HomeMy WebLinkAbout34165-02 Response to City Review DS JH 9-4-20 DL
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September 4, 2020 File No. 34165-02
Julie Laughton Design Build
28885 Woodspring Circle Trabuco Canyon, CA 92679 Attention: Ms. Julie Laughton, CEO Subject: RESPONSE TO CITY REVIEW NOTICE OF INCOMPLETE FILING Oceanfront Project – Coastal Development Permit No. CD2020-126 (PA2020-178) 1616 West Ocean Front Newport Beach, California
Dear Ms. Laughton:
This is our response to the City of Newport Beach Notice of Incomplete Filing for Coastal Development
Permit No. CD2020-126 (PA2020-178) dated August 18, 2020 and attached hereto as Appendix A. The
Notice of Incomplete Filing included three numbered comments. Comment 1 covered Property
Development Standards and issues related to the project plan set. Comment 2 covered issues related to
our Report of Coastal Hazards Analyses dated June 8, 2020. Comment 3 covered administrative issues
related to resubmittal of response documents. The purpose of this report is to respond to issues in
Comment 2.
BACKGROUND
Our June 8, 2020 report provided a comprehensive analysis of coastal hazards that may affect the
proposed redevelopment at the site. The work included identification of the closest tidal station and
summary of the data from that station, analysis of historic versus modern offshore bathymetry to identify
seafloor features that may indicate erosion, analysis of historic shoreline change either erosion or
aggradation, analysis of wave height/runup, analysis of a modeled 100 year storm event and the
implications of that event in terms of erosion and wave height/runup, analysis of Sea Level Rise (SLR)
combined with various scenarios, analysis of FEMA flood rate zones for the local area and analysis of
Tsunami hazards.
The primary issue raised in Comment 2 from the Notice of Incomplete Filing is related to our
recommendations regarding SLR and what the reviewer feels was our failure to follow the California
File No. 34165-02 September 4, 2020 Page 2
Coastal Commission’s adopted Sea Level Rise Guidance document updated in 2018. We reviewed the
2018 guidance document, City of Newport Beach Municipal Code Chapter 21.30, and other documents
related to site development. To be clear, we reviewed the following documents, among others, as part of
our work:
1. State of California, Natural Resources Agency, 2018 Update, Sea-Level Rise Guidance.
2. City of Newport Beach Municipal Code Chapter 21.30, Sections 21.30.010 to 21.30.050 inclusive.
3. Griggs, G, et. Al., April 2017, California Ocean Protection Council Science Advisory Team Working
Group. Rising Seas in California: An Update on Sea-Level Rise Science.
Our analysis of site specific SLR was based on the most recent Sea Level Rise (SLR) estimates from
researchers working for the National Oceanic and Atmospheric Administration (NOAA) and completed in
2017. We charted the recent SLR modelling using a web-based tool developed by the U.S. Army Corps of
Engineers Climate Change Adaptation Website. Results were presented on Plate 5 from our June 8, 2020
report. After accounting for NAVD88 elevation differences versus local mean sea level, the NOAA 2017
Intermediate SLR Scenario for the Los Angeles Tidal Gauge is very close to SLR results from the 2018
California guidance document when considering the upper-end of the likely range, low risk aversion sites,
and high-emission scenarios as identified in Table 28 on page 72 of that document. Plate 5 from our June
8, 2020 report is attached hereto and has been annotated to show the analysis we used regarding SLR
modelling projections. It should be noted that the 2018 California guidance document is based on a
probabilistic analysis of SLR modelling estimates that were completed prior to 2014.
All SLR models shown on Plate 5 use a baseline of year 2000. We have a twenty-year record of empirical
measurements of SLR at the Los Angeles Tidal Station that covers the interval between the baseline year
and today. We compared 2020 SLR model predictions versus actual measurements to evaluate the
predictive capacity of the models. Whereas the actual measured SLR at the Los Angeles station is about
0.81 inches over that twenty-year period, the SLR models show wide variation. The upper bound scenario
is 54 times larger than the lower bound scenario. The intermediate scenario predicts about 4.44 inches of
SLR in the twenty years between 2000 and 2020. The intermediate scenario overpredicts SLR by a factor
of about 5.48 (548%). Because of the nature of the models and model input parameters, the disparity
between model predictions and measured SLR will likely get larger in the future. This is the deterministic
analysis we used in our recommendation for design SLR. We recommended using the 96-year empirical
record at the Los Angeles Tidal Station and the calculated relative SLR from those measurements as the
File No. 34165-02 September 4, 2020 Page 3
basis of our SLR estimate, we then applied a factor-of-safety of 2.4 to come to our recommendation. We
did identify the design life of residential structures as 50 years, and this was a mistake. The Newport
Beach Municipal Code requires a design life of 75 years.
We discussed our estimate of SLR with the City reviewer and he advised that we must use the analysis
technique that has been adopted by the City and specified in his review letter and couple that SLR estimate
with the highest observed tide measured at the Los Angeles Tidal Station. Other analysis techniques will
not be approved.
REVISED SEA LEVEL RISE ESTIMATE
In accordance with City of Newport Beach requirements we used Table 28 on page 72 of the 2018
California guidance document to estimate SLR at the subject site. We assumed a design life for the
structure of 75 years. Table 28 annotated with site-specific information is attached as Appendix B. This
analysis shows that in the year 2095 the site may be subjected to 2.95 feet (~90 cm) of SLR.
MODELLED EFFECTS OF SLR AND HIGH TIDE
To visualize the effects of this SLR estimate we used the geospatial visualization tools recommended on
page 34 of the 2018 California guidance document. Figure 1 attached hereto shows the site area with
estimated flooding and wave runup conditions assuming 3.3 feet of SLR combined with high tide in the
year 2095 as modelled by the USGS CoSMoS system and visualized with the tools at the Our Coast Our
Future (OCOF) website. We selected 3.3 feet on the (OCOF) website because it was the closest modelled
scenario to the site-specific SLR estimate of 2.95 feet and it is conservative with respect to the site-specific
estimate. We also checked site conditions using the next lowest SLR scenario of 2.5 feet and found similar
conditions with slightly less flooding and less coastline retreat. We verified the OCOF modelling by
comparing it to modelling of similar parameters on the NOAA Sea Level Rise Viewer website also
recommended on page 34 of the 2018 guidance document. Both visualization tools show similar results.
The north property line of the subject site is minimally impacted by potential flooding in the scenario
described above. It appears that flood waters would occupy West Ocean Front and lap onto the front
portion of the property. It appears that the depth of flooding in the street would be less than about 12
inches. The duration of the flooding would be greater than 18 hours and likely permanent. This is shown
File No. 34165-02 September 4, 2020 Page 4
in the enlargement box on Figure 1. The scenario shows that about 350 feet of beach erosion has
occurred to the beach strand on the south side of the site, but that the erosion does not impact the site.
The estimate of wave runup also indicates that waves do not impact the site.
Though the site is not significantly impacted by flooding, erosion, wave runup, or wave impacts, large areas
of the surrounding peninsula are heavily impacted by these phenomena. We estimate that about 50% to
60% of the existing landmass of the peninsula would be under water with a permanent flood depth between
0 feet to 8 feet. Nearby residential properties to the north, northwest, and northeast would be significantly
impacted by flooding. The two main access roads into and out of the peninsula, Newport Boulevard and
West Balboa Boulevard, would be under water and not passable to wheeled vehicles. It would no longer
be possible to drive on paved roads to the site. It may be possible to drive on the remaining beach strand.
MODELLED EFFECTS OF SLR PLUS 100 YEAR STORM
We used similar model parameters and incorporated a modelled 100-year storm to visualize the effects of
the storm when occurring in the year 2095 during the time that the site has experienced 2.95 feet of SLR.
This condition is shown on Figure 2. Results of this analysis indicate minor additional flooding to the north
and minor additional wave runup to the south, but the site remains only minimally impacted by flooding.
