2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
February 20, 2025 1-23
Education for Property Owners, Operators, Tenants, Occupants or Employees – Educational materials will be provided to commercial tenants at lease signing and employees upon hire by the owner and periodically thereafter to inform them of their potential impacts to downstream water quality. Materials include those described in Attachment D of this WQMP and provided in the Final WQMP.
Activity Restrictions – Activity restrictions to minimize potential impacts to water quality and with the purpose of protecting water quality will be prescribed via lease agreements or other equally effective measure.
Irrigation and Landscape Maintenance – Maintenance activities for landscape areas shall be consistent with City, County and manufacturer guidelines for fertilizer and pesticide use.
Maintenance includes trimming, weeding and debris removal and vegetation planting and replacement. Stockpiled materials during maintenance activities shall be placed away from drain inlets and runoff conveyance devices. Wastes shall be properly disposed of or recycled.
Common Area Litter Control – Litter control onsite will include the use of litter patrols by owner and management, violation reporting and clean up during landscaping maintenance activities and as needed to ensure good housekeeping of the project’s common areas.
Street Sweeping Private Streets and Parking Lots – The project’s private drives and parking areas shall be vacuum swept, at minimum, on a monthly basis.
Drainage Facility Inspection and Maintenance – Inspect catch basins twice per year (minimum) for accumulated debris. Increase frequency as needed during rainy months. Remove when debris reaches 40% of capacity, or once a year prior to rainy season.
Storm Drain Inlet Stenciling and Signage – Storm drain stencils or signage prohibiting dumping and discharge of materials (“No Dumping – Drains to River”) shall be provided adjacent to each of the project’s proposed inlets. The stencils shall be inspected and restenciled as needed to maintain legibility.
Landscape and Irrigation System Design – In conjunction with routine landscaping maintenance activities, inspect irrigation for signs of leaks, overspray and repair or adjust accordingly. Adjust system cycle to accommodate seasonal fluctuations in water demand and temperatures. Ensure use of native or drought tolerant/non-invasive plant species to minimize water consumption.
Protect Slopes and Channels – Project slopes and channels will be inspected during routine landscaping activities for plant health, signs of erosion and other damages and repaired as needed.
Air/Water Supply Area Drainage – Area shall be inspected on the daily basis with use. All water shall be contained and prohibited from entering the storm drain system.
Trash Storage Areas – Designated trash enclosure areas shall be covered and designed to preclude trash and pad area from run-on, run-off and wind. Any drains within area shall be connected to the sanitary sewer system, with proper approval from the sewer company. Site shall be inspected with use to ensure all materials are disposed of properly.
Loading Docks – Loading areas shall be kept in an orderly manner and designed to prevent the discharge of runoff. Area shall be inspected with use and cleaned up as soon as possible Item Number: 1.
2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
February 20, 2025 1-24
following any spills or waste accumulation. If wash-down of the area is employed, all wash water shall be prevented from entering the storm drain system.
Wash Water Controls for Food Preparation Areas – All proposed food preparation areas will be equipped with indoor sinks and contained areas for disposal of wash water containing food wastes. These facilities shall be connected to the sanitary sewer system.
Appendix D includes copies of the educational materials (described in Section 3.5.2.1 of the WQMP Guidance document) that will be used in implementing this project-specific WQMP.
Item Number: 1.
2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
February 20, 2025 1-25
V.3 EQUIVALENT TREATMENT CONTROL BMP ALTERNATIVES
Not applicable. Project retains the 100-year event onsite.
V.4 REGIONALLY-BASED BMPS
Not applicable. Project retains the 100-year event onsite.
Item Number: 1.
2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
February 20, 2025 1-26
VI. Operation and Maintenance Responsibility for
BMPs
Appendix G of this project-specific WQMP includes copies of CC&Rs, Covenant and Agreements, BMP Maintenance Agreement and/or other mechanisms used to ensure the ongoing operation, maintenance, funding, transfer and implementation of the project-specific WQMP requirements.
The following Operation and Mainteancne Responsibility Matrix has been prepared for this project:
Item Number: 1.
2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
February 20, 2025 1-27
BMP RESPONSIBILITY BMP START DATE FREQUENCY
Education for Property
Owners, Operators,
Tenants, Occupants, or
Employees
Owner At lease signing or
upon hire
At lease signing or initial hire,
educational information to be
provided to tenants and employees.
Thereafter periodically by the
owner.
http://www.floodcontrol.co.riverside
.ca.us/stormwater/
Irrigation System and
Landscape
Maintenance Owner
Upon completion of
project
improvements
Monthly during regular
maintenance, manage landscaping
in accordance with the County of
Riverside Water Conservation
Ordinance and with the State of
California Department of Pesticides
management guidelines for use of
fertilizers and pesticides.
Common Area Litter
Control Owner
Upon completion of
project
improvements
Weekly sweeping and trash pickup
within project areas. Daily
inspections of site conditions.
Street Sweeping Private
Streets and Parking Lots
(SC-70)
Owner
Upon completion of
project
improvements
Streets shall be swept on a monthly
basis, at minimum. Sweeping will
intensify during non-rainy days after
October 1st (Rainy season).
Drainage Facility
Inspection and
Maintenance (SC-74)
Owner
Upon completion of
project
improvements
Inspect catch basins twice per year
(minimum) for accumulated debris.
Increase frequency as needed
during rainy months. Remove when
debris reaches 40% of capacity, or
once a year prior to rainy season.
Storm Drain Inlet
Stenciling and Signage Owner
Upon completion of
project
improvements
Every 6 months: inspect for restenciling needs and re-stencil as necessary.
Landscape and
Irrigation System Design
(SD-10 & SD-12)
Owner
Upon completion of
project
improvements
Monthly with routine landscaping
service.
Protect Slope and
Channels Owner
Upon completion of
project
improvements
Monthly with routine landscaping
service.
Item Number: 1.
2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
February 20, 2025 1-28
BMP RESPONSIBILITY BMP START DATE FREQUENCY
Air/Water Supply Area
Drainage Owner, Tenant Upon completion of project site Work area inspected daily with use.
Trash Storage Areas Owner Upon completion of
project site
Patrol trash storage areas on a daily
basis.
Loading Docks Owner, Tenant Upon completion of
project site Inspect daily with use.
Wash Water Controls
for Food Preparation
Areas
Owner, Tenant Upon completion of
project site Inspect daily with use.
Item Number: 1.
2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
February 20, 2025 1-29
VII. Funding
The Owner of the project site/property shall responsible for the long-term funding, inspection, maintenance and enforcement of the BMPs presribed in this WQMP.
Item Number: 1.
2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
Appendix A
Conditions of Approval
Planning Commission Resolution TBD
Dated TBD
Item Number: 1.
2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
Appendix B
Vicinity Map, WQMP Site Plan, and Receiving Waters Map
Item Number: 1.
PREPARED BY: DRAWN BY: TIH
DATE: 02.19.2025
W.O.: 4645-1
PROJECT SITE
TENTATI9E PARCE/ 0AP NO. 914
WEST OF 9ARNER ROAD PA/0 DRI9E
CITY OF DESERT HOT SPRIN*S
RI9ERSIDE CO8NTY CA
SWPPP
9ICINITY
0AP
PREPARED FOR:
Item Number: 1.
TENTATIVE PARCEL MAP NO. 39143
WEST OF VARNER ROAD AND PALM DRIVE
CITY OF DESERT HOT SPRINGS
RIVERSIDE COUNTY, CA
WATER QUALITY MANAGEMENT PLAN
BMP SITE PLAN
ACRE
DA#-#
LEGEND
12.6 DA1-A
76.3 DA2-A
Item Number: 1.
TREES SYMBOL TREE NAME QTY. WUCOLS NEW STREET TREE ALONG VERNAN ROAD. PROSOPIS CHILENSIS, CHILEAN MESQUITE 24" BOX SIZE. STANDARD TRUNK 83 L NEW STREET TREE ALONG WEST DRIVE. GEIJERIA PARVIFLORA, AUSTRLIAN WILLOW 24" BOX SIZE. STANDARD TRUNK 46 L EVERGREEN PARKING LOT TREE QUERCUS VIRGINIANA, SOUTHERN LIVE OAK 24" BOX SIZE. STANDARD TRUNK. 97 M PROSOPIS CHILENSIS, CHILEAN MESQUITE 15 GAL. SIZE. STANDARD TRUNK. 153 L FLOWERING TREE AT ENTRY CERCIDIUM F. 'DESERT MUSEUM', BLUE PALO VERDE 24" BOX SIZE. STANDARD TRUNK. 4 L SCREEN TREE PINUS HALEPENSIS, ALEPPO PINE ALT: PINUS ELDARICA, AFGHAN PINE 15 GAL. SIZE. STANDARD TRUNK. 144 ML CHILOPSIS LINEARIS, DESERT WILLOW TREE 15 GAL. SIZE. STANDARD TRUNK. 59 L FLOWERING ACCENT TREE CHITALPA X TASHKATENSIS, CHITALPA TREE 24" BOX SIZE. STANDARD TRUNK, 8 L PLANTING LEGEND NOTE: ALL LANDSCAPE AREA NOT COVERED BY PLANTS SHALL RECEIVE A 2" LAYER OF 34" CRUSHED ROCK - CALIFORNIA GOLD. SHRUBS- SHRUBS SHALL CONSIST OF THE FOLLOWING: SYMBOL SHRUB NAME WUCOLS FURCRAEA MACDOUGALLII, MACDOUGALL'S CENTURY PLANT 5 GAL. SIZE L ECHINOCACTUS GRUSONII, BARREL CACTUS 5 GAL. SIZE L EUPHORBIA AMMAK, AFRICAN CANDELABRA 5 GAL. SIZE L FOUQUIERIA SPELNDENS, OCOTILLO 5 GAL. SIZE VL ANISACANTHUS QUADRAFIDUS, DESERT HONEY SUCKLE 5 GAL. SIZE L HESPERALOE PARVIFLORA, RED YUCCA 5 GAL. SIZE L LEUCOPHYLLUM F. 'GREEN CLOUD', TEXAS RANGER 5 GAL. SIZE @ 60" O.C. L OLEA EUROPAEA 'SKYLARK DWARF', DWARF OLIVE SHRUB 5 GAL. SIZE @ 72" O.C. L RHAPHIOLEPIS 'PINK LADY', INDIAN HAWTHORNE 5 GAL. SIZE @ 48" O.C. M BACCHARIS 'CENTENNIAL', CENTENNIAL DESERT BROOM 5 GAL. SIZE @ 48" O.C. L BACCHARIS PILULARIS', DWARF COYOTE BRUSH 5 GAL. SIZE @ 42" O.C. M ENCELIA FARINOSA, DESERT ENCELIA 5 GAL. SIZE @ 48" O.C. VL SALVIA GREGGII, AUTUMN SAGE 5 GAL. SIZE @ 48" O.C. M CALLIANDRA ERIOPHYLLA, FAIRY DUSTER 5 GAL. SIZE @ 60" O.C. L JUSTICIA CALIFORNICA, CHUPAROSA 5 GAL. SIZE @ 60" O.C. VL LEUCOPHYLLUM FRUITESCENS, TEXAS RANGER 5 GAL. SIZE @ 60" O.C. L LIGUSTRUM J.' TEXANUM', JAPANESE PRIVET 5 GAL. SIZE @ 60" O.C. M RHUS OVATA, HOLLY BERRY 5 GAL. SIZE @ 48" O.C. L REFERENCE NOTES: A. SIDEWALK PER CIVIL PLANS. B. NON-IRRIGATED DETENTION BASIN PER CIVIL PLANS. C. RETAINING WALL PER CIVIL PLANS. D. ADA RAMP PER CIVIL PLANS. E. OPEN AREA PER CIVIL PLANS.
MATCH LINE TO L-2
MATCH LINE TO L-1
40'-0"
40'-0"
40'-0" 1 A A C B 3 8 7 2 P.L. P.L. R.O.W. E 11 HYDROSEED APPLICATION SYMBOL SEED TYPE NON-IRRIGATED HYDROSEED MIX AT BOTTOM OF BASIN, CONSISTING OF SHRUBS AND GRASSES TOLERANT OF SEASONAL HYDROSEED MIX CONSISTING OF THE FOLLOWING: · ACHILLEA MILLEFOLIUM 1.0 LBS/ ACRE · ESCHSCHOLZIA CAESPITOSA 1.0 LBS/ ACRE · JUNCUS BUFONIUS 1.0 LBS/ ACRE · LEYMUS TRITICODIDESRIO 6.0 LBS/ ACRE · DESCHAMSIA DESPITOSA 4.0 LBS/ ACRE · FESTUCA RUBRA 'MOLATE' 10.0 LBS/ ACRE · HORDEUM BRACHYANTHERUM 6.0 LBS/ ACRE · MUHLENBERGIA RIGENS 1.0 LBS/ ACRE · MUHLENBERGIA MICROSPERMA 3.0 LBS/ ACRE · HORDEUM DEPRESSUM 3.0 LBS/ ACRE NATIVE NON-IRRIGATED HYDROSEED APPLICATION CONSISTING OF THE FOLLOWING: · ATRIPLEX CANESCENS 4.0 LBS/ ACRE · ATRIPLEX POLYCARPA 2.0 LBS/ ACRE · CHAENACTIS FREMONTII 0.5 LBS/ ACRE · CHRYSOTHAMNUS NAUSEOSUS 2.0 LBS/ ACRE · ENCELIA FARINOSA 4.0 LBS/ ACRE · ERIODICTYON CRASSIFOLIUM 1.0 LBS/ ACRE · ERIOGONUM FASCICULATUM 8.0 LBS/ ACRE · ERIOGONUM FASCICULATUM 2.0 LBS/ ACRE · FESTUCA OCTOFLORA 3.0 LBS/ ACRE · LASTHENIA CALIFORNICA 0.5 LBS/ ACRE · SPHAERALCEA AMBIGUA 4.0 LBS/ ACRE NON-ORGANIC MULCH SYMBOL ROCK MULCH TYPE DECORATIVE ROCK CONTRASTING COLOR FROM NON-ORGANIC MULCH AT SHRUB PLANTING AREAS. 1-3" SIZE CRUSHED ROCK. 2" MIN. LAYER. ALT: 2" LAYER OF DECOMPOSED GRANITE, TAN COLOR. (COLOR AND OR TEXTURE TO BE CONTRASTING COLOR COMPARED TO SHRUB PLANTING AREAS SHOWN ABOVE) DESIGN KEY NOTES: 1. PROPOSED STREET TREE PER LEGEND. 2. FLOWERING ACCENT TREE PER LEGEND. 3. DROUGHT TOLERANT SHRUB AND GROUND COVER PLANTING PER LEGEND. ALL SHRUB PLANTING AREAS TO RECEIVE A 3" LAYER OF DECORATIVE ROCK MULCH OR DECOMPOSED GRANITE. 4. PROPOSED PARKING LOT SHADE TREE PER TREE LEGEND. 5. FOUNDATION SHRUB PLANTING PER LEGEND. 6. VERTICAL TREE ALONG BUILDING FACADE PER TREE LEGEND. 7. EVERGREEN SCREEN TREE ALONG PROPERTY LINE PER TREE LEGEND. 8. ALL TREES LOCATED 5' OR LESS TO CURB, WALKWAY OR WALL SHALL BE INSTALLED WITH DEEP ROOT BARRIER PANELS. 18" MIN. DEPTH X 10' WIDE PANEL. 9. ALLOW 24" CLEARANCE FROM BACK OF CURB TO SHRUB. PROVIDE ROCK MULCH BETWEEN BACK OF CURB TO SHRUB. 10. ENHANCED PAVING AT VEHICULAR AND BUILDING ENTRY AREAS AND OUTDOOR PATIO AREA. INTEGRAL COLORED CONC. 11. DECORATIVE ROCK WITH ASSORTED SUCCULENTS AND BOULDERS. DECORATIVE ROCK AREAS TO BE CONTRASTING COLOR OR SIZE FROM NON-ORGANIC MULCH AT SHRUB PLANTING AREAS. 12. STORM WATER INFILTRATION AREA PER CIVIL WQMP. REFER TO PLANTING PALETTE FOR HYDROSEED APPLICATION. 13. SHADE STURCTURE. FEBRUARY 10, 2025 NEWLAND PALM SPRINGS VARNER ROAD & WEST DRIVE, DESERT HOT SPRINGS, CA CONCEPTUAL LANDSCAPE PLAN L-1 WUCOLS PLANT FACTOR THIS PROJECT IS LOCATED IN 'WUCOLS' REGION '6-LOW DESERT'. H = HIGH WATER NEEDS M = MODERATE WATER NEEDS L = LOW WATER NEEDS VL= VERY LOW WATER NEEDS · ROCK RIP-RAP MATERIAL SHALL BE INSTALLED WHERE DRAIN LINES CONNECT TO INFILTRATION AREAS. · ALL UTILITY EQUIPMENT SUCH AS BACKFLOW UNITS, FIRE DETECTOR CHECKS, FIRE CHECK VALVE, AND AIR CONDITIONING UNITS WILL BE SCREENED WITH EVERGREEN PLANT MATERIAL ONCE FINAL LOCATIONS HAVE BEEN DETERMINED. GENERAL NOTES: THIS IS A CONCEPTUAL LANDSCAPE PLAN. IT IS BASED ON PRELIMINARY INFORMATION WHICH IS NOT FULLY VERIFIED AND MAY BE INCOMPLETE. IT IS MEANT AS A COMPARATIVE AID IN EXAMINING ALTERNATE DEVELOPMENT STRATEGIES AND ANY QUANTITIES INDICATED ARE SUBJECT TO REVISION AS MORE RELIABLE INFORMATION BECOMES AVAILABLE. IRRIGATION NOTE: THE PROJECT WILL BE EQUIPPED WITH A LOW FLOW IRRIGATION SYSTEM CONSISTING OF ET WEATHER BASED SMART CONTROLLER, LOW FLOW ROTORS, BUBBLER AND/ OR DRIP SYSTEMS USED THROUGHOUT. THE IRRIGATION WATER EFFICIENCY WILL MEET OR SURPASS THE CURRENT STATE MANDATED AB-1881 WATER ORDINANCE. CONCEPTUAL PLAN NOTE: BUILDING VARNER ROAD SCALE: 1" = 80'-0" 0 80' 160' 240' NORTH SONNY BONO MEM FREEWAY NEWLAND ONCEPTUAL Item Number: 1.
MATCH LINE TO L-2
MATCH LINE TO L-1
40'-0"
40'-0" 40'-0" A AA B BB 1 1133 4 3 7 2 P.L. C R.O.W. R.O.W. R.O.W. 3 8 11 TREES SYMBOL TREE NAME QTY. WUCOLS NEW STREET TREE ALONG VERNAN ROAD. PROSOPIS CHILENSIS, CHILEAN MESQUITE 24" BOX SIZE. STANDARD TRUNK 83 L NEW STREET TREE ALONG WEST DRIVE. GEIJERIA PARVIFLORA, AUSTRLIAN WILLOW 24" BOX SIZE. STANDARD TRUNK 46 L EVERGREEN PARKING LOT TREE QUERCUS VIRGINIANA, SOUTHERN LIVE OAK 24" BOX SIZE. STANDARD TRUNK. 97 M PROSOPIS CHILENSIS, CHILEAN MESQUITE 15 GAL. SIZE. STANDARD TRUNK. 153 L FLOWERING TREE AT ENTRY CERCIDIUM F. 'DESERT MUSEUM', BLUE PALO VERDE 24" BOX SIZE. STANDARD TRUNK. 4 L SCREEN TREE PINUS HALEPENSIS, ALEPPO PINE ALT: PINUS ELDARICA, AFGHAN PINE 15 GAL. SIZE. STANDARD TRUNK. 144 ML CHILOPSIS LINEARIS, DESERT WILLOW TREE 15 GAL. SIZE. STANDARD TRUNK. 59 L FLOWERING ACCENT TREE CHITALPA X TASHKATENSIS, CHITALPA TREE 24" BOX SIZE. STANDARD TRUNK, 8 L PLANTING LEGEND NOTE: ALL LANDSCAPE AREA NOT COVERED BY PLANTS SHALL RECEIVE A 2" LAYER OF 34" CRUSHED ROCK - CALIFORNIA GOLD. SHRUBS- SHRUBS SHALL CONSIST OF THE FOLLOWING: SYMBOL SHRUB NAME WUCOLS FURCRAEA MACDOUGALLII, MACDOUGALL'S CENTURY PLANT 5 GAL. SIZE L ECHINOCACTUS GRUSONII, BARREL CACTUS 5 GAL. SIZE L EUPHORBIA AMMAK, AFRICAN CANDELABRA 5 GAL. SIZE L FOUQUIERIA SPELNDENS, OCOTILLO 5 GAL. SIZE VL ANISACANTHUS QUADRAFIDUS, DESERT HONEY SUCKLE 5 GAL. SIZE L HESPERALOE PARVIFLORA, RED YUCCA 5 GAL. SIZE L LEUCOPHYLLUM F. 'GREEN CLOUD', TEXAS RANGER 5 GAL. SIZE @ 60" O.C. L OLEA EUROPAEA 'SKYLARK DWARF', DWARF OLIVE SHRUB 5 GAL. SIZE @ 72" O.C. L RHAPHIOLEPIS 'PINK LADY', INDIAN HAWTHORNE 5 GAL. SIZE @ 48" O.C. M BACCHARIS 'CENTENNIAL', CENTENNIAL DESERT BROOM 5 GAL. SIZE @ 48" O.C. L BACCHARIS PILULARIS', DWARF COYOTE BRUSH 5 GAL. SIZE @ 42" O.C. M ENCELIA FARINOSA, DESERT ENCELIA 5 GAL. SIZE @ 48" O.C. VL SALVIA GREGGII, AUTUMN SAGE 5 GAL. SIZE @ 48" O.C. M CALLIANDRA ERIOPHYLLA, FAIRY DUSTER 5 GAL. SIZE @ 60" O.C. L JUSTICIA CALIFORNICA, CHUPAROSA 5 GAL. SIZE @ 60" O.C. VL LEUCOPHYLLUM FRUITESCENS, TEXAS RANGER 5 GAL. SIZE @ 60" O.C. L LIGUSTRUM J.' TEXANUM', JAPANESE PRIVET 5 GAL. SIZE @ 60" O.C. M RHUS OVATA, HOLLY BERRY 5 GAL. SIZE @ 48" O.C. L HYDROSEED APPLICATION SYMBOL SEED TYPE NON-IRRIGATED HYDROSEED MIX AT BOTTOM OF BASIN, CONSISTING OF SHRUBS AND GRASSES TOLERANT OF SEASONAL HYDROSEED MIX CONSISTING OF THE FOLLOWING: · ACHILLEA MILLEFOLIUM 1.0 LBS/ ACRE · ESCHSCHOLZIA CAESPITOSA 1.0 LBS/ ACRE · JUNCUS BUFONIUS 1.0 LBS/ ACRE · LEYMUS TRITICODIDESRIO 6.0 LBS/ ACRE · DESCHAMSIA DESPITOSA 4.0 LBS/ ACRE · FESTUCA RUBRA 'MOLATE' 10.0 LBS/ ACRE · HORDEUM BRACHYANTHERUM 6.0 LBS/ ACRE · MUHLENBERGIA RIGENS 1.0 LBS/ ACRE · MUHLENBERGIA MICROSPERMA 3.0 LBS/ ACRE · HORDEUM DEPRESSUM 3.0 LBS/ ACRE NATIVE NON-IRRIGATED HYDROSEED APPLICATION CONSISTING OF THE FOLLOWING: · ATRIPLEX CANESCENS 4.0 LBS/ ACRE · ATRIPLEX POLYCARPA 2.0 LBS/ ACRE · CHAENACTIS FREMONTII 0.5 LBS/ ACRE · CHRYSOTHAMNUS NAUSEOSUS 2.0 LBS/ ACRE · ENCELIA FARINOSA 4.0 LBS/ ACRE · ERIODICTYON CRASSIFOLIUM 1.0 LBS/ ACRE · ERIOGONUM FASCICULATUM 8.0 LBS/ ACRE · ERIOGONUM FASCICULATUM 2.0 LBS/ ACRE · FESTUCA OCTOFLORA 3.0 LBS/ ACRE · LASTHENIA CALIFORNICA 0.5 LBS/ ACRE · SPHAERALCEA AMBIGUA 4.0 LBS/ ACRE NON-ORGANIC MULCH SYMBOL ROCK MULCH TYPE DECORATIVE ROCK CONTRASTING COLOR FROM NON-ORGANIC MULCH AT SHRUB PLANTING AREAS. 1-3" SIZE CRUSHED ROCK. 2" MIN. LAYER. ALT: 2" LAYER OF DECOMPOSED GRANITE, TAN COLOR. (COLOR AND OR TEXTURE TO BE CONTRASTING COLOR COMPARED TO SHRUB PLANTING AREAS SHOWN ABOVE) REFERENCE NOTES: A. SIDEWALK PER CIVIL PLANS. B. NON-IRRIGATED DETENTION BASIN PER CIVIL PLANS. C. RETAINING WALL PER CIVIL PLANS. D. ADA RAMP PER CIVIL PLANS. E. OPEN AREA PER CIVIL PLANS. DESIGN KEY NOTES: 1. PROPOSED STREET TREE PER LEGEND. 2. FLOWERING ACCENT TREE PER LEGEND. 3. DROUGHT TOLERANT SHRUB AND GROUND COVER PLANTING PER LEGEND. ALL SHRUB PLANTING AREAS TO RECEIVE A 3" LAYER OF DECORATIVE ROCK MULCH OR DECOMPOSED GRANITE. 4. PROPOSED PARKING LOT SHADE TREE PER TREE LEGEND. 5. FOUNDATION SHRUB PLANTING PER LEGEND. 6. VERTICAL TREE ALONG BUILDING FACADE PER TREE LEGEND. 7. EVERGREEN SCREEN TREE ALONG PROPERTY LINE PER TREE LEGEND. 8. ALL TREES LOCATED 5' OR LESS TO CURB, WALKWAY OR WALL SHALL BE INSTALLED WITH DEEP ROOT BARRIER PANELS. 18" MIN. DEPTH X 10' WIDE PANEL. 9. ALLOW 24" CLEARANCE FROM BACK OF CURB TO SHRUB. PROVIDE ROCK MULCH BETWEEN BACK OF CURB TO SHRUB. 10. ENHANCED PAVING AT VEHICULAR AND BUILDING ENTRY AREAS AND OUTDOOR PATIO AREA. INTEGRAL COLORED CONC. 11. DECORATIVE ROCK WITH ASSORTED SUCCULENTS AND BOULDERS. DECORATIVE ROCK AREAS TO BE CONTRASTING COLOR OR SIZE FROM NON-ORGANIC MULCH AT SHRUB PLANTING AREAS. 12. STORM WATER INFILTRATION AREA PER CIVIL WQMP. REFER TO PLANTING PALETTE FOR HYDROSEED APPLICATION. 13. SHADE STURCTURE. FEBRUARY 10, 2025 NEWLAND PALM SPRINGS VARNER ROAD & WEST DRIVE, DESERT HOT SPRINGS, CA CONCEPTUAL LANDSCAPE PLAN SCALE: 1" = 80'-0" 0 80' 160' 240' NORTH L-2 BUILDING VARNER ROAD WEST DRIVE WUCOLS PLANT FACTOR THIS PROJECT IS LOCATED IN 'WUCOLS' REGION '6-LOW DESERT'. H = HIGH WATER NEEDS M = MODERATE WATER NEEDS L = LOW WATER NEEDS VL= VERY LOW WATER NEEDS NEWLAND PALM SPRINGS CONCEPTUAL LANDSCAPE PLAN NEWLAND ONCEPTUAL Item Number: 1.
Item Number: 1.
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Screenwall Elevations DAB-A1.6 fax: 949 863 0851 tel: 949 863 1770 email: [email protected] 92612 hpa, inc. Owner: Project: Consultants: Project Number: Revision: Date: Drawn by: Title: Sheet: Civil: Structural: Mechanical: Plumbing: Electrical: Landscape: Soils Engineer: Fire Protection:
- HUNSAKER--- DESERT HOT SPRINGS, CA24132 RC RLA-- 02/10/2025 18831 bardeen avenue - ste. #100 irvine, ca NEWLAND CAPITAL GROUP -- NEWLAND DHS
Item Number: 1.
Overall Floor Plan DAB-A2.1 fax: 949 863 0851 tel: 949 863 1770 email: [email protected] 92612 hpa, inc. Owner: Project: Consultants: Project Number: Revision: Date: Drawn by: Title: Sheet: Civil: Structural: Mechanical: Plumbing: Electrical: Landscape: Soils Engineer: Fire Protection: - HUNSAKER--- DESERT HOT SPRINGS, CA24132 RC RLA-- 02/10/2025 18831 bardeen avenue - ste. #100 irvine, ca NEWLAND CAPITAL GROUP -- NEWLAND DHS KEYNOTES - FLOOR PLAN GENERAL NOTES - FLOOR PLAN Item Number: 1.
Overall Roof Plan DAB-A2.2 fax: 949 863 0851 tel: 949 863 1770 email: [email protected] 92612 hpa, inc. Owner: Project: Consultants: Project Number: Revision: Date: Drawn by: Title: Sheet: Civil: Structural: Mechanical: Plumbing: Electrical: Landscape: Soils Engineer: Fire Protection: - HUNSAKER--- DESERT HOT SPRINGS, CA24132 RC RLA-- 02/10/2025 18831 bardeen avenue - ste. #100 irvine, ca NEWLAND CAPITAL GROUP -- NEWLAND DHS REQUIRED PROVIDED MODEL FUTURE SOLAR READY AREA CALCULATION Item Number: 1.
Elevations DAB-A3.1 fax: 949 863 0851 tel: 949 863 1770 email: [email protected] 92612 hpa, inc. Owner: Project: Consultants: Project Number: Revision: Date: Drawn by: Title: Sheet: Civil: Structural: Mechanical: Plumbing: Electrical: Landscape: Soils Engineer: Fire Protection: - HUNSAKER--- DESERT HOT SPRINGS, CA24132 RC RLA-- 02/10/2025 18831 bardeen avenue - ste. #100 irvine, ca NEWLAND CAPITAL GROUP -- NEWLAND DHS KEYNOTES - ELEVATIONS GENERAL NOTES - ELEVATIONS COLOR SCHEDULE - ELEVATIONS GLAZING LEGEND Item Number: 1.
Elevations DAB-A3.2 fax: 949 863 0851 tel: 949 863 1770 email: [email protected] 92612 hpa, inc. Owner: Project: Consultants: Project Number: Revision: Date: Drawn by: Title: Sheet: Civil: Structural: Mechanical: Plumbing: Electrical: Landscape: Soils Engineer: Fire Protection: - HUNSAKER--- DESERT HOT SPRINGS, CA24132 RC RLA-- 02/10/2025 18831 bardeen avenue - ste. #100 irvine, ca NEWLAND CAPITAL GROUP -- NEWLAND DHS KEYNOTES - ELEVATIONS GENERAL NOTES - ELEVATIONS COLOR SCHEDULE - ELEVATIONS GLAZING LEGEND Item Number: 1.
Elevations DAB-A3.3 fax: 949 863 0851 tel: 949 863 1770 email: [email protected] 92612 hpa, inc. Owner: Project: Consultants: Project Number: Revision: Date: Drawn by: Title: Sheet: Civil: Structural: Mechanical: Plumbing: Electrical: Landscape: Soils Engineer: Fire Protection: - HUNSAKER--- DESERT HOT SPRINGS, CA24132 RC RLA-- 02/10/2025 18831 bardeen avenue - ste. #100 irvine, ca NEWLAND CAPITAL GROUP -- NEWLAND DHS KEYNOTES - ELEVATIONS GENERAL NOTES - ELEVATIONS COLOR SCHEDULE - ELEVATIONS GLAZING LEGEND Item Number: 1.
