Area, Riverside County, California, PN 11813.002, dated April 7.
OSHPD, 2021, Seismic Design Maps, an interactive computer program on OSHPD website to calculate Seismic Response and Design Parameters based on ASCE 7-16 seismic procedures, https://seismicmaps.org/
.
The Galloway Group, 2021, Conceptual Site Plan, Golden Meadows, dated March 16, 2021.
³