The depth of flooding at the north property line would be minimally increased, but the duration of the
increased flooding would likely be 18 hours or less.
The site is not significantly impacted by flooding, erosion, wave runup, or wave impacts when considering
SLR combined with a 100-year storm. The same comments about flooding impacts to surrounding areas
apply.
GEOLOGIC STABILITY AND OTHER IMPACTS
Geologic stability of the site including the potential for liquefaction, consolidation settlement, high
groundwater, foundation design, waterproofing requirements, etc. was addressed in a separate
geotechnical report dated May 5, 2020. The May 5, 2020 report is attached as Appendix C.
File No. 34165-02 September 4, 2020 Page 5
PROJECT IMPACT ON COASTAL RESOURCES
The site is a single lot residential development of one single-family residence. The total lot size is about
3,090 square feet or about 0.07 acres. The site itself is largely unaffected by SLR. Though public access
and recreation would be significantly impacted by SLR under City mandated SLR analysis procedures, that
impact has no relation to the proposed construction on site. The proposed project would have no
significant impact on coastal resources related to public access and recreation.
The site is in a built-out portion of the peninsula with existing development on all sides except to the south
where open beach strand exists. The proposed project would have no significant impact on coastal
resources related to coastal habitats.
The site is in a built-out portion of the peninsula with existing development on all sides except the south.
The site will utilize municipal sewer and comply with existing code requirements for runoff waters. The
proposed project would have no significant impact on coastal resources related to water quality.
The site is in a built-out portion of the peninsula with existing modern development on all sides except the
south. We understand the beach strand has subject to one or more beach maintenance projects to prevent
erosion of the shoreline. We are aware of no existing paleontological or archeological resources onsite.
The proposed project would have no significant impact on coastal resources related to paleontological or
archeological issues.
The site is in a built-out portion of the peninsula with existing development on all sides except the south.
The proposed project will comply with existing codes related to view resources. The proposed project
would have no significant impact on coastal resources related to scenic resources.
We believe the proposed project would have no significant resource impacts and therefore recommend no
changes or alternatives to the current plan set.
File No. 34165-02 September 4, 2020 Page 6
CONCLUSIONS
Results of our coastal hazards analyses discussed above are summarized in the following table.
Coastal Hazard 1616 West Ocean Front
Anticipated Affect1
Empirically Measured SLR (1923 – 2020) No Anticipated Affect
Shoreline Change No Anticipated Affect
Predicted Future SLR No Anticipated Affect
100-Year Storm
Wave Height
Wave Run-up
Wave Damage
Storm-Related Shoreline Change
Storm-Related Flooding
No Anticipated Affect
No Anticipated Affect
No Anticipated Affect
No Anticipated Affect
No Anticipated Affect
Predicted Future SLR + 100-Year Strom No Anticipated Affect
FEMA FIRM Zone X 0.2% Annual Chance Flood
Tsunami Located in Tsunami Run-Up Zone
1During estimated facility design life and based on current storm and SLR modeling results.
Based on our coastal hazards analyses discussed and summarized above, it is our conclusion that the
proposed residential redevelopment at 1616 West Ocean Front site will neither create nor contribute
significantly to erosion, geologic instability, or destruction of the site or surrounding areas or in any way
requires the construction of protective devices that would substantially alter natural landforms along
shoreline, bluffs and cliffs.
File No. 34165-02 September 4, 2020 Page 7
Respectfully submitted,
AMERICAN GEOTECHNICAL, INC. Reviewed by: Douglas S. Santo, Fei-chiu (Jerry) Huang, Ph.D.
Chief Engineering Geologist/Hydrogeologist Principal Engineer CEG 1866, CHg 450 R.C.E. 55670, G.E. 2601 Attachments: Plate 5 Figures 1 and 2 Appendix A – Notice of Incomplete Filing for CDP No. CD2020-126 (PA2020-178) Appendix B – Table 28 from 2018 California Guidance Document Appendix C – May 5, 2020 Geotechnical Report Distribution: Addressee (Email: julie@julielaughton.com) wpdata/OC/34165-02 Response to City Review DS JH 9-4-20 DL
NOAA SEA LEVEL RISE ESTIMATES BASED ON LOS ANGELES TIDAL GAUGE
SLR estimates at 1616 West Ocean Front based on the NOAA Los Angeles Tidal Station.
Intermediate estimate shows 66th percentile confidence range.
Reference:
Sweet W.V., et. al., 1/2017, Global and Regional Sea Level Rise Scenarios for the United States, NOAA Technical Report NOS
CO-OPS 083, Chart from USACOE Climate Change Adaptation Website, http://www.corpsclimate.us/ccaceslcurves.cfm,
Accessed June 2020.
AMERICAN GEOTECHNICAL INC , .522725 OLD CANAL ROAD, YORBA LINDA, CA 92887
(714) 685-3900 (714) 685-3909
www.amgt.com
TITLE:SEA LEVEL RISE MODELING
FILE NO .:DATE:SCALE:
PLATE
34165-026/20 - rev. 8/20As Shown
1616 Ocean Front, , Newport Beach CA
Residential Redevelopment
Year 2000 Baseline = 2.8’
SLR Model Predictions for year 2020
versus empirically measured SLR
Model predictions
Upper Bound 6.48”
Middle 4.44”
Lower Bound 0.12”
SLR based on empirical measurements
Upper 95% CI 0.99”
Middle 0.81”
Lower 95% CI 0.63”
Design Life = 75 years
34165-029/4/20NTS
FIGUREAMERICAN GEOTECHNICAL, INC.122725 OLD CANAL ROAD,YORBA LINDA, CA 92887
(714) 685-3900 (714) 685-3909
www.amgt.com
TITLE:
FILE NO.:DATE:SCALE:
SEA LEVEL RISE MODELING YEAR 2095
1616 Ocean Front, , Newport Beach CA
Residential Redevelopment
Model shows flooding and wave runup resulting from 3.3’ of SLR
in 2095 with high tide condition
Enlargement
Note that Newport Blvd. and
W. Balboa Blvd. are under
about 1’ of sea water in this
scenario. At least 50% of the
peninsula is under water.
About 350 linear feet of
beach strand is under water
compared to current
condition.
Annotated screen capture from Our Coast Our Future website showing flooding condition with 100 cm or
about 3.3 feet of SLR in the year 2095. SLR scenarios are fixed as shown in Topic 2 in left hand column.
Site specific SLR using City of Newport Beach analysis techniques is 2.95 feet. Though the site is
minimally impacted by flooding in this scenario, the two main access roads that service the peninsula are
both underwater and unusable to wheeled vehicles. More than half of the existing residences are
experiencing flooding conditions. The depth of flooding is between 0 to 12 inches. The estimated duration
is more than 18 hours and likely permanent. We understand this scenario includes high tide conditions.
Flooding impacts
front portion of lot.
Access restricted to
boat or beach strand
34165-029/4/20NTS
FIGUREAMERICAN GEOTECHNICAL, INC.222725 OLD CANAL ROAD,YORBA LINDA, CA 92887
(714) 685-3900 (714) 685-3909
www.amgt.com
TITLE:
FILE NO.:DATE:SCALE:
SEA LEVEL RISE MODELING YEAR 2095
1616 Ocean Front, , Newport Beach CA
Residential Redevelopment
Model shows flooding and wave runup resulting from 3.3’ of SLR
in 2095 plus a 100-year storm event
Enlargement
Note that Newport Blvd. and
W. Balboa Blvd. are under
about 1’ of sea water in this
scenario. At least 50% of the
peninsula is under water.
About 350 linear feet of
beach strand is under water
compared to current
condition.
Flooding impacts
front portion of lot.
Access restricted to
boat or beach
Blue circles indicate limit of
wave runup during 100-year
storm scenario
Annotated screen capture from Our Coast Our Future website showing flooding condition with 100 cm or
about 3.3 feet of SLR in the year 2095. SLR scenarios are fixed as shown in Topic 2 in left hand column.