Elevations DAB-A3.4 fax: 949 863 0851 tel: 949 863 1770 email: [email protected] 92612 hpa, inc. Owner: Project: Consultants: Project Number: Revision: Date: Drawn by: Title: Sheet: Civil: Structural: Mechanical: Plumbing: Electrical: Landscape: Soils Engineer: Fire Protection: - HUNSAKER--- DESERT HOT SPRINGS, CA24132 RC RLA-- 02/10/2025 18831 bardeen avenue - ste. #100 irvine, ca NEWLAND CAPITAL GROUP -- NEWLAND DHS KEYNOTES - ELEVATIONS GENERAL NOTES - ELEVATIONS COLOR SCHEDULE - ELEVATIONS GLAZING LEGEND Item Number: 1.
fax: 949 863 0851 tel: 949 863 1770 email: [email protected] 92612 hpa, inc. Owner: Project: Consultants: Project Number: Revision: Date: Drawn by: Title: Sheet: Civil: Structural: Mechanical: Plumbing: Electrical: Landscape: Soils Engineer: Fire Protection: - HUNSAKER--- DESERT HOT SPRINGS, CA24132 RC RLA-- 02/10/2025 18831 bardeen avenue - ste. #100 irvine, ca NEWLAND CAPITAL GROUP -- NEWLAND DHS MA G N N O Y L I C E N S E D A R C H I T E C T S T A T E O F C A L I F O R N I A DATE RENEWAL 3-31-25 C-29451 SECTION DAB-A4.1 Item Number: 1.
fax: 949 863 0851 tel: 949 863 1770 email: [email protected] 92612 hpa, inc. Owner: Project: Consultants: Project Number: Revision: Date: Drawn by: Title: Sheet: Civil: Structural: Mechanical: Plumbing: Electrical: Landscape: Soils Engineer: Fire Protection: - HUNSAKER--- DESERT HOT SPRINGS, CA24132 RC RLA-- 02/10/2025 18831 bardeen avenue - ste. #100 irvine, ca NEWLAND CAPITAL GROUP -- NEWLAND DHS MA G N N O Y L I C E N S E D A R C H I T E C T S T A T E O F C A L I F O R N I A DATE RENEWAL 3-31-25 C-29451 TRASH ENCLOSURE DAB-A4.2 Item Number: 1.
Site Sections DAB-A4.3 fax: 949 863 0851 tel: 949 863 1770 email: [email protected] 92612 hpa, inc. Owner: Project: Consultants: Project Number: Revision: Date: Drawn by: Title: Sheet: Civil: Structural: Mechanical: Plumbing: Electrical: Landscape: Soils Engineer: Fire Protection: - HUNSAKER--- DESERT HOT SPRINGS, CA24132 RC RLA-- 02/10/2025 18831 bardeen avenue - ste. #100 irvine, ca NEWLAND CAPITAL GROUP -- NEWLAND DHS MA G N N O Y L I C E N S E D A R C H I T E C T S T A T E O F C A L I F O R N I A DATE RENEWAL 3-31-25 C-29451 KEYMAP Item Number: 1.
Site Sections DAB-A4.4 fax: 949 863 0851 tel: 949 863 1770 email: [email protected] 92612 hpa, inc. Owner: Project: Consultants: Project Number: Revision: Date: Drawn by: Title: Sheet: Civil: Structural: Mechanical: Plumbing: Electrical: Landscape: Soils Engineer: Fire Protection: - HUNSAKER--- DESERT HOT SPRINGS, CA24132 RC RLA-- 02/10/2025 18831 bardeen avenue - ste. #100 irvine, ca NEWLAND CAPITAL GROUP -- NEWLAND DHS MA G N N O Y L I C E N S E D A R C H I T E C T S T A T E O F C A L I F O R N I A DATE RENEWAL 3-31-25 C-29451 KEYMAP Item Number: 1.
2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
Appendix C
Supporting Detail Related to Hydrologic Conditions of Concern Item Number: 1.
2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
Appendix D
Educational Materials
Item Number: 1.
2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
Appendix E
Soils Report
Item Number: 1.
Newland Development Land Services, LLC
215 Park Avenue S, 11th Floor
New York, NY 10003
File No.: 306837-001
Doc. No.: 24-10-700
Geotechnical Engineering Report Update
Proposed Warehouse
SWC Varner Road and West Drive
Desert Hot Springs, Riverside County, California
October 7, 2024
© 2024 Earth Systems Pacific
Unauthorized use or copying of this document is strictly prohibited without the express written consent of Earth Systems Pacific.
Item Number: 1.
Earth Systems________________________________________________ 79-811 Country Club Drive, Suite B | Bermuda Dunes, CA 92203 | Ph: 760.345.1588 | www.earthsystems.com October 7, 2024 File No.: 306837-001
Doc No.: 24-10-700
Newland Development Land Services, LLC
215 Park Avenue S, 11th Floor
New York, NY 10003
Attention: Mr. Matthew Frank
Subject: Geotechnical Engineering Report Update
Project: Proposed Warehouse
SWC Varner Road and West Drive
Desert Hot Springs, Riverside County, California
Earth Systems Pacific [Earth Systems] is pleased to submit this geotechnical engineering report update for the proposed new warehouse project. This update and addendum reference the initial project soils reports prepared for the site (Earth Systems, 2007 and 2017).
This report completes our geotechnical update scope of services in accordance with our Work Order SWO-24-119 dated of April 5, 2024. Other geotechnical related services that may be required, such as plan reviews, responses to inquiries, and grading observation are additional services and will be billed according to the agreed upon Fee Schedule in effect at the time services are provided. Unless requested in writing, the client is responsible to distribute the report to the appropriate governing agency and other members of the design team. Please review the Limitations (Section 6) of this report as it is vital to the understanding of this report.
We appreciate the opportunity to provide our professional services. Please contact our office if there are any questions or comments concerning this report or its recommendations.
Respectfully submitted,
EARTH SYSTEMS PACIFIC
Kevin L. Paul, PE, GE
Principal Engineer
Distribution: Newland Development Land Services, LLC via email to:
Matthew Frank: [email protected]
1/BER
Item Number: 1.
i
EARTH SYSTEMS PACIFIC
TABLE OF CONTENTS
Page
Section 1 INTRODUCTION ...........................................................................................1
1.1 Background.......................................................................................... 1
1.2 Site Description.................................................................................... 2
1.3 Purpose and Scope of Services ............................................................ 2 Section 2 METHODS OF EXPLORATION AND TESTING..................................................3
2.1 Field Exploration.................................................................................. 3
2.2 Laboratory Testing............................................................................... 3 Section 3 DISCUSSION.................................................................................................4
3.1 Geologic Setting................................................................................... 4
3.2 Site Reconnaissance............................................................................. 4
3.3 Groundwater ....................................................................................... 7
3.4 Collapse/Consolidation Potentials....................................................... 7
3.5 Expansive Soils..................................................................................... 7
3.6 Corrosivity............................................................................................ 7
3.7 Geologic Hazards................................................................................. 7
3.8 Retention Basin Infiltration Testing ..................................................... 8 Section 4 CONCLUSIONS..............................................................................................9 Section 5 RECOMMENDATIONS ................................................................................10
5.1 Site Development – Grading.............................................................. 10
5.2 Excavations and Utility Trenches....................................................... 10
5.3 Slope Construction............................................................................. 10
5.4 Shallow Foundations.......................................................................... 10
5.5 Seismic Coefficients........................................................................... 11
5.6 Slabs................................................................................................... 13
5.7 Retaining Walls and Lateral Earth Pressures...................................... 13
5.8 Site Drainage and Maintenance......................................................... 13
5.9 Streets, Driveways and Parking Areas................................................ 13
5.10 Site Drainage and Maintenance......................................................... 14 Section 6 LIMITATIONS AND ADDITIONAL SERVICES .................................................17
6.1 Uniformity of Conditions and Limitations.......................................... 17 REFERENCES..........................................................................................................18
APPENDIX A
Plate 1 – Site Location Map
Plate 2 – Project Overlay and Previous Boring Map
Table A-1 CBC 2022 Seismic Parameters
Seismic Settlement (2 pages)
Earth Systems 2017 Project Soils Report
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Geotechnical Engineering Report Update
Proposed Warehouse
SWC Varner Road and West Drive
Desert Hot Springs, Riverside County, California
EARTH SYSTEMS PACIFIC
Section 1
INTRODUCTION
1.1 Background
Earth Systems has previously prepared geotechnical reports for the project (Earth Systems, 2007 and 2017). The most current geotechnical report (2017) was prepared to the 2016 California Building Code (CBC) and was prepared for a light industrial use project. We understand that the new proposed project will be for a warehouse. As such, we are also updating the 2017 soils report to pertain to the new proposed project. This update report will refer back to the 2017 report (attached) for which we will provide review and comment on the previous report sections.
It is our opinion the some of the project soils report Section 1.1 still applies; however, an addendum to Section 1.1 is provided below. A preliminary site conceptual plan was provided by the client. This geotechnical engineering update report has been prepared for a proposed warehouse to be used for storage, distribution or fulfillment and is located north of I- 10 and west of Palm Drive in Desert Hot Springs, California (see below). We understand that development plans are preliminary at this stage and are assumed as follows:
1. One to two-story warehouse building on the order of 1.2 million square feet.
2. Asphalt concrete and/or Portland cement concrete aisles for Bobtail Tractor Trailer and/or HS20 type truck vehicles.
3. Automotive drives and parking stalls.
We also understand that the proposed buildings will be developed under the regulation of the current California Building Code (2022, CBC). Based on the anticipated conditions, the following sections describe our understanding of the project and our anticipated scope of services.
It is assumed that the structures will be one to two-story in extended wall height made of masonry, concrete “tilt-up”, wood-framed and/or steel construction founded on shallow permanent foundations with slabs-on-grade. We have assumed a maximum column load on the order of 100 kips, for a square footing up to 7 feet wide and a maximum wall loading of 4 kips per linear foot for a footing with a maximum width of 4 feet. As the basis for the foundation recommendations, all loading is assumed to be dead plus actual live load. No preliminary design loading was provided by the structural engineer. If actual structural loading exceeds these assumed values, we will need to reevaluate the given recommendations. In addition, the geotechnical engineer of record should evaluate structural plans for additive pressures from closely spaced footings and differential settlements between nearby heavily and lightly loaded footings. Below grade levels are not proposed.
Site development will include clearing and grubbing of vegetation, site grading, building pad preparation, underground utilities, and concrete driveway and sidewalk placement. Based on Item Number: 1.
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existing site topography and ground conditions, site grading is assumed to consist of fills on the order of 3 to 15 feet and cuts on the order of 8 feet (excluding depth of over-excavation for buildings). The northern parcel (North of Varner Road) is designated as Open Space and will be undeveloped.
Figure 1 Excerpt from Conceptual Site Plan, date August 19, 2024, Scheme 5
1.2 Site Description
It is our opinion the project soils report Section 1.2 still applies.
1.3 Purpose and Scope of Services
It is our opinion the project soils report Section 1.3 still applies; however, an addendum to Section
1.3 is as follows: This report updates the project soils report to the 2022 CBC and references a new project type.
The scope of services included:
• Earth Systems performed a site visit to visually observe site conditions and confirm conditions were similar to those that formed the basis for the 2017 soils report. • This report update and addendum were prepared summarizing our geologic and geotechnical findings in accordance with the 2022 California Building Code. This report includes:
Review and comment on previous report sections.
A “General Procedure” seismic analysis including geotechnical seismic design coefficients in accordance with the 2022 CBC.
Updated Appendix.
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Section 2
METHODS OF EXPLORATION AND TESTING
2.1 Field Exploration
It is our opinion the project soils report Section 2.1 still applies. No additional field drilling was performed for this update.
2.2 Laboratory Testing
It is our opinion the project soils report Section 2.2 still applies. No lab testing was performed for this update report.
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Section 3
DISCUSSION
3.1 Geologic Setting
It is our opinion the project soils (Earth Systems, 2017) report Section 3.1 still applies.
3.2 Site Reconnaissance
On September 6, 2024, an Earth Systems’ representative visited the project site to visually observe the site to confirm site conditions were similar to those that formed the basis for the 2017 project soils report. Site conditions were confirmed to be similar and relatively unchanged.
Notes from the visit are that an area in the north-west corner of: “the site appears to have been disturbed for the purpose of mining rocks or trying to clean the area up. There were piles of boulders and some piles of trash so either could be assumed. There is a lot of trash along the road and it looks somewhat recent, I would imagine that illegal dumping is a ongoing issue for that area.”
Select site visit pictures are below.
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3.3 Groundwater
It is our opinion the project soils report Section 3.3 still applies. Groundwater is expected to be at similar levels.
3.4 Collapse/Consolidation Potentials
It is our opinion the project soils report Section 3.4 still applies.
3.5 Expansive Soils
It is our opinion the project soils report Section 3.5 still applies.
3.6 Corrosivity
It is our opinion the project soils report Section 3.6 still applies.
3.7 Geologic Hazards
It is our opinion the project soils report Sections 3.7, 3.7.1 and 3.7.2 still apply. However, an addendum to Section 3.7 is provided below.
Seismic Risk: A recent major earthquake to be felt in the Desert Hot Springs area was the July 2019 Ridgecrest earthquake (Magnitude 7.1). Surface rupture occurred near segments of the Little Lake fault zone near Ridgecrest. No significant damage was reported in the Desert Hot Springs area.
Based on a recent paleoseismic study, a maximum magnitude of 7.9 is suggested, assuming a multi-segment rupture event (Scharer, Katherine M., and Yule, Doug, 2020, A Maximum Rupture Model for the Southern San Andreas and San Jacinto Faults, California, Derived from Paleoseismic Item Number: 1.
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Earthquake Ages: Observations and Limitations, Geophysical Research Letters
10.1029/2020GL088532, July 8, 2020).
Dry Seismic Settlement: The amount of dry seismic settlement is dependent on relative density of the soil, ground motion, and earthquake duration. In accordance with current CGS policy (Earth Systems discussion with Jennifer Thornburg, CGS May 2014), we used a site peak ground acceleration of ⅔ PGAM. The reasoning for using ⅔ PGAM has stemmed from the limitations of the Pradel (modified Tokimatsu and Seed) method of calculating dry seismic settlement. This issue manifested during the code change from ASCE 7-05 to ASCE 7-10 (2013) and has been continued into the ASCE 7-16 document, where it was no longer codified to evaluate liquefaction and seismic settlement as a design value (SDS/2.5) but to evaluate it at full PGA. PGAM equated to a maximum considered value and the design spectral response, SDS, is equal to ⅔ SMS, where SMS is the Site Class adjusted maximum considered earthquake value. When using the full PGAM in Pradel’s method, (Pradel’s method is the Standard of Care methodology of calculating dry sand settlement), the potential settlements increased dramatically resulting in unreasonable amounts of assumed settlement (stress/strain curves defaulted to 10 percent vertical strain as high acceleration) which did not correlate with field observations of earthquake events. Given these unreasonably high potential settlements and after much discussion with agencies and CGS, the PGA used for dry seismic analysis was returned to a “design” value in practice. This is on the basis that since dry seismic shaking will typically not cause bearing failure (like liquefaction will) but is only settlement related deformation. Earth Systems is in concurrence with this methodology and thus the method utilized for our analysis and that ⅔ PGAM may be used as an appropriate acceleration in the analysis of seismic settlement of unsaturated soils.
As this project will be constructed under the 2022 California Building code, Earth Systems evaluated the potential site peak ground acceleration for the 2022 CBC case. For the 2022 CBC case, PGAM = 1.15g. An earthquake magnitude of 7.9 was used to evaluate dry seismic settlement potential and considered multidirectional shaking, as well as current paleo-seismic research.
Based upon methods presented by Tokimatsu and Seed (1987), the potential for seismically induced dry settlement of soils above the groundwater table for the full soil column height within the foundation zone (50 feet) was calculated in our deep borings (Earth Systems, 2017, B-5 and B-2 combined with B-5) at the site and estimated to be approximately 0.9 and 1.1 inches respectively. Seismic settlement is based on post grading recommendations stated in Section 5.1 (Earth Systems, 2017). Therefore, the differential settlement from dry seismic settlement is estimated to be similar to that documented in the 2017 report’s Section 3.7.2.
3.8 Retention Basin Infiltration Testing
It is our opinion the project soils report Section 3.8 still applies for the locations tested.
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Section 4
CONCLUSIONS
Based upon our review of the referenced reports in light of the requirements of the 2022 California Building Code, it is our opinion that the recommendations provided in the project geotechnical (soils) report (Earth Systems, 2017), remain applicable to the proposed project; however, updated recommendations are provided in this report and supersede the referenced geotechnical report recommendations as applicable. Earth Systems has not reviewed the project grading plans or structural plans but should for geotechnical conformance.
It is our opinion the project soils report Section 4 still applies; however, an addendum to Section 4 is provided below.
Where referenced in the 2017 report, the cited applicable California Building Code (CBC) should be changed to refer to the 2022 CBC.
The conclusions and recommendations of the 2017 report are considered to still apply and should be followed during design and construction, except where amended within.
The seismic coefficients have been updated relative to the project soils report (Earth Systems, 2017).
Gravel, cobbles, and boulders of significant quantity will likely be encountered during grading and require special processing and removal of oversize.
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Section 5
RECOMMENDATIONS
5.1 Site Development – Grading
It is our opinion the project soils report Section 5.1 still applies. However, an addendum to Section 5.1 is provided below.
Our site visit indicated surface disturbance between 2021 and present date. The geotechnical engineer of record or his representative should observe and test subgrade soils (over-excavation depths) prior to placing fill, and for remediating any past grading.
5.2 Excavations and Utility Trenches
It is our opinion the project soils report Section 5.2 still applies.
5.3 Slope Construction
It is our opinion the project soils report Section 5.3 still applies.
5.4 Shallow Foundations
It is our opinion the project soils report Sections 5.4 and 5.4.1 still apply.
Earthquake Performance Statement: Depending upon the extent of structural design of exterior flatwork, walls, utilities, roadways, and other site improvements, some damage due to seismic events will occur. We recommend a standard statement for purchasers of the property and within title reports that seismic induced damage may occur. Note that all of southern California in general is in earthquake country. Site developments in southern California are typically not designed to mitigate anticipated seismic events without some damage. In fact, the Building Code is intended to provide Life-Safety performance, not complete damage-free design. In other words, some damage from earthquakes in the form of structural damage, settlement, cracking, and disruption of utilities is expected and that repair after an earthquake event will likely be required. It is not the current standard of care for site developers to fully mitigate all anticipated earthquake induced hazards. It is incumbent on the developer to advise the end-users of the project of the anticipated hazards in the form of disclosure statements during the initial and subsequent purchase processes.
According to literature form Robert W. Day, doors and windows may stick at distortion angles between 1:240 and 1:175. In this situation, a human being could be put in a life-threatening situation. Therefore, Earth Systems recommends the maximum distortion angle using all the settlement conditions including seismic settlements be 1:240. For all settlement conditions, the structure’s maximum distortion angle should be County’s required 1:360.
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5.5 Seismic Coefficients
It is our opinion the project soils report Section 5.5 no longer applies and is superseded below.
This site is subject to strong ground shaking due to potential fault movements along regional faults including San Andreas and San Jacinto fault zones. Engineered design and earthquakeresistant construction increase safety and allow development of seismic areas. The minimum seismic design should comply with the 2022 edition of the California Building Code and ASCE 7- 16 (Supplement 3) using the seismic coefficients given in the table below, which assume Exception 11.4.8 in ASCE7-16 applies. The site was found not to have liquefiable soil. Based on this section, the site is classified as Site Class D. If these exceptions do not apply, the structural engineer should contact Earth Systems for a Site-Specific Ground Motion Analysis, as the values below would no longer be valid.
Note to the Structural Engineer: the seismic coefficients in the Table below, apply to the general procedure for determining seismic coefficients. In other words, the seismic coefficients were not determined by a Site-Specific Ground Motion Analysis, which is allowed if ASCE 7-16’s Section
11.4.8 Supplement 3 Exceptions are accepted by the structural engineer.
According to the current procedure as outlined in ASCE 7-16, Supplement 3, a ground motion hazard analysis shall be performed in accordance with Section 21.2 for structures:
1) On Site Class D sites with S1 greater than or equal to 0.2.
EXCEPTION Item 1: A ground motion hazard analysis is not required where the value of the parameter SM1 determined by Eq. (11.4-2) is increased by 50% for all applications of SM1 in this Standard. The resulting value of the parameter SD1 determined by Eq. (11.4-4) shall be used for all applications of SD1 in this Standard.
During plan review of the foundation, Earth Systems will request a letter from the structural engineer stating ASCE 7-16’s Section 11.4.8 Exception 1 applies to the structures applicable to this report’s Table below, which contains the modified SM1 and resultant modified SD1 values. The structural engineer and client should contact Earth Systems if ASCE 7-16’s Exceptions do not apply to the structure/s and request Earth Systems to perform a Site-Specific Ground Motion Hazard Analysis.
General Procedure for seismic parameters is presented below considering a Site Class D shear wave velocity (results in Appendix A). Values were obtained from a web site (https://seismicmaps.org/) using coordinates as provided in Section 1.2. The structural design engineer should use the most conservative results based of the specific building design and spectral response.
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2022 CBC (ASCE 7-16, Supplement 3) Seismic Parameters
Site Class:
Risk Category:
Seismic Design Category
D
II
E
Maximum Considered Earthquake [MCE] Ground Motion
Short Period Spectral Response Ss: 2.453g
1 second Spectral Response, S1: 1.039g
Code Design Earthquake Ground Motion
Fa
Fv
FPGA
SMS
SM1 (unmodified)
SM1 (ASCE 7-16 Supplement 3 Modified)
1.00 1.70
1.10 2.453g
1.766g
2.649g
Short Period Spectral Response, SDS 1.635g
1 second Spectral Response, SD1 (unmodified)
*1 second Spectral Response, SD1
(ASCE 7-16 Supplement 3 Modified)
1.178g
1.766g
Peak Ground Acceleration (PGAM) Eq 11.8-1 1.15g
* Only if Exceptions is used, see Section 5.5 text, otherwise Site Specific Analysis required.
The intent of the CBC lateral force requirements is to provide a structural design that will resist collapse to provide reasonable life safety from a major earthquake but may experience some structural and nonstructural damage. A fundamental tenet of seismic design is that inelastic yielding is allowed to adapt to the seismic demand on the structure. In other words, damage is allowed. The CBC lateral force requirements should be considered a minimum design. The owner and the designer may evaluate the level of risk and performance that is acceptable.
Performance-based criteria could be set in the design. The design engineer should exercise special care so that all components of the design are fully met with attention to providing a continuous load path. An adequate quality assurance and control program is urged during project construction to verify that the design plans and good construction practices are followed.
This is especially important for sites lying close to the major seismic sources.
Spectral accelerations will exceed one g. Actual acceleration may be more or less than estimated.
Vertical accelerations are typically ⅓ to ⅔ of the horizontal accelerations, but can equal or exceed the horizontal accelerations, depending upon the local site effects and amplification.
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5.6 Slabs
It is our opinion the project soils report Section 5.6 still applies.
5.7 Retaining Walls and Lateral Earth Pressures
It is our opinion the project soils report Section 5.7 still applies.
5.8 Site Drainage and Maintenance
It is our opinion the project soils report Section 5.8 still applies.
5.9 Streets, Driveways and Parking Areas
It is our opinion the Streets, Driveways and Parking Areas Section found in the project soils report (Earth Systems, 2017) Section 5.9 still applies and should be followed; however with the change to a potential warehouse use, truck traffic may increase. Based on information provided by Terra Nova Planning and Research, Inc. (emails to Earth Systems on September 16 and 26, 2024), we understand truck traffic trips is still undetermined for design purposes and that final trips will be provided by the Traffic Engineer once the site use is determined for actual design. Initial information from Terra Nova indicated that Total trips likely to be in the 4,000-4,500 ADT, about 2,000-2,500 of which would be truck trips (actual vehicles, ranging from 2 to 4 axles). Other information provided indicated that 4,500 trips may be a high estimate and that 3,000 trip may be acceptable. As such, given the uncertainty in trips, Earth Systems is only providing an estimated Traffic Index (TI) of 15 for this report assuming Bobtail Tractor Trailer or HS20 type loading (20 year design life with maintenance). This assumed TI should be reviewed by the project Civil/Traffic Engineer to evaluate the suitability for this project, and if different, provide additional or alternate TI’s for actual design. All design should be based upon an appropriately selected Traffic Index. Changes in the traffic indices will affect the corresponding pavement section.
Preliminary Flexible Pavement Section Recommendations
Onsite/Interior Truck Drive Areas
R-Value of Subgrade Soils - 60 (tested) Design Method – CALTRANS Traffic Index
(Assumed) Pavement Use
Flexible Pavements
Asphalt-Concrete
Thickness (inches)
Class 2
Aggregate Base
Thickness (inches)
15 Drive Paths 11.0 11.0
The presented Traffic Indices should be confirmed by the project civil/traffic engineer. Changes to the Traffic Index will result in a differing pavement section required.
Conventional, rigid pavements, i.e. Portland cement concrete (PCC) pavements, can be used in areas subject to relatively high static wheel loads and/or heavy vehicle loading and unloading and turning areas (i.e. truck/bus lanes). The pavement section below is based upon Caltrans Highway Design Manual, (2023), and the assumptions outlined below.
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Preliminary Jointed Plain Portland Cement Concrete Pavement Sections Areas
Minimum Pavement
PCC* Thickness
(feet)
Caltrans Lean
concrete Base –
LCB (feet)
Caltrans Class 2
Subbase
(feet)
Annual Average Daily
Truck Traffic (AADTT) =
4,000
0.80 0.35 0.35
*Modulus of Rupture: 637 psi – See Caltrans Highway Design Manual for Other Properties In addition to the recommendations of the 2017 report, the following items are also recommended. PCC control (transverse construction, approach, and transverse) joints should use dowels as per Caltrans Standard Plans to strengthen control and construction joints. Dowels placed within dowel baskets should be incorporated into the concrete at each saw-cut control joint (i.e. dowel baskets and dowels are set in place before placement of concrete).
Portland cement concrete pavements should be constructed with transverse joints as per Caltrans Standard Specifications/Plans. A thickened edge should be used where possible and, as a minimum, where concrete pavements abut asphalt pavements. The thickened edge should be
1.2 times the thickness of the pavement (0.96 feet for a 0.80 foot pavement), and should taper back to the pavement thickness over a horizontal distance on the order of 3 feet.
Proper methods, such as hot-sealing or caulking, should be employed to limit water infiltration into the pavement base course and/or subgrade at construction/expansion/transverse joints and/or between existing and reconstructed asphalt or PCC concrete sections. Water infiltration could lead to premature pavement failure.
5.10 Site Drainage and Maintenance
The following recommendations are in addition to the 2017 report recommendations.
Positive drainage should be maintained away from the structure foundations (5 percent for 10 feet minimum) to prevent ponding, water intrusion, and subsequent saturation of the foundation soils. Gutters and downspouts in conjunction with a 2 percent (%) hardscape grade sloped away from structures draining to area drains can be considered as a means to convey water away from foundations if increased fall is not provided. A minimum 2% fall is required by the 2022 CBC.
There is an exception where less than 2% grade is allowable if the area is for a door landing or ramp per ADA regulations.
Drainage should be maintained for paved areas. Water should not pond on or near paved areas, slabs, or foundations. Ponded water can saturate subgrade soils and lead to pavement, slab, flooring, and foundation failure. The following recommendations are provided in regard to site drainage and structure performance:
• It is highly recommended that landscape irrigation or other sources of water be collected and conducted to an approved drainage device. Landscaping grades should be lowered and sloped such that water drains to appropriate collection and disposal areas. All runoff water should be controlled, collected, and drained into proper drain outlets. Control methods may Item Number: 1.
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include curbing, ribbon gutters, 'V' ditches, area drains, or other suitable containment and redirection devices.
• Site drainage should be devised such that runoff should be directed away from the tops of all graded slopes. Water should not freely flow over slopes. Diversion and conveyance structures which can accommodate water and eroded soil should be constructed at the tops and toes of all slopes. Lined swales or berms at the top and bottom of slopes are recommended.
• Applied irrigation to maintain landscaping should be controlled to the minimum volume and frequency necessary to sustain plant material. Excess and frequent watering could lead to saturated areas and standing water which can cause slab, flooring, and foundation distress.
The irrigation system designer should consider these conditions in their design and control irrigation accordingly.
• In no instance should water be allowed to flow or pond against structures, slabs or foundations or flow over unprotected slope faces. Adequate provisions should be employed to control and limit moisture changes in the subgrade beneath foundations or structures to reduce the potential for soil saturation and intrusion. Landscape borders should not act as traps for water within landscape areas. Potential sources of water such as piping, drains, over-spray, broken sprinklers, etc., should be frequently examined. Any such leakage, overspray, or plugging should be immediately repaired. • The drainage pattern should be established at the time of final grading and maintained throughout the life of the project. Additionally, drainage structures should be maintained (including the de-clogging of piping) throughout their design life. Structural and aesthetic performance is dependent on many drainage-related factors such as landscaping, irrigation, lateral drainage patterns and other improvements. Cleanoutsshould be provided in drainage piping.
• Maintenance of drainage systems and infiltration structures can be the most critical element in determining the success of a design. They must be protected and maintained from sediment-laden water both during and after construction to prevent clogging of the surficial soils any filter medium. The potential for clogging can be reduced by pre-treating structure inflow through the installation of maintainable forebays, biofilters, or sedimentation chambers. In addition, sediment, leaves, and debris must be removed from inlets and traps on a regular basis. Since these and other factors (such as varying soil conditions) may affect the rate of water infiltration, it is imperative to apply a conservative factor of safety [FOS] to the unfactored Basic Percolation/Infiltration Rates to provide a reliable basis for design. In order to account not only for the unknown factors above but also for changes of conditions during the use of the structures such as potential clogging effects due to washing in of soil fines, a FOS between 3 and 10 should be applied to lower design infiltration rates. • The factor of safety should be selected by the project drainage engineer and may be dependent on agency guidelines and the presence of filters and sedimentation structures. If these measures are provided, the factor of safety can be reduced. • We recommend drywells or infiltrating structure be located at least 20 feet from structure foundations, slopes, or settlement sensitive features.
• Water should not be allowed to pond within 10 feet of building foundations. The civil engineer producing the grading plan is notified that a gap made of clean sand is typically Item Number: 1.
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found between the vapor barrier and bottom of slabs or foundations. If water intrusion into this gap is possible the civil engineer shall either provide for no ponding or an impervious material to prevent water intrusion into the sand gap.
When grades of 5 percent for 10 feet away from foundations are not possible, the CBC allows for alternative drainage systems (Section 1804.3). Earth Systems experience has found that alternative methods may include impervious surface material (such as concrete and asphalt), area drains, and horizontal moisture barriers. Please contact Earth Systems for additional information or if the project has difficulty making grades.
Figure 2 Example Area Drains Used Within 10 Feet of Foundations Item Number: 1.
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Section 6
LIMITATIONS AND ADDITIONAL SERVICES
6.1 Uniformity of Conditions and Limitations
It is our opinion the project soils report Section 6.1 still applies.
6.2 Additional Services
It is our opinion the project soils report Section 6.2 still applies. -o0oAppendices as cited are attached and complete this report.
Item Number: 1.
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REFERENCES
American Society of Civil Engineers [ASCE]/Structural Engineering Institute [SEI], 2017, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, ASCE 7-16, including Supplement 3.
Department of Water Resources (DWR), 2024, Groundwater Level Data, http://well.water.ca.gov/gw/.
Earth Systems Southwest (ESSW), 2007, Geotechnical Engineering Report and Infiltration Testing for Storm Water Retention, Proposed Light Industrial Development, North of Interstate 10, West of Palm Drive, Desert Hot Springs area of Riverside County, California, dated July 18, 2007, File No.: 11131-01, Doc. No.: 07-07-733.
Earth Systems Southwest (ESSW), 2017, Geotechnical Engineering and Infiltration Update Report, Tentative Tract Map No. 37185, SWC Varner Road and West Drive, Desert Hot Springs, Riverside County, California, dated February 27, 2017, File No.: 11131-01, Doc. No.: 17- 02-705.