Site specific SLR using City of Newport Beach analysis techniques is 2.95 feet. This analysis includes the
impacts of a 100-year storm. Though the site is minimally impacted by flooding in this scenario, the two
main access roads that service the peninsula are both underwater and unusable to wheeled vehicles. More
than half of the existing residences are experiencing flooding conditions. The depth of flooding is between
0 to 12 inches. The estimated duration is more than 18 hours and likely permanent. We understand this
scenario includes high tide conditions.
File No. 34165-02 September 4, 2020
APPENDIX A
Notice of Incomplete Filing for CDP No. CD2020-126 (PA2020-178)
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COMMUNITY DEVELOPMENT DEPARTMENT
PLANNING DIVISION
100 Civic Center Drive, P.O. Box 1768, Newport Beach, CA 92658-8915
949-644-3200 Fax: 949-644-3229
www.newportbeachca.gov
NOTICE OF INCOMPLETE FILING
August 18, 2020
Julie Laughton
Julie@julielaughton.com
Application No. • Coastal Development Permit No. CD2020-126
(PA2020-178)
Address 1616 West Ocean Front
Please be advised that after reviewing the subject application, your submittal has been
deemed incomplete and further information is required before we are able to proceed
with the application process. Note the following may require substantial revision
and may necessitate redesign. Please contact the Planner to discuss.
The following documentation is required to complete the application:
1. Property Development Standards.
Please be advised, the project as designed does not comply with all required property
development standards identified in Newport Beach Municipal Code (NBMC)
Chapter 21.30 (Property Development Standards).
Reference the attached correction sheet and redlined plan set for the required
changes.
2. Coastal Hazards Report.
Please update the Coastal Hazards Report using the California Coastal
Commission’s adopted State of California, Sea Level Rise Guidance: 2018 Update
as the current best available science. In January 22, 2019, City Council directed
staff to evaluate Coastal Development Permits for flood protection based on the
following parameters:
• Port of Los Angeles tide gauge (the closest tide gauge analyzed in the document)
• Using the upper end of the likely range for probabilistic scenarios (66%
probability, low risk-aversion column)
• Using the high emissions scenario.
• Setting a 75-year economic life of a structure (projected SLR of +2.9 feet for
2094).
• Projections can be interpolated based on this set of data for the 75- year design
life of the structure (currently the year 2094).
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•The minimum elevation for low-risk aversion is calculated as follows for flood
protection:
o 7.7 feet NAVD88 (current historical max. sea level for Port of LA) +
2.95 feet NAVD88 (low risk aversion projection, high risk scenario
interpolated for 75 years) = 10.65 feet NAVD88.
Please include Table 28 of the Sea Level Rise Guidance as an exhibit and use to
establish to projections.
Additionally, see attached Appendix A procedure for coastal hazards reports and
revise analysis to reflect requirements. Analysis must use project-specific
information such as referencing the proposed finish floor elevations (in NAVD88) to
substantiate claims. Design features such as required flood proofing should be
discussed.
Please make explicit mention of the pickleball court area, which is currently
proposed below the 9.00-foot NAVD88 minimum required top of slab elevation for
interior living areas. A determination should be made whether this area is
reasonably safe from coastal hazards per the above requirements.
Please be advised this report serves as a certified, professional recommendation to
staff. Statements that suggest otherwise must be removed. For example, the
“contents of the report are not perfect,” transfer of the report should have it be
considered “advice by the client,” and that the client is the “only party intended by
this office to directly receive the advice.” Staff relies on this report to make required
findings for the project and this must be based off a professionally certified report
using the best available science as determined by the California Coastal
Commission.
3.Electronic Copy. Please provide all submitted and revised applications materials
in an electronic form (email, DropBox, CD, etc.) USBs are not accepted.
Due to the nature of these comments, additional corrections will apply upon
resubmittal.
Upon verification of completion, the application will be processed and scheduled for a
Zoning Administrator Hearing. Should you have any questions regarding submittal
requirements, please contact Patrick Achis at 949-644-3237 or
pachis@newportbeachca.gov.
By:
Attachments: Planning Division Corrections
Appendix A
Redlined Coastal Hazards Report
Residential Zoning Corrections
Community Development Department
Planning Division
100 Civic Center Drive; P.O. Box 1768
Newport Beach, CA 92658
949-644-3200
www.newportbeachca.gov
Plan Check No.:
Address: 1616 West Ocean Front
Date: 8/18/2020
Corrections Required Contact Information
“1” (First Review): 1
“2” (Second Review):
“3” (Third Review):
If you have questions regarding your plan check, please contact:
Plan Checker: Patrick Achis
Email/Phone: pachis@newportbeachca.gov - 949-644-3237
Please contact me to discuss corrections prior to resubmitting.
GENERAL INFORMATION
1. Zone: R-2 Setback Map No: PC Text:
2. Proposal: New Addition Alteration Other
3. No. of Units Allowed: No. of Units Proposed:
4. Demo Proposed Yes No If Yes, number of units to be demolished
COASTAL COMMISSION REVIEW
5. Coastal Zone: Yes Exclusion Zone No
6. Exempt because:
7. Categorical Exclusion No.: Effective Date:
8. Waiver No: Effective Date:
9. AIC No: Coastal Development Permit No: Effective Date:
10. Coastal Approval Letter (all pages) to be scanned into plans.
11. 1
Comments: Prior to the issuance of a building permit, the property owner shall
submit a notarized signed letter acknowledging all hazards present at the site, assuming the risk of injury or damage from such hazards, unconditionally waiving any claims of damage against the City from such hazards, and to indemnify and hold
harmless City, its City Council, its boards and commissions, officials, officers, employees, and agents from and against any and all claims, demands, obligations, damages, actions, causes of action, suits, losses, judgments, fines, penalties,
liabilities, costs and expenses (including without limitation, development. This letter shall be scanned into the plan set prior to building permit issuance.
DISCRETIONARY ACTION
12. Application required: Reason:
13.
Previous Discretionary Approvals:
1. Application Type No. For:
2. Application Type No. For:
3. Application Type No. For:
4. Application Type No. For:
5. Application Type No. For:
14. Please make an appt with: Phone: Email:
Residential Zoning Corrections (Cont’d)
Updated: 09/11/2018
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15. Scan approval letter / resolution (including conditions) into plan sets. Copy attached
16. HOLD ON FINAL. The following items must be completed before the building permits are finaled:
17. Comments:
Residential Zoning Corrections (Cont’d)
Updated: 09/11/2018
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REQUIRED FEES
18. Fairshare Fee Contribution: 19. San Joaquin Hills Transportation Corridor Fee:
20. Other:
LOT OR PARCEL STATUS
21. Legal Description: Lot: Block: Section: Tract:
22. Easement(s) on-site: Yes No Verify with Public Works
23.
No person shall develop any structure including, but not limited to, a principal or accessory structure across a lot
line per Section 19.04.035 (Development Across Property Lines) of the Subdivision Code. Please apply for a
Parcel Map, Lot Merger, Lot Line Adjustment, or Certificate of Compliance to address underlying legal lot
lines.
24. Comments:
SETBACKS
25.
Setback Regulations (20.30.110)
*Setbacks are measured from property line to finished surface, unless otherwise specified.
Front: Left Side: Right Side: Rear: Other:
26. 1
Third Floor Step-backs (20.48.180A.3.b.) (Applicable to all R-1 and R-2 zoning districts, except: R-BI; R-1-6000;
R-1-7,200; R-1-10,000, lots 25 feet wide or less in R-2; and Planned Community district)
Front: 15 Left Side: 0 Right Side: 0 Rear: 15 N/A:
27.
On residential lots wider than thirty (30) feet, if the primary entrance to a dwelling faces a side setback area the
entry door shall be set back a minimum of five feet from the side property line and a three-foot-wide unobstructed
walkway shall be provided up to a minimum height of eight feet between the primary entrance and the public
street or alley.
28.
A minimum thirty-six (36) inch wide passageway shall be maintained within at least one side setback area
adjacent to the principal structure. The passageway shall be free of any encroachments or obstructions from
ground level to a height of eight feet, including mechanical equipment, and other items attached to, or detached
from, the principal structure.
29. 1 Comments: Please dimension the 15' third floor stepback. Redesign if habitable area encroaches into the stepback.
FLOOR AREA/SITE AREA LIMITATIONS
30. Lot Size: square feet Lot Dimensions: See attached subdivision map with dimensions
31. Buildable Area: lot area minus required setback areas =
32.
Floor Area Limitation: x buildable area + (200 Square Feet for R-BI only) = maximum square footage
• Calculation includes exterior walls, stairway(s) on first level of occurrence, daylighting basements, and
enclosed parking (including subterranean)
• Calculation does not include subterranean basements
33. Proposed Floor Area: square feet
34.
Site (Lot) Coverage Limitation: percent of total lot area
• Calculation includes the percentage of a site covered by structures, including eaves and overhangs, and
accessory structures and by decks more than 30 inches in height.
35. Proposed Lot Coverage: square feet or percent of total lot area
36. Provide a floor area calculations exhibit (to scale) verifying proposed square footage (show dimensions &
calculations).
Residential Zoning Corrections (Cont’d)
Updated: 09/11/2018
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37. Comments:
For 38 - 40, applicable to all R-1 and R-2 zoning districts, except: R-BI; R-1-6000; R-1-7,200; R-1-10,000, lots 25 feet wide or less in R-2; and Planned Community district
38.
Third Floor Limitation (20.48.180 3.)
15% of the total buildable area for lots wider than 30 feet:
Maximum: 0.15 x buildable area = Proposed:
20% of the total buildable area for lots 30 feet wide or less:
Maximum: 0.20 x buildable area = Proposed:
• Enclosed square footage located on the third floor shall be set back a minimum of 15 feet from the front and
rear setback lines
• For lots greater than 30 feet in width a minimum of 2 feet from each side setback line, including bay windows.
39. Comments:
40. 1
Open Volume Area Required (20.48.180 4.)
15% of the buildable area of the lot in addition to the required setback areas
Required: 0.15 x buildable area: square feet
Proposed: square feet
• Open volume must be located within the buildable envelope (within the setback; under 24 FEET)
• Open Volume must have a minimum dimension of 5 feet in depth from the setback line on which it is located
• Open volume must be open on a minimum of one side and have minimum clear vertical dimension of 7.5 feet
41. 1 Comments: Please list minimum open volume area and proposed open volume area on cover sheet. Additionally identify open volume area on an exhibit or site/floor plans.
PLOT PLAN/SITE PLAN/FLOOR PLANS
42. 1
Provide fully dimensioned Site Plan and Floor Plans. 1. It appears the demolition plan was inadvertantly used as the architectural site plan, please revise accordingly. Site plan should include call outs of hardscape, landscape, and new and existing walls. Note the approved demolition plan was for the entire structure including the 11-foot walls. All walls in the required 3-foot side setback cannot be greater than 6 feet in height measured from exisiting grade prior to construction.
2. The wall existing to remain fronting the boardwall will need to be confirmed with Public Works and will be addressed in their review of the project, which is
forthcoming. 2. Please match grading plan and site plan work to be consistent with one another, reflecting all changes.
43. Show the location of all buildings on-site and dimension distance to property lines.
44. Dimension the distance from face of curb to front property line (verify with Public Works).
45. 1 Indicate the second and third floor footprints (if applicable).
46. 1 Dimension all projections (e.g., fireplaces, bay windows, eaves), label distance(s) to property lines.
47. Provide separate existing and proposed floor plans fully dimensioned showing all room uses for all buildings on-
site. Existing floor plans shall illustrate walls to be demolished
Residential Zoning Corrections (Cont’d)
Updated: 09/11/2018
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48. 1
Plot property lines on site plan and all floor plans with setbacks dimensioned. 1. Setbacks are measured from the property line to the face of finish. Note ornamental moldings, pilasters
and similar architecture features may encroach up to six inches into a required setback, though the brick veneer as proposed is not consisent with this provision. Please revise plans to remove brick veneer out of the setback or update.
2. Please remove roofing, siding, and other elements that are shown to extend off property. These improvements shall not extend off-property.
49. Indicate the location of easement(s) plotted on site plan.
50. Comments:
OFF-STREET PARKING (20.40)
Single-Unit Dwellings – Attached 2 per unit in a garage
Single-Unit Dwellings – Detached and less than 4,000 sq. ft.
of gross floor area*
2 per unit in a garage
Single-Unit Dwellings – Detached and 4,000 sq. ft. or
greater of gross floor area*
3 per unit in a garage
Single-Unit Dwellings – Balboa Island 2 per unit in a garage
Two-Unit Dwellings 2 per unit; 1 in a garage and 1 covered or in a garage
Other:
*Gross Floor Area in this case shall include the square footage of basements, but shall not include the square footage of
garages.
Minimum Interior Dimensions
The minimum interior dimensions for parking spaces in residential zoning districts shall be as provided below (unless
otherwise stated in a Planned Community). The Director may approve a reduced width for duplex units when two separate
single car garages are proposed side by side and the applicant has proposed the maximum width possible.
Lot Width Single Car/Tandem* Two Car Three Car
30 feet or less 9’-3” x 19’ (35’)* 17’-6” x 19’ -
30.1 - 39.99 feet 10’ x 19’ (35’)* 18’-6” x 19’ 26’-9” x 19’
40 feet or more 10’ x 20’ 20’ x 20’ 28’-3” x 20’
* The minimum depth for a 2-car tandem space is 35 feet
51. Gross Floor Area for purposes of calculating the number of parking spaces:
Gross Floor Area (don't include garage) + Basement =
52. 1 Number of Parking Spaces Required: 2 Minimum interior clear dimensions required: 17'-6" x 19'
53. 1 Label interior clear dimensions of the garage free of all obstructions such as cabinetry, appliances, steps, posts,
etc. (one riser is allowed, maximum 6 inches high, encroaching no more than 18 inches into garage).
54. Indicate on the plans that the garage doors are automatic roll-up doors. Garages with doors that face the street
that are located within twenty (20) feet of the front property line are required to be equipped with automatic roll-up
doors.
55. Comments:
Residential Zoning Corrections (Cont’d)
Updated: 09/11/2018
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HEIGHT LIMITATION (20.30.060)
• 20.30.050 Grade Establishment
• Measured from average grade if slope is 5% or less
• Roofs over the Flat Roof Limit must have a minimum 3:12 pitch
• Sloped roofs with a pitch less than 3:12 and parapets, railings, etc are considered flat roof for the purpose of height limits
• Heights are measured to the top of all finished materials.
• Height certification will be required in some cases
56. Flat Roof Limit: feet Sloped Roof Allowable Ridge Height: feet
57. 1 Height certification inspection required? Yes No If so, add note to elevations stating Height Certification Required.
58. Provide topographic survey (stamped and signed by a licensed surveyor) to establish slope and average grade or,
use subdivision grading plan, if applicable.
59. Provide a sheet showing the outline of the proposed structure over a topographic survey to verify determination
of slope and grade to be used for measuring height.
60. 1
Provide slope of the lot. The slope of a lot shall be determined using a four-sided polygon that most closely
approximates the actual footprint of the proposed structure. The area of the four-sided polygon shall not be smaller
than the footprint of the proposed structure and shall be located entirely within the buildable area of the lot. Identify
the elevation points from survey and distance used to calculate slope.
61. 1
Establishment of Grade (Five Percent or Less Slope)- The grade of the surface from which structure height is
measured shall be a plane established using the average of the elevations at each corner of the four-sided
polygon. Example: A + B + C + D = X; X/4 = Established grade elevation from which to measure structure height.