International Code Council [ICC], 2022, California Building Code, 2022 Edition.
Scharer, Matherine M., and Yule, Doug, 2020, A Maximum Rupture Model for the Southern San Andreas and San Jacinto Faults, California, Derived From Paleoseismic Earthquake Ages:
Observations and Limitations, Geophysical Research Letters 10.1029/2020GL088532, July 8, 2020
Sneed, Michelle and Brandt T. Justin, 2020, Detection and Measurement of Land Subsidence and Uplift Using Global Positioning System Surveys and Interferometric Synthetic Aperture radar, Coachella Valley, California, 2010-17; Scientific Investigations Report 2020-5093; United States Geological Survey (USGS), 86 pages, digital copy.
United States Geologic Survey, 2024, Design Maps website: http://ehp3- earthquake.wr.usgs.gov/designmaps/.
Item Number: 1.
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APPENDIX A
Plate 1 – Site Location Map
Plate 2 – Project Overlay and Previous Boring Map
Table A-1 CBC 2022 Seismic Parameters
Seismic Settlement (2 pages)
Earth Systems 2017 Project Soils Report
Item Number: 1.
Approximate Site Location
LEGEND
Approximate Scale: 1" = 1 Mile
0 1 Mile 2 Miles
Source: Google Earth satellite image with USGS Topographic map overlay.
Palm Drive
Approximate
Site Location
Varner Road
I-10 Freeway
10/7/2024 File No.: 306837-001
Earth Sy s te m s
Plate 1
Site Location Map
Ware Malcomb Newland Varner
Varner Road & West Drive
Corona, Riverside County, California
Item Number: 1.
(2017)
(2017)
(2017)
10/7/2024 File No.: 306837-001
Earth Systems
Plate 2
Project Overlay and Previous Boring Map
Ware Malcomb Newland Varner
Varner Road & West Drive
Corona, Riverside County, California
Item Number: 1.
Ware Malcomb 33.8927 -116.511 Lat/Long 306837001
Seismic Design Category E CBC Reference ASCE 7-16 Reference Site Class D Table 1613.5.6 Table 11.6-2
Latitude: 33.893 Table 1613.5.2 Table 20.3-1
Longitude: -116.511
Maximum Considered Earthquake (MCE) Ground Motion
Short Period Spectral Reponse SS 2.453 g Figure 1613.5 Figure 22-1 1 second Spectral Response S1 1.039 g Figure 1613.5 Figure 22-2 Site Coefficient Fa 1.00 Table 1613.5.3(1) Table 11.4-1 Site Coefficient Fv 1.70 Table 1613.5.3(2) Table 11-4.2 SMS 2.453 g = FaxSS
SM1 1.766 g = FvxS1
ASCE7-16 Supplement 3, Exception 1* SM1* 2.649 g =SM1x1.5 Exception 1, 11.4.8, Supplement 3 Design Earthquake Ground Motion
Short Period Spectral Reponse SDS 1.635 g = 2/3xSMS
Unadjusted 1 second Spectral Response SD1 1.178 g = 2/3xSM1 Modified 1 second Spectral Response* SD1* 1.766 g = 2/3xSM1* *Exception 1, 11.4.8, Supplement 3 To 0.14 sec = 0.2*SD1/SDS
Ts (11.4.8 ASCE 7-16 Exception Assumed) 0.72 sec = SD1/SDS Risk Category II Table 1604.5
Seismic Importance Factor 1.00
FPGA 1.10 Table 1604.5
PGAM 1.15 Table 11.5-1 Design
Vertical Coefficient (CV) 1.50 Table 11.9-1 Period Sa
T (sec) (g)
0.00 0.654
0.05 0.995
0.14 1.635
0.72 1.635
0.90 1.308
1.10 1.070
1.30 0.906
1.50 0.785
1.70 0.693
1.90 0.620
2.10 0.561
2.30 0.512
2.50 0.471
2.70 0.436
2.90 0.406
3.10 0.380
Site Specific Evaluation May Be Required for Site Class=D or E & S1>=0.2. The Above SDS and SD1 are NOT Valid Unless the Exception of ASCE7-16 Supplement 3, Section
11.4.8 Applies & the SM1* & SD1* Values are used for Site Class D.
Table A-1 - General Procedure Seismic Design Values
(Values presented should only be used by a Structural Engineer to determine if the exception in 11.4.8 (ASCE 7-16) can be used) 2022 California Building Code (CBC) (ASCE 7-16, Supplement 3) Seismic Design Parameters
0.0 0.2
0.4 0.6
0.8 1.0
1.2 1.4
1.6 1.8
2.0 2.2
2.4 2.6
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Spectral Acceleration, Sa (g)
Period (sec)
2022 CBC Equivalent Elastic Static Response Spectrum
Design
MCE
Earth Systems Pacific 10/7/2024
Item Number: 1.
EARTH SYSTEMS - EVALUATION OF LIQUEFACTION POTENTIAL AND INDUCED SUBSIDENCE Ware Malcomb - Varner and West Project No: 306837-001 1996/1998 NCEER Method Ground Compaction Remediated to 5 foot depth
Boring: B-2/B-5 Earthquake Magnitude: 7.9 PGA, g: 0.77 Calc GWT (feet): 100 Total Thickness of Liquefiable Layers: 0.0 feet Estimated Total Ground Subsidence: 1.1 inches 0 1020304050
0.0 0.2 0.4 0.6 0.8
Depth (feet)
Cyclic Stress Ratio
EQ CSR CRR
0 1020304050
0.0 1.0 2.0
Depth (feet)
Factor of Safety
0 1020304050
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Depth (feet)
Volumetric Strain (%)
0 1020304050
0 10 20 30 40 50 60 70
Depth (feet)
SPT N
SPT N N1(60)
Item Number: 1.
EARTH SYSTEMS - EVALUATION OF LIQUEFACTION POTENTIAL AND INDUCED SUBSIDENCE Ware Malcomb - Varner and West Project No: 306837-001 1996/1998 NCEER Method Ground Compaction Remediated to 5 foot depth
Boring: B-5 Earthquake Magnitude: 7.9 PGA, g: 0.77 Calc GWT (feet): 100 Total Thickness of Liquefiable Layers: 0.0 feet Estimated Total Ground Subsidence: 0.9 inches 0 1020304050
0.0 0.2 0.4 0.6 0.8
Depth (feet)
Cyclic Stress Ratio
EQ CSR CRR
0 1020304050
0.0 1.0 2.0
Depth (feet)
Factor of Safety
0 1020304050
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Depth (feet)
Volumetric Strain (%)
0 1020304050
0 10 20 30 40 50 60 70
Depth (feet)
SPT N
SPT N N1(60)
Item Number: 1.
Desert Land Ventures, III, LLC
2100 Palomar Airport Road, Suite 209
Carlsbad, California 92011
File No.: 11131‐01
Doc. No.: 17‐02‐705
Geotechnical Engineering and Infiltration Update Report Tentative Tract Map No. 37185
SWC Varner Road and West Drive
Desert Hot Springs, Riverside County, California
February 27, 2017
© 2017 Earth Systems Southwest
Unauthorized use or copying of this document is strictly prohibited without the express written consent of Earth Systems Southwest.
Item Number: 1.
79‐811B Country Club Drive
Bermuda Dunes, CA 92203
(760) 345‐1588
(800) 924‐7015
FAX (760) 345‐7315
February 27, 2017 File No.: 11131‐01
Doc. No.: 17‐02‐705
Desert Land Ventures, III, LLC
2100 Palomar Airport Road, Suite 209
Carlsbad, California 92011
Attention: Mr. Richard L. Sax
Project: Tentative Tract Map No. 37185
SWC Varner Road and West Drive
Desert Hot Springs, Riverside County, California
Subject: Geotechnical Engineering and Infiltration Update Report Earth Systems Southwest is pleased to submit this geotechnical and percolation report for Tentative Tract Map No. 37185, totaling approximately 115‐acres (including 35.5 acres of open space for the Willow Hole Conservation Area (that portion of the site north of Varner Road). This report will update our referenced Earth Systems 2007 feasibility study (ESSW, 2007). in order to provide design‐level recommendations. This project is located north of Interstate‐10 freeway (I‐ 10) and approximately a half (1/2) mile west of Palm Drive in Desert Hot Springs, Riverside County, California.
We understand that development plans for south of Varner include five parcels for light‐ industrial development, and eight areas for infiltration basins. An on‐site sewage treatment package is proposed. This report completes our scope of services in accordance with our agreement Control No.: 3160, File No. 11131‐01, dated November 21, 2016. Other services may be required, such as plan review, construction testing, inspection, and grading observation, are additional services and will be billed according to our Fee Schedule in effect at the time services are provided. Unless requested in writing, the client is responsible for distributing this report to the appropriate governing agency or other members of the design team.
We appreciate the opportunity to provide our professional services. Please contact our office if there are any questions or comments concerning this report or its recommendations.
Respectfully submitted,
EARTH SYSTEMS SOUTHWEST
Anthony Colarossi Dale Hamelehle
Project Engineer Senior Engineering Geologist
CE 60302 PG 5551 EG 1760
SER/ac/klp/mr
Distribution: 4/Desert Land Ventures, III, LLC
2/Hunsaker & Associates Irvine, Inc., Plus email [email protected] 1/BD File Item Number: 1.
i
EARTH SYSTEMS SOUTHWEST
TABLE OF CONTENTS
Page
Section 1 INTRODUCTION ...........................................................................................1
1.1 Project Description ........................................................................................... 1
1.2 Site Description................................................................................................. 2
1.3 Scope of Services .............................................................................................. 2 Section 2 METHODS OF EXPLORATION AND TESTING..................................................4
2.1 Field Exploration ............................................................................................... 4
2.2 Laboratory Testing ............................................................................................ 5 Section 3 DISCUSSION.................................................................................................7
3.1 Geologic Setting ................................................................................................ 7
3.2 Site Reconnaissance.......................................................................................... 8
3.3 Groundwater..................................................................................................... 8
3.4 Collapse/Consolidation Potential ................................................................... 10
3.5 Expansive Soils................................................................................................ 11
3.6 Corrosivity ....................................................................................................... 11
3.7 Geologic Hazards ............................................................................................ 13
3.7.1 Seismic Hazards......................................................................................... 13
3.7.2 Secondary Hazards.................................................................................... 15
3.8 Retention Basin Infiltration Testing ................................................................ 16 Section 4 CONCLUSIONS............................................................................................19 Section 5 RECOMMENDATIONS ................................................................................21
5.1 Site Development – Grading........................................................................... 21
5.2 Excavations and Utility Trenches.................................................................... 26
5.3 Slope Construction.......................................................................................... 27
5.4 Shallow Foundations....................................................................................... 28
5.4.1 Estimated Settlements for Foundations................................................... 32
5.5 Seismic Coefficients........................................................................................ 32
5.6 Slabs................................................................................................................ 33
5.7 Retaining Walls and Lateral Earth Pressures.................................................. 36
5.8 Site Drainage and Maintenance...................................................................... 37
5.9 Streets, Driveways and Parking Areas............................................................ 38 Section 6 LIMITATIONS AND ADDITIONAL SERVICES .................................................42
6.1 Uniformity of Conditions and Limitations ...................................................... 42
6.2 Additional Services.......................................................................................... 43 REFERENCES..........................................................................................................45 Item Number: 1.
Table of Contents, continued ii
EARTH SYSTEMS SOUTHWEST
APPENDIX A
Plate 1 – Site Vicinity Map
Plate 2 – Test Location Map
Plate 3a – Regional Geology Map
Plate 3b Regional Geologic Map Legend
Terms and Symbols Used on Boring Logs
Soil Classification System
Logs of Borings and Test pits
Total Static Load (Spread Footing)
Total Static Load (Continuous Footing)
Dry Seismic Settlement after OX
Site Class Estimator
APPENDIX B
Laboratory Test Results
Item Number: 1.
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Geotechnical Engineering and Infiltration Update Report Tentative Tract Map No. 37185
SWC Varner Road and West Drive
Desert Hot Springs, Riverside County, California
EARTH SYSTEMS SOUTHWEST
Section 1
INTRODUCTION
1.1 Project Description
This geotechnical engineering and infiltration update report has been prepared for the proposed light industrial development located north of I‐ 10 and west of Palm Drive in Desert Hot Springs, California, more specifically Tentative Tract Map No. 37185. We understand that development plans are very preliminary at this stage. The proposed development will include several improvements:
1. One to two‐story light industrial structures,
2. Asphalt concrete aisles and parking stalls
3. Concrete driveways
4. Landscape and infiltration basins
5. On‐site sewage treatment facility (MempacTM Municipal Membrane Bio Reactor Package)
6. On‐site treated wastewater disposal
We also understand that the proposed buildings will be developed under the regulation of the current California Building Code (2016, CBC). Based on the anticipated conditions, the following sections describe our understanding of the project and our anticipated scope of services.
It is assumed that the structures will be one to two‐story in height made of masonry, concrete “tilt‐up”, wood‐framed or metal stud construction founded on shallow permanent foundations with slabs‐on‐grade. The onsite sewage treatment facility is proposed to be founded upon skids/ slabs‐on‐grade. Additionally, we have assumed a maximum column load on the order of 100 kips, for a square footing up to 7 feet wide and a maximum wall loading of 4 kips per linear foot for a footing with a maximum width of 4 feet. As the basis for the foundation recommendations, all loading is assumed to be dead plus actual live load. No preliminary design loading was provided by the structural engineer. If actual structural loading exceeds these assumed values, we will need to reevaluate the given recommendations. In addition, the geotechnical engineer of record should evaluate structural plans for additive pressures from closely spaced footings and differential settlements between nearby heavily and lightly loaded footings. Below grade levels are not proposed.
Site development will include clearing and grubbing of vegetation, site grading, building pad preparation, underground utilities, and concrete driveway and sidewalk placement. Basins are estimated to be on the order of 5 feet deep below existing grades. Based on existing site topography and ground conditions, site grading is expected to consist of fills on the order of 3 to 11 feet and cuts on the order of 3 feet (excluding depth of over‐excavation for buildings). The Item Number: 1.
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northern parcel (North of Varner Road) will be used as conservation area and will be undeveloped.
1.2 Site Description
The approximate center of Parcel 2 (that section south of Varner Road) has an approximate latitude and longitude of 33.8918°N/‐116.5147°W. The northeastern corner of the site (33.892758/‐116.510783) is closest to the San Andreas fault zone and the latitude and longitude for this location will be used in our seismic analysis. The legal description of the land is identified as Assessor Parcel Number’s [APN] 669‐150‐001 (north of Varner Road) & 669‐150‐002 (south of Varner Road) encompassing approximately 115 acres. The site is bounded by the I‐10 freeway to the south, vacant desert land to the west and east and north. Varner Road bisects APN 669‐ 150 Parcels 1 and 2.
Topographically the site is generally flat and level with drainage by concentrated and sheet flow flowing to the south and southeast. The elevation at the center of the project is approximately 652 feet above mean sea level. However, the site surface is generally undulatory with highs and lows on the order of 2 feet.
The surface of the project contains some desert scrub with wind dunes. The surface shows some boulders and cobbles in a matrix of gravelly sand with silt. There are underground utilities near and within the project area. Two natural gas lines were found at the site. Other utility lines include, but are not limited to, domestic water, electric, sewer, telephone, cable, and irrigation lines.
1.3 Scope of Services
Geotechnical Engineering Report
The scope of services provided by Earth Systems consisted of the following items:
1. We performed a visual geologic reconnaissance of the site area to observe overall geologic conditions. In addition, we reviewed our files and select available published reports pertinent to the site vicinity. Data found in a past geotechnical report (ESSW, 2007) was reviewed.
2. We conducted exploration of the near surface soil by means of drilling and sampling with 5 exploratory borings, 5 backhoe exploration pits, and 8 shallow pits for single ring infiltration tests.
3. Laboratory testing was performed on selected soil samples obtained from the exploratory borings. These test results aided in the classification and evaluation of the pertinent engineering properties of the various soils encountered.
4. We conducted a geotechnical engineering analysis of the data generated from this exploration and prepared a design‐level written report presenting our findings and recommendations related to the following:
A description of the proposed project including a site plan showing the approximate boring and test pit locations (based upon maps provided);
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A description of the surface and subsurface site conditions including groundwater conditions, as encountered in our field exploration;
A description of the site geologic setting and possible associated geology‐related hazards, including liquefaction, lateral spreading, subsidence, and seismic settlement analysis; A discussion of regional geology and site seismicity; A description of local and regional active faults, their distances from the site, their potential for future earthquakes;
A discussion of other geologic hazards such as ground shaking, landslides, flooding, and tsunamis;
A discussion of site conditions, including the geotechnical suitability of the site for the general type of construction proposed;
A seismic analysisincluding geotechnicalseismic design coefficientsin accordance with the 2016 California Building Code;
Recommendations for imported fill (if required) for use in compacted fills; Recommendations for foundation design including parameters for shallow foundations, and subgrade preparation;
Anticipated total and differential settlements for the recommended foundation system; Preliminary recommendations for the mitigation of liquefaction; Recommendationsfor lateral earth pressures(active, at‐rest, and passive) for below grade structures and retaining walls, including drainage requirements, coefficients of friction and seismic earth pressures;
Recommendations for site preparation, earthwork, and fill compaction specifications; Discussion of anticipated excavation conditions, including shrinkage and/or bulking; Recommendations for underground utility trench backfill; Recommendations for stability of temporary trench excavations; Recommendations for location specific infiltration rates; Recommendations for slabs‐on‐grade (building slabs and walkways), including recommendations for reducing the potential for moisture transmission through interior slabs.
Recommendations for collapsible or expansive soils (expansive soils were not observed). Preliminary recommendations for asphalt concrete (AC) and Portland Cement Concrete (PCC) pavement design criteria for parking and drive (fire) lane areas. A discussion of the corrosion potential of the near‐surface soils encountered during our field exploration.
An appendix, which includes a summary of the field exploration and laboratory testing program.
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Section 2
METHODS OF EXPLORATION AND TESTING
2.1 Field Exploration
Exploratory Borings
Five exploratory borings were drilled to depths ranging from 11 to 51‐½ feet below the existing ground surface to observe soil profiles and obtain samples for laboratory testing. The borings were drilled on January 12, 2017, using an 8‐inch outside diameter hollow‐stem auger. Augers were powered by a Mobile B‐61 truck‐mounted rubber tired drill rig. Refusal was encountered at various depths(11 to 28 feet) in four borings due to hard drilling on cobbles and/or boulders. The boring locations are shown on the Boring Location Map, Plate 2, in Appendix A. The locations shown are approximate, established by pacing and line‐of‐sight bearings from adjacent landmarks and consumer grade GPS coordinates (+/‐ 15 feet).
A representative from Earth Systems maintained a log of the subsurface conditions encountered and obtained samples for visual observation, classification and laboratory testing. Subsurface conditions encountered in the borings were categorized and logged in general accordance with the Unified Soil Classification System [USCS] and ASTM D 2487 and 2488 (current edition). Our typicalsampling interval within the borings was approximately every 2½ to 5 feet to the full depth explored; however, sampling intervals were adjusted depending on the materials encountered onsite. Samples were obtained within the test borings using a Standard Penetration [SPT] sampler (ASTM D 1586) and a Modified California [MC] ring sampler (ASTM D 3550 with those similar to ASTM D 1586). The SPT sampler has a 2‐inch outside diameter and a 1.38‐inch inside diameter. The MC sampler has a 3‐inch outside diameter and a 2.4‐inch inside diameter.
Both the ring and SPT samplers were mounted on drill rod and driven using a rig‐mounted 140‐ pound automatic hammer falling for a height of 30 inches. The number of blows necessary to drive either a SPT sampler or a MC type ring sampler within the borings was recorded.
Design parameters provided by Earth Systems in this report have considered an estimated 68% hammer efficiency based on data provided by the drilling subcontractor. The number of blows necessary to drive either a SPT sampler or a MC type ring sampler within the borings was recorded. Since the MC sampler was used in our field exploration to collect ring samples, the N‐ values using the California sampler can be roughly correlated to SPT N‐values using a conversion factor that may vary from about 0.5 to 0.7. In general, a conversion factor of approximately 0.63 from the recent study at the Port of Los Angeles (Zueger and McNeilan, 1998 per SP 117A) is considered satisfactory. A value of 0.63 was applied in our calculations for this project.
Bulk samples of the soil materials were obtained from the drill auger cuttings, representing a mixture of soils encountered at the depths noted. Following drilling, sampling, and logging the borings were backfilled with native cuttings and tamped upon completion. Our field exploration was provided under the direction of a registered Geotechnical Engineer from our firm.
The final logs of the borings represent our interpretation of the contents of the field logs and the results of laboratory testing performed on the samples obtained during the subsurface Item Number: 1.
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exploration. The final logs are included in Appendix A of this report. The stratification lines represent the approximate boundaries between soil types, although the transitions may be gradual. In reviewing the logs and legend, the reader should recognize the legend is intended as a guideline only, and there are a number of conditions that may influence the soil characteristics observed during drilling. These include, but are not limited to, the presence of cobbles or boulders, cementation, variations in soil moisture, presence of groundwater, and other factors.
The boring logs present field blowcounts per 6 inches of driven embedment (or portion thereof) for a total driven depth attempted of 18 inches. The blowcounts on the logs are uncorrected (i.e. not corrected for overburden, sampling, etc.). Consequently, the user must correct the blowcounts per standard methodology if they are to be used for design and exercise judgment in interpreting soil characteristics, possibly resulting in soil descriptions that vary somewhat from the legend.
Test Pits
Five exploratory test pits (TP‐1 through TP‐5) were excavated using a mechanical backhoe with 2‐foot bucket to a depth ranging between nine (9) and ten (10) feet below existing surface. The test pits were excavated for classification, more specifically plus 6‐inch oversize material. The pits were excavated January 11, 2017 and January 16, 2017. The test pit locations are shown on Plate 2 in Appendix A. The locations shown are approximate, established by pacing and line‐of‐ sight bearings from adjacent landmarks and survey stakes.
Infiltration Test Pits
Eight (8) exploratory test pits were excavated using a mechanical backhoe with 2‐foot bucket to depths ranging between four (4) and five (5) feet below existing surface so that infiltration test locations will represent the bottom of the proposed infiltration systems. The pits were excavated on January 11, 2017. The test pit locations are shown on Plate 2 in Appendix A. The locations shown are approximate, established by pacing and line‐of‐sight bearings from adjacent landmarks and survey stakes.
A staff scientist from Earth Systems maintained a log of the subsurface test pit conditions encountered and performed visual observation of the soils and approximate oversize rock content in the test pits indicated above. Subsurface conditions encountered in the test pits were categorized and logged in general accordance with the Unified Soil Classification System [USCS] and ASTM D 2487 and 2488 (current edition).
2.2 Laboratory Testing
Samples were reviewed along with field logs to select those that would be analyzed further.
Those selected for laboratory testing include soils exposed and used during grading and those deemed to be within the influence of the proposed structures. Test results are presented in graphic and tabular form in Appendix B of this report. The tests were conducted in general accordance with the procedures of the American Society for Testing and Materials [ASTM] or other standardized methods as referenced below. Our testing program consisted of the following:
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Density and Moisture Content of select samples of the site soils (ASTM D 2937 & 2216). Maximum density tests to evaluate the moisture‐density relationship of typical soils encountered (ASTM D 1557).
Particle Size Analysis to classify and evaluate soil composition. The gradation characteristics of selected samples were made by sieve analysis procedures (ASTM D 6913).
Expansion Index (EI) test to evaluate the expansive nature of the soil. The samples were surcharged under 144 pounds per square foot at moisture content of near 50% saturation. The samples were then submerged in water for 24 hours and the amount of expansion recorded with a dial indicator (ASTM D 4829). Consolidation/Collapse Potential to evaluate the compressibility and hydroconsolidation (collapse) potential of the soil upon wetting (ASTM D 5333). Chemical Analyses(Soluble Sulfates and Chlorides(ASTM D 4327), pH (ASTM D 1293), and Electrical Resistivity/Conductivity (ASTM D 1125) to evaluate the potential for adverse effects of the soil on concrete and steel.
Direct shear testing to estimate shear strength characteristics (ASTM D 3080). R‐Value to evaluate pavement support characteristics (CTM 301) Item Number: 1.
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Section 3
DISCUSSION
3.1 Geologic Setting
Regional Geology: The site lies within the Coachella Valley, a part of the Colorado Desert geomorphic province. A significant feature within the Colorado Desert geomorphic province is the Salton Trough. The Salton Trough is a large northwest‐trending structural depression that extends approximately 180 miles from the San Gorgonio Pass to the Gulf of California. Much of this depression in the area of the Salton Sea is below sea level.
The Coachella Valley formsthe northerly part of the Salton Trough and contains a thick sequence of Miocene to Holocene sedimentary deposits. Mountains surrounding the Coachella Valley include the Little San Bernardino Mountains on the northeast, foothills of the San Bernardino Mountains on the northwest, and the San Jacinto and Santa Rosa Mountains on the southwest.
These mountains expose primarily Precambrian metamorphic and Mesozoic granitic rocks. The San Andreas fault zone within the Coachella Valley consists of the Garnet Hill fault, the Banning fault, South/North Branches of the San Andreas fault, and the Mission Creek fault that traverse along the northeast margin of the valley, see Plate 3.
Local Geology: The projectsite islocated in the northwestern portion of the Coachella Valley. The upper sediments observed primarily consist of native alluvial fan deposits associated with deposition of Mission Creek and Morongo Wash. Broad and coalesced alluvial fans emanating from the San Bernardino and Little San Bernardino Mountains underlie the site. There are isolated areas with artificial fill which overly the native alluvial fan deposits. These areas of artificial fill are typically associated with fill and spoils placed during the construction of any existing site improvementssuch as Varner Road, dirt roads, above and below ground utilities and with dumping of trash and debris (concrete chunks, wood, grass, metal etc.). These artificial fills are anticipated to be less than 5 feet thick. Local native soils consist of interbedded sands and gravels. Cobbles and boulders are common. The depth to crystalline basement rock beneath the site is estimated to be in excess of 1,500 feet (Envicom, 1976). There are no active faults currently mapped within the project limits, however the southern branch or Banning segment of the San Andreas fault is located approximately 0.5 miles southwest of the project.
Site Soil Conditions: The field exploration indicates that site soils consist generally of native alluvial sand and silty sand with gravel, cobbles, and boulders to the maximum depth of exploration of 51½ feet below the ground surface. Although not present at our exploration locations, spoil piles of trash and debris are present. Soils are predominantly sands, sand with silts, gravels, and gravels with silts (SP, SM, SP‐SM, SW‐SM, GW, GP, and GW‐SM) soil types were classified according to the Unified Soil Classification System). Cobbles and boulders were present in the uppersoils. Some areas of the site are predominantly cobbles and boulder in a sand matrix.
Estimated cobble and boulder contents is discussed in Section 5.1.
The site lies within an area of moderate to high potential for wind and water erosion. Fine particulate matter (PM10) can create an air quality hazard if dust is blowing. Watering the surface, planting grass or landscaping, or placing hardscape normally mitigates this hazard.
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The boring and trench logs provided in Appendix A include more detailed descriptions of the soils encountered. Site soils are classified as Type C in accordance with Cal OSHA.
The site lies within a recognized blow sand hazard area. Fine particulate matter (PM10) can create an air quality hazard if dust is blowing. Watering the surface, planting grass or landscaping, or placing hardscape normally mitigates this hazard.
3.2 Site Reconnaissance
Earth Systems personnel visited the site on multiple days: January 11, 12, and 15, 2017. During our field explorations, we observed the current site conditions and possible land use. Earth Systems personnel also reviewed historic aerial photographs of the project site. The proposed site layout is presented in Plate 2. A summary of our findings is presented below. The site appears to be undeveloped land.
Topography appears flat with small uneven dunes with desert scrub. Improved on‐site drainage facilities, like concrete channels, were not observed. Significant wide‐area drainage features were not noted. Historical aerial photographs (Google earth, between 1995 and 2016) revealed the following:
o Very little man made changes to most of the site was observed. o Several small dry stream channels are found having a southeast alignment; however, Interstate 10 Freeway cuts off these stream channels.
o The projectsite islocated between braided and meandering intermittentstream beds flowing in a southeast direction and appear to have formed by large tributary area upstream from the project. The meandering streams (both upstream and downstream of the project) do not appear to be protected from erosion and scour due to storm runoff.
Electrical overhead lines are located to the north.
Gas and oil lines run across the southern border of the project. There is a dirt road within the southern side of the site (Mihalyo Road). Surface debris was found at various locations of the site. The debris consisted mainly of concrete, asphalt, brick, paper, rubber tires, and discarded rock.
3.3 Groundwater
This section will discuss both current and historic groundwater levels at or near the project site.
For this report, we used information dated back to 1961 to use as historic information. Also, this section provides a brief discussion of the moisture contents of the soils found during the exploration and the ability of storm water retention facilities to produce a perched water table.
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Recent Exploration Information
Free groundwater was not encountered in borings nor test pits during our explorations conducted on January of 2017. Moisture contents of the soils indicate the soils are dry to damp. In‐ situ soils at depths between approximately 2‐1/2 and 12 feet were tested for moisture contents and they varied between 0 % and 1%.
Nearby Well Information
We researched the California Department of Water Resources groundwater database and found two wells close to the project. Well No. 1 is found approximately 7,400 LF northwest of the project and Well 2 is found approximately 11,100 LF southwest of the project site. The well reading information is provided in Table 1.
Table 1
Groundwater Information from Nearby Wells
*Well site 1 is located at latitude/longitude of 33.9102/‐116.5284 **Well site 2 is located at latitude/longitude of 33.8628/‐116.5236 Historic Groundwater Information
From observation of a map (see Figure 1) produced using spring of 1961 information (Department of Water Resources Bulletin 108, Plate 6 in that report), the historic groundwater contour nearest the project is 530 feet Mean Sea Level. This map also indicatesthe project lies between two major faults having various groundwater depths on both sides of the faults. The project islocated within a “Garnet Hill Subarea”.
Location (mi) Date
(mm/dd/year) GSE
(ft)
WSE
(ft)
Water
Depth
(ft)
Comments
Project Site 01/17/2017 ~640 Not Found NA Boring B‐5
Well No. 1* 11/04/2015 760 536 224 north of project
Well No. 2** 12/05/2011 549 288 261 south of project
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Figure 1 Historic Groundwater Contours
Estimated Project Groundwater Depth
Knowing the site has an approximate surface elevation of 640 feet and the DWR information provided in Table 1 above and Historic Groundwater Map (Bulletin 108), it is anticipated that the current depth of groundwater below the projects surface is over 100 feet. Groundwater levels may fluctuate with precipitation, irrigation, drainage, regional pumping from wells, site grading, and nearby faults.
3.4 Collapse/Consolidation Potential
Collapsible soil deposits generally exist in regions of moisture deficiency. Collapsible soils are generally defined as soils having potential to suddenly decrease in volume upon increase in moisture content even without an increase in external loads. Soilssusceptible to collapse include loess, weakly cemented sands and silts where the cementing agent is soluble (e.g. soluble gypsum, halite), valley alluvial deposits within semi‐arid to arid climate, and certain granite residual soils above the groundwater table.
In arid climatic regions, granular soils may have a potential to collapse upon wetting. Collapse (hydroconsolidation) may occur when the soluble cements (carbonates) in the soil matrix dissolve, or particles are lubricated causing the soil to densify from its loose configuration from deposition.
The degree of collapse of a soil can be defined by the Collapse Potential [CP] value, which is expressed as a percent of collapse of the total sample using the Collapse Potential Test (ASTM Standard Test Method D 5333). Based on the Naval Facilities Engineering Command (NAVFAC) Design Manual 7.1, the severity of collapse potential is commonly evaluated by the following Table 2, Collapse Potential Values.
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Table 2
Collapse Potential Values
Collapse Potential Value Severity of Problem
0‐1% No Problem
1‐5% Moderate Problem
5‐10% Trouble
10‐20% Severe Trouble
> 20% Very Severe Trouble
The projectsite islocated in a geologic environment where the potential for collapsible soil exists.
The results of collapse potential tests performed on selected samples from different depths indicated a range of collapse potential on the order of 0 to 0.8 percent at an applied vertical stress of 2,000 psf. Collapse testing indicated no samples showed collapse higher than 1%; therefore, it is our opinion that the site soils have a low potential for hydro collapse. Collapse related settlement is estimated to be minor.
3.5 Expansive Soils
Expansive soils are characterized by their ability to undergo significant volume change (shrink or swell) due to variations in moisture content. Changes in soil moisture content can result from rainfall, landscape irrigation, utility leakage, roof drainage, perched groundwater, drought, or other factors, and may cause unacceptable settlement or heave of structures, concrete slabs supported‐on‐grade, or pavements supported over these materials. Depending on the extent and location below finished subgrade, expansive soils can have a detrimental effect on structures.
Based on our visual observations, site soils were observed to be granular. As such, the Expansion Index of the onsite soils is anticipated to be “very low” as defined by ASTM D 4829. Samples of building pad soils should be observed or tested during grading to confirm or modify these findings.
3.6 Corrosivity
Two samples of the near‐surface soil within the site area were was tested for potential to corrosion of concrete and ferrous metals. The tests were conducted in general accordance with the ASTM test methods to evaluate pH, resistivity, and water‐soluble sulfate and chloride content. The test results are presented in Appendix B. These tests should be considered as only an indicator of corrosivity for the sample tested. Other earth materials found on site may be more, less, or of a similar corrosive nature. Water‐soluble sulfatesin soil can react adversely with concrete. ACI 318 provides the relationship between corrosivity to concrete and sulfate concentration, presented in the table below:
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Table 3
Sulfate Corrosion Correlations
Water‐Soluble Sulfate in Soil
(ppm) Corrosivity to Concrete
0‐1,000 Negligible
1,000 – 2,000 Moderate
2,000 – 20,000 Severe
Over 20,000 Very Severe
In general, the lower the pH (the more acidic the environment), the higher the soil corrosivity will be with respect to ferrous structures and utilities. As soil pH increases above 7 (the neutral value), the soil is increasingly more alkaline and less corrosive to buried steel structures, due to protective surface films, which form on steel in high pH environments. A pH between 5 and 8.5 is generally considered relatively passive from a corrosion standpoint. High chloride levels tend to reduce soil resistivity and break down otherwise protective surface deposits, which can result in corrosion of buried steel or reinforced concrete structures. Soil resistivity is a measure of how easily electrical current flows through soils and is the most influential factor. Based on the findings of studies presented in ASTM STP 1013 titled “Effects of Soil Characteristics on Corrosion” (February, 1989), the approximate relationship between soil resistivity and soil corrosivity was developed as shown in Table 4.
Table 4
Resistivity Corrosion Correlations
Soil Resistivity
(Ohm‐cm) Corrosivity to Ferrous Metals
0 to 900 Very Severely Corrosive
900 to 2,300 Severely Corrosive
2,300 to 5,000 Moderately Corrosive
5,000 to 10,000 Mildly Corrosive
10,000 to >100,000 Very Mildly Corrosive
Two samples (B1@0‐5’, and B3@0‐5’) recovered from our field sampling were tested for pH, Resistivity, Chlorides, and Sulfate Content. Test results(presented in Appendix B)show a pH value of 6.5 and 6.9, chloride content of 7.9 ppm and 4.2 ppm, sulfate content of 17 ppm and 5 ppm, and resistivity of 10,000 Ohm‐cm and 35,200 Ohm‐cm. Previous testing (2007) by Earth Systems indicated pH of 7.5 and 7.7 chlorides of 28 and 32 ppm sulfates of 3 ppm and resistivities of 2900 and 2,950 Ohm‐cm. Although Earth Systems does not practice corrosion engineering, the corrosion values from the soil tested are normally considered as being “Very Mildly to Moderately Corrosive” to buried metals and as possessing a “Negligible” exposure to sulfate attack for concrete as defined in American Concrete Institute (ACI) 318, Section 4.3. The above Item Number: 1.
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values can potentially change based on several factors, such as importing soil from another job site and the quality of construction water used during grading and subsequent landscape irrigation. As such, we recommend an engineer competent in corrosion mitigation review these results and design corrosion protection appropriately. Additionally, we recommend engineer competent in corrosion analysis evaluate the results presented in Appendix B within in relation to other constituents that may be of concern such as nitrates, ammonium, etc.
3.7 Geologic Hazards
Geologic hazards that may affect the region include seismic hazards (ground shaking, surface fault rupture, soil liquefaction, and other secondary earthquake‐related hazards), ground subsidence, slope instability, flooding, and erosion. A discussion follows on the specific hazards to this site.
3.7.1 Seismic Hazards
Seismic Sources: Approximately 39 active faults orseismic zoneslie within 50 miles of the project site. The primary seismic hazard to the site is strong ground shaking from earthquakes along regional faults including the San Andreas and San Jacinto faults. The South Branch (Banning) segment of the San Andreas fault is located approximately 0.7 miles northeast of the site. The Garnet Hill segment of the San Andreas Fault is located approximately 0.14 miles southwest of the site.
Surface Fault Rupture: The project site does not lie within a currently delineated State of California, Alquist‐Priolo Earthquake Fault Zone (Bryant, 2007). Well‐delineated fault lines cross through this region as shown on California Geological Survey [CGS] maps (Jennings, 2010); however, no active faults are mapped in the immediate vicinity of the site. Therefore, active fault rupture is unlikely to occur at the project site. While fault rupture would most likely occur along previously established fault traces, future fault rupture could occur at other locations The South Branch segment of the San Andreas fault is located about 0.7 miles northeast of the site. This segment of the fault is well‐recognized with known active surface fault rupture. In the event of future fault rupture on this fault, it is likely that local primary access routes, including Palm Drive will be adversely affected and probably closed for several days where this roadway crosses the fault. The Garnet Hill fault is located just south of the subject site and is not located within an Alquist‐Priolo special studies zone. The Garnet Hill fault is a right‐lateral strike‐slip type of fault.
The most recent surface rupture for this segment of the fault is late Quaternary and is not considered to be active. Aerial photographsfrom 1995 to 2016 were reviewed and no lineaments were observed within or adjacent to the site
Historic Seismicity: The site is located within an active seismic area in southern California where large numbers of earthquakes are recorded each year. Approximately 39 magnitude 5.5 or greater earthquakes have occurred within 60 miles of the site since 1856. Six historic seismic events(5.9 M or greater) have significantly affected the Coachella Valley in the last 70 years. They are as follows:
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Desert Hot Springs Earthquake – On December 4, 1948, a magnitude 6.5 ML (6.0MW) earthquake occurred east of Desert Hot Springs. This event wasstrongly felt in the Desert Hot Springs area.
Palm Springs Earthquake – A magnitude 5.9 ML (6.2MW) earthquake occurred on July 8, 1986 in the Painted Hills, causing minor surface creep of the Banning segment of the San Andreas fault. This event was strongly felt in the Desert Hot Springs area and caused structural damage, as well as injuries.
Joshua Tree Earthquake – On April 22, 1992, a magnitude 6.1 ML (6.1MW) earthquake occurred in the mountains 9 miles east of Desert Hot Springs. Structural damage and minor injuries occurred in the Coachella Valley area as a result of this earthquake. Landers and Big Bear Earthquakes – Early on June 28, 1992, a magnitude 7.5 MS (7.3MW) earthquake occurred near Landers, the largest seismic event in Southern California for 40 years. Surface rupture occurred just south of the town of Yucca Valley and extended some 43 miles toward Barstow. About three hours later, a magnitude 6.6 MS (6.4MW) earthquake occurred near Big Bear Lake. No significant structural damage from these earthquakes was reported in the Desert Hot Springs area.
Hector Mine Earthquake – On October 16, 1999, a magnitude 7.1MW earthquake occurred on the Lavic Lake and Bullion Mountain faults north of Twentynine Palms. While this event was widely felt, no significant structural damage has been reported in the Coachella Valley.
Seismic Risk: While accurate earthquake predictions are not possible, various agencies have conducted statistical risk analyses. In 2002 and 2008, the California Geological Survey [CGS] and the USGS completed of probabilistic seismic hazard maps. We have used these maps in our evaluation of the seismic risk at the site. The recent Working Group of California Earthquake Probabilities (WGCEP, 2008) estimated a 58% conditional probability that a magnitude 6.7 or greater earthquake may occur between 2008 and 2038 along the southern segment of the San Andreas fault.
The primary seismic risk at the site is a potential earthquake along the San Andreas fault that is about 0.7 miles from the site and is considered as fault Type A per the CGS. Geologists believe that the San Andreas fault has characteristic earthquakes that result from rupture of each fault segment. The estimated mean characteristic earthquake is magnitude 7.7 for the Southern Segment of the fault (USGS, 2002). However, recent standard of practice suggests a maximum magnitude of 8.2 be used for analysis, assuming a multi‐segment rupture event.
Thissegment hasthe longest elapsed time since rupture of any part of the San Andreasfault. The last rupture occurred about 1680 AD, based on dating by the USGS near Indio (WGCEP, 2008).
This segment has also ruptured on about 1020, 1300, and 1450 AD, with an average recurrence interval of about 220 years. The San Andreas fault may rupture in multiple segments, producing a higher magnitude earthquake. Recent paleoseismic studies suggest that the San Bernardino Mountain Segment to the north and the Coachella Segment may have ruptured together in 1450 and 1690 AD (WGCEP, 1995).
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3.7.2 Secondary Hazards
Secondary seismic hazards related to ground shaking include soil liquefaction, ground subsidence, tsunamis, flooding, slope instability, erosion and seiches. The site is far inland, so the hazard from tsunamisis non‐existent. The site isrelatively flatso the hazard from slope instability is not considered a significant issue for this site.
Seiches: At the present time, two water storage tanks are located approximately 5 miles north of the project. In the event of tank rupture due to seiching, there is a remote possibility of some flooding at or near the site, depending on localized drainage courses and man‐made modifications to drainage paths.
Soil Liquefaction and Lateral Spreading: Liquefaction isthe loss ofsoilstrength from sudden shock (usually earthquake shaking), causing the soil to become a fluid mass. Liquefaction describes a phenomenon in which saturated soil loses shear strength and deforms as a result of increased pore water pressure induced by strong ground shaking during an earthquake. Dissipation of the excess pore pressures will produce volume changes within the liquefied soil layer, which can cause settlement. Shear strength reduction combined with inertial forces from the ground motion may also result in lateral migration (lateral spreading). Factors known to influence liquefaction include soil type, structure, grain size, relative density, confining pressure, depth to groundwater (typically occurs in the upper 50 feet), and the intensity and duration of ground shaking. Soils most susceptible to liquefaction are saturated, loose sandy soils and low plasticity clay and silt. The results of our analysesindicate that historic groundwater depth is below 50 feet and therefore liquefaction potential is low.
Percolation and infiltration evaluation by Earth Systems indicates saturated conditions which may develop in the vicinity of the retention facility after a design storm will dissipate quickly. As such the potential for a design storm event and saturated soil conditions and the design seismic event to occur concurrently are considered low.
Dry Seismic Settlement: The amount of dry seismic settlement is dependent on relative density of the soil, ground motion, and earthquake duration. In accordance with current CGS policy (Earth Systems discussion with Jennifer Thornburg, CGS May 2014), we used a site peak ground acceleration of 2/3PGAM and an earthquake magnitude of 8.2. Based upon methods presented by Tokimatsu and Seed (1987), the potential for seismically induced dry settlement ofsoils above the groundwater table for the full soil column height (50 feet) was calculated for boring B‐2 as
1.2 inches before mitigation and 0.8 inches after mitigation. Note, since boring B‐2 did not reach a 50 foot depth, partial soil profile data from our deep boring B‐5 was used. Please note, the drilling operations experienced refusal several times before reaching the standard of care depth of 50 feet. Due to the general uniformity of the soils encountered,seismic settlement is expected to occur on an areal basis and as such per Special Publication 117 (2008), the calculated differential settlement (after Section 5.1 mitigation) between all five (5) borings is estimated to be less than 0.3 inches.
Ground Subsidence: The latest report for subsidence information (Sneed, Michelle, Brandt, J.T., and Solt, Mike, 2014, Land Subsidence, Groundwater Levels, and Geology in the Coachella Valley) indicates this project does not lie in a known subsidence area.
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Flooding: The project site lies within a designated FEMA Flood Zone A (see Figure 2) defined as No Base Flood Elevation determined. This is shown on FEMA Panel 895 of 3805 Map Number 06065C0895G effective 8/38/2008. The project site is in an area where sheet & concentrated flow and erosion could occur. Appropriate project design by the civil engineer, construction, and maintenance can minimize the sheet flooding potential.
Figure 2 Zone A Flood Boundary
From Section 3.3 of this report, please be aware the 1996 google photo shows what looks like braided and meandering dry stream beds are present upstream and downstream of this project.
Therefore, uncontrolled concentrated flows may exist at or near the project site and debris flow may occur.
3.8 Retention Basin Infiltration Testing
As indicated in Section 2.1 of this report, eight (8) exploratory test pits were excavated using a mechanical backhoe to depths ranging between four (4) and five (5) feet below the existing surface so that infiltration test locations will represent the bottom of the proposed infiltration systems as presented to us. The percolation boring locations are shown on the Test Location Map, in Appendix A.
To evaluate the soils encountered, eight infiltration tests were performed. Testing was performed at approximately five feet below existing grade. The infiltration testing was performed with single‐ring infiltrometers, following the general guidelines contained in ASTM D5126, Section 4.1.2.1, Standard Guide for Comparison of Field Methods for Determining Hydraulic Conductivity in Vadose Zone. Single ring test procedures simulate the low water head conditions typically present during shallow infiltration into basins.
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For each test location and elevation, an approximately five‐foot deep pit was excavated using a mechanical backhoe (JD‐310) and the ring of the test apparatus driven with a sledgehammer into the ground an additional approximate three inches. As necessary, powdered bentonite was placed around the edges of the ring in order to create a watertight seal. Care was taken to not alter the structure of the soil during hand excavation. Per ASTM test procedure, potable water was used to evaluate the basic infiltration rate. The tests were performed for a period of at least 6 hours. The soils encountered at each test location and the results of the infiltration testing are presented in Table 5 below.
Table 5
Infiltration Test Results
Test
Location
Test
Description USCS Soil Description
Estimated Unfactored
Approximate
Infiltration Rate*
I‐1
Single Ring
Infiltrometer
Boulders and Cobbles in a Poorly
Graded Sand with Silt Matrix
To 4 feet
21.3 inches/hour
I‐2
Single Ring
Infiltrometer
Poorly Graded Sand with Silt and
Boulders and Cobbles
To 5 feet
21.1 inches/hour
I‐3
Single Ring
Infiltrometer
Borderline Poorly Graded Sand with
Boulders and some Cobbles / Well
Graded Sand with Boulders and some
Cobbles
To 5 feet
14.2 inches/hour
I‐4
Single Ring
Infiltrometer Silty Sand
To 4 feet 5.8 inches/hour
I‐5
Single Ring
Infiltrometer Silty Sand with Boulders and Cobbles
To 5 feet 8.6 inches/hour
I‐6
Single Ring
Infiltrometer Poorly Graded Sand with Silt
To 5 feet 19.2 inches/hour
I‐7
Single Ring
Infiltrometer Poorly Graded Sand with Silt
To 5 feet 21.4 inches/hour
I‐8
Single Ring
Infiltrometer
Poorly Graded Sand with Silt and
some Boulders and Cobbles
To 5 feet
21.3 inches/hour
*Field Values, no factor of safety applied. Typical factors of safety range from 3 to 10 depending on the type of system which will be designed using the field values and depending on the level of pre‐treatment and influent which will be discharged into the basins as per Riverside County BMP Manual (2011).
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As noted in the USCS Soil Description column in Table 5, numerous infiltration test pits had boulders and cobbles. The material tested above considered only the infiltration of the soil matrix. Based on a rock count and estimated volume of the excavated test pits, Earth Systems provides infiltration loss due to impermeable boulders as shown in the following table:
Table 6
Estimated Infiltration Volume Loss Due to Impermeable Boulders and Cobbles Test
Location USCS Soil Description
Estimated Infiltrating
Volume Loss Due to
Impermeable
Boulders and Cobbles
(%)
I‐1
Boulders and Cobbles in a Poorly
Graded Sand with Silt Matrix
To 4 feet
74 I‐2
Poorly Graded Sand with Silt and
Boulders and Cobbles
To 5 feet
24 I‐3
Borderline Poorly Graded Sand with
Boulders and some Cobbles / Well
Graded Sand with Boulders and some
Cobbles
To 5 feet
25 I‐4 Silty Sand
To 4 feet 2
I‐5 Silty Sand with Boulders and Cobbles
To 5 feet 20
I‐6 Poorly Graded Sand with Silt
To 5 feet 0
I‐7 Poorly Graded Sand with Silt
To 5 feet 2
I‐8
Poorly Graded Sand with Silt and
some Boulders, and Cobbles
To 5 feet
11 When calculating basin volumes, these are the losses of infiltrating volume that occur due to the impermeable boulders and cobbles within the site soils. Basin volume calculations should consider these losses.
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Section 4
CONCLUSIONS
The following is a summary of our conclusions and professional opinions based on the data obtained from a review of selected technical literature and the site evaluation.
General:
From a geotechnical perspective, the site is suitable for the proposed development, provided the recommendations in this report are followed in the design and construction of this project.
Geotechnical Constraints and Mitigation:
The primary geologic hazard is severe ground shaking from earthquakes originating on regional faults. A major earthquake above magnitude 7 to 8 originating on the local segment of the San Andreas or nearby fault zones would be the critical seismic event that may affect the site within the design life of the proposed development. Engineered design and earthquake‐resistant construction increase safety and allow development of seismic areas. The underlying geologic condition for seismic design is Site Class D. A qualified professional should design any permanent structure constructed on the site. The minimum seismic design should comply with the 2016 edition of the California Building Code. The site is about 0.7 milesfrom a Type A seismic source as defined in the California Geological Survey. A qualified professional should design any permanent structure constructed on the site. The minimum seismic design should comply with the 2016 edition of the California Building Code.
The soils are susceptible to wind and water erosion. Preventative measures to reduce seasonal flooding and erosion should be incorporated into site grading plans. Dust control should also be implemented during construction. Site grading should be in strict compliance with the requirements of the South Coast Air Quality Management District [SCAQMD]. Other geologic hazards, including fault rupture, liquefaction, seismically induced flooding, and lateral spreading are considered low.
Site soils are generally very low in Expansion Index. Site soils are potentially very mildly corrosive to buried metallic elements and “negligible” for sulfate exposure. See Section 3.6 for further information. Site soils should be reviewed by an engineer competent in corrosion evaluation.
Currently the site is outside the defined area where damaging subsidence related settlement has occurred. Groundwater overdraft is occurring in the Coachella Valley on a regional level and must be addressed ultimately on a regional level through decreased pumping and increased recharge. It is important to emphasize increased pumping and continued groundwater overdraft may lead to increased subsidence related settlement which is Item Number: 1.
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impossible to predict the magnitude of given the current level of information. If differential pumping occurs, subsidence and the damaging effects of differential settlement occur. Site soils are non‐uniform and generally in a medium to dense compact condition.
Overexcavation and recompaction is required to reduce the potential for settlement by providing a compacted fill mat below foundations in order to better distribute loading. Significand trash and debris (scattered and spoil piles) exist onsite consisting of all form of construction and house hold materials (concrete chunks, metal, vegetation, trash, wood, etc.).
Site soil has a large percentage of boulders and cobbles, which are “oversize” and must be handled during grading.
Site soils were generally dry to damp with moisture contents less than approximately 1%.
Optimum moisture content for compaction purposes was on the order of 9%. The addition of significant water for compaction moisture conditioning will likely be required.
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Section 5
RECOMMENDATIONS
5.1 Site Development – Grading
A representative of Earth Systems should observe site clearing, grading, and the bottoms of excavations before placing fill. Local variations in soil conditions may warrant increasing the depth of recompaction and over‐excavation.
Proper geotechnical observation and testing during construction is imperative to allow the geotechnical engineer the opportunity to verify assumptions made during the design process, to verify our geotechnical recommendations have been properly interpreted and implemented during construction, and is required by the 2016 California Building Code. Observation of fill placement by the Geotechnical Engineer of Record should be in conformance with Section 17 of the 2016 California Building Code. California Building Code requires full time observation by the geotechnical consultant during site grading (fill placement). Therefore, we recommend Earth Systems be retained during the construction of the proposed improvements to provide testing and observe compliance with the design concepts and geotechnical recommendations, and to allow design changes in the event subsurface conditions or methods of construction differ from those assumed while completing our previous study. Additionally, the California Building Code requiresthe testing agency to be employed by the project owner or representative (i.e. architect) to avoid a conflict of interest if employed by the contractor.
Clearing and Grubbing: At the start ofsite grading, existing vegetation, pavement,septic systems, irrigation systems, undocumented fill, construction debris, foundations, structures, trash, and underground utilities should be removed from the proposed building pad and improvement areas. Onsite soil with deleterious material may be reused if the deleterious material can be removed. Oversize material, trash, debris, vegetation (greater than 1% organic content), etc. should be removed before use as engineered fill.
Undocumented fill, and buried utilities may be located in the vicinity of the planned structures and within other areas of the project site. All buried structures which are removed should have the resultant excavation backfilled with soil compacted as engineered fill described herein or with a minimum 2‐sack sand slurry approved by the project geotechnical engineer. Abandoned utilities should be removed entirely, or pressure‐filled with concrete or grout and be capped.
Abandoned buried utilities structures, or foundations should not extend under building limits.
After stripping and grubbing operations, areas to receive fill should be stripped of loose or soft earth materials until a firm subgrade is exposed, as evaluated by the geotechnical engineer or geologist. Before the placement of fill or after cut, the existing surface soils within the building pads and improvement areas should be over‐excavated as follows:
Pad Preparation: Due to the non‐uniform and variable low‐density of shallow soils, the existing soils within the building pad and foundation areas should be over‐excavated a minimum of four feet below existing or finished grade, or two feet below the bottom of the deepest foundation, whichever is lower. Due to the undulatory nature of the ground surface, the overexcavation depth is as measured from the “lowest” adjacent grade in undulatory areas, i.e. from the “valley” Item Number: 1.
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not the “peaks”. The exposed subgrade bottom should be observed and tested by the geotechnical engineer or his representative to verify an in‐place density of the subgrade is at or greater than 85% relative compaction per ASTM D 1557 or soils are firm (as determined by the geotechnical engineer). Deeper over‐excavation may be recommended if the required in‐place density is not achieved or soils are not firm.
Once the subgrade is attained and approved, the surface should be scarified an additional 12 inches, moisture conditioned to near optimum moisture and recompacted to a minimum of 90% relative compaction per ASTM D 1557. Moisture conditioned, compacted engineered fill should then be placed to finished grade. The over‐excavation should extend for at least 5 feet beyond the outer edge of the building pad and include all exterior footings or slabs, where possible, and include any overhead canopy/or covered walkway and patio areas.
Auxiliary Structures Subgrade Preparation: Auxiliary structures such as garden, trash enclosure, or retaining walls, and slabs‐on‐grade for support of structures/skids should have the foundation subgrade prepared similar to the building pad recommendations given above depending on their location. The lateral extent of the over‐excavation needs only to extend 2 feet beyond the face of the footing. Moisture conditioned, compacted engineered fillshould then be placed to finished grade.
Pavement Area Preparation: In street, drive, and permanent parking areas, the exposed subgrade should be over‐excavated, scarified, moisture conditioned, and compacted to at least 90% relative compaction (ASTM D 1557) for a depth of two foot below existing grade or finish grade (whichever is deeper). Engineered fill should then be moisture conditioned, placed in suitable lifts, and compacted to a minimum of 90% relative compaction to finish grade, with the upper 1 foot compacted to at least 95% relative compaction. Compacted fill should be placed to finish subgrade elevation. Compaction should be verified by testing.
All over‐excavations should extend to a depth where the project geologist, engineer or his representative has deemed the exposed soils as being suitable for receiving compacted fill. The materials exposed at the bottom of excavations should be observed by a geotechnical engineer or geologist from our office before the placement of any compacted fill soils to verify all old fill is removed. Additional removals may be required as a result of observation and/or testing of the exposed subgrade after the required over‐excavation.
Subgrade Preparation: In areas to receive fill not supporting structures or lightly loaded hardscape (i.e. no vehicle traffic), the subgrade should be overexcavated; moisture conditioned, and compacted to at least 90% relative compaction (ASTM D 1557) for a depth of 2 foot below existing or finished subgrade, whichever is lower. Compaction should be verified by testing.
Stormwater Infiltration Bottom Preparation: Compaction effort should be kept to a minimum at retention basin bottom areas and bottom areas used for infiltrators (except under foundations).
The bottom of basins and infiltrator bottomsshould be compacted to approximately 85% relative compaction. Side slopes and any other fill should be compacted to at least 90% relative compaction.
Item Number: 1.
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The materials exposed at the bottom of excavations should be observed by a geotechnical engineer or geologist from our office before the placement of any compacted fillsoils. Additional removals may be required as a result of observation and/or testing of the exposed subgrade after the required over‐excavation.
Engineered Fill Soils: The native soil is suitable for use as engineered fill and utility trench backfill provided it is free of significant organic or deleterious matter (less than 1%), debris, concrete, and oversize rock. From research of USDA and during drill logging, oversize rock (cobbles and boulders) exist onsite. The USDA designation of Carsitas Fine Sand indicates 0‐15 percent of 3 inch or larger rock may exist. Construction debris, concrete, asphalt, etc. is not suitable for placement within fill in building pads, but concrete or asphalt may be processed to smaller than 1‐inch in maximum dimension and blended within parking lot fills. Fill should remain substantially soil (at least 70% passing a ¾” sieve and similar to the gradation below for import soils, although an actual specification is not proposed). Unprocessed materials should be hauled offsite.
Screening and crushing will likely be required to properly remove oversize material and obtain a soil fill. Rock fills are not recommended due to the shallow fill and overexcavation depths.
Imported fill soils (if needed) should be non‐expansive, granular soils meeting the USCS classifications of SM, SP‐SM, or SW‐SM with a maximum rock size of 3 inches and have at least 70% passing a ¾ inch sieve and at least 40% passing No. 16 sieve and 5 to 35% passing the No. 200 sieve (or as approved by the geotechnical engineer). The geotechnical engineer should evaluate the import fill soils before hauling to the site. However, because of the potential variations within the borrow source, import soil will not be prequalified by Earth Systems.
Within areas to receive foundations and slabs‐on‐grade the fill should be “very low” in Expansion Index. Expansive soils which are identified should be removed and replaced with low permeability soils which are “very low” in expansion potential. Soils which are found to have an Expansive Index greater than “very low” will require differing compaction and moisture conditioning requirements which should be provided on a case by case basisfor each specific building location.
All fill should be placed in maximum 8‐inch lifts (loose thickness), moisture conditioned to near optimum moisture content, and compacted to at least 90 percent relative compaction in general accordance with ASTM D 1557 (current edition). In parking and drive areas the upper one foot of subgrade and all aggregate base should be compacted to a minimum of 95 percent relative compaction. Compaction should be verified by testing. In general, oversize rocks larger than 6‐ inch in greatest dimension should be removed from fill. Oversize material may be hauled offsite, used for landscaping, or crushed for use as engineered fill. Crushed rock should conform to the specification for import fill. All soils should be moisture conditioned before application of compactive effort. Moisture conditioning of soils refers to adjusting the soil moisture to just above optimum moisture content. If the soils are overly moist so that instability occurs, or if the minimum recommended compaction cannot be readily achieved, it may be necessary to aerate to dry the soil to optimum moisture content or use other means to address soft soils.
A program of compaction testing, including frequency and method of test, should be developed by the project geotechnical engineer at the time of grading. Acceptable methods of testing may include Nuclear methods such as those outlined in ASTM D 6938 (Standard Test Methods for In‐ Item Number: 1.
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Place Density and Water Content of Soil and Soil‐Aggregate by Nuclear Methods) or correlated hand‐probing. Fill must remain less than 30% retained on a ¾” sieve and meet the requirements for oversize.
Shrinkage and Oversize Losses: Based upon three in‐place soil densities in the upper five feet of soil, and one maximum density curve, assuming an average 93% compaction for fill placement, we calculate the shrinkage limits as ‐5 to 8% with a mean shrinkage of 1%. One standard deviation from the mean is 6% (Negative shrinkage is bulking).
Greater soil loss from shrinkage will result from the removal of oversize material (rocks larger than 6 inches). We have performed a rock volume estimate based upon a rock count performed at each test pit in relation to the volume of the test pits excavated and have considered rock volumes in the upper approximate five feet. Oversize rock quantity estimates are presented in the table below. Rock count data is presented on the attached test pit logsin Appendix A. Losses from oversize rock quantity are in addition to losses from soil shrinkage.
Table 7
Estimated Losses Due to Oversize Rock
Test pit Location
Estimated Oversize Rock
Percentage
by Volume
Estimated Oversize Rock
Percentage
by Weight
TP‐1 8 10
TP‐2 4 5
TP‐3 59 63
TP‐4 56 60
TP‐5 53 58
I‐1 83 85
I‐2 50 54
I‐3 46 51
I‐4 4 4
I‐5 36 40
I‐6 0 0
I‐7 3 4
I‐8 18 21
Fugitive Dust
Site soils are generally dry and have a high potential for wind erosion. General requirements for dust control include:
Utilize continuous to semi‐continuous moisture conditioning of disturbed surfaces, including graded areas and haul roads.
Use best management practices during construction to minimize dust generation, including reduced speeds for vehicular traffic across unpaved areas.
Item Number: 1.
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Terminate dust generating activities when wind speeds exceed 20 mph and employ high‐ wind dust mitigation protocols during high wind events. Use track out devices to eliminate generation of dust onto paved access roads. Pave or use gravel surfaces on haul roads.
Use chemical binders or palliatives on exposed surfaces to maintain surface crusts. Cover exposed stock piles.
Minimize areas of soil disturbance by phased construction practices to avoid large expanses of disturbed land at any given time.
The proposed site lies within an area of high potential for wind erosion. The site soils have a fine‐ grained component of their composition. As such, exposed soil surfaces may be subject to disturbed fine particulate matter (PM10) which can create airborne dust if the soil surface or roadways are not maintained. During construction, watering the soilsurface can reduce airborne dust. Alternatively, a dust control palliative may be spray applied to the soil surface to act as a tackifier which contains loose soil particles. Palliatives must be reapplied periodically as they weather and degrade. Further guidance for dust palliatives can be found in reviewing the United States Department of Agriculture publication Dust Palliative Selection and Application Guide, Document No. 9977‐1207‐SDTDC. Soil data related to dust palliative selection is provided in the Guide’s Table 3 as shown in Figure 3 below.
Figure 3 Excerpt from United States Department of Agriculture (Table 3) Item Number: 1.
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5.2 Excavations and Utility Trenches
Excavations should be made in accordance with OSHA requirements. Using the OSHA standards and generalsoil information obtained from the field exploration, classification of the nearsurface on‐site soils will likely be characterized as Type C. Actual classification ofsite specific soil type per OSHA specifications as they pertain to trench safety should be based on real‐time observations and determinations of exposed soils by the contractor’s Competent Person (as defined by OSHA) during grading and trenching operations.
Our site exploration and knowledge of the general area indicates there is a high potential for caving and slaking of site excavations (overexcavation areas, utilities, footings, etc.). Boulders, cobbles and gravels were common in the explorations. Where excavations over 4 feet deep are planned lateral bracing or appropriate cut slopes of 1½:1 (horizontal/vertical) should be provided. No surcharge loads from stockpiled soils or construction materials should be allowed within a horizontal distance measured from the top of the excavation slope and equal to the depth of the excavation.