Identify the four points used to determine grade plane on site plan and illustrate average grade calculation. The figures provided on the roof plan to establish grade cannot be located on the
topographic survey. Please clarify. If these points were interpolated, please label as such and provide the reference points and calculation breakdown for reference. If this changes the estalished grade, please update/redesign all applicable exhibits.
62.
Establishment of Grade (More than Five Percent Slope)- The established grade from which structure height is
measured shall be a plane established by determining the elevation of the lot at five evenly spaced points along
each of the two side property lines and connecting each of the points along a side property line with the
corresponding point on the opposite side property line. The five evenly spaced points along each side property
line shall be located so that one point is located at the intersection of the front setback line with the side property
line and another point is located at the intersection of the rear setback line with the side property line. The other
three points along the side property line shall be located so that all five points are equidistant from each other.
Provide a grade plane exhibit per the methodology above and clearly identify the survey points used to
establish the grade plane.
63. Label the established grade on all elevation sheets.
64. For lots with a more than 5 percent slope, plot roof plan over established grade plan exhibit to assist with
determination of grade points located directly below ridge peaks, roof areas and/or parapets.
65. Label interpolated grade points (based on established grade plane) below any critical ridge, parapet, etc.
66. 1
Dimension heights from established grade to: top of flat roof ridge peak all roof top equipment
deck rails any flat elements Please provide on all elevation exhibits to show compliance.
67. 1
All new structures shall have a minimum top of slab elevation of 9.0 (88 NAVD datum) pursuant to Section
20.30.060.B.3. When the top of slab is required to be raised, the height of the principal building shall be
measured from the 9.0 (88 NAVD datum) elevation. Please note the pickleball court is below the 9.00 feet NAVD and may require a redesign if the coastal hazards report does not conclude it is reasonably safe for the projected 75-year life of the structure.
68. Provide a complete roof plan.
Residential Zoning Corrections (Cont’d)
Updated: 09/11/2018
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69. 1 Label roof pitches on roof plan and elevations.
70. 1 Label and dimension eave overhang to property line on all exterior elevations.
71. 1 Comments: Please remove all proposed roofing and siding off the property. These improvements may not extend off property.
EXCEPTIONS TO HEIGHT LIMITS (20.30.060 D)
72.
Interior Fireplaces- The overall chimney height for an interior fireplace is permitted to exceed the height limit by
two feet above the roof plane plus an additional two foot maximum for the cap/spark arrestor. The additional two
foot section is not only limited in height but also to 2 feet by 4 feet in width and depth. In addition, the chimney
must be located a minimum distance of 10 feet from the nearest roof plane. Label dimensions of the chimney
plus any portion of the cap/arrestor.
73. Elevator Shafts/Enclosed Stairwells- Flat roofs above elevator shafts and enclosed stairwell housings may
exceed the allowed height limit up to the maximum height for a sloped roof, provided they do not exceed thirty
(30) square feet in area. Label applicable elevator shaft/enclosed stairwell dimensions and area.
74. Comments:
LANDSCAPING
75. 1
LANDSCAPING – TITLE 14
Chapter 14.17 of the Municipal Code (Water-Efficient Landscaping) applies to landscape installation projects
requiring a ministerial or discretionary permit and exceed the following thresholds:
1. New landscape project with greater than 500 square feet of landscape area
2. Rehabilitated landscaped project with greater than 2,500 square feet of landscape area
New Landscape Project:
Please provide. total sq ft of new landscaped area
Provide Landscape Documentation Package prepared in accordance with Design Standards or, if landscape
area is 2,500 square feet or less, comply with the Prescriptive Compliance Option (Appendix H of Design
Standards).
Rehabilitated Landscape Project: total sq ft of rehabilitated landscaped area
1. Provide Landscape Documentation Package prepared in accordance with Design Standards or;
2. Rehabilitated projects with replacement plantings with equal or less water need than the existing landscaping
and the irrigation system is designed, operable and programmed to comply with the City’s water conservation
regulations are exempt from the ordinance and the requirement to provide a complete landscape documentation
package. To qualify for this exemption, the applicant must provide a landscape and irrigation plan and letter from
a licensed professional stating that the replacement landscaping and irrigation system complies with the terms
of this exemption.
76. Comments:
77.
LANDSCAPING – TITLE 20 (20.36.050A)
Impervious surfaces in R-1 and R-2 zones.
1. Impervious surface areas, excluding driveways, shall not exceed 50 percent of the front yard area with
the remaining area landscaped with plant material. The use of pervious materials for walkways,
porches, and outdoor living areas is allowed.
2. Where the typical neighborhood pattern of front yards has been developed with hardscaped outdoor
living areas that exceed the 50 percent maximum for impervious surfaces the Director may waive this
requirement.
Project complies with: No.1 Yes No
No.2 Yes No
Residential Zoning Corrections (Cont’d)
Updated: 09/11/2018
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78. Comments:
DESIGN CRITERIA (20.48.180 B.)
For 78-83 below, applicable to all single-unit and two-unit residential building citywide
79.
Walls: Long unarticulated exterior walls are discouraged on all structures. The visual massing of a building should
be reduced by incorporating appropriate design elements; including variation in the wall plane, building modulation,
opening, recesses, vertical element, varied textures, and design accents (e.g. moldings, pilasters, etc.). Front
facades shall include windows.
80. Upper floors: Portions of upper floors should be set back in order to scale down facades that face the street,
common open space, and adjacent residential structures. Upper story setbacks are recommended either as full
length “stepbacks” or partial indentations for upper story balconies, decks, and/or aesthetic setbacks.
81. Architectural treatment: Architectural treatment of all elevations visible from public places, including alleys, is
encouraged. Treatments may include window treatments, cornices, siding, eaves, and other architectural features.
82.
Front façade: Where the neighborhood pattern is for the primary entrance to face the street, the primary entry and
windows should be the dominate elements of the front façade. Primary entrances should face the street with a
clear, connecting path to the public sidewalk or street. Alternatively, entry elements may be visible from the street
without the door necessary facing the street.
83. Main entrance: The main dwelling entrance should be clearly articulated through the use of architectural detailing.
84. Comments:
MISCELLANEOUS ITEMS
85.
TWO- TO FOUR-UNIT DWELLING PROJECTS A notice shall be signed by property owners and copied into the
plan set prior to the issuance of a building permit for development of two- to four-unit dwellings. The notice serves
as a record of acknowledgement that property owners understand should they choose to pursue the approval of a
Parcel Map for condominium purposes during the construction, they fully understand that the Parcel Map
application is a discretionary process and is not guaranteed.
86.
CONDOS - (Existing Structures) Before a condominium unit may be sold, a condominium conversion building
permit must be signed off by the Planning Department. The Parcel Map must be signed off by the Public Works
Department, approved by the County and RECORDED at the County. Proof of recordation will be required before
Planning can sign off on the building permit final. Provide a copy of the first page of the recorded document.
87.
CONDOS - (New Structures) Before a condominium unit may be sold, a building permit is required for a
description change from “duplex” to “condominiums.” Before building permits can be finaled, the Parcel Map must
be signed off by the Public Works Department, approved by the County and RECORDED at the County. Proof of
recordation will be required before Planning can sign off on the description change. Provide a copy of the first page
of the recorded document.
88.
20.30.130 (Traffic Safety Visibility Area):
Design includes accessory improvements and/or landscaping within traffic safety visibility triangle: Yes No
• If Yes, label and illustrate traffic safety visibility triangle as follows:
• Label proposed improvements and heights within triangle as follows:
89.
20.30.020.A (Screening of Roof-Mounted and Ground-Mounted Mechanical Equipment)- The screening of
mechanical equipment is required in all zoning districts at the time of new installation or replacement. Roof-
mounted and ground-mounted mechanical equipment (e.g., air conditioning, heating, ventilation ducts and
exhaust vents, swimming pool and spa pumps and filters, transformers and generators, and similar equipment,
but excluding solar collectors and related equipment), shall be screened from public view and adjacent
residential districts, and shall comply with the requirements:
90. ACCESSORY STRUCTURES Accessory structures, including fences, hedges, walls, and retaining walls, are
typically limited to 6 feet in side and rear setbacks and 42 inches in front setbacks. Please label height from
natural grade below to highest point of structure.
91. FYI ASSOCIATION APPROVAL (ADVISORY) Issuance of a Building Permit by the City does not relieve applicant of
legal requirement to observe covenants, conditions and restrictions which may be recorded against the property
or to obtain community association approval of plans.
92. 1 TRASH AREA Indicate the location of the screened trash area on the site plan or floor plan.
Residential Zoning Corrections (Cont’d)
Updated: 09/11/2018
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93. Comments:
GENERAL NOTES
94. 1
Add the following note(s) as indicated below:
“Pools, spas, walls, fences, patio covers and other freestanding structures require separate reviews and
permits.”
“Fences, hedges, walls, retaining walls, guardrails and handrails or any combination thereof shall not exceed
42 inches from existing grade prior to construction within the required front setback area(s).”
Attic space with ceiling heights greater than 6 feet - “Not to contain any air registers, electrical outlets, or
lighting other than is required by Code. Not to contain any insulation, drywall, or similar interior wall finishing material.”
Accessory Living Areas- “There shall be no facilities used for food preparation within or be used for residential purposes separately or independently from occupants of principal structure.”
Other:-
HOLD ON FINAL
95. FYI
The following Hold(s) on Final will be applied to your building permit:
Height Certification of critical roof height elevations.
Condominium Conversions- Parcel Map recordation.
New Condominiums (1-4 units) - Parcel Map recordation and issuance of Description Change permit
Landscape Certification- For projects requiring landscape documentation package, applicant must provide third-
party stamped and signed Certificate of Completion (Appendix E of Design Standards).
Other:-
96. Comments: Please note due to the nature of these comments, additional corrections may apply upon resubmission.
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IV. Review of Coastal Development Permits.
Upon certification of the Local Coastal Program, the City will issue coastal development permits,
based on policies and standards contained therein.
The City will use the best-available science to determine a range of sea level rise projections for
use in reviewing coastal development permit applications. Sea level rise science continues to evolve,
and some processes that are not fully understood may potentially have large effects on future sea
level rise. Therefore, the City will re-examine the best available science periodically in conjunction with
the release of new information on sea level rise. The City will consider relevant science that is current,
peer-reviewed, and widely accepted among the scientific community.
The National Research Council’s 2012 report, Sea-Level Rise for the Coasts of California, Oregon
and Washington: Past, Present and Future (NRC 2012) provides sea level rise projections of 2-12
inches by 2030, 5-24 inches by 2050, and 17-66 inches by 2100 for Southern California. Sea level rise
amounts expected by years other than 2030, 2050, and 2100 should be calculated by interpolating or
extrapolating data points using best fit equations. Sea level rise projections that match the anticipated
project life of the development under consideration should be used.
In its review of coastal development permits, the following policy shall be implemented in addition to
the relevant policies stated in Section III.
2.8.3-1. Require all coastal development permit applications for new development on a beach
or on a coastal bluff property subject to wave action to assess the potential for flooding or
damage from waves, storm surge, or seiches, through a wave uprush and impact reports
prepared by a licensed civil engineer with expertise in coastal processes. The conditions that
shall be considered in a wave uprush study are: a seasonally eroded beach combined with long-
term (75 years) erosion; high tide conditions, combined with long-term (75 year) projections for
sea level rise; storm waves from a 100-year event or a storm that compares to the 1982/83 El
Nino event.
Applicability. Sea level rise should be considered in the review of a CDP when the project is in an
area that is reasonably expected to be impacted by sea level rise over the lifetime of the new
development, including but not limited to areas on low-lying land, on eroding coastal bluffs, or are in
proximity to water. These include:
• “Low-lying land” areas include the Semeniuk Slough, West Newport, Lido Peninsula, Balboa
Peninsula, Bay Island, Balboa Island, Little Balboa Island, Collins Island, Balboa Coves,
Mariners’ Mile, Balboa Bay Club Resort, Bay Shores, Harbor Island, and Beacon Bay.
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• “Eroding coastal bluffs” include those along Ocean Boulevard in Corona del Mar and in
Shorecliffs and Cameo Shores.
• “Proximity to water” includes all of the above areas and shoreline properties in Newport
Shores, Newport Island, Lido Isle, Harbor Island, Bayside, Carnation Cove, China Cove, Bayside
Village, Newport Dunes, and Dover Shores.
To facilitate this review, the following steps/analysis shall be required in developing the application
submittal.
Step 1. Establish the projected sea level rise range for the proposed project’s planning
horizon (life of project) using the current best available science.
Step 2. For each sea level rise scenario identified in Step 1, determine how physical impacts from
sea level rise may impact the project site, including erosion, structural and geological stability, flooding
and inundation.
1. Wave Uprush and Wave Impacts (see Section 21.30.015.E.2). The wave uprush and
wave impact analysis should identify risks that potentially could occur over the anticipated
life of the project from 1) a seasonally eroded beach combined with long term (75-year)
erosion, including accelerated erosion rates resulting from sea level rise; 2) high tide
conditions, combined with long-term (75 year) projections for sea level rise; and 3) storm
waves from a 100-year event or a storm that compares to the 1982/83 El Niño event.
2. Geologic Stability (see Section 21.30.015.E.4). Geologic stability reports should
analyze site-specific stability and structural integrity without reliance upon existing or new
protective devices (including cliff-retaining structures, seawalls, revetments, groins, buried
retaining walls, and caisson foundations) that would substantially alter natural landforms
along bluffs and cliffs. Geologic stability can include, among others, concerns such as
landslides, slope failure, liquefiable soils, and seismic activity. In most situations, the
analyses of these concerns will be combined with the erosion analysis to fully establish the
safe developable area.
3. Erosion. The erosion analysis should establish the extent of erosion that could occur
from current processes, as well as future erosion hazards associated with the identified sea
level rise scenarios over the life of the project. If possible, these erosion conditions should
be shown on a site map, and the erosion zone, combined with the geologic stability
concerns, can be used to help establish locations on the parcel or parcels that can be
developed without reliance upon existing or new protective devices (including cliff-retaining
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structures, seawalls, revetments, groins, buried retaining walls, and caissons) that would
substantially alter natural landforms along bluffs and cliffs.
4. Flooding and Inundation. The flooding or inundation analysis should identify the
current tidal datum and include analysis of the extent of flooding or inundation that
potentially could occur from the identified sea level rise scenarios.
5. Other Impacts. Any additional sea level rise related impacts that could be expected to
occur over the life of the project, such as saltwater intrusion should be evaluated. This may
be especially significant for areas with a high groundwater table such as wetlands or coastal
resources that might rely upon groundwater.
Step 3. Determine how the project may impact coastal resources, considering the
influence of sea level rise over the life of the project. Resources to consider shall include
public access and recreation, coastal habitats, water quality, archaeological/paleontological
resources and scenic resources.
Step 4. Seek alternatives to avoid resource impacts and minimize risk to the project, such
as increasing heights of sea walls or finished floor elevations.
Step 5. In conjunction with the approval of the CDP, appropriate conditions of approval
will be placed on the project.