Excavations which parallel structures, pavements, or other flatwork, should be planned so that they do not extend into a plane having a downward slope of 1.5:1 (horizontal: vertical) from the bottom edge of the footings, pavements, or flatwork. Shoring or other excavation techniques may be required where these recommendations cannot be satisfied due to space limitations or foundation layout. Where overexcavation will be performed adjacent to existing structures, ABC slot cutting techniques may be used. The width of the slot cuts will depend on the soils encountered at the point of excavation (slot cut widths are generally no greater than 5 to 8 feet and excavated in an alternating A then B, then C pattern to minimize disturbance and undermining to the existing foundations).
Utilities and Trenches: Backfill of utilities within roads or public right‐of‐ways should be placed in conformance with the requirements of the governing agency (water district, public works department, etc.). Utility trench backfill within private property should be placed in conformance with the provisions of this report. In general, service lines extending inside of property may be backfilled with native soils compacted to a minimum of 90% relative compaction per ASTM D 1557. Backfill operations should be observed and tested to monitor compliance with these recommendations. The trench bottom should be in a firm condition before placing pipe, bedding, or fill. Bedding may be required to properly seat utilities due to the anticipated rocky nature of native site soils.
Under pavement sections, the upper 12 inches of trench backfill soil below the pavement section should be compacted to at least 95 percent relative compaction (ASTM D 1557). Backfill materials should be brought up at substantially the same rate on both sides of the pipe or conduit.
Reduction of the lift thickness may be necessary to achieve the above recommended compaction.
Mechanical compaction is recommended; ponding or jetting is not recommended.
In general, coarse‐grained sand and/or gap graded gravel (i.e. ¾‐inch rock or pea‐gravel, etc.) should not be used for pipe/conduit or trench zone backfill due to the potential for soil migration into the relatively large void spaces present in this type of material and water seepage along Item Number: 1.
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trenches backfilled with coarse‐grained sand and/or gravel. Loss of soil may cause damaging settlement.
NOTE: Rocks greater than 3 inches in diameter should not be incorporated within utility trench backfill.
Shoring: Shoring may be required where soil conditions, space or other restrictions do not allow a sloped excavation. A braced or cantilevered shoring system may be used.
A temporary cantilevered shoring system should be designed to resist an active earth pressure equivalent to a fluid weighing 38 pounds per cubic foot (pcf). Braced or restrained excavations above the groundwater table should be designed to resist a uniform horizontal equivalent soil pressure of 59 pounds per cubic foot (pcf). The values provided above assume a level ground surface adjacent to the top of the shoring and do not include a factor of safety.
Fifty percent of an areal surcharge placed adjacent to the shoring may be assumed to act as a uniform horizontal pressure against the shoring. Special cases such as combinations of slopes and shoring or other surcharge loads may require an increase in the design values recommended above. These conditions should be evaluated by the project geotechnical engineer on a case‐by‐case basis.
Cantilevered shoring must extend to a sufficient depth below the excavation bottom to provide the required lateral resistance. We recommend required embedment depths be determined using methods for evaluating sheet pile walls and based on the principles of force and moment equilibrium. For this method, the allowable passive pressure against shoring, which extends below the level of excavation, may be assumed to be equivalent to a fluid weighing 375 pcf.
Additionally, we recommend a factor of safety of at least 1.2 be applied to the calculated embedment depth and passive pressure be limited to 2,000 psf.
The contractorshould be responsible for the structural design and safety of all temporary shoring systems. The contractor should carefully review the boring logs in this report, and perform their own assessment of potential construction difficulties, and methods should be selected accordingly. The method of excavation and support is ultimately left to the contractor with guidance and restrictions provided by the designer and owner.
A representative from our firm should be present during all site demolition, and clearing and grading operations to monitor site conditions; substantiate proper use of materials; evaluate compaction operations; and verify the recommendations contained herein are met.
5.3 Slope Construction
Slopes are not generally proposed for this project; however, minor slopes (less than 5 feet in height) may be constructed. Site soils are highly susceptible to erosion. Compacted fill slopes protected against erosion (per approved methods such as significant planting, facing, or erosion blankets, etc.) should be constructed at 2:1 (horizontal: vertical) or flatter inclinations.
Unprotected slopes with exposed native soils at the surface should be expected to require repair after heavy nuisance or storm runoff occurs due to significant erosion. The above slope Item Number: 1.
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recommendations may change pending a more in‐depth geotechnical evaluation once design plans are developed. Slopes used as nuisance or storm drainage channel slopes which should be no steeper than 3:1.
Compacted fillshould be placed at near optimum moisture content and compacted to a minimum 90 percent of the maximum dry unit weight, as measured in relation to ASTM D 1557 test procedures. The exposed face of any cut or fill slope (upper 12 inches) should have a minimum relative density of 90 percent of the maximum dry unit weight, as measured in relation to ASTM D 1557 test procedures, and be compacted at near optimum moisture content. Due to the highly erodible site soils, slope faces should be protected with facing or densely spaced vegetation to reduce the erosion potential.
5.3.1 Surficial Slope Failures
Site soils are highly susceptible to erosion from wind and water sources. All slopes will be exposed to weathering, resulting in decomposition of surficial earth materials, thus potentially reducing shear strength properties of the surficial soils. In addition, these slopes become increasingly susceptible to rodent burrowing. As these slopes deteriorate, they can be expected to become susceptible to surficial instability such as soil slumps, erosion, soil creep, and debris flows. Development areas immediately adjacent to ascending or descending slopes should addressfuture surficial sloughing ofsoil material and erosion. Such measures may include debris fences, slope facing, catchment areas or walls, diversion ditches or berms, soil planting, velocity reducers or other techniques to contain soil material away from developed areas and reduce erosion. Additionally, foundations should be set back at least 5 feet from the edge of slope or as per the 2013 and 2016 CBC, whichever is greater.
Operation and maintenance inspections should be done after a significant rainfall event and on a time‐based criteria (annually or less) to evaluate distress such as erosion, slope condition, rodent infestation burrows, etc. Inspections should be recorded and photographs taken to document current conditions. The repair procedure should outline a plan for fixing and maintaining surficial slope failures, erosional areas, gullies, animal burrows, etc. Repair methods could consist of excavating and infilling with compacted soil erosional features, track walking the slope faces with heavy equipment, as determined by the type and size of repair. These repairs should be performed in a prompt manner after their occurrence. Slope inclinations should be maintained and a maintenance program should include identifying areas where slopes begin to steepen. Where future maintenance is not possible,slopesshould be faced to reduce the erosion and degradation potential.
Slope faces are highly erodible even if compacted and will gradually erode and move down slope presenting maintenance issues and debris deposited in drainage devices and flatwork areas. The minimum material necessary to support landscaping should be specified by the landscape consultant (typically less than 6 inches).
5.4 Shallow Foundations
In our professional opinion, foundations for the structures proposed (as presented within) could be supported on shallow foundations bearing in properly prepared and compacted soils placed Item Number: 1.
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as recommended in Section 5.1. The following recommendations are based on “very low” expansion category soils in the upper 5 feet of subgrade. Soils which are found to be more expansive than a “very low” Expansion Index will require differing foundation requirements which should be provided on a case by case basis.
Footing design of widths, depths, and reinforcing are the responsibility of the Structural Engineer, considering the structural loading and the geotechnical parameters given in this report. A minimum footing depth of 18 inches below lowest adjacent grade should be maintained (lowest grade within 2 feet laterally as measured from the foundation bottom). Earth Systems should be retained to observe foundation excavations before placement of reinforcing steel or concrete.
Loose soil or construction debris should be removed from footing excavations before placement of concrete. All footing excavations should be probed for uniformity. Soft or loose zones should be excavated and recompacted to finish foundation bottom subgrade. The bottom of all foundations should be tested to confirm a minimum of 90% relative compaction (ASTM D 1557).
Slope Setback for Foundations: Earth Systems recommends a minimum setback distance of 5 feet. The 2016 California Building Code provides setback distances for foundations along slopes.
Setback distances are measured differently for foundations located above the slope and those located below the slope. For foundations located at the top of the slope, the measurement is taken horizontally from the outside face of the foundation footing to the face of the slope. For foundations located below the slope, the horizontal distance is measured from the face of the structure to the top of the slope. For pools and slopes steeper than 1(H):1(V), please contact Earth System for these setbacks with submittal of detailed information using plan form.
Conventional Spread Foundations: Allowable soil bearing pressures are given below for foundations bearing on recompacted soils as described in Section 5.1. Allowable bearing pressures are net (weight of footing and soil surcharge may be neglected). Continuous wall foundations, 12‐inch minimum and 4‐feet maximum width and 18 inches below grade and maximum width dimension of 4 feet:
2000 psf for dead plus design live loads
Pad foundations, 2 x 2 foot minimum and 7 x 7 foot maximum in plan and 18 inches below grade:
2000 psf for dead plus design live loads
An increase of 300 psf can be included for each additional 0.5 foot of embedment or width increase up to a maximum of 2,900 psf allowable bearing capacity for continuous and isolated foundations.
A one‐third (⅓) increase in the allowable bearing pressure may be used when calculaƟng resistance to wind or seismic loads. The allowable bearing values indicated are based on the anticipated maximum loads of 100 kips for isolated spread footings (7’x7’ maximum) and 4 kip/ft for continuous footings. If the anticipated loads exceed these values, the geotechnical engineer must reevaluate the allowable bearing values as the allowable bearing was controlled by the allowable settlement such that total settlement due to static and seismic is kept at less than 1 inch.
Item Number: 1.
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The spacing between any large spread footingsshould be evaluated by the geotechnical engineer during the plan review stage to confirm or modify the settlement estimates and bearing capacity due to large footings and the influences from adjacent footings. A preliminary analysis suggests spacing the footings(adjacent edge to adjacent edge) a lateral distance from one another of twice the width of the largest footing from any adjacent footing, such that influence effects are minor.
Maximum foundation sizes given above are based on settlement due to Dead + Live loads.
Transect loads such as earthquake or wind loads are not subject to the stated size limitations; however, the allowable bearing pressure (including ⅓ increase) should be followed considering the relevant foundation sizes given above.
An average modulus of subgrade reaction, k, of 200 pounds per cubic inch (pci) can be used to design lightly loaded footings and slabs founded upon compacted fill. Other foundations such as mat slabs, will require the use of differing modulus of subgrade reaction values than used for lightly loaded slabs.
Minimum Foundation Reinforcement: Minimum reinforcement should be provided by the structural engineer to accommodate the settlement potentials presented within. Minimum reinforcement for continuous wall footings should be two, No. 4 steel reinforcing bars, one placed near the top and one placed near the bottom of the footing. This reinforcing is not intended to supersede any structural requirements provided by the structural engineer.
Minor Deep Foundations: Although no specific elements were identified by the architect, miscellaneous structural components such as light poles, gate posts, temporary retaining walls, and flag poles less than 8 feet in embedment length may be supported on cast‐in‐place piles, or direct embed in drilled holes filled with concrete, and the design be based on parameters presented in the subsequent sections of this report. Construction employing poles or posts may utilize design methods presented in Section 1807 of the CBC for sand (SP) material class. For designs utilizing allowable frictional resistance, Earth Systems recommends the use of Section 1810.3.3.1.4 of the CBC. These design methods apply for piles spaced at least 3 pile diameters center to center for axial loads and at least 6 pile diameters center to center for lateral loads as graded in accordance with Section 5.1. Piles spaced closer than these limits could have soil strength reduction and should be evaluated on a case‐by‐case basis by geotechnical engineer.
For piers founded in areas with native soil at the surface, an additional 1.5 feet should be added to the calculated pile embedment due to the potential effects of long‐term surficial disturbance and erosion. Additionally, where piers are constructed adjacent to the tops of slopes, there should be a minimum distance between the top of the slope and the closest edge of the pier of H/3, where ‘H’ isthe height of the slope, otherwise a lateral resistance reduction must be applied.
For piers founded closer than a distance H/3 to the crest or within the slope area itself, the calculated lateral resistance of the soil should be reduced by 30 percent. The above recommendations have considered slopes no steeper than 2:1 (horizontal:vertical). Steeper slopes will require additional analysis and may change the recommendations presented.
The on‐site soils are expected to be excavatable with conventional drilling equipment; however, oversize material of cobbles and boulders should be expected below the depth of over‐ excavation and drilling refusal may occur. Drilled piers should have a minimum 3 inches of Item Number: 1.
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clearance between the embedded post and the soil side wall to allow for adequate placement and flow of concrete.
Drill holes may end up oversize. Casing or other means may be required in a drilled hole. Any "slough" or loose soils at the bottom of the shaft must be removed or tamped prior to setting rebar cages and placing concrete. Extreme care must be exercised to carefully position reinforcing steel cages and place concrete without disturbing the sidewalls of the drilled shafts.
We recommend centralizers be used to positively locate rebar cages within the pier shaft. It is recommended that pier excavations that have not received concrete, not be left open overnight and concrete should be placed the same day.
Normally, drilled pier excavations should be made without the use of water. If necessary, water may be used to facilitate removal of cuttings unless it aggravates caving problems. Added water that may accumulate at the bottom of the hole should be removed from the drilled hole prior to placing the concrete. Sidewalls which have softened from the addition of water should be cleaned of the soft/loose material. Each excavation should be completed in a continuous operation and the concrete should be placed without undue delay. The contractor should use appropriate means to clean the bottom of the excavation so that no loose material is present at the base of the pier. We do not recommend overdrilling beyond specified pier tip elevations to eliminate the need for bottom cleaning in order to account for slough or loose materials at the excavation bottom. To reduce the potential for caving and sidewall sloughing which may contaminate concrete during placement, and segregation, concrete should be placed by tremie methods and not directly chute‐dumped into the hole.
Where casing is used with drilled holes and cannot be withdrawn, the skin friction capacity is theoretically reduced, as are passive resistance and stiffness. The amount of reduction is subject to assessment by the geotechnical consultant. The use of casing with drilled holes should be approved prior to use by the geotechnical engineer.
If casing is required, it should be withdrawn as the concrete is being placed, maintaining a 3‐foot minimum head of concrete within the casing. This is to prevent reduction in the diameter of the drilled shaft due to earth pressure on the fresh concrete and to prevent extraneous material from falling in from the sides and mixing with the concrete. Concrete placement should continue in this manner until suitable concrete extends to the top of the excavation or forms. The upper eight feet of the pier should be consolidated by vibratory means.
Pier capacity is greatly dependent on the soil conditions at the location of the pier and upon contractor means and methods of placement. It is recommended that pier driving or drilled pier drilling operations and concrete placement be performed in the continuous presence of the geotechnical consultant or his representative to confirm that suitable materials for pier support are penetrated, that the dimensions of the installed piers meet the design dimensions, and that the installation has been performed as specified by the 2016 California Building Code.
Observation during drilling or driving is required by the 2016 California Building Code on a full‐ time basis by the geotechnical engineer or his representative. If subsurface conditions noted during drilled pier installation are significantly different than those encountered in our borings, it may be necessary to adjust the overall length of the pier.
Item Number: 1.
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Prior to the placement of steel, and again prior to and during the placement of concrete, the excavation must be examined by the geotechnical consultant before proceeding with construction. The contractor should provide all aid and assistance required by the geotechnical and geologic consultants for field monitoring of the drilled pier operations.
Piers are accepted or rejected based on visual observation and testing during construction. The contractor should not allow nor cause any of this work to be permanently enclosed or covered up until it has been observed, tested, and accepted by the geotechnical engineer and all legally constituted authorities having jurisdiction.
5.4.1 Estimated Settlements for Foundations
Estimated total static settlement should be less than 0.5‐inches, based on footings founded on firm soils as recommended. Total dry sand settlement is estimated to be on the order of about
0.8 inches after recommendations in Section 5.1 are followed. Therefore, a total settlement of
1.2 inches is estimated. The total estimated differential settlement for the combined static and dry seismic settlement is estimated to be less than ¾‐inch. As such, considering both static and seismic differential settlement applied over a typical foundation distance of 40 feet, we recommend the structural engineer design for the standard angular distortion of 1:480, which is normally defined as a tolerable level for typical commercial buildings (County of Riverside, 2000, page 39).
5.5 Seismic Coefficients
This site is subject to strong ground shaking due to potential fault movements along regional faults including the San Andreas and San Jacinto faults. Engineered design and earthquake‐ resistant construction increase safety and allow development of seismic areas. The minimum seismic design should comply with the 2016 edition of the California Building Code [CBC] and ASCE 7‐10 (with July 2013 errata) using the seismic coefficients given in the table below. We have classified this site as Site Class D based on the evaluation presented in Appendix A. Seismic parameters are based upon computation by the Ground Motion Parameter Calculator provided by the United States Geological Survey [USGS] at:
http://earthquake.usgs.gov/designmaps/us/application.php (January 19, 2017).
Item Number: 1.
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2016 CBC (ASCE 7‐10 w/ July 2013 errata) Seismic Parameters
Site Location: 33.89276°N/116.51078°W
Site Class: D
Maximum Considered Earthquake [MCE] Ground Motion
Short Period Spectral Response Ss: 3.008 g
1 second Spectral Response, S1: 1.293 g
Design Earthquake Ground Motion
Short Period Spectral Response, SDS 2.006 g
1 second Spectral Response, SD1 1.293 g
PGAM 1.17 g
The intent of the CBC lateral force requirements are to provide a structural design that will resist collapse to provide reasonable life safety from a major earthquake, but may experience some structural and nonstructural damage. A fundamental tenet of seismic design is inelastic yielding is allowed to adapt to the seismic demand on the structure. In other words, damage is allowed.
The CBC lateral force requirements should be considered a minimum design. The owner and the designer may evaluate the level of risk and performance that is acceptable. Performance based criteria could be set in the design. The design engineer should exercise special care so that all components of the design are fully met with attention to providing a continuous load path. An adequate quality assurance and control program is urged during project construction to verify the design plans and good construction practices are followed. This is especially important for sites lying close to major seismic sources. Design peak horizontal ground accelerations are estimated to be above 1.00 g. Vertical accelerations are typically 1/3 to 2/3 of the horizontal acceleration, but can equal or exceed horizontal accelerations depending upon underlying geologic conditions and basin effects.
5.6 Slabs
Subgrade: Concrete slabs‐on‐grade and flatwork should be supported by compacted soil placed in accordance with Section 5.1 of this report.
Vapor Retarder: In areas of moisture‐sensitive floor coverings, coatings, adhesives, underlayment, goods or equipment stored in direct contact with the top of the slab, bare slabs, humidity controlled environments, or climate‐controlled cooled environments, an appropriate vapor retarder that maintains a permeance of 0.01 perms or less after ASTM E1745’s mandatory conditioning tests should be installed to reduce moisture transmission from the subgrade soil to the slab. For these areas, a vapor retarder (Stego wrap 15‐mil thickness or equal)should underlie the floor slabs. If a Class A vapor retarder (ASTM E 1745) is specified, the retarder can be placed directly on non‐expansive soil, and be covered with a minimum 2 inches of clean sand.
Clean sand is defined as well or poorly‐graded sand (ASTM D 2488) of which less than 5 percent passes the No. 200 sieve and all the material passes a No. 4 sieve. The site soils do not fulfill the criteria to be considered clean sand. Alternatively, the slab designer may consider the use of other vapor retarder systems that are recommended by the American Concrete Institute.
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Low‐slump concrete should be used to help reduce the potential for concrete shrinkage. The effectiveness of the membrane is dependent upon its quality, the method of overlapping, its protection during construction, the successful sealing of the membrane around utility lines, and sealing the membrane at perimeter terminations and of all penetrations. Capillary breaks, if any, beneath slabs should consist of a minimum of at least four inches of permeable base material with the following specified gradation.
Table 8
Percent Passing Sieve Size
Sieve Size Percent Passing
1 inch 100
¾ Inch 90‐100
3/8 Inch 40‐100
#4 25‐40
#8 18‐33
#30 5‐15
#50 0‐7
#200 0‐3
Where vapor retarders are placed directly on a gravel capillary break, they should be a minimum of 15 mil thickness.
Where concrete is placed directly on the vapor retarder “plastic”, proper curing techniques are essential to minimizing the potential of slab edge curl and shrinkage cracking. The edges of slabs can curl upward because of differential shrinkage when the top of the slab dries to lower moisture content than the bottom of the slab. Curling is caused by the difference in drying shrinkage between the top and bottom of the slab. Curling can be exacerbated by hot weather, or dry condition concrete placement, even with proper curing techniques.
The following minimum slab recommendations are intended to address geotechnical concerns such as potential variations of the subgrade and are not to be construed as superseding any structural design. A design engineer should be retained to provide building specific systems to handle subgrade moisture to ensure compliance with SB800 with regards to moisture and moisture vapor.
Slab Thickness and Reinforcement: Slab thickness and reinforcement of slabs‐on‐grade are contingent on the recommendations of the structural engineer or architect and the expansion index of the supporting soil. Based upon our findings, a modulus of subgrade reaction of approximately 200 pounds per cubic inch can be used in concrete lightly loaded (not mat) slab design for the expected compacted subgrade. Mat slab design will require differing modulus values. ACI Section 4.3, Table 4.3.1 should be followed for recommended cement type, water cement ratio, and compressive strength.
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Concrete slabs and flatwork should be a minimum of five inches thick (actual, not nominal). If heavily loaded flatwork is proposed (forklift drive areas, heavy racking, etc.), the actual thickness should be designed by the structural engineer utilizing techniques of the American Concrete Institute (ACI) and may be greater than 5 inches in thickness. We suggest the concrete slabs be reinforced with a minimum of No. 3 rebar at 18‐inch centers, both horizontal directions, placed at slab mid‐height to resist cracking. Concrete floor slabs may either be monolithically placed with the foundations or doweled (No. 4 bar embedded at least 40 bar diameters) after footing placement. The thickness and reinforcing given are not intended to supersede any structural requirements provided by the structural engineer. The project architect or concrete inspector should continually observe all reinforcing steel in slabs during placement of concrete to check for proper location within the slab.
Sidewalks: For sidewalks, 6x6 10/10 welded wire fabric or No. 3 rebar at 18 inches on center may be used. Sidewalks should be at least four inches in actual thickness.
A minimum concrete gap of three (3) inches should be provided around the steel reinforcing fabric and the edge of the formwork. Reinforcing steel should be placed at mid‐height within the sidewalk and placed upon centralizers rather than lifted into place during placement. Flat sheets should be used instead of rolls, as rolls do not allow for accurate locating of the fabric at mid height of the slab. Where the reinforcing steel does not have adequate cover, it will corrode and can fracture the cured concrete and produce unsightly rust discoloration when exposed to the corrosive site soils and landscape water. Fabric should be overlapped at least six inches at joints.
Control joints should be provided in all concrete slabs‐on‐grade at a maximum spacing of approximately four to six feet. All joints should form approximately square patterns to reduce the potential for randomly oriented, contraction cracks. Contraction joints in the slabs should be tooled at the time of the pour or saw cut (¼ of slab depth (1 inch for a 4‐inch slab)) within eight hours of concrete placement. Construction (cold) joints should consist of thickened butt joints with one‐half inch dowels at 18 inches on center or a thickened keyed‐joint to resist vertical deflection at the joint.
Slab‐On‐Grade Control Joints: Control joints should be provided in all regular concrete slabs‐on‐ grade at a maximum spacing of 36 times the slab thickness (12 feet maximum on‐center, each way) as recommended by American Concrete Institute [ACI] guidelines. All joints should form approximately square patterns to reduce the potential for randomly oriented shrinkage cracks.
Control jointsin the slabsshould be tooled at the time of the concrete placement orsaw cut (¼ of slab depth) as soon as practical but not more than 8 hours from concrete placement.
Construction (cold) joints should consist of thickened butt joints with ½‐inch dowels at 18 inches on center embedded per ACI or a thickened keyed‐joint to resist vertical deflection at the joint.
All control joints in exterior flatwork should be sealed to reduce the potential of moisture or foreign material intrusion. These procedures will reduce the potential for randomly oriented cracks, but may not prevent them from occurring.
Curing and Quality Control: The contractor should take precautions to reduce the potential of curling and cracking of slabs in this arid desert region using proper batching, placement, and curing methods. Curing is highly affected by temperature, wind, and humidity.
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Quality control procedures should be used, including trial batch mix designs, batch plant inspection, and on‐site special inspection and testing. Curing should be in accordance with ACI recommendations contained in ACI 211, 304, 305, 308, 309, and 318. Additionally, the concrete should be vibrated during placement. Concrete should be wet cured for at least 7 days with burlap or plastic and not allowed to dry out to minimize surface cracking.
5.7 Retaining Walls and Lateral Earth Pressures
Retaining Walls:
Retaining walls should be designed for an active soil pressure equivalent to a fluid density of 38 pcf. The active lateral earth pressures are for horizontal (level) backfills using the on‐site native soils on walls free to rotate at least 0.1 percent of the wall height. Walls, which are restrained against movement or rotation at the top, should be designed for an at‐rest equivalent fluid pressure of 59 pcf. The lateral earth pressure values presented are for level backfill and are provided for walls backfilled with drainage materials and existing on‐site soils. Walls retaining sloping backfill or other conditions should be evaluated on a case‐by‐case basis by the geotechnical engineer. In addition to the active or at rest soil pressure, the proposed wall structures should be designed to include forces from dynamic (seismic) earth pressure. Dynamic pressures are additive to active and at‐rest earth pressure and should be considered as 93 pcf for flexible walls, and 111 pcf for rigid walls. Seismic pressures are based on PGAM (see Section 5.5) and the near fault location of the site.
Retaining wall foundations should be placed upon compacted fill described in Section 5.1. A backdrain or an equivalent system of backfill drainage should be incorporated into the wall design, whereby the collected water is conveyed to an approved point of discharge.
Design should be in accordance with the 2016 California Building Code. Drain rock should be wrapped in filter fabric such as Mirafi 140N as a minimum. Backfill immediately behind the retaining structure should be a free‐draining granular. Waterproofing should be according to the designer’s specifications. Water should not be allowed to pond or infiltrate near the top of the wall. To accomplish this, the final backfill grade should divert water away from retaining walls.
Compaction on the retained side of the wall within a horizontal distance equal to one wall height (to a maximum of six feet) should be performed by hand‐operated or other lightweight compaction equipment (90% compaction relative to ASTM D 1557 at near optimum moisture content). This is intended to reduce potential locked‐in lateral pressures caused by compaction with heavy grading equipment or dislodging modular block type walls.
The above recommended values do not include compaction or truck‐induced wall pressures. Care must be taken during the compaction operation not to overstress the wall. Heavy construction equipment should be maintained a distance of at least three feet away from the walls while the backfill soils are placed. Upward sloping backfill or surcharge loadsfrom nearby footings can create largerlateral pressures. Should any walls be considered for retaining sloped backfill or placed next to foundations, our office should Item Number: 1.
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be contacted for recommended design parameters. Surcharge loads should be considered if they exist within a zone between the face of the wall and a plane projected 45 degrees upward from the base of the wall. The increase in lateral earth pressure should be taken as 50% of the surcharge load within this zone. Retaining walls subjected to traffic loadsshould include a uniform surcharge load equivalent of 240 psf for auto and 450 psf for truck traffic located at least three feet from the wall back edge. Retaining walls should be designed with a minimum factor of safety of 1.5.
Frictional and Lateral Coefficients:
Resistance to lateral loads(including those due to wind orseismic forces) may be provided by frictional resistance between the bottom of concrete foundations and the underlying soil, and by passive soil pressure against the foundations. An allowable coefficient of friction of 0.50 may be used between cast‐in‐place concrete foundations and slabs and the underlying soil. An allowable coefficient of friction of 0.40 may be used between pre‐ cast or formed concrete foundations and slabs and the underlying soil Allowable passive pressure may be taken as equivalent to the pressure exerted by a fluid weighing 375 pounds per cubic foot (pcf). Vertical uplift resistance may consider a soil unit weight of 105 pounds per cubic foot. The upper one foot of soil should not be considered when calculating passive pressure unless confined by overlying asphalt concrete pavement or Portland cement concrete slab. The soils pressures presented have considered onsite fill soils. Testing or observation should be performed during grading by the soils engineer or his representative to confirm or revise the presented values. Passive resistance for thrust blocks bearing against firm natural soil or properly compacted backfill can be calculated using an equivalent fluid pressure of 375 pcf. The maximum passive resistance should not exceed 2,000 psf. Construction employing poles or posts (i.e. lamp posts) may utilize design methods presented in Section 1807.3 of the CBC for sand (SW, SP, SM, SC, GM and GC) material class.
The passive resistance of the subsurface soils will diminish or be non‐existent if trench sidewalls slough, cave, or are over widened during or following excavations. If this condition is encountered, our firm should be notified to review the condition and provide remedial recommendations, if warranted.
5.8 Site Drainage and Maintenance
Positive drainage in native soils should be maintained away from the structures (5% for five feet minimum) to prevent ponding and subsequent saturation of the foundation soils. Gutters and downspouts in conjunction with a 1 to 2% paved or hardscape grade should be considered as a means to convey water away from foundations if increased fall is not provided.
Drainage should be maintained for all areas. Water should not pond on or near paved areas or foundations. The following recommendations are provided in regard to site drainage and structure performance:
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In no instance should water be allowed to flow or pond against structures, slabs or foundations or flow over unprotected slope faces. Adequate provisions should be employed to control and limit moisture changes in the subgrade beneath foundations or structures to reduce the potential for soil saturation and erosion. Landscape borders should not act as traps for water within landscape areas. Potential sources of water such as piping, drains, broken sprinklers, etc., should be frequently examined for leakage or plugging. Any such leakage or plugging should be immediately repaired. It is highly recommended landscape irrigation or other sources of water be collected and conducted to an approved drainage device. Landscaping and drainage grades should be lowered and sloped such that water drains to appropriate collection and disposal areas.
All runoff water should be controlled, collected, and drained into proper drain outlets.
Control methods may include curbing, ribbon gutters, 'V' ditches, or other suitable containment and redirection devices.
Maintenance of drainage systems and infiltration structures (basins) can be the most critical element in determining the success of a design. They must be protected and maintained from sediment‐laden water both during and after construction to prevent clogging of the surficial soils and any filter medium. The potential for clogging can be reduced by pre‐treating structure inflow through the installation of maintainable forebays, biofilters, or sedimentation chambers. In addition, sediment, leaves, and debris must be removed from inlets and traps and basin bottoms on a regular basis, and basin bottoms must have silt soils removed periodically from the bottom. The drainage pattern should be established at the time of final grading and maintained throughout the life of the project. Additionally, drainage structures should be maintained (including the de‐clogging of piping, basin bottom scarification and removal, etc.) throughout their design life. Maintenance of these structuresshould be incorporated into the facility operation and maintenance manual. Structural performance is dependent on many drainage‐related factors such as landscaping, irrigation, lateral drainage patterns and other improvements.
5.9 Streets, Driveways and Parking Areas
Pavement structural sections for associated drive areas including recommendations for standard asphalt concrete, and Portland cement concrete are provided below.
Pavement Area Preparation: In street, drive, and parking areas, the exposed subgrade should be overexcavated as recommended in Section 5.1, moisture conditioned, and compacted.
Compaction should be verified by testing. Aggregate base should be compacted to a minimum 95% relative compaction (ASTM D 1557).
Automobile Traffic and Parking Areas
Pavement sections presented in the following Table for automobile type traffic areas and are based on assumed R‐values and current Caltrans design procedures. Traffic Indices (TI) of 5 and 7 were used to facilitate the design of asphalt concrete pavements for parking and main drives.
The TI’s assumed below should be reviewed by the project Civil Engineer to evaluate the Item Number: 1.
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suitability for this project. All design should be based upon an appropriately selected Traffic Index. Changes in the traffic indices will affect the corresponding pavement section.