File No. 34165-02 September 4, 2020
APPENDIX B Table 28 from 2018 California Guidance Document
File No. 34165-02 September 4, 2020
APPENDIX C May 5, 2020 Geotechnical Report
22725 Old Canal Road, Yorba Linda, CA 92887 - (714) 685-3900 - FAX (714) 685-3909 2640 Financial Court, Suite A, San Diego, CA 92117 - (858) 450-4040 - FAX (858) 457-0814
3100 Fite Circle, Suite 103, Sacramento, CA 95827 - (916) 368-2088 - FAX (916) 368-2188 5600 Spring Mountain Road, Suite 201, Las Vegas, NV 89146 - (702) 562-5046 - FAX (702) 562-2457
May 5, 2020 File No. 34165-01
Julie Laughton Design Build 28885 Woodspring Circle
Trabuco Canyon, CA 92679 Attention: Ms. Julie Laughton Subject: PRELIMINARY GEOTECHNICAL INVESTIGATION Proposed residential development 1616 West Oceanfront Newport Beach, California Dear Ms. Laughton:
In accordance with your request, American Geotechnical performed a geotechnical investigation of the subject site. The purpose for the investigation was to evaluate the geotechnical conditions at the site and provide soil design parameters and earthwork recommendations for the project. This report is prepared in
general conformance with our proposal dated December 5, 2019, and your written authorization.
The results of the investigation indicate that the proposed development is feasible provided the
recommendations contained herein are incorporated into the project plans and specifications. This report should be reviewed in detail by all parties involved with the construction prior to proceeding further with the planned development and should be considered part of the construction documents. Should you have any
questions regarding the information contained herein, please do not hesitate to contact our office. When formal plans become available, they should be forwarded to our office for review and comment before being submitted to the permitting authority.
We appreciate the opportunity to be of service. Should you have any questions regarding the information contained in this report, please do not hesitate to contact us.
Sincerely, AMERICAN GEOTECHNICAL, INC.
Arumugam Alvappillai, Ph.D. Gregory W. Axten Principal Engineer Principal Engineer/CEO
G.E. 2504 G.E. 103 Enclosures: Appendix A – Boring Logs
Appendix B – Summary of Laboratory Data Appendix C – Liquefaction Analysis Appendix D – Geotechnical Guidelines for Grading Projects Distribution: Addressee (Email: Julie@julielaughton.com)
wpdata/OC/34165-01 – Preliminary Geotechnical Investigation – AA GWA 5-5-20 DL
File No. 34165-01 May 5, 2020 Page 2
1.0 INTRODUCTION
1.1 PURPOSE
The purpose of this investigation was to evaluate the site geotechnical conditions and to provide geotechnical
recommendations for design and construction of the proposed development.
1.2 SCOPE OF SERVICES
The scope of the work performed during this investigation involved the following:
• Research and review of available pertinent geotechnical literature.
• Site reconnaissance to observe general site conditions.
• Subsurface exploration consisting of drilling two (2) small-diameter borings, AGSB-1 and AGSB-2,
in the area of the proposed construction.
• Sampling and logging of the subsurface soil.
• Laboratory testing of select soil samples collected from the exploratory boring to determine the
engineering properties of the soil.
• Engineering and geologic analyses of the field and laboratory data.
• Preparation of this report summarizing our findings, conclusions, and recommendations for the
proposed construction.
1.3 SITE DESCRIPTION AND PROPOSED CONSTRUCTION
The site is located within the Balboa Peninsula of the City of Newport Beach. The property is relatively flat, a
roughly rectangular lot, and is presently occupied with a two- story residential structure and the associated
appurtenant improvements. The property is bounded by West Oceanfront in the north, beach front in the
south, and similar residential properties to the east and west. A City owned asphalt paved walkway exists in
the south portion of the property. A site location map is shown in Plate 1 and an aerial view is presented in
Plate 2.
As we understand, the proposed construction includes demolishing all existing improvements including the
structure and constructing a new three-level residential building. The new building will be constructed at an
approximately same lot elevation of the existing building and will incorporate a pickleball ball court and a pool
in the lower and roof levels of the structure, respectively. It is our understanding that data obtained from this
investigation will be used in the development of grading and foundation plans. When grading and foundation
File No. 34165-01 May 5, 2020 Page 3
plans for the specific type(s) of construction become available, the plans must be submitted to this office for
review and comment. The recommendations provided herein may be revised upon our review of the
grading/construction plan(s) and further site analyses.
2.0 INVESTIGATION
2.1 FIELD EXPLORATION
A subsurface investigation was performed at the subject site on February 27, 2020 and
March 11, 2020, and consisted of drilling two (2) small-diameter hollow-stem auger borings, AGSB-1and
AGSB-2. AGSB-1 was drilled in the north side of the property under the covered carport using a tri-pod drilling
equipment. The boring AGSB-2 was drilled in the south side patio area using limited access drilling rig. The
purpose of the exploratory borings was to determine the existing subsurface conditions and to collect
subsurface data in areas of anticipated new construction.
The borings were drilled to a maximum depth of 50 feet below the existing ground surface. The materials
encountered within all our borings consisted of poorly graded beach sand. Groundwater was encountered at
6.5 to 7 feet from the ground surface in both borings. The exploratory borings were logged by field personnel
using both visual and tactile means. Bulk and relatively undisturbed drive samples, considered representative
of subsurface material, were collected and forwarded to the laboratory for testing. Drive samples from the
exploratory borings were obtained with:
1. A 2.5-inch inside diameter (3.0-inch outside diameter) split barrel, thin-wall sampler equipped with brass
liner rings.
2. A standard split-spoon sampler with dimensions in accordance with ASTM D1586.
Both samplers were driven with a 140-pound weight falling 30 inches. The blow counts to drive the thin-wall
sampler were corrected and the equivalent Standard Penetration Test ("N") values are indicated on the boring
logs. The Standard Penetration Test values were obtained with the standard split-spoon sampler and are also
shown on the logs.
The approximate location of the borings is shown on Plate 2. The logs of the exploratory borings are
presented in Appendix A.
File No. 34165-01 May 5, 2020 Page 4
2.2 LABORATORY TESTING
Laboratory testing was performed on representative samples obtained during our field exploration. Samples
were tested for the purpose of estimating material properties for use in subsequent engineering evaluations.
Testing included in-situ moisture and density, gradation, chemical soil testing, and strength testing. A
summary of laboratory test results is included in Appendix B.
3.0 GEOLOGY AND SEISMICITY
3.1 GEOLOGY
The site is located on the Balboa Peninsula behind the modern beach strand of Newport Beach. The elevation
at the site is about 10 feet above mean sea level. The site is underlain by unconsolidated, beach sand and
eolian sand of latest Holocene age. Geotechnical characteristics of earth materials encountered in subsurface
exploration completed on site are described in previous sections of this report.
Groundwater
Groundwater was encountered in the exploratory borings at a depth of 6.5 to 7 feet below the ground surface.
The groundwater table appears to be roughly coincident with sea level.
Landslides
No known landslides are mapped on or adjacent to the site based on regional geologic maps. The site is not
located in a State of California Seismic Hazard Zone for Earthquake Induced landslides.
3.2 SEISMICITY
A risk common to all areas of southern California that should not be overlooked is the potential for damage
resulting from seismic events. There are no known faults cross or project into the site based on regional
geologic maps; however, the site is located within the surface expression of the Newport-Inglewood Fault
Zone. The site is not located in a State of California Earthquake Fault Hazard Zone. The active portion of the
fault is located about 3 miles northwest of the site.
3.2.1 Fault Rupture
Surface rupture occurs when movement on a fault breaks through to the surface. The rupture almost always
follows preexisting faults, which are zones of weakness, and may occur suddenly during an earthquake or
File No. 34165-01 May 5, 2020 Page 5
slowly in the form of fault creep. Sudden displacements are more damaging to structures because they are
accompanied by shaking.
The project area is not located within an Alquist-Priolo Earthquake Fault Zone, and no active faults are mapped
to pass through the project site. Therefore, the risk of ground surface fault rupture at the project site is low.
3.2.2 Ground Shaking
The intensity of the seismic shaking or strong ground motion at the project site during an earthquake depends
on the distance between the project area and the epicenter of the earthquake, the magnitude of the
earthquake, and the geologic conditions underlying and surrounding the site. Earthquakes occurring on faults
closest to the project site would most likely generate the largest ground motions within the project area.