Table 9
Preliminary Flexible Pavement Section Recommendations
Onsite/Interior Automobile Drive Areas
R‐Value of Subgrade Soils ‐ 60 (tested) Design Method – CALTRANS Traffic Index
(Assumed) Pavement Use
Flexible Pavements
Asphaltic
Asphalt‐Concrete
Thickness (inches)
Aggregate
Aggregate Base
Thickness (inches)
5 Parking Areas 3.0 4.0
7 Drive Areas 4.0 4.0
The presented Traffic Indices should be confirmed by the project civil engineer. Changes to the Traffic Index will result in a differing pavement section required.
Conventional, rigid pavements, i.e. Portland cement concrete (PCC) pavements, can be used in areassubject to relatively high static wheel loads and/or heavy vehicle loading and unloading and turning areas (i.e. truck/bus lanes). The pavement section below is based upon the American Concrete Institute (ACI) Guide for Construction of Concrete Parking Lots, ACI 330R, and the assumptions outlined below.
Table 10
Preliminary Portland Cement Concrete Pavement Sections
Areas
Minimum Pavement
PCC Thickness
(inches)
Minimum
28‐Day Flexural
Strength
(psi)
Concrete‐Compressive
Strength
(psi)
Truck Access or
Loading/Unloading Areas
(Traffic Category C, ADTT
=100)
6.0* 550 4,000
Modulus of Subgrade Reaction drive area fill, k = 200 pci *Concrete Pavement may be placed directly on the compacted subgrade (minimum 95% relative compaction ASTM D 1557)
Should the actual traffic category vary from those assumed and listed above, these sections should be modified. All above recommended preliminary pavement sections are contingent on the following recommendations being implemented during construction:
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Pavement should be placed upon compacted fill processed as described in Section 5.1. The upper 12 inches of subgrade soils beneath the asphalt concrete and conventional PCC pavement section should be compacted to a minimum of 95 percent relative compaction (ASTM D 1557).
Subgrade soils and aggregate base should be in a stable, non‐pumping condition at the time of placement and compaction. Exposed subgrades should be proof‐rolled to verify the absence of soft or unstable zones.
Aggregate base materialsshould be compacted at near optimum moisture content to at least 95 percent relative compaction (ASTM D 1557) and should conform to Caltrans Class II criteria. Compaction efforts should include proof‐rolling of the aggregate base with heavy compaction‐specific equipment (i.e. drum rollers).
All concrete curbs separating pavement from landscaped areas should extend at least 6 inches into the subgrade soils to reduce the potential for movement of moisture into the aggregate base layer (this reduces the risk of pavement failures due to subsurface water originating from landscaped areas).
Asphaltic concrete should be Caltrans, ½‐in. or ¾‐in. grading and compacted to a minimum of 95% of the 75‐blow Marshall density (ASTM D 1559) or equivalent. Portland cement concrete pavements should be constructed with transverse joints at maximum spacing of 12 feet. A thickened edge should be used where possible and, as a minimum, where concrete pavements abut asphalt pavements. The thickened edge should be 1.2 times the thickness of the pavement (7.2 inches for a 6‐inch pavement), and should taper back to the pavement thickness over a horizontal distance on the order of 3 feet. All longitudinal or transverse control joints should be constructed by hand forming or placing pre‐molded filler such as "zip strips." Expansion joints should be used to isolate fixed objects abutting or within the pavement area.
The expansion joint should extend the full depth of the PCC pavement. Joints should run continuously and extend through integral curbs and thickened edges. We recommend joint layout be adjusted to coincide with the corners of objects and structures. In addition, the following is recommended for concrete pavements:
1. Slope pavement at least ½ percent to provide drainage;
2. Provide rough surface texture for traction;
3. Cure PCC concrete with curing compound or keep continuously moist for a minimum of seven days;
4. Keep all traffic off concrete until PCC compressive strength exceeds 2,000 pounds persquare inch (truck traffic should be limited until the concrete meetsthe design strength (4,000 psi); and
5. Consideration should be given to having PCC construction joints keyed or using slip dowels on 24‐inch centers to strengthen control and construction joints.
Dowels placed within dowel baskets should be incorporated into the concrete at each saw‐cut control joint (i.e. dowel baskets and dowels are set in place before placement of concrete).
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Portland cement concrete placement and curing should, at a minimum, be in accordance with the American Concrete Institute [ACI] recommendations contained in ACI 211, 304, 305, 308, 309, and 318.
Within the structural pavement section areas, positive drainage (both surface and subsurface) should be provided. In no instance should water be allowed to pond on the pavement. Roadway performance depends greatly on how well runoff water drains from the site. This drainage should be maintained both during construction and over the entire life of the project.
Proper methods, such as hot‐sealing or caulking, should be employed to limit water infiltration into the pavement base course and/or subgrade at construction/expansion joints and/or between existing and reconstructed asphalt concrete sections (if any). Water infiltration could lead to premature pavement failure.
To reduce the potential for detrimental settlement, excess soil material, and/or fill material removed during any footing or utility trench excavation, should not be spread or placed over compacted finished grade soils unless subsequently compacted to at least 95 percent of the maximum dry unit weight, as evaluated by ASTM D 1557 test procedure, at near optimum moisture content, if placed under areas designated for pavement. Where new roadways will be installed against existing roadways, the repaired asphalt concrete pavement section should be designed and constructed to have at least the pavement and aggregate base section as the original pavement section thickness (for both AC and base) or upon the newly calculated pavement sections presented within, whichever is greater.
The appropriate pavement design section depends primarily on the shear strength of the subgrade soil exposed after grading and anticipated traffic over the useful life of the pavement.
R‐value testing or observation of subgrade soils should be performed during grading to verify and/or modify the preliminary pavement sections presented within this report. Pavement designs assume heavy construction traffic will not be allowed on base cap or finished pavement sections.
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Section 6
LIMITATIONS AND ADDITIONAL SERVICES
6.1 Uniformity of Conditions and Limitations
Our evaluation ofsubsurface conditions at the site has considered subgrade soil and groundwater conditions present at the time of our study. The influence(s) of post‐construction changes to these conditions such as introduction or removal of water into or from the subsurface will likely influence future performance of the proposed project. The magnitude of the introduction or removal, and the effect on the surface and subsurface soils is currently unknown.
It should be recognized that definition and evaluation of subsurface conditions are difficult.
Judgments leading to conclusions and recommendations are generally made with incomplete knowledge of the subsurface conditions due to the limitation of data from field studies. The availability and broadening of knowledge and professional standards applicable to engineering services are continually evolving. As such, our services are intended to provide the Client with a source of professional advice, opinions and recommendations based on the information available as applicable to the project location and scope. Recommendations contained in this report are based on our field observations and subsurface explorations, select published documents (referenced), and our present knowledge of the proposed construction. If the scope of the proposed construction changes from that described in this report, the conclusions and recommendations contained in this report are not considered valid unless the changes are reviewed, and the conclusions of this report are modified or approved in writing by Earth Systems.
Final grading and foundation plans were not available for our review before the preparation of thisreport, and therefore, the recommendations presented within may change pending a review of the final grading and foundation plans. Recommendations presented in this report should not be extrapolated to other areas or be used for other projects without our prior review.
Findings of this report are valid as of the issued date of the report and are strictly for the client.
Changes in conditions of a property can occur with passage of time, whether they are from natural processes or works of man, on this or adjoining properties. In addition, changes in applicable standards occur, whether they result from legislation or broadening of knowledge.
Accordingly, findings of this report may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and should not be relied upon after a period of one year. Land use, site conditions (both on site and off site) or other factors may change over time, and additional work may be required with the passage of time.
If during construction, soil conditions are encountered which differ from those described herein, we should be notified immediately in order that a review may be made and any supplemental recommendations provided. In such an event, the contractor should promptly notify the owner so that Earth Systems geotechnical engineer can be contacted to confirm those conditions. We recommend the contractor describe the nature and extent of the differing conditions in writing and that the construction contract include provisions for dealing with differing conditions.
Contingency funds should be reserved for potential problems during earthwork and foundation construction.
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If the scope of the proposed construction changes from that described in this report, the conclusions and recommendations contained in this report are not considered valid unless the changes are reviewed, and the conclusions of this report are modified or approved in writing by Earth Systems.
This report is issued with the understanding that the owner or the owner’s representative has the responsibility to bring the information and recommendations contained herein to the attention of the architect and engineersfor the projectso that they are reviewed for applicability and conformance to the current design and incorporated into the plans for the project.
Earth Systems has striven to provide our services in accordance with generally accepted geotechnical engineering practices in this locality at this time. No warranty or guarantee, express or implied, is made. This report was prepared for the exclusive use of the Client and the Client’s authorized agents.
Demolition, grading and compaction operations should be performed in conjunction with observation and testing. The recommendations provided in this report are based on the assumption that Earth Systems will be retained to provide observation during the construction phase to evaluate our recommendations in relation to the apparent site conditions at that time.
If we are not accorded this observation, Earth Systems assumes no responsibility for the suitability of our recommendations. In addition, if there are any changes in the field to the plans and specifications, the Client must obtain written approval from Earth Systems engineer that such changes do not affect our recommendations. Failure to do so will vitiate Earth Systems recommendations. These services will be performed on a time and expense basis in accordance with our agreed upon fee schedule once we are authorized and contracted to proceed.
Maintaining Earth Systems as the geotechnical consultant from beginning to end of the project will provide continuity of services. The geotechnical engineering firm providing tests and observations shall assume the responsibility of Geotechnical Engineer of Record.
Any party other than the client who wishes to use this report shall notify Earth Systems of such intended use. Based on the intended use of the report, Earth Systems may require that additional work be performed and that an updated report be issued. Non‐compliance with any of these requirements by the client or anyone else will release Earth Systems from any liability resulting from the use of this report by any unauthorized party.
6.2 Additional Services
This report is based on the assumption that an adequate program of client consultation, construction monitoring, and testing will be performed during the final design and construction phases to check compliance with these recommendations. Maintaining Earth System as the geotechnical consultant from beginning to end of the project will provide continuity of services.
Proper geotechnical observation and testing during construction is imperative to allow the geotechnical engineer the opportunity to verify assumptions made during the design process and to verify that our geotechnical recommendations have been properly interpreted and implemented during construction and is required by the 2016 California Building Code.
Therefore, we recommend that Earth Systems be retained during the construction of the proposed improvements to provide testing and observe compliance with the design concepts Item Number: 1.
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and geotechnical recommendations, and to allow design changes in the event that subsurface conditions or methods of construction differ from those assumed while completing our previous study. Additionally, the California Building Codes requires the testing agency to be employed by the project owner or representative (i.e. architect) to avoid a conflict of interest if employed by the contractor.
Construction monitoring and testing would be additional services provided by our firm. The costs of these services are not included in our present fee arrangements, but can be obtained from our office. The recommended review, tests, and observations include, but are not necessarily limited to, the following:
Consultation during the final design stages of the project. A review of the building and grading plansto observe that recommendations of our report have been properly implemented into the design.
Observation and testing during site preparation, grading, and placement of engineered fill and Special Inspection as required by CBC Sections or local grading ordinances. Consultation as needed during construction.
‐o0o‐
Appendices as cited are attached and complete this report.
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REFERENCES
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American Society of Civil Engineers [ASCE], 2010, Minimum Design Loads for Buildings and Other Structures, ASCE 7‐10.
American Society for Testing Materials, 1989, STP 1013, Effects of Soil Characteristics on Corrosion (February, 1989).
Boulanger, R. W., and Idriss, I. M., 2006, Liquefaction susceptibility criteria for silts and clays, J.
Geotechnical and Geoenvironmental Eng., ASCE 132 (11), 1413‐1426.
Bowles, J.E., 1988, Foundation Analysis and Design, Fourth Edition, McGraw‐Hill Book Company.
Bryant, W.A. and Hart, E.W., 2007, Fault Rupture Hazard Zones in California, Division of Mines and Geology, Special Publication 42.
California Department of Water Resources, 1964, Coachella Valley Investigation, Bulletin No. 108, 146 pp.
California Geologic Survey‐SP117A, 2008, Guidelines for Evaluating and Mitigating Seismic Hazards in California.
California Geologic Survey [CGS], 1992, Geologic Map of California, Sana Ana Sheet, GAM019, scale 1:250,000.
California Geologic Survey, 1980, Alquist‐Priolo Earthquake Fault Studies Zone, Desert Hot Springs Quadrangle, January 1, 1980.
County of Riverside, 2015, Geographic Information Services (GIS), Transportation and Land Management Agency, http://www3.tlma.co.riverside.ca.us/pa/rclis/index.html.
County of Riverside, 2000, Technical Guidelinesfor Review of Geotechnical and Geologic Reports, Transportation and Land Management Agency,
http://rctlma.org/Portals/4/Handouts/Grading/technical_guide_geotechnical_geologic_ reports.pdf
Coachella Valley Water District, Coachella Valley Water Management Plan Update, Draft Report, December 2010.
Dept. of the Navy, 1986, NAVFAC DM 7.01: Soil Mechanics, Naval Facilities Engineering Command, Alexandria, Virginia.
Dept. of the Navy, 1986, NAVFAC DM 7.02: Foundations and Earth Structures, Naval Facilities Engineering Command, Alexandria, Virginia.
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Earth Systems Southwest (ESSW), 2007, Geotechnical Engineering Report and Infiltration Testing for Storm Water Retention, Proposed Light Industrial Development, North of Interstate 10 West of Palm Drive, Desert Hot Springs Area of Riverside County, California, dated July 18, 2007, File No.: 11131‐01, Doc No.: 07‐07‐733.
Envicom Corporation and the County of Riverside Planning Department, 1976, Seismic Safety and Safety General Plan Elements Technical Report, County of Riverside.
FEMA, 2017, Map Service Center website http:// msc.fema.gov/ Google Earth, 2017, Aerial Photograph Library, 1996‐2016 Hunt, Roy E., 1984, Geotechnical Engineering Practice, McGraw‐Hill Book Company.
International Code Council [ICC], 2016, California Building Code, 2016 Edition.
Jennings, C.W, 2010, Fault Activity Map of California: California Geologic Survey, Geological Data Map No. 6, scale 1:750,000.
Reichard, E.G. and Mead, J.K., 1991, Evaluation of a Groundwater Flow and Transport Model of the Upper Coachella Valley, California, U.S.G.S. Open‐File Report 91‐4142.
Riverside County Planning Department, 2003, Geotechnical Element of the Riverside County General Plan.
Riverside County Transportation and Land Management Agency, 2003, Riverside County Land Information Service, www.tlma.co.riverside.ca.us/gis/gisdevelop.html.
Sneed, Michelle and Brandt, Justin T., 2007, Detection and Measurement of Land Subsidence Using Global Positioning System Surveying and Interferometric Synthetic Aperture Radar, Coachella Valley, California, 1996‐2005, United States Geologic Survey Scientific Investigations Report 2007‐5251, 31 p.
Sneed, Michelle, 2010, Measurement of Land Subsidence using Interferometry, Coachella Valley, California, Land Subsidence, Associated Hazards and the Role of Natural Resources Development, Proceedings of EISOLS 2010, Queretaro, Mexico, IAHS Publ. 339.
Sneed, Michelle, et al, 2014, Land Subsidence, Groundwater Levels, and Geology in the Coachella Valley, California, United States Geological Survey, Scientific Investigations Report 2014‐ 5075.
Southern California Earthquake Center (S.C.E.C.), 1999, Recommended Procedures for Implementation of DMG Special Publication 117, Guidelines for Analyzing and Mitigating Liquefaction in California: available at web site: http://www.scecdc.scec.org.
Tokimatsu, K, and Seed, H.B., 1987, Evaluation of Settlements in Sands Due To Earthquake Shaking, ASCE, Journal of Geotechnical Engineering, Vol. 113, No. 8, August 1987.
Item Number: 1.
February 27, 2017 47 File No.: 11131‐01
Doc. No.: 17‐02‐705
EARTH SYSTEMS SOUTHWEST
United States Department of Agriculture Soil Conservation Service, 1980, Soil Survey of Riverside County, California Coachella Valley Area, Issued September 1980, Print.
United States Geological Survey, 2008, Documentation for the 2008 Update of the United States National Seismic Hazard Maps: U.S. Geological Survey Open‐File Report 2008–1128, 61 p.
United States Geologic Survey, 2015, Design Maps website: http://ehp3‐ earthquake.wr.usgs.gov/designmaps/.
Wallace, R. E., 1990, the San Andreas Fault System, California: U.S. Geological Survey Professional Paper 1515, 283 p.
Working Group on California Earthquake Probabilities, 2008, The Uniform California Earthquake Rupture Forecast, Version 2 [UCERF 2]: U.S. Geological Survey Open‐File Report 2007‐ 1437 and California Geological Survey Special Report 203, 104 p.
Youd, T.L., and Idriss, I.M., 2001, Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 127, No. 10, October 2001.
Item Number: 1.
EARTH SYSTEMS SOUTHWEST
APPENDIX A
Plate 1 – Site Vicinity Map
Plate 2 – Test Location Map
Plate 3a – Regional Geology Map
Plate 3b Regional Geologic Map Legend
Terms and Symbols Used on Boring Logs
Soil Classification System
Logs of Borings and Test pits
Total Static Load (Spread Footing)
Total Static Load (Continuous Footing)
Dry Seismic Settlement after OX
Site Class Estimator
Item Number: 1.
Light Industrial Business Park
North of I-10 West of Palm Drive
Desert Hot Springs, Riverside County, California
2/27/2017 File No.: 11131-01
Plate 1
Site Vicinity Map
Approximate Site Location
LEGEND
Approximate Scale: 1" = 1 Mile
0 1 Mile 2 Miles
Source: Google Earth satellite image with USGS Topographic map overlay.
Palm Drive
Approximate
Site Location
Earth Systems
Global
Varner Road
I-10 Freeway
Item Number: 1.
A@
A@
A@
A@
A@
#7
#7
#7
#7
#7
#7
#7
#7
""
"
""
"
""
"
""
"
""
"
A@
A@
A@
A@
A@
A@
B-6
B-5
B-4
B-3
B-2
B-1
B-5
B-4
B-3
B-2
B-1
I-8
I-7
I-6
I-5
I-4
I-3
I-2
I-1
TP-5
TP-4
TP-3
TP-2
TP-1
116.50694° W
116.50694° W
116.50833° W
116.50833° W
116.50972° W
116.50972° W
116.51111° W
116.51111° W
116.5125° W
116.5125° W
116.51389° W
116.51389° W
116.51528° W
116.51528° W
116.51667° W
116.51667° W
116.51806° W
116.51806° W
116.51944° W
116.51944° W
116.52083° W
116.52083° W
116.52222° W
116.52222° W
116.52361° W
116.52361° W
33.89583° N33.89583° N
33.89444° N33.89444° N
33.89306° N33.89306° N
33.89167° N33.89167° N
33.89028° N33.89028° N
33.88889° N33.88889° N
A@
A@
A@
A@
A@
#7
#7
#7
#7
#7
#7
#7
#7
""
"
""
"
""
"
""
"
""
"
A@
A@
A@
A@
A@
A@
B-6
B-5
B-4
B-3
B-2
B-1
B-5
B-4
B-3
B-2
B-1
I-8
I-7
I-6
I-5
I-4
I-3
I-2
I-1
TP-5
TP-4
TP-3
TP-2
TP-1
116.50694° W
116.50694° W
116.50833° W
116.50833° W
116.50972° W
116.50972° W
116.51111° W
116.51111° W
116.5125° W
116.5125° W
116.51389° W
116.51389° W
116.51528° W
116.51528° W
116.51667° W
116.51667° W
116.51806° W
116.51806° W
116.51944° W
116.51944° W
116.52083° W
116.52083° W
116.52222° W
116.52222° W
116.52361° W
116.52361° W
33.89583° N33.89583° N
33.89444° N33.89444° N
33.89306° N33.89306° N
33.89167° N33.89167° N
33.89028° N33.89028° N
33.88889° N33.88889° N
0 165 330 660 990 1,320 1,650
Feet
I
2/27/2017
Test Location Map
Light Industrial Business Park
North of I-10 West of Palm Drive
Desert Hot Springs, Riverside County, California
File No.: 11131-01
LEGEND
A@ Approximate Boring Locations
#7 Approximate Infiltration Test Locations
""
" Approximate Test Pit Locations
A@ Approximate Previous Boring Locations (2007)
Earth Systems
Southwest
Test_No Lat_Lon_NAD83
B-1 33.89457N,116.51844W
B-2 33.89237N,116.51431W
B-3 33.89275N,116.51162W
B-4 33.88898N,116.51145W
B-5 33.89028N,116.51435W
Test_No Lat_Lon_NAD83
I-1 33.89471N,116.5188W
I-2 33.89299N,116.51082W
I-3 33.88979N,116.51092W
I-4 33.88875N,116.51081W
I-5 33.88895N,116.51102W
I-6 33.88964N,116.51336W
I-7 33.89152N,116.51625W
I-8 33.89218N,116.51586W
Test_No Lat_Lon_NAD83
TP-1 33.89313N,116.517W
TP-2 33.89356N,116.51455W
TP-3 33.89092N,116.51181W
TP-4 33.88902N,116.51241W
TP-5 33.89097N,116.51544W
Test_No (2007) Lat_Lon_NAD83
B-1 33.89425N,116.51793W
B-2 33.89504N,116.51646W
B-3 33.8932N,116.51502W
B-4 33.89222N,116.51179W
B-5 33.8893N,116.51275W
B-6 33.89222N,116.51667W
Plate 2
Item Number: 1.
Plate 3a
Regional Geologic Map
Earth Systems
Southwest
2/27/2017 File No.: 11131-01
Light Industrial Business Park
North of I-10 West of Palm Drive
Desert Hot Springs, Riverside County, California
LEGEND
Scale: 1" = 1 Mile ¾
0 1¾ Mile 3 Miles ½
ApproximateSite Location
See Plate 3b for description of map units.
Item Number: 1.
DESCRIPTION OF MAP UNITS
Plate 3b
Regional Geologic Map Legend
Earth Systems
Southwest
2/27/2017 File No.: 11131-01
Light Industrial Business Park
North of I-10 West of Palm Drive
Desert Hot Springs, Riverside County, California
Item Number: 1.
Terms and Symbols Used on Boring Logs
Earth Systems
Southwest
DESCRIPTION FIELD TEST
A 1/8 in. (3-mm) thread cannot be rolled
at any moisture content.
Nonplastic
PLASTICITY
Low
Medium
High
The thread can barely be rolled.
The thread is easy to roll and not much
time is required to reach the plastic limit.
The thread can be rerolled several times
after reaching the plastic limit.
MOISTURE CONDITION
Dry.....................Absence of moisture, dusty, dry to the touch Damp................Slight indication of moisture
Moist.................Color change with short period of air exposure (granular soil) Below optimum moisture content (cohesive soil)
Wet....................High degree of saturation by visual and touch (granular soil) Above optimum moisture content (cohesive soil)
Saturated..........Free surface water
RELATIVE PROPORTIONS
Trace.............minor amount (<5%)
with/some......significant amount
modifier/and...sufficient amount to
influence material behavior
(Typically >30%)
Moisture Condition:
Moisture Content:
Dry Density:
An observational term; dry, damp, moist, wet, saturated.
The weight of water in a sample divided by the weight of dry soil in the soil sample expressed as a percentage.
The pounds of dry soil in a cubic foot.
MOISTURE DENSITY
Very Soft
Soft
Medium Stiff
Stiff
Very Stiff
Hard
*N=0-1
N=2-4
N=5-8
N=9-15
N=16-30
N>30
*C=0-250 psf
C=250-500 psf
C=500-1000 psf
C=1000-2000 psf
C=2000-4000 psf
C>4000
Squeezes between fingers
Easily molded by finger pressure
Molded by strong finger pressure
Dented by strong finger pressure
Dented slightly by finger pressure
Dented slightly by a pencil point or thumbnail
CONSISTENCY OF COHESIVE SOILS (CLAY OR CLAYEY SOILS)
Very Loose
Loose
Medium Dense
Dense
Very Dense
*N=0-4
N=5-10
N=11-30
N=31-50
N>50
RD=0-30
RD=30-50
RD=50-70
RD=70-90
RD=90-100
Easily push a 1/2-inch reinforcing rod by hand
Push a 1/2-inch reinforcing rod by hand
Easily drive a 1/2-inch reinforcing rod with hammer
Drive a 1/2-inch reinforcing rod 1 foot with difficulty by a hammer Drive a 1/2-inch reinforcing rod a few inches with hammer *N=Blows per foot in the Standard Penetration Test at 60% theoretical energy. For the 3-inch diameter Modified California sampler,140-pound weight, multiply the blow count by 0.63 (about 2/3) to estimate N. If automatic hammer is used, multiply a factor of 1.3 to 1.5 to estimate N. RD=Relative Density (%). C=Undrained shear strength (cohesion).
RELATIVE DENSITY OF GRANULAR SOILS (GRAVELS, SANDS, AND NON-PLASTIC SILTS)
SOIL GRAIN SIZE
12” 3” 3/4” 4 10 40 200
305 76.2 19.1 4.76 2.00 0.42 0.074 0.002
SOIL GRAIN SIZE IN MILLIMETERS
U.S. STANDARD SIEVE
COARSE FINE BOULDERS COBBLES
GRAVEL SAND
COARSE MEDIUM FINE SILT CLAY
Soil classification is based on ASTM Designations D 2487 and D 2488 (Unified Soil Classification System). Information on each boring log is a compilation of subsurface conditions obtained from the field as well as from laboratory testing of selected samples. The indicated boundaries between strata on the boring logs are approximate only and may be transitional.
DESCRIPTIVE SOIL CLASSIFICATION
LOG KEY SYMBOLS
Bulk, Bag or Grab Sample
Standard Penetration
Split Spoon Sampler
(2” outside diameter)
Modified California Sampler
(3” outside diameter)
No Recovery
GROUNDWATER LEVEL
Water Level (measured or after drilling)
Water Level (during drilling)
Item Number: 1.
Soil Classification System
Earth Systems
Southwest
MAJOR DIVISIONS GRAPHIC
SYMBOL
LETTER
SYMBOL TYPICAL DESCRIPTIONS
COARSE
GRAINED SOILS
FINE-GRAINED
SOILS
GRAVEL AND
GRAVELLY
SOILS
SAND AND
SANDY SOILS
SILTS AND
CLAYS
CLEAN
GRAVELS
GRAVELS
WITH FINES
CLEAN SAND
(Little or no fines)
SAND WITH FINES
(appreciable
amount of fines)
LIQUID LIMIT
LESS THAN 50
LIQUID LIMIT
THAN 50
GREATER
HIGHLY ORGANIC SOILS
VARIOUS SOILS AND MAN MADE MATERIALS
MAN MADE MATERIALS
PT
GW
GP
GM
GC
SW
SP
SM
SC
ML
CL
OL
MH
CH
OH
Well-graded gravels, gravel-sand
mixtures, little or no fines
Poorly-graded gravels, gravel-sand
mixtures. Little or no fines
Silty gravels, gravel-sand-silt
mixtures
Clayey gravels, gravel-sand-clay
mixtures
More than 50% of
material is
than No. 200
sieve size
larger
More than 50% of
material is
than No. 200
sieve size
smaller
More than 50% of
coarse fraction
passing No. 4 sieve
Well-graded sands, gravelly sands,
little or no fines
Poorly-graded sands, gravelly
sands, little or no fines
Silty sands, sand-silt mixtures
Clayey sands, sand-clay mixtures
Inorganic silts and very fine sands,
rock flour, silty low clayey fine sands
or clayey silts with slight plasticity
Inorganic clays of low to medium
plasticity, gravelly clays, sandy
clays, silty clays, lean clays
Organic silts and organic silty
clays of low plasticity
Inorganic silty, micaceous, or
diatomaceous fine sand or
silty soils
Inorganic clays of high plasticity,
fat clays
Organic clays of medium to high
plasticity, organic silts
Peat, humus, swamp soils with
high organic contents
Fill Materials
Asphalt and concrete
More than 50% of
coarse fraction
on No. 4
sieve
retained
Item Number: 1.
0 5
10 15
20 25
30 35
40 45
50 55
60 Boring No.
Project Name
Project Number:
Boring Elevation:
Drilling Method:
Depth (Ft.)
Sample
Type Penetration
Resistance
(Blows/6")
Symbol
USCS
Dry Density
Drilling Date:
Drill Type:
Logged By:
Bulk
SPT
MOD Calif.
Description of Units
(pcf)
Moisture
Content (%)
Note: The stratification lines shown represent the
approximate boundary between soil and/or rock types
and the transition may be gradational. Blow Dry
Graphic Trend
Earth Systems
Southwest
Count Density
Boring completed at 13-1/2 feet due to refusal
No groundwater encountered
Backfilled with cuttings
no recovery
auger bouncing, grinding, with cobbles to 8" and possible boulders
auger refusal at 13 1/2 feet due to bouncing on cobbles and possible boulders
SILTY SAND: brown, medium dense, damp, fine to medium
grained sand, trace fine gravel
POORLY GRADED GRAVEL WITH SAND: gray brown, very
dense, damp, fine to medium grained sand, fine to coarse gravel to 3", some cobbles to 8"
SILTY SAND WITH GRAVEL: light brown to gray, very dense, damp, fine to coarse grained sand, fine to coarse gravel to 3" 1 1
1 122
133
115
SM
GP
SM
4, 5, 8
16, 50/2"
24, 50/2"
21, 45, 40
50/6"
B-1
Light Industrial Business Park TM 37185
11131-01
Approximately 654 feet (MSL)
January 12, 2017
8" HSA
B61 w/Autohammer
R. Howe
79-811B Country Club Drive, Bermuda Dunes, Ca 92203
Phone (760) 345-1588, Fax (760) 345-7315
Item Number: 1.
0 5
10 15
20 25
30 35
40 45
50 55
60 Boring No.
Project Name
Project Number:
Boring Elevation:
Drilling Method:
Depth (Ft.)
Sample
Type Penetration
Resistance
(Blows/6")
Symbol
USCS
Dry Density
Drilling Date:
Drill Type:
Logged By:
Bulk
SPT
MOD Calif.
Description of Units
(pcf)
Moisture
Content (%)
Note: The stratification lines shown represent the
approximate boundary between soil and/or rock types
and the transition may be gradational. Blow Dry
Graphic Trend
Earth Systems
Southwest
Count Density
Boring completed at 28 feet due to refusal
No groundwater encountered
Backfilled with cuttings
no recovery, medium dense
some cobble
no recovery, some cobbles to 8"
auger refusal at 28 feet due to auger bouncing, grinding, binding on cobbles and possible boulders
dry
no recovery
POORLY GRADED SAND WITH SILT: brown, loose, damp,
fine to medium grained sand, some fine gravel, some cobbles to 6"
POORLY GRADED SAND: brown, medum dense, damp, fine
to medium grained sand, trace fine gravel
WELL GRADED GRAVEL WITH SAND: light gray brown,
medium dense, dry, fine to coarse grained sand, fine to coarse gravel to 1"
WELL GRADED SAND WITH SILT AND GRAVEL: light
brown, dense, damp, fine to coarse grained sand, fine to coarse gravel to 1"
1 1
0 0
122
134
128
127
SP-SM
SP
GW
SW-SM
3, 4, 6
6, 16, 32
7, 15, 15
11, 37,
50/5"
17, 19, 21
12, 22, 22
11, 11, 12
20, 25, 33
B-2
Light Industrial Business Park TM 37185
11131-01
Approximately 654 feet (MSL)
January 12, 2017
8" HSA
B61 w/Autohammer
R. Howe
79-811B Country Club Drive, Bermuda Dunes, Ca 92203
Phone (760) 345-1588, Fax (760) 345-7315
Item Number: 1.
0 5
10 15
20 25
30 35
40 45
50 55
60 Boring No.
Project Name
Project Number:
Boring Elevation:
Drilling Method:
Depth (Ft.)
Sample
Type Penetration
Resistance
(Blows/6")
Symbol
USCS
Dry Density
Drilling Date:
Drill Type:
Logged By:
Bulk
SPT
MOD Calif.
Description of Units
(pcf)
Moisture
Content (%)
Note: The stratification lines shown represent the
approximate boundary between soil and/or rock types
and the transition may be gradational. Blow Dry
Graphic Trend
Earth Systems
Southwest
Count Density
Boring completed at 23 feet due to refusal
No groundwater encountered
Backfilled with cuttings
dry, possible cobbles to 12"
very dense, damp, some fine gravel
auger refusal at 23 feet due to auger bouncing, possible cobbles and boulders
POORLY GRADED SAND WITH SILT: light brown, medium
dense, damp, fine to medium grained sand, some cobbles to 6" WELL GRADED GRAVEL WITH SILT AND SAND: brown to
gray, very dense, damp, fine to coarse grained sand, fine to coarse gravel, some cobble to 6", no recovery, logged from auger pull
POORLY GRADED SAND: brown, dense, damp, fine to
medium grained sand, trace fine gravel
1 0
1 1
107
--
117
138
SP-SM
GWGM
SP
7, 11, 15
6, 9, 14
15, 23, 33
19, 37, 44
11, 12, 13
11, 17, 18
B-3
Light Industrial Business Park TM 37185
11131-01
Approximately 645 feet (MSL)
January 12, 2017
8" HSA
B61 w/Autohammer
R. Howe
79-811B Country Club Drive, Bermuda Dunes, Ca 92203
Phone (760) 345-1588, Fax (760) 345-7315
Item Number: 1.
0 5
10 15
20 25
30 35
40 45
50 55
60 Boring No.
Project Name
Project Number:
Boring Elevation:
Drilling Method:
Depth (Ft.)
Sample
Type Penetration
Resistance
(Blows/6")
Symbol
USCS
Dry Density
Drilling Date:
Drill Type:
Logged By:
Bulk
SPT
MOD Calif.
Description of Units
(pcf)
Moisture
Content (%)
Note: The stratification lines shown represent the
approximate boundary between soil and/or rock types
and the transition may be gradational. Blow Dry
Graphic Trend
Earth Systems
Southwest
Count Density
Boring completed at 11 feet due to refusal
No groundwater encountered
Backfilled with cuttings
auger refusal at 11 feet due to auger binding on possible cobbles and boulders
POORLY GRADED SAND WITH SILT: light brown, medium
dense, damp, fine to medium grained sand, trace fine to coarse gravel
WELL GRADED GRAVEL WITH SILT AND SAND: gray,
medium dense, damp, fine to coarse grained sand, fine to coarse gravel, some cobbles to 12"
POORLY GRADED SAND WITH SILT: brown, dense, damp,
fine to medium grained sand, trace fine to coarse gravel, no recovery, logged from auger pull
1 1
1 117
--
123
SP-SM
GWGM
SP-SM
8, 14, 19
20, 27, 24
20, 20, 32
50/5"
B-4
Light Industrial Business Park TM 37185
11131-01
Approximately 623 feet (MSL)
January 12, 2017
8" HSA
B61 w/Autohammer
R. Howe
79-811B Country Club Drive, Bermuda Dunes, Ca 92203
Phone (760) 345-1588, Fax (760) 345-7315
Item Number: 1.
0 5
10 15
20 25
30 35
40 45
50 55
60 Boring No.
Project Name
Project Number:
Boring Elevation:
Drilling Method:
Depth (Ft.)
Sample
Type Penetration
Resistance
(Blows/6")
Symbol
USCS
Dry Density
Drilling Date:
Drill Type:
Logged By:
Bulk
SPT
MOD Calif.
Description of Units
(pcf)
Moisture
Content (%)
Note: The stratification lines shown represent the
approximate boundary between soil and/or rock types
and the transition may be gradational. Blow Dry
Graphic Trend
Earth Systems
Southwest
Count Density
Boring completed at 51-1/2 feet
No groundwater encountered
Backfilled with cuttings
serious auger bouncing, grinding, binding, possible cobbles and boulders
no recovery, some cobbles to 8"
no recovery, some cobbles to 8"
no recovery
POORLY GRADED SAND WITH SILT: light gray brown,
medium dense, dry, fine to medium grained sand
POORLY GRADED SAND: light brown, dense, damp, fine to
medium grained sand, minor coarse gravel, some cobbles to 8" POORLY GRADED SAND WITH SILT: light brown, very
dense, damp, fine to coarse grained sand
WELL GRADED GRAVEL WITH SILT AND SAND: brown,
dense, dry, fine to medium grained sand, fine to coarse gravel to 3"
POORLY GRADED SAND: brown, dense, damp, fine to coarse
grained sand
POORLY GRADED SAND WITH GRAVEL: brown, very
dense, damp, fine to coarse grained sand, fine to coarse gravel to 1"
POORLY GRADED SAND WITH SILT: gray, very dense,
moist, fine to coarse grained sand
POORLY GRADED GRAVEL WITH SAND: brown to gray,
very dense, moist, fine grained sand, fine to coarse gravel to 3" POORLY GRADED SAND WITH GRAVEL: brown to gray,
very dense, moist, fine to medium grained sand, fine gravel 0 1
0 0
121
--
126
126
SP-SM
SP
SP-SM
GW-GM
SP
SP
SP-SM
GP
SP
4, 9, 15
3, 11, 31
12, 19, 16
50/6"
24, 41, 45
20, 26, 30
7, 13, 15
50/6"
6, 16, 27
8, 22, 25
26, 44, 42
14, 30, 35
12, 23, 39
B-5
Light Industrial Business Park TM 37185
11131-01
Approximately 633 feet (MSL)
January 12, 2017
8" HSA
B61 w/Autohammer
R. Howe
79-811B Country Club Drive, Bermuda Dunes, Ca 92203
Phone (760) 345-1588, Fax (760) 345-7315
Item Number: 1.
TP-1
Horizontal and Vertical
Scale: 1" = 5’
05’ 10’ Earth Systems
Southwest
2/27/2017 File No.: 11131-01
0’5’
10’
10’ 15’
Depth (feet)
TP-2
No groundwater encountered
Light Industrial Business Park
North of I10 and West of Palm Drive
Desert Hot Springs, Riverside County, California
0’5’
10’
0 5’ 10’ 15’
Depth (feet)
No groundwater encountered
S NS N
0 - 3’: SP: Poorly Graded Sand, Brown, Fine to Medium Grained Sand, Moist3’ - 5’: SP: Poorly Graded Sand, Brown, Fine to Medium Grained Sand, Damp5’ - 10’: SP-SM: Poorly Graded Sand with Silt and with some Boulders, Brown, Fine to Medium Grained Sand, First Boulder at 5.5’
Approximately 6 Boulders > 1’No Large Cobbles Observed
0 5’
0 - 3’: SP-SM: Poorly Graded Sand with Silt, Brown, Fine to Medium Grained Sand, Moist
3’ - 5’: SW: Well Graded Sand with Gravel, Brown, Fine to Medium Grained Sand, Moist
5’ - 10’: Interbedded SP-SM/SW-SM: Poorly Graded Sand with Cobbles and Boulders, Brown, Fine to Medium Grained Sand/Well Graded Sandwith Gravel and Cobbles and Boulders, Brown, Fine to Coarse GrainedSand Test Pit Logs
SP
SP
SP-SM
SP-SM
SP-SM/SW-SM
SW
Note: Graphical Rock Depictions are Not to Scale or Quantity 2 Boulders > 1’3 Cobbles 8” - 12”
Item Number: 1.
TP-3
Earth Systems
Southwest
File No.: 11131-01
0’5’
10’
0 5’ 10’ 15’
Depth (feet)
TP-4
No groundwater encountered
Light Industrial Business Park
North of I10 and West of Palm Drive
Desert Hot Springs, Riverside County, California
0’5’
10’
0 5’ 10’ 15’
Depth (feet)
No groundwater encountered
E WE W
0 - 3’: SP-SM: Poorly Graded Sand with Silt, Brown, Fine to Medium Grained Sand, Moist
3’ - 9’: Cobbles and Boulders in a Gravelly Sand Matrix (SW), Brown, Fine to Coarse Grained Sand
Approximately 25-30 Boulders <1’Approximately 40-50 Large Cobbles (8”-12”)Approximately 15-25 Small Cobbles (6”-8”) 0 - 2’: SP-SM: Poorly Graded Sand with Silt, Brown, Fine to Medium Grained Sand, Moist
2’ - 5’: Cobbles and Boulders in a Poorly Graded Sand (SP) Matrix, Brown, Fine to Medium Grained Sand, Damp
5’ - 9’: Cobbles and Boulders in a Poorly Graded Sand (SP) Matrix, Brown, Fine to Medium Grained Sand, Moist
Approximately 20-25 Boulders <1’Approximately 35-40 Cobbles 8”-12” 2/27/2017
Horizontal and Vertical
Scale: 1" = 5’
05’ 10’
Test Pit Logs
SP-SM
Cobbles & Boulders
SP-SM
Cobbles & Boulders
Cobbles & Boulders
Note: Graphical Rock Depictions are Not to Scale or Quantity Item Number: 1.
TP-5
Earth Systems
Southwest
File No.: 11131-01
Test Pit Logs
Light Industrial Business Park
North of I10 and West of Palm Drive
Desert Hot Springs, Riverside County, California
0’5’
10’
0 5’ 10’ 15’
Depth (feet)
No groundwater encountered
W E
0 - 2’: SP-SM: Poorly Graded Sand with Silt, Brown, Fine to Medium Grained Sand, Moist, with some Boulders and Cobbles
2’ - 10’: Cobbles and Boulders in a Poorly Graded Sand with Silt (SP-SM) Matrix, Brown, Fine to Medium Grained Sand, Damp
Approximately 30-40 Boulders <1’Approximately 15-25 Large Cobbles (8”-12”) 2/27/2017
Horizontal and Vertical
Scale: 1" = 5’
05’ 10’
SP-SM
Cobbles & Boulders
Note: Graphical Rock Depictions are Not to Scale or Quantity Item Number: 1.
I-1
Earth Systems
Southwest
2/27/2017
Infiltration Test Pit Logs
0’5’
10’
0 5’ 10’ 15’
Depth (feet)
I-2
No groundwater encountered
0’5’
10’
0 5’ 10’ 15’
Depth (feet)
No groundwater encountered
W EW E
File No.: 11131-01
Light Industrial Business Park
North of I10 and West of Palm Drive
Desert Hot Springs, Riverside County, California
Boulders and Cobbles in Sand with Silt (SP-SM) Matrix, Brown, Fine to Medium Grained Sand, Trace Gravel, Moist to 2’, Damp 2’ to 4’
Approximately 40 Large Boulders (1’ - 4’)Approximately 40 - 50 Large Cobble (8”-12”)SP-SM: Poorly Graded Sand with Silt Boulders and Cobbles, Brown Fine to Medium Grained Sand, Moist, Trace Gravel
Approximately 15 Boulders < 1’Approximately 8-10 Cobbles 8”-12” Horizontal and Vertical
Scale: 1" = 5’
05’ 10’
Boulders & Cobbles/
Sand Matrix
SP-SM
Note: Graphical Rock Depictions are Not to Scale or Quantity Item Number: 1.
I-3
Earth Systems
Southwest
0’5’
10’
0 5’ 10’ 15’
Depth (feet)
I-4
No groundwater encountered
0’5’
10’
0 5’ 10’ 15’
Depth (feet)
No groundwater encountered
W EE W
Light Industrial Business Park
North of I10 and West of Palm Drive
Desert Hot Springs, Riverside County, California
SP/SW: Poorly Graded to Well Graded Sand with Boulders and some Cobbles, Brown, Fine to Coarse Grained Sand, SP with Pockets of SW, Moist, TraceGravel Approximately 13 Boulders < 1’Approximately 6-7 Cobbles 8”-12”SM: Silty Sand, Brown, Fine to Medium Grained Sand, Moist to 2’, Damp 2’-4’Approximately 1 Boulder < 1’Approximately 1 Cobble 8”-12” 2/27/2017
Infiltration Test Pit Logs
File No.: 11131-01
Horizontal and Vertical
Scale: 1" = 5’
05’ 10’
SP/SW
SM
Note: Graphical Rock Depictions are Not to Scale or Quantity Item Number: 1.
I-5
Earth Systems
Southwest
0’5’
10’
0 5’ 10’ 15’
Depth (feet)
I-6
No groundwater encountered
0’5’
10’
0 5’ 10’ 15’
Depth (feet)
No groundwater encountered
NW SE
W E
Light Industrial Business Park
North of I10 and West of Palm Drive
Desert Hot Springs, Riverside County, California
SM: Silty Sand with Boulders and Cobbles, Brown, Fine to Medium Grained Sand, Moist to 3’, Damp 3-5’, Trace Gravel
Approximately 13 Boulders < 1’Approximately 8-9 Cobbles 8”-12”SP-SM: Poorly Graded Sand with Silt, Brown, Fine to Medium Grained Sand, Moist to 1.5’, Damp 1.5’ to 4.5’, Trace Gravel, Trace Small Cobble to 6” 0 Boulders < 1’0 Cobbles 8”-12”
2/27/2017
Infiltration Test Pit Logs
File No.: 11131-01
Horizontal and Vertical
Scale: 1" = 5’
05’ 10’
SM
SP-SM
Note: Graphical Rock Depictions are Not to Scale or Quantity Item Number: 1.
I-7
Horizontal and Vertical
Scale: 1" = 5’
05’ 10’
Earth Systems
Southwest
0’5’
10’
0 5’ 10’ 15’
Depth (feet)
I-8
No groundwater encountered
0’5’
10’
0 5’ 10’ 15’
Depth (feet)
No groundwater encountered
E W
E W
Light Industrial Business Park
North of I10 and West of Palm Drive
Desert Hot Springs, Riverside County, California
SP-SM: Poorly Graded Sand with Silt, Brown, Fine
to Medium Grained Sand, Trace Gravel
Approximately 1 Boulders < 1’Approximately 2 Cobbles 8”-12”SP-SM: Poorly Graded Sand with Silt and some Cobbles and Boulders, Brown, Fine to Medium Grained Sand, Moist to 2’, Damp 2-4’, Some Gravel Approximately 4 Boulders < 1’Approximately 9 Cobbles 8”-12” 2/27/2017
Infiltration Test Pit Logs
File No.: 11131-01
SP-SM
SP-SM
Note: Graphical Rock Depictions are Not to Scale or Quantity Item Number: 1.
EARTH SYSTEMS SOUTHWEST - SETTLEMENT ANALYSES
Proposed TM 37185 11131
Width, ft: 7.1 Length, ft: 7.1 Net pressure, ksf: 2.00 Settlement, inches: 0.5 Load, Q: 100 kips Embedment, feet: 1.5 Boring: 3
05 101520253035404550
0.0 0.2 0.4 0.6 0.8 1.0
Depth (feet)
Influence Factor
SchmertmanConsolidation
05 101520253035404550
0 1 2 3 4 5 6 7 8 9 1011
Depth (feet)
Vetical Stresses (ksf)
AppliedEffective
05 101520253035404550
012
Settlement (% of layer)
05 101520253035404550
0 10 20 30 40 50
Depth (feet)
SPT N Values
Item Number: 1.
EARTH SYSTEMS SOUTHWEST - SETTLEMENT ANALYSES
Proposed TM 37185 11131
Width, ft: 2.0 Length, ft: 40.0 Net pressure, ksf: 2.00 Settlement, inches: 0.2 Load, Q: 4 kpf Embedment, feet: 1.5 Boring: 3
05 101520253035404550
0.0 0.2 0.4 0.6 0.8 1.0
Depth (feet)
Influence Factor
SchmertmanConsolidation
05 101520253035404550
0 1 2 3 4 5 6 7 8 9 1011
Depth (feet)
Vetical Stresses (ksf)
AppliedEffective
05 101520253035404550
012
Settlement (% of layer)
05 101520253035404550
0 10 20 30 40 50
Depth (feet)
SPT N Values
Item Number: 1.
EARTH SYSTEMS - EVALUATION OF LIQUEFACTION POTENTIAL AND INDUCED SUBSIDENCE TTM 37185 Lgt Industial Project No: 11131-01 1996/1998 NCEER Method Ground Compaction Remediated to 5 foot depth
Boring: 2 Earthquake Magnitude: 8.2 PGA, g: 0.78 Calc GWT (feet): 100 Total Thickness of Liquefiable Layers: 0.0 feet Estimated Total Ground Subsidence: 0.8 inches 0 1020304050
0.0 0.2 0.4 0.6 0.8
Depth (feet)
Cyclic Stress Ratio
EQ CSR CRR
0 1020304050
0.0 1.0 2.0
Depth (feet)
Factor of Safety
0 1020304050
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Depth (feet)
Volumetric Strain (%)
0 1020304050
0 10 20 30 40 50 60 70
Depth (feet)
SPT N
SPT N N1(60)
Item Number: 1.
Boring No. Project and Number
ESSW Field Staff Depth (ft) Blow Type of di N60 N60HE Vsi** Vsi Фi di/N60i di/Vsi di/Фi Consistency if Consistency if Drilling Company Count Sampler (feet) (blows/ft) (blows/ft) (m/sec) (ft/sec) (degrees) Coarse Grained Fine Grained Drilling Method 2.5 8 c 2.5 4.56 6.07 169.59 556.24 27.41 0.41155 0.00449 0.091201 Loose Firm Degrees Minutes Seconds Decimal (deg.) 5.0 24 c 2.5 13.67 18.22 233.21 764.94 31.82 0.13718 0.00327 0.078571 Medium Dense Stiff
33.8907 7.5 44 c 2.5 25.06 33.41 278.03 911.94 34.91 0.07483 0.00274 0.071622 Medium Dense Very Stiff
10.0 35 c 2.5 19.93 26.58 260.18 853.39 33.68 0.09407 0.00293 0.074234 Medium Dense Very Stiff Degrees Minutes Seconds Decimal (deg.) 12.5 100 c 2.5 64.54 75.93 352.77 1157.09 40.03 0.03292 0.00216 0.062453 Very Dense Hard ‐116.5146 15.0 86 c 2.5 55.51 65.30 337.67 1107.57 39.00 0.03828 0.00226 0.064108 Very Dense Hard
20.0 56 c 5.0 40.40 42.52 298.17 978.00 36.29 0.11758 0.00511 0.137784 Dense Hard Date Drilled 25.0 28 s 5.0 36.18 31.73 273.91 898.42 34.62 0.15756 0.00557 0.144417 Dense Hard 1/12/2017 30.0 100 c 5.0 75.93 75.93 352.77 1157.09 40.03 0.06585 0.00432 0.124906 Very Dense Hard
35.0 43 s 5.0 58.48 48.73 310.20 1017.44 37.11 0.10260 0.00491 0.134722 Very Dense Hard Hammer Weight (lbs) 40.0 47 s 5.0 63.92 53.27 318.30 1044.03 37.67 0.09387 0.00479 0.132734 Very Dense Hard 140 985 Upper 51.5 feet) 45.0 86 s 5.0 116.96 97.47 379.26 1243.97 41.84 0.05130 0.00402 0.119496 Very Dense Hard
50.0 65 s 5.0 88.40 73.67 349.68 1146.96 39.82 0.06787 0.00436 0.125569 Very Dense Hard Hammer Drop (inches) 51.5 62 s 1.5 84.32 70.27 344.92 1131.35 39.49 0.02135 0.00133 0.037981 Very Dense Hard 30 Energy Ratio (%)68Borehole Correction (Cb)*1
*inside diameter of Hollow Stem Auger 990 (Upper 100 feet) Sampler Liner Correction (Cs) Total: 51.5 Total: 1.46681 0.05226 1.399799
1.2 Applied if SPT Sampler Used
1.0 Applied if Cal Sampler Used **Caltrans Geotechnical Services Design Manual, Version 1.0, August 2009 using N60HE corrected only for Hammer Energy
Rod Length Above Ground (ft)3 Consistency classification based upon ASCE 1996Depth to Estimate Vs Over (ft)*100 Spreadsheet Version 2.2.1, 2011: Prepared by Kevin L. Paul, PE, GE *Caltrans Estimation Method
Equipment variable
Correction (%/100)
Donut Hammer 0.50 to 1.00Safety Hammer 0.70 to 1.20AutomaticTrip DonutEnergy ratio (Skempton, 1986) type Hammer 0.80 to 1.30 Desert Ventures: Lgt In 11131‐01
8" HSAR HoweCalPac
Site Latitude (North)Site Longitude (West)
Estimated Shear Wave Velocity **Soil Profile Type (Site Class) DAve. SPT N-value (blows/ft)35Ave. Shear Wave Velocity (ft/sec)**D B‐5
Ave. Friction Angle (degrees)37Based on Depth Less than 100' (ft/sec)Soil Profile Type (Site Class)** Item Number: 1.
EARTH SYSTEMS SOUTHWEST
APPENDIX B
Laboratory Test Results
Item Number: 1.
File No.: 11131‐01
Lab No.: 17‐008
UNIT DENSITIES AND MOISTURE CONTENT ASTM D2937 & D2216
Job Name: Light Industrial Park
Unit Moisture USCS
Sample Depth Dry Content Group
Location (feet) Density (pcf) (%) Symbol
B1 7.5 122 1 GP
B1 10 133 1 SM
B1 12.5 115 1 SM
B2 7.5 122 1 SP
B2 10 134 1 SP
B2 12.5 128 0 SP
B2 15 127 0 GW
B3 2.5 107 1 SP‐SM
B3 5 ‐‐‐ 0 SP‐SM
B3 7.5 117 1 SP‐SM
B3 10 138 1 GW‐GM
B4 2.5 117 1 SP‐SM
B4 5 ‐‐‐ 1 GW‐GM
B4 7.5 123 1 SP‐SM
B5 5 121 0 SP
B5 7.5 ‐‐‐ 1 SP‐SM
B5 12.5 126 0 GW‐GM
B5 15 126 0 GW‐GM
February 27, 2017
EARTH SYSTEMS SOUTHWEST
Item Number: 1.
File No.: 11131‐01
Lab No.: 17‐008
SIEVE ANALYSIS ASTM D6913
Job Name: Light Industrial Park
Sample ID: B1 @ 0‐5 feet
Description: Silty Sand (SM)
Sieve Size % Passing
3" 100
2" 100
1‐1/2" 100
1" 100
3/4" 100
1/2" 99
3/8" 99
#4 98
#10 92
#16 83
#30 65
#40 56
#100 25
#200 13.0
% Coarse Gravel: 0 % Coarse Sand: 6
% Fine Gravel: 2 % Medium Sand: 35 Cu: NA
% Fine Sand: 43 Cc: NA Gradation
% Total Gravel 2 % Total Sand 85 % Fines: 13.0 NA
2/27/2017
0 10
20 30
40 50
60 70
80 90
100
100 10 1 0.1 0.01
% Passing
SIEVE Size, mm
Coarse Gravel Fine Gravel Coarse
Sand Medium Sand Fine Sand Silts and Clays
EARTH SYSTEMS SOUTHWEST
Item Number: 1.
File No.: 11131‐01
Lab No.: 17‐008
SIEVE ANALYSIS ASTM D6913
Job Name: Light Industrial Park
Sample ID: B5 @ 30 feet
Description:
Sieve Size % Passing
3" 100
2" 100
1‐1/2" 100
1" 100
3/4" 91
1/2" 81
3/8" 78
#4 69
#10 52
#16 41
#30 27
#40 21
#100 8
#200 4.6
% Coarse Gravel: 9 % Coarse Sand: 17
% Fine Gravel: 23 % Medium Sand: 31 Cu: 17.82
% Fine Sand: 16 Cc: 0.899 Gradation
% Total Gravel 32 % Total Sand 64 % Fines: 4.6 Poorly Graded 2/27/2017
Poorly Graded Sand w/ Gravel (SP)
0 10
20 30
40 50
60 70
80 90
100
100 10 1 0.1 0.01
% Passing
SIEVE Size, mm
Coarse Gravel Fine Gravel Coarse
Sand Medium Sand Fine Sand Silts and Clays
EARTH SYSTEMS SOUTHWEST
Item Number: 1.
File No.: 11131‐01
Job Name: Light Industrial Park
Lab Number: 17‐008
AMOUNT PASSING NO. 200 SIEVE ASTM D 1140
Fines USCS
Sample Depth Content Group
Location (feet) (%) Symbol
B3 15 4.5 SP
B5 20 4.5 SP
February 27, 2017
EARTH SYSTEMS SOUTHWEST
Item Number: 1.
File No.: 11131‐01
Lab No.: 17‐008
CONSOLIDATION TEST ASTM D 2435
Light Industrial Park Initial Dry Density: 131.2 pcf
B1 @ 10 feet Initial Moisture: 3.3%
Specific Gravity: 2.67
Initial Void Ratio: 0.271
Ring Sample
February 27, 2017
Silty Sand w/Gravel (SM)
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0 1
2 0.1 1.0 10.0
Percent Change in Height
Vertical Effective Stress, ksf
% Change in Height vs Normal Presssure Diagram
Before Saturation Hydrocollapse
After Saturation Rebound
Poly. (After Saturation)
EARTH SYSTEMS SOUTHWEST
Item Number: 1.
File No.: 11131‐01
Lab No.: 17‐008
CONSOLIDATION TEST ASTM D 2435 & D 5333
Light Industrial Park Initial Dry Density: 112.8 pcf
B2 @ 12 1/2 feet Initial Moisture: 0.9%
Specific Gravity: 2.67
Initial Void Ratio: 0.478
Ring Sample
Hydrocollapse: 0.7% @ 2.0 ksf
February 27, 2017
Poorly Graded Sand (SP)
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0 1
2 0.1 1.0 10.0
Percent Change in Height
Vertical Effective Stress, ksf
% Change in Height vs Normal Presssure Diagram
Before Saturation Hydrocollapse
After Saturation Rebound
Poly. (After Saturation)
EARTH SYSTEMS SOUTHWEST
Item Number: 1.
File No.: 11131‐01
Lab No.: 17‐008
CONSOLIDATION TEST ASTM D 2435 & D 5333
Light Industrial Park Initial Dry Density: 116.0 pcf
B3 @ 7 1/2 feet Initial Moisture: 0.9%
Specific Gravity: 2.67
Initial Void Ratio: 0.437
Ring Sample
Hydrocollapse: 0.6% @ 2.0 ksf
February 27, 2017
Poorly Graded Sand w/Silt
(SP‐SM)
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0 1
2 0.1 1.0 10.0
Percent Change in Height
Vertical Effective Stress, ksf
% Change in Height vs Normal Presssure Diagram
Before Saturation Hydrocollapse
After Saturation Rebound
Poly. (After Saturation)
EARTH SYSTEMS SOUTHWEST
Item Number: 1.
File No.: 11131‐01
Lab No.: 17‐008
CONSOLIDATION TEST ASTM D 2435 & D 5333
Light Industrial Park Initial Dry Density: 115.4 pcf
B5 @ 5 feet Initial Moisture: 0.6%
Specific Gravity: 2.67
Initial Void Ratio: 0.445
Ring Sample
Hydrocollapse: 0.5% @ 2.0 ksf
February 27, 2017
Poorly Graded Sand (SP)
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0 1
2 0.1 1.0 10.0
Percent Change in Height
Vertical Effective Stress, ksf
% Change in Height vs Normal Presssure Diagram
Before Saturation Hydrocollapse
After Saturation Rebound
Poly. (After Saturation)
EARTH SYSTEMS SOUTHWEST
Item Number: 1.
File No.: 11131‐01
Lab No.: 17‐008
CONSOLIDATION TEST ASTM D 2435 & D 5333
Light Industrial Park Initial Dry Density: 116.3 pcf
B5 @ 15 feet Initial Moisture: 0.7%
Specific Gravity: 2.67
Initial Void Ratio: 0.434
Ring Sample
Hydrocollapse: 0.8% @ 2.0 ksf
Well Graded Gravel with Silt and
Sand (GW‐GM)
February 27, 2017
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0 1
2 0.1 1.0 10.0
Percent Change in Height
Vertical Effective Stress, ksf
% Change in Height vs Normal Presssure Diagram
Before Saturation Hydrocollapse
After Saturation Rebound
Poly. (After Saturation)
EARTH SYSTEMS SOUTHWEST
Item Number: 1.
File No.: 11131‐01 February 27, 2017
Lab No.: 17‐008
EXPANSION INDEX ASTM D‐4829
Job Name: Light Industrial Park
Sample ID: B5 @ 0‐5 feet
Soil Description: Poorly Graded Sand with Silt (SP‐SM)
Initial Moisture, %: 8.8
Initial Compacted Dry Density, pcf: 115.3
Initial Saturation, %: 52
Final Moisture, %: 13.5
Volumetric Swell, %: ‐0.1
Expansion Index, EI: 0 Very Low
EI ASTM Classification
0‐20 Very Low
21‐50 Low
51‐90 Medium
91‐130 High
>130 Very High
EARTH SYSTEMS SOUTHWEST
Item Number: 1.
File No.: 11131‐01
Lab No.: 17‐008
MAXIMUM DRY DENSITY / OPTIMUM MOISTURE ASTM D 1557 (Modified) Job Name: Light Industrial Park Procedure Used: A
Sample ID: 1 Preparation Method: Moist
Location: B1 @ 0‐5 feet Rammer Type: Mechanical
Description: Lab Number: 17‐008
Sieve Size % Retained (Cumulative)
Maximum Dry Density: 124.1 pcf 3/4" 0.0
Optimum Moisture: 8.7% 3/8" 0.2
#4 1.6
February 27, 2017
Brown Silty F‐M Sand w/Trace
Gravel (SM)
100
105
110
115
120
125
130
135
140
0 5 10 15 20 25 30 35
Dry Density, pcf
Moisture Content, percent
<----- Zero Air Voids Lines,
sg =2.65, 2.70, 2.75
EARTH SYSTEMS SOUTHWEST
Item Number: 1.
File No.: 11131‐01 2/27/2017
Lab No.: 17‐008
SOIL CHEMICAL ANALYSES
Job Name: Light Industrial Park
Job No.: 11131‐01
Sample ID: B1 @ B3 @
Sample Location: 0‐5 feet 0‐5 feet
Resistivity (Units)
as-received (ohm-cm) 36,800 168,000
saturated (ohm-cm) 10,000 35,200
pH 6.5 6.9
Electrical Conductivity (mS/cm) 0.08 0.04
Chemical Analyses
Cations
calcium Ca2+ (mg/kg) 67 42
magnesium Mg2+ (mg/kg) 4.4 4.7
sodium Na1+ (mg/kg) 15 6.6
potassium K1+ (mg/kg) 17 10
Anions
carbonate CO3
2- (mg/kg) N.D. N.D.
bicarbonate HCO3
1-(mg/kg) 137 85
fluoride F1- (mg/kg) N.D. N.D.
chloride Cl1- (mg/kg) 7.9 4.2
sulfate SO4
2- (mg/kg) 17 4.7
phosphate PO4
3- (mg/kg) N.D. 1.1
Other Tests
ammonium NH4
1+ (mg/kg) 1.4 1.2
nitrate NO3
1- (mg/kg) 30 3.5
sulfide S2- (qual) na na
Redox (mV) na na
Note: Tests performed by Subcontract Laboratory: mg/kg = milligrams per kilogram (parts per million) of dry soil.
HDR Engineering, Inc. Redox = oxidation‐reduction potential in millivolts 431 West Baseline Road ND = not detected
Calremont, California 91711 Tel: (909) 962‐5485 na = not analyzed T.O.P. = top of pipe
General Guidelines for Soil Corrosivity
Soluble 0 ‐1,000 mg/Kg (ppm) [ 0‐.1%] Low
Sulfates1 1,000 ‐ 2,000 mg/Kg (ppm) [0.1‐0.2%] Moderate 2,000 ‐ 20,000 mg/Kg (ppm) [0.2‐2.0%] Severe
> 20,000 mg/Kg (ppm) [>2.0%] Very Severe
Resistivity
2 0‐ 900 ohm‐cm Very Severely Corrosive
(Saturated) 900 to 2,300 ohm‐cm Severely Corrosive
2,300 to 5,000 ohm‐cm Moderately Corrosive
5,000‐10,000 ohm‐cm Mildly Corrosive
10,000+ ohm‐cm Progressively Less Corrosive
3 ‐ Earth Systems does not practice corrosion engineering. Results should be reviewed by an engineer competent in corrosion evaluation, especially in regard to nitrites and ammonium.