Seismic design parameters regarding the ground shaking are presented in Section 4.3.
3.2.3 Liquefaction and Seismic Settlement
The site is located within an area identified as having a potential liquefaction hazard. Liquefaction is a
phenomenon in which saturated granular sediments temporarily lose their shear strength during periods of
earthquake-induced strong ground shaking. The susceptibility of a site to liquefaction is a function of the
depth, density, and water content of the sediments and the magnitude of an earthquake. Saturated,
unconsolidated silts, sands, silty sands, and gravels within 50 feet of the ground surface are most susceptible
to liquefaction. Typical effects of liquefaction include loss of bearing strength, lateral spreading, and
settlement.
In order to determine the liquefaction potential at the site, a site-specific liquefaction analysis was performed
using the computer program LiquefyPro and the subsurface data collected in our boring AGSB-2. Using the
USGS Earthquake Hazard Tool as well as site specific ground motion procedures outlined in the code, a
design earthquake magnitude of 6.7 and site peak ground acceleration (PGAM) of 0.718g were selected for our
analysis. A depth to groundwater of 5 feet was used. The results of our liquefaction analyses (see Appendix
C) indicate that most of the soil layers under the groundwater are potentially liquefiable. Our analyses also
predicted about 0.4 inch of liquefaction settlement during the design seismic event. The potential differential
settlement from liquefaction is approximately half of the total settlement (i.e., about 0.2 inches).
File No. 34165-01 May 5, 2020 Page 6
3.2.4 Tsunami
The site is in a California Geological Survey Tsunami Inundation Zone.
4.0 CONCLUSIONS & RECOMMENDATIONS
4.1 BASIS
Conclusions and recommendations contained in this report are based upon information provided, information
gathered, laboratory testing, engineering and geologic evaluations, experience, and judgment.
Recommendations contained herein should be considered minimums consistent with industry practice. More
rigorous criteria could be adopted if a lower risk of future problems is desired. Where alternatives are presented,
regardless of what approach is taken, some risk will remain, as is always the case. Usually the lowest risk is
associated with the greatest cost.
4.2 SITE SUITABILITY
Geotechnical exploration, analyses, experience, and judgment result in the conclusion that the proposed
development is geotechnically feasible. It is our opinion that the site can be improved without hazard of
landslide, slippage, or damaging settlement, and improvement can occur without similar adverse impact on
adjoining properties. Realizing this expectation will require adherence to good construction practice, agency
and code requirements, the recommendations in this report, and possible addendum recommendations made
after plan review and at the time of construction.
4.3 SEISMIC DESIGN CONSIDERATION
4.3.1 CBC Design Parameters
Based on the available information about the fault zone closet to the site and the soil conditions, the following
seismic design parameters are recommended according to the 2019 Edition of the California Building Code
(CBC)/ ASCE 7-16. Final selection of the appropriate seismic design coefficients should be made by the
structural consultant based on the local laws and ordinances, expected response of the proposed structure and
desired level of conservatism.
File No. 34165-01 May 5, 2020 Page 7
TABLE 1
Seismic Hazard Response Parameters and Design Parameters
Latitude: 33.607° - Longitude: -117.923°
Seismic Parameter Symbol Value
Site Class - F
Risk Category - II
Spectral response acceleration parameter at short periods adjusted for site
class effects SMS 1.827g
Spectral response acceleration parameter at a period of 1 s adjusted for site
class effects SM1 1.108g
Design spectral response acceleration parameter at short periods SDS 1.218g
Design spectral response acceleration parameter at a period of 1 s SD1 0.739g
Peak Ground Acceleration adjusted for site class effects PGAM 0.718g
Notes: 1. The site is located within a liquefaction zone and as such a site Class of F should be used in the design. 2. The above design parameters are determined based on site class D and using Southern California Earthquake Center (SCEC) UGMS MCER Tool. Per ASCE 7-16, Section 20.3, site class D can be utilized for structures that have fundamental periods of vibration equal to or less than 0.5s. If the fundamental period is more than 0.5s, above parameters should not be used and a site response analysis should be performed.
It should be realized that the purpose of the seismic design utilizing the above parameters is to safeguard against
major structural failures and loss of life, but not to prevent damage altogether. Even if the structural engineer
provides designs in accordance with the applicable codes for seismic design, the possibility of damage cannot be
ruled out if moderate to strong shaking occurs as a result of a large earthquake. This is the case for essentially
all structures in Southern California.
4.3.2 Liquefaction Potential
As discussed before, the site is located within a liquefaction zone. A total and differential liquefaction
settlement of approximately 0.4 and 0.2 inches, respectively are predicted based on a design earthquake
magnitude of 6.7 and site peak ground acceleration (PGAM) of 0.718g. A groundwater depth of 5 feet below
ground surface was assumed in the analysis under these conditions. Since the predicated liquefaction
settlement is not very significant, no special mitigation methods are recommended.
File No. 34165-01 May 5, 2020 Page 8
4.4 Grading
General
Grading is required for the proposed construction. When grading is conducted, it should be done in
accordance with good construction practices, minimum code requirements, and the recommendations to
follow. General guidelines for grading projects are also provided in Appendix D.
Site Preparation and Grading
Prior to the start of grading operations, utility lines within the project area, if any, should be located and marked
in the field so they can be rerouted or protected during site development. All concrete, debris and perishable
material within the area of construction should be removed from the site. The concrete foundation for the
existing building should be entirely removed from the site.
Based on the information obtained from our investigation, a minimum over-excavation of 4 feet is
recommended throughout the pad area for the proposed building addition. The actual removal depth may be
locally increased based on the soil conditions encountered during grading. The over-excavation should also
provide for a minimum of 2 feet of a properly compacted fill blanket below the bottom of the foundation system.
In areas where less critical improvements such as walkways and pavements are planned, minimum depth of
over-excavation and re-compaction is 2 feet.
Based on our exploration at the site, the material present on-site can be easily excavated with conventional
construction equipment. A representative of the geotechnical engineer should be present to review all
excavations prior to placing fill. Except at fixed boundary conditions, such as the property boundaries, the
limits of remedial grading should extend a minimum of 5 feet beyond the footprint of the proposed
improvements. In the area where the construction abuts the property line walls or existing buildings, it is
recommended that a temporary 1.5:1 (horizontal to vertical) backcut be made to help mitigate potential
damage to existing structure. When excavations deeper than 4 feet are made, the contractor should provide
temporary construction slopes and/or shoring as necessary. Temporary construction slopes should be no
steeper than 1.5:1 (horizontal to vertical). It should be realized that the site is underlain by sand that are
subjected to sloughing and caving. Sheeting and bracing should be provided by the contractor, as necessary,
to protect workers in the excavation.
File No. 34165-01 May 5, 2020 Page 9
Where excavations undermine existing improvements, such as the existing walls, etc., temporary structural
support should be provided to reduce the risk of damage resulting from undercutting. Even though not
anticipated at this time, any permanent cut and fill slopes should not be constructed steeper than 2:1, and
should be considered subject to review by the geotechnical consultant at the time of grading. These slopes
should possess sufficient compacted fines to limit erosion risk. If upon construction, relatively clean,
cohesionless sands are encountered, reconstruction by blending in fines to compacted fill and/or flattening of
slopes will be advised.
Where fill is to be placed, the upper 6 to 8 inches of the surface exposed by the excavation should be scarified,
moisture-conditioned to 2 to 3 percent over optimum moisture content, and compacted to 90 percent relative
compaction.1 If localized areas of relatively loose soil prevent proper compaction, over-excavation and re-
compaction will be necessary. The on-site soil is generally suitable for use as compacted fill and backfill,
provided that any cobbles or rock fragments greater than 4 inches are screened and removed from the soil prior
to placement and compaction. A limitation of particle size to 2 inches is preferred.
All grading should be conducted in accordance