Resistivity per ASTM G187, Cations per ASTM D6919, Anions per ASTM D4327, and Alkalinity per APHA 2320‐B. Electrical conductivity in millisiemens/cm and chemical analyses were made on a 1:5 soil‐to‐water extract.
Chemical Agent Amount in Soil Degree of Corrosivity
1 ‐ General corrosivity to concrete elements. American Concrete Institute (ACI) Water Soluble Sulfate in Soil by Weight, ACI 318, Tables 4.2.2 ‐ Exposure Conditions and Table 4.3.1 ‐ Requirements for Concrete Exposed to Sulfate‐Containing Solutions. It is recommended that concrete be proportioned in accordance with the requirements of the two ACI tables listed above (4.2.2 and 4.3.1). The current ACI should be referred to for further information. 2 ‐ General corrosivity to metallic elements (iron, steel, etc.). Although no standard has been developed and accepted by corrosion engineering organizations, it is generally agreed that the classification shown above, or other similar classifications, reflect soil corrosivity. Source: Corrosionsource.com. The classification presented is excerpted from ASTM STP 1013 titled “Effects of Soil Characteristics on Corrosion” (February, 1989) EARTH SYSTEMS SOUTHWEST Item Number: 1.
File No.: 11131-01
JOB NAME: Light Industrial Park
SAMPLE I. D.: B1 @ 0-5'
SOIL DESCRIPTION: Silty Fine to Medium Sand (SM)
SPECIMEN NUMBER ABC
EXUDATION PRESSURE 693 487 277
RESISTANCE VALUE 83 80 73
EXPANSION DIAL(0.0001") 000
EXPANSION PRESSURE (PSF) 0.0 0.0 0.0
% MOISTURE AT TEST 8.9 9.9 10.8
DRY DENSITY AT TEST 126.3 125.5 124.9
R-VALUE @ 300 PSI EXUDATION 74
R-VALUE by Expansion Pressure* 100
*Based on a Traffic Index of 5.0 and a Gravel Factor of 1.70 February 27, 2017
0 20
40 60
80 100
800 700 600 500 400 300 200 100
R-Value
Exudation Pressure
EXUDATION PRESSURE CHART
0.00 0.50
1.00 1.50
2.00 0.00 0.50 1.00 1.50 2.00
Cover Thickness by Stabilometer
(Ft)
Cover Thickness by Expansion Pressure (Ft)
EXPANSION PRESSURE CHART
Earth Systems Southwest
Item Number: 1.
DIRECT SHEAR DATA*
Sample Location: B1 @ 0-5 feet
Material: Silty Sand w/Trace Gravel (SM)
Dry Density (pcf): 111.7
Initial Final
Moisture Content (%): 9 14.6
Saturation (%): 49 100
Peak Ultimate
Angle of Friction (degrees): 32 31
c Cohesive Strength (psf): 410 220
Test Type: Peak and Ulitimate
Shear Rate (in/min): 0.008
* Test Method: ASTM D-3080
Desert Hot Springs, California
2/27/2021 11131-01
DIRECT SHEAR TEST
Light Industrial Park
0 500
1000
1500
2000
2500
3000
3500
4000
4500
0 500 1000 1500 2000 2500 3000 3500 4000 4500
Shearing Stress (psf)
Normal Load (psf)
PEAK
ULTIMATE
0 500
1000
1500
2000
2500
3000
3500
4000
4500
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
Shearing Stress (psf)
Horizontal Displacement (in.)
1000 psf 2000 psf 4000 psf
Earth Systems
Southwest
Item Number: 1.
2014 Whitewater River Region WQMP
Tentative Parcel Map No. 39143
Appendix F
Structural BMP and/or Retention Facility Sizing Calculations and Design Details
Item Number: 1.
HYDROLOGY ANALYSIS
FOR
TENTATIVE PARCEL MAP NO. 39143
City of Desert Hot Springs
County of Riverside
February 17, 2025
Prepared for:
NEWLAND CAPITAL GROUP
200 Spectrum Center Drive, Suite 200
Irvine, CA 92618
(949) 214-4779
Prepared by:
Hunsaker & Associate Irvine, Inc.
157 Technology Drive
Irvine, CA 92618
(949)583-1010
Item Number: 1.
HYDROLOGY ANALYSIS
FOR
TENTATIVE PARCEL
MAP No. 39143
CITY OF DESERT HOT SPRINGS
COUNTY OF RIVERSIDE
Prepared Date: 02/17/2025
PREPARED UNDER THE SUPERVISION OF:
02/17/2025
Jianhua “Gary” Guan, R.C.E. 64519, Exp. 06/30/25 Date:
Item Number: 1.
TABLE OF CONTENTS
SECTION TITLE
1 INTRODUCTION
2 EXHIBITS
· EXHIBIT 1 - FEMA MAP
· EXHIBIT 2 – EXISTING CONDITION HYDROLOGY MAP
· EXHIBIT 3 – PROPOSED CONDITION HYDROLOGY MAP
· EXHIBIT 4 – INFILTRATION BASIN EXHIBIT
3 EXISTING CONDITION HYDROLOGY CALCULATIONS
A. 10-YEAR STORM
B. 100-YEAR STORM
4 PROPOSED CONDITION HYDROLOGY CALCULATIONS
A. 10-YEAR STORM
B. 100-YEAR STORM
5 UNIT HYDROGRAPH CALCUALTIONS
6 INFILTRATION BASIN SIZING CALCULATIONS
7 OFF-SITE DRAINAGE ANALYSIS PREPARED BY JE
FULLER
Item Number: 1.
SECTION 1
INTRODUCTION
Item Number: 1.
1 A. INTRODUCTION
The project site is Tentative Parcel Map (TPM) No. 39143 in the City of Desert Hot Springs, County of Riverside. The site consists of approximately 123.4 acres of undeveloped site in the southern end of the City of Desert Hot Springs, generally located north of Interstate 10 (I-10) and west of the intersection of Palm Drive and Varner Road. The general location of the project site can be found from the Vicinity Map below.
B. STUDY PURPOSE
The purpose of this study is to provide a hydrology analysis for the flow rates produced from existing and proposed site conditions for comparison purposes. It also serves as the basis for analyzing and designing proposed and required infiltration basins. The infiltration basins are designed to contain 100% of 100- year 24-hour storm event runoffs per City Ordinance #1997-03 Section
13.08.100. In addition, the infiltration basins also serve as the water quality treatment measures to ensure the developed flows are treated prior to releasing to downstream water courses. This hydrology study is mainly focused on the onItem Number: 1.
2 site development areas and the off-site runoff studies which were prepared by JE Fuller can be found in Section 7.
C. EXISTING CONDITION
The entire project site consists of desert land, with shrubs, boulders and rocks scattered throughout the area. Onsite vegetation consists mainly of Sonoran Creosote Brush Scrub in areas not disturbed by existing roads that traverse the project site. Topographically, the site is generally flat and slopes downward to the southeast.
There are no existing storm drain systems available off-site and on-site. Natural drainage channels convey the storm runoff into the project area on the north side and continue through the project area toward the south side of the site with storm runoff generally characterized as sheet flow to the existing drainage swale along I-10 and continue southeastern direction.
The portion north of Varner Road is completely within the Willow Hole Conservation Area. Currently, Varner Road is an unmarked, partially paved road from Palm Drive on the east to its existing terminus near Mission Creek. Mihalyo Road, which is an unpaved dirt road, terminates near the northwestern portion of the site. Mihalyo road will not be developed as a street. It is being removed as part of TPM. Additionally, two existing underground 30-inch diameter gas transmission lines traverse the area in a northwest-southeast alignment within a 40-ft wide utility easement.
Currently, flooding and drainage conditions and issues associated with Mission Creek and the Big Morongo Wash constrain the project developments and its surroundings. The entire project site is located within the 100-year flood plain with no base flood elevations determined (Zone A) per Flood Insurance Rate Map (FIRM) Map No. 06065C0895G dated August 28, 2008, receiving flows from the Mission Creek and Big Morongo Wash watersheds, the FIRM map with the project site can be found in Exhibit 1.
In response to these conditions and to comply with the National Flood Insurance Program (NFIP) requirements, a revision to the effective Flood Insurance Rate Map (FIRM) is required to remove the project site from the 100-year floodplain.
To comply with the NFIP requirements, a Letter Of Map Revision (LOMR) will be applied via FEMA after the improvements are completed.
D. PROPOSED CONDITION
The proposed development encompasses an industrial building with loading docks, drive-through facilities, parking areas, landscaping, and ancillary features designed to support the area’s growing industrial needs.
Item Number: 1.
3 development provides solutions to ensure that the drainage flows of the area are maintained and to ensure that flooding is not an issue for the development areas. Solutions include raising the development pads above the areas flood zone level/line and incorporating wide drainage channels and infiltration basins that function as an engineering solution to the area’s drainage and flooding issues. The infiltration basins will be designed and constructed not only for the retention of 100-year 24-hour storm runoffs in accordance with the City’s requirements, but also for water quality purposes. The infiltration basins will serve as water quality treatment measures to ensure the developed onsite flows are treated prior to releasing downstream water courses.
E. HYDROLOGY METHODOLOGY
The rational method was used to calculate the design discharge for the local drainage areas since the watershed area to the proposed storm drain systems is less than one square mile.
Hydrologic calculations to determine the 10-year and 100-year discharges at critical locations were performed using the Riverside County Rational Method. A technical description of the rational method is provided in the Riverside County Flood Control and Water Conservation District Hydrology Manual dated April, 1978.
The hydrology calculations are based on the Riverside County Hydrology Program, as incorporated by CIVILCADD/CIVILDESIGN Engineering Software for determining peak runoff. The equations, charts, soils maps and rainfall intensity curves maps used are from the Hydrology Manual. The precipitation data was from the latest NOAA atlas rainfall. The rational method was used to calculate the 10-year and 100-year storm frequency peak flow rates for a 1-hour storm event.
Synthetic Unit Hydrograph Method was used to calculate the storm runoff volumes. It was discovered that the peak flow rates generated by the synthetic unit hydrographs were quite different than those generated by the rational method. The Riverside County Flood Control & Water Conservation District informed us that the way they solve the same problem is by adjusting the Manning “n” value used to develop the Synthetic Unit Hydrograph. The manning “n” may be adjusted until the peak flow rate given from the Synthetic Unit Hydrograph matches that of the rational method peak flow rate.
This method was then implemented. Using “UNRIV”, it was possible to match the peak flow rate of U.H. to that of the rational run, by refining the “n” value repeatedly. Once the peak flow rates matched for the 1-hour storm, the same Manning “n” was applied to 24-hour period. All pertinent information is included on the hydrology maps contained in this report.
Item Number: 1.
4 The project site lies within the soil boundary of Riverside County Flood Control District Hydrology Manual; Soil Type A was selected in the hydrology analysis per the Hydrology Manual. Hydrologic soils ratings are based on a scale of A through D, where A is the most pervious, providing the least runoff.
F. HYDROLOGY CALCULATION RESULTS
The hydrology calculations were performed for the on-site development areas only. The off-site flows and conveyance studies prepared by JE Fuller can be found in Section 7 as references.
Existing Condition
There is only one drainage area in the existing condition. The studied Drainage Area contains an approximate area of 93.0 acres of on-site development areas and produces a 100-year storm peak flow rate of 212.1 cfs. Detailed hydrology calculations can be found in Section 3 and the existing condition hydrology map (Exhibit 2) can be found in Section 2.
Proposed Condition
In the proposed condition, the same drainage area was studied and analyzed.
Detailed hydrology calculations can be found in Section 4 and the proposed condition hydrology map (Exhibit 3) can be found in Section 2.
There will have three on-site infiltration basins to contain and infiltrate the development area 100-year 24-hour storm volumes. The tributary areas, required 100-year 24-hour storm volumes and provided basin volumes are illustrated in Exhibit 4. Overall, the drainage path is similar to the existing condition with all the project flows sheet flow to the existing drainage swale along I-10.
The hydrology summary with the comparison with existing conditions is illustrated in Table 1.
Item Number: 1.
5 TABLE 1 SUMMARY OF HYDROLOGY ANALYSIS
TPM 39143 in City of Desert Hot Springs, Riverside County Existing (1) Proposed (2) Difference (3) = (2) - (1)
Drainage
Area
Area 10-year 100-year Drainage
Area
Area 10-year 100-year Area 10-year 100-year
(ac) (cfs) (cfs) (ac) (cfs) (cfs) (ac) (cfs) (cfs)
A 93.0 100.1 212.1 A 93.0 146.5 280.4 0.0 46.4 68.3
Total 93.0 100.1 212.1 Total 93.0 146.5 280.4 0.0 46.4 68.3 Note:
The proposed onsite basins will be proposed to collect and infiltrate the 100-year 24-hour storm volumes Unit Hydrograph Analysis
Synthetic Unit Hydrograph Method was used to calculate the storm runoff volumes. Only the proposed condition unit hydrograph calculations were performed. The 100-year storm with 1-hour and 24-hour storm period was analyzed for sizing the required infiltration basins.
The Project would provide three (3) on-site stormwater infiltration basins that during the life of the project will comply with the Stormwater Management and Discharge Controls stipulated in Chapter 13.08 of the Desert Hot Springs Municipal Code (Ordinance #1997-03). The provided basin capacities are sized to contain the 100-year, 24-hour duration storm event and therefore meet the City’s requirements on Stormwater Management and Discharge Controls and minimize the discharge and transport of pollutants associated with the new developments.
The volumes for the proposed condition 100-year 24-hour storm events are used in the infiltration basin volume design to meet the City’s requirements for the low impact developments (LID) and water quality treatments due to the project developments. Detailed unit hydrograph calculations can be found in Section 5.
Infiltration Basins
There are 3 infiltration basins proposed for the project site – Basin B, Basin C and Basin D. Basin B and Basin D interconnected together with a concrete spillway in between. The concrete spillway was provided for the protection of the existing gas lines and was used to bypass the off-site storm runoffs. The volumes below the spillways were used for on-site storm runoff infiltration. The basins are proposed for LID and water quality treatment purposes. As shown from the basin sizing calculations in Section 6, the infiltration basins are all sized Item Number: 1.
6 larger than the 100-year 24-hour storm runoff volumes as required by City of Desert Hot Springs.
The detailed basin sizing calculations can be found in Section 6 and the summary of unit hydrograph and basin sizing calculations can be found in Table 2.
TABLE 2 SUMMARY OF UNIT HYDROGRAPH ANALYSIS AND INFILTRATION BASINS
TPM 39143 in City of Desert Hot Springs, Riverside County Infiltration
Basin
Area 1-HR Unit
Hydrograph
24-HR Unit
Hydrograph
Basin Volume
provided
(ac) (ac-ft) (ac-ft) (ac-ft)
B & C 76.3 9.3813 23.5849 40.37
D 12.6 1.4373 2.8105 3.16
Item Number: 1.
Item Number: 1.
Item Number: 1.
Item Number: 1.
Item Number: 1.
Item Number: 1.
SECTION 2
EXHIBITS
Item Number: 1.
Item Number: 1.
200 SPECTRUM CENTER DRIVE, SUITE 200
IRVINE, CA 92618
PH: (949) 214-4779
Item Number: 1.
200 SPECTRUM CENTER DRIVE, SUITE 200
IRVINE, CA 92618
PH: (949) 214-4779
Item Number: 1.
200 SPECTRUM CENTER DRIVE, SUITE 200
IRVINE, CA 92618
PH: (949) 214-4779
Item Number: 1.
200 SPECTRUM CENTER DRIVE, SUITE 200
IRVINE, CA 92618
PH: (949) 214-4779
Item Number: 1.
SECTION 3
EXISTING CONDITION HYDROLOGY
CALCULATIONS
Item Number: 1.
A. 10-YEAR STORM
Item Number: 1.
1 Riverside County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software,(c) 1989 - 2014 Version 9.0 Rational Hydrology Study Date: 02/07/25 File:39143exist.out ------------------------------------------------------------------------ Hydrology Study for TPM 39143
In the City of Desert Hot Springs
Existing Condition Onsite Areas
10-year Storm
------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** English (in-lb) Units used in input data file
------------------------------------------------------------------------ Program License Serial Number 6406
------------------------------------------------------------------------ Rational Method Hydrology Program based on
Riverside County Flood Control & Water Conservation District 1978 hydrology manual
Storm event (year) = 10.00 Antecedent Moisture Condition = 2 2 year, 1 hour precipitation = 0.454(In.)
100 year, 1 hour precipitation = 1.690(In.)
Storm event year = 10.0
Calculated rainfall intensity data:
1 hour intensity = 0.963(In/Hr)
Slope of intensity duration curve = 0.5800
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 10.000 to Point/Station 11.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ Initial area flow distance = 280.000(Ft.)
Top (of initial area) elevation = 660.900(Ft.)
Bottom (of initial area) elevation = 657.000(Ft.)
Difference in elevation = 3.900(Ft.)
Slope = 0.01393 s(percent)= 1.39
TC = k(0.530)*[(length^3)/(elevation change)]^0.2
Initial area time of concentration = 11.867 min.
Rainfall intensity = 2.464(In/Hr) for a 10.0 year storm UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.711
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Initial subarea runoff = 1.050(CFS)
Total initial stream area = 0.600(Ac.)
Pervious area fraction = 1.000
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 11.000 to Point/Station 12.000 **** NATURAL CHANNEL TIME + SUBAREA FLOW ADDITION ****
______________________________________________________________________ Top of natural channel elevation = 657.000(Ft.)
End of natural channel elevation = 653.000(Ft.)
Length of natural channel = 260.000(Ft.)
Item Number: 1.
2 Estimated mean flow rate at midpoint of channel = 3.151(CFS) Natural valley channel type used
L.A. County flood control district formula for channel velocity:
Velocity(ft/s) = (7 + 8(q(English Units)^.352)(slope^0.5) Velocity using mean channel flow = 2.35(Ft/s)
Correction to map slope used on extremely rugged channels with drops and waterfalls (Plate D-6.2)
Normal channel slope = 0.0154
Corrected/adjusted channel slope = 0.0154
Travel time = 1.84 min. TC = 13.71 min.
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.698
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 2.266(In/Hr) for a 10.0 year storm Subarea runoff = 3.795(CFS) for 2.400(Ac.)
Total runoff = 4.846(CFS) Total area = 3.000(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 12.000 to Point/Station 13.000 **** NATURAL CHANNEL TIME + SUBAREA FLOW ADDITION ****
______________________________________________________________________ Top of natural channel elevation = 653.000(Ft.)
End of natural channel elevation = 646.000(Ft.)
Length of natural channel = 530.000(Ft.)
Estimated mean flow rate at midpoint of channel = 9.691(CFS) Natural valley channel type used
L.A. County flood control district formula for channel velocity:
Velocity(ft/s) = (7 + 8(q(English Units)^.352)(slope^0.5) Velocity using mean channel flow = 2.85(Ft/s)
Correction to map slope used on extremely rugged channels with drops and waterfalls (Plate D-6.2)
Normal channel slope = 0.0132
Corrected/adjusted channel slope = 0.0132
Travel time = 3.10 min. TC = 16.81 min.
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.679
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 2.013(In/Hr) for a 10.0 year storm Subarea runoff = 8.198(CFS) for 6.000(Ac.)
Total runoff = 13.044(CFS) Total area = 9.000(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 13.000 to Point/Station 14.000 **** NATURAL CHANNEL TIME + SUBAREA FLOW ADDITION ****
______________________________________________________________________ Top of natural channel elevation = 646.000(Ft.)
End of natural channel elevation = 638.500(Ft.)
Length of natural channel = 750.000(Ft.)
Estimated mean flow rate at midpoint of channel = 23.044(CFS) Item Number: 1.
3 Natural valley channel type used
L.A. County flood control district formula for channel velocity:
Velocity(ft/s) = (7 + 8(q(English Units)^.352)(slope^0.5) Velocity using mean channel flow = 3.11(Ft/s)
Correction to map slope used on extremely rugged channels with drops and waterfalls (Plate D-6.2)
Normal channel slope = 0.0100
Corrected/adjusted channel slope = 0.0100
Travel time = 4.01 min. TC = 20.82 min.
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.657
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 1.778(In/Hr) for a 10.0 year storm Subarea runoff = 16.129(CFS) for 13.800(Ac.)
Total runoff = 29.173(CFS) Total area = 22.800(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 14.000 to Point/Station 15.000 **** NATURAL CHANNEL TIME + SUBAREA FLOW ADDITION ****
______________________________________________________________________ Top of natural channel elevation = 638.500(Ft.)
End of natural channel elevation = 630.000(Ft.)
Length of natural channel = 630.000(Ft.)
Estimated mean flow rate at midpoint of channel = 39.409(CFS) Natural valley channel type used
L.A. County flood control district formula for channel velocity:
Velocity(ft/s) = (7 + 8(q(English Units)^.352)(slope^0.5) Velocity using mean channel flow = 4.20(Ft/s)
Correction to map slope used on extremely rugged channels with drops and waterfalls (Plate D-6.2)
Normal channel slope = 0.0135
Corrected/adjusted channel slope = 0.0135
Travel time = 2.50 min. TC = 23.32 min.
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.645
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 1.665(In/Hr) for a 10.0 year storm Subarea runoff = 17.195(CFS) for 16.000(Ac.)
Total runoff = 46.367(CFS) Total area = 38.800(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 15.000 to Point/Station 16.000 **** NATURAL CHANNEL TIME + SUBAREA FLOW ADDITION ****
______________________________________________________________________ Top of natural channel elevation = 630.000(Ft.)
End of natural channel elevation = 625.500(Ft.)
Length of natural channel = 460.000(Ft.)
Estimated mean flow rate at midpoint of channel = 57.242(CFS) Item Number: 1.
4 Natural valley channel type used
L.A. County flood control district formula for channel velocity:
Velocity(ft/s) = (7 + 8(q(English Units)^.352)(slope^0.5) Velocity using mean channel flow = 3.98(Ft/s)
Correction to map slope used on extremely rugged channels with drops and waterfalls (Plate D-6.2)
Normal channel slope = 0.0098
Corrected/adjusted channel slope = 0.0098
Travel time = 1.93 min. TC = 25.25 min.
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.637
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 1.590(In/Hr) for a 10.0 year storm Subarea runoff = 18.434(CFS) for 18.200(Ac.)
Total runoff = 64.801(CFS) Total area = 57.000(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 16.000 to Point/Station 17.000 **** NATURAL CHANNEL TIME + SUBAREA FLOW ADDITION ****
______________________________________________________________________ Top of natural channel elevation = 625.500(Ft.)
End of natural channel elevation = 622.000(Ft.)
Length of natural channel = 310.000(Ft.)
Estimated mean flow rate at midpoint of channel = 85.264(CFS) Natural valley channel type used
L.A. County flood control district formula for channel velocity:
Velocity(ft/s) = (7 + 8(q(English Units)^.352)(slope^0.5) Velocity using mean channel flow = 4.81(Ft/s)
Correction to map slope used on extremely rugged channels with drops and waterfalls (Plate D-6.2)
Normal channel slope = 0.0113
Corrected/adjusted channel slope = 0.0113
Travel time = 1.07 min. TC = 26.32 min.
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.632
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 1.552(In/Hr) for a 10.0 year storm Subarea runoff = 35.339(CFS) for 36.000(Ac.)
Total runoff = 100.140(CFS) Total area = 93.000(Ac.)
End of computations, total study area = 93.00 (Ac.)
The following figures may
be used for a unit hydrograph study of the same area.
Area averaged pervious area fraction(Ap) = 1.000
Area averaged RI index number = 67.0
Item Number: 1.
Item Number: 1.
B. 100-YEAR STORM
Item Number: 1.
1 Riverside County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software,(c) 1989 - 2014 Version 9.0 Rational Hydrology Study Date: 02/07/25 File:39143exist.out ------------------------------------------------------------------------ Hydrology Study for TPM 39143
In the City of Desert Hot Springs
Existing Condition Onsite Areas
100-year Storm
------------------------------------------------------------------------ ********* Hydrology Study Control Information ********** English (in-lb) Units used in input data file
------------------------------------------------------------------------ Program License Serial Number 6406
------------------------------------------------------------------------ Rational Method Hydrology Program based on
Riverside County Flood Control & Water Conservation District 1978 hydrology manual
Storm event (year) = 100.00 Antecedent Moisture Condition = 2 2 year, 1 hour precipitation = 0.454(In.)
100 year, 1 hour precipitation = 1.690(In.)
Storm event year = 100.0
Calculated rainfall intensity data:
1 hour intensity = 1.690(In/Hr)
Slope of intensity duration curve = 0.5800
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 10.000 to Point/Station 11.000 **** INITIAL AREA EVALUATION ****
______________________________________________________________________ Initial area flow distance = 280.000(Ft.)
Top (of initial area) elevation = 660.900(Ft.)
Bottom (of initial area) elevation = 657.000(Ft.)
Difference in elevation = 3.900(Ft.)
Slope = 0.01393 s(percent)= 1.39
TC = k(0.530)*[(length^3)/(elevation change)]^0.2
Initial area time of concentration = 11.867 min.
Rainfall intensity = 4.326(In/Hr) for a 100.0 year storm UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.781
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Initial subarea runoff = 2.028(CFS)
Total initial stream area = 0.600(Ac.)
Pervious area fraction = 1.000
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 11.000 to Point/Station 12.000 **** NATURAL CHANNEL TIME + SUBAREA FLOW ADDITION ****
______________________________________________________________________ Top of natural channel elevation = 657.000(Ft.)
End of natural channel elevation = 653.000(Ft.)
Length of natural channel = 260.000(Ft.)
Item Number: 1.
2 Estimated mean flow rate at midpoint of channel = 6.084(CFS) Natural valley channel type used
L.A. County flood control district formula for channel velocity:
Velocity(ft/s) = (7 + 8(q(English Units)^.352)(slope^0.5) Velocity using mean channel flow = 2.74(Ft/s)
Correction to map slope used on extremely rugged channels with drops and waterfalls (Plate D-6.2)
Normal channel slope = 0.0154
Corrected/adjusted channel slope = 0.0154
Travel time = 1.58 min. TC = 13.45 min.
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.774
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 4.023(In/Hr) for a 100.0 year storm Subarea runoff = 7.471(CFS) for 2.400(Ac.)
Total runoff = 9.499(CFS) Total area = 3.000(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 12.000 to Point/Station 13.000 **** NATURAL CHANNEL TIME + SUBAREA FLOW ADDITION ****
______________________________________________________________________ Top of natural channel elevation = 653.000(Ft.)
End of natural channel elevation = 646.000(Ft.)
Length of natural channel = 530.000(Ft.)
Estimated mean flow rate at midpoint of channel = 18.999(CFS) Natural valley channel type used
L.A. County flood control district formula for channel velocity:
Velocity(ft/s) = (7 + 8(q(English Units)^.352)(slope^0.5) Velocity using mean channel flow = 3.40(Ft/s)
Correction to map slope used on extremely rugged channels with drops and waterfalls (Plate D-6.2)
Normal channel slope = 0.0132
Corrected/adjusted channel slope = 0.0132
Travel time = 2.60 min. TC = 16.05 min.
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.762
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 3.631(In/Hr) for a 100.0 year storm Subarea runoff = 16.606(CFS) for 6.000(Ac.)
Total runoff = 26.105(CFS) Total area = 9.000(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 13.000 to Point/Station 14.000 **** NATURAL CHANNEL TIME + SUBAREA FLOW ADDITION ****
______________________________________________________________________ Top of natural channel elevation = 646.000(Ft.)
End of natural channel elevation = 638.500(Ft.)
Length of natural channel = 750.000(Ft.)
Estimated mean flow rate at midpoint of channel = 46.119(CFS) Item Number: 1.
3 Natural valley channel type used
L.A. County flood control district formula for channel velocity:
Velocity(ft/s) = (7 + 8(q(English Units)^.352)(slope^0.5) Velocity using mean channel flow = 3.78(Ft/s)
Correction to map slope used on extremely rugged channels with drops and waterfalls (Plate D-6.2)
Normal channel slope = 0.0100
Corrected/adjusted channel slope = 0.0100
Travel time = 3.31 min. TC = 19.35 min.
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.749
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 3.257(In/Hr) for a 100.0 year storm Subarea runoff = 33.670(CFS) for 13.800(Ac.)
Total runoff = 59.775(CFS) Total area = 22.800(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 14.000 to Point/Station 15.000 **** NATURAL CHANNEL TIME + SUBAREA FLOW ADDITION ****
______________________________________________________________________ Top of natural channel elevation = 638.500(Ft.)
End of natural channel elevation = 630.000(Ft.)
Length of natural channel = 630.000(Ft.)
Estimated mean flow rate at midpoint of channel = 80.749(CFS) Natural valley channel type used
L.A. County flood control district formula for channel velocity:
Velocity(ft/s) = (7 + 8(q(English Units)^.352)(slope^0.5) Velocity using mean channel flow = 5.17(Ft/s)
Correction to map slope used on extremely rugged channels with drops and waterfalls (Plate D-6.2)
Normal channel slope = 0.0135
Corrected/adjusted channel slope = 0.0135
Travel time = 2.03 min. TC = 21.38 min.
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.742
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 3.074(In/Hr) for a 100.0 year storm Subarea runoff = 36.479(CFS) for 16.000(Ac.)
Total runoff = 96.254(CFS) Total area = 38.800(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 15.000 to Point/Station 16.000 **** NATURAL CHANNEL TIME + SUBAREA FLOW ADDITION ****
______________________________________________________________________ Top of natural channel elevation = 630.000(Ft.)
End of natural channel elevation = 625.500(Ft.)
Length of natural channel = 460.000(Ft.)
Estimated mean flow rate at midpoint of channel = 118.829(CFS) Item Number: 1.
4 Natural valley channel type used
L.A. County flood control district formula for channel velocity:
Velocity(ft/s) = (7 + 8(q(English Units)^.352)(slope^0.5) Velocity using mean channel flow = 4.95(Ft/s)
Correction to map slope used on extremely rugged channels with drops and waterfalls (Plate D-6.2)
Normal channel slope = 0.0098
Corrected/adjusted channel slope = 0.0098
Travel time = 1.55 min. TC = 22.93 min.
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.736
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 2.952(In/Hr) for a 100.0 year storm Subarea runoff = 39.556(CFS) for 18.200(Ac.)
Total runoff = 135.810(CFS) Total area = 57.000(Ac.)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 16.000 to Point/Station 17.000 **** NATURAL CHANNEL TIME + SUBAREA FLOW ADDITION ****
______________________________________________________________________ Top of natural channel elevation = 625.500(Ft.)
End of natural channel elevation = 622.000(Ft.)
Length of natural channel = 310.000(Ft.)
Estimated mean flow rate at midpoint of channel = 178.698(CFS) Natural valley channel type used
L.A. County flood control district formula for channel velocity:
Velocity(ft/s) = (7 + 8(q(English Units)^.352)(slope^0.5) Velocity using mean channel flow = 6.02(Ft/s)
Correction to map slope used on extremely rugged channels with drops and waterfalls (Plate D-6.2)
Normal channel slope = 0.0113
Corrected/adjusted channel slope = 0.0113
Travel time = 0.86 min. TC = 23.79 min.
Adding area flow to channel
UNDEVELOPED (poor cover) subarea
Runoff Coefficient = 0.733
Decimal fraction soil group A = 1.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 0.000
RI index for soil(AMC 2) = 67.00
Pervious area fraction = 1.000; Impervious fraction = 0.000 Rainfall intensity = 2.890(In/Hr) for a 100.0 year storm Subarea runoff = 76.293(CFS) for 36.000(Ac.)
Total runoff = 212.104(CFS) Total area = 93.000(Ac.)
End of computations, total study area = 93.00 (Ac.)
The following figures may
be used for a unit hydrograph study of the same area.
Area averaged pervious area fraction(Ap) = 1.000
Area averaged RI index number = 67.0
Item Number: 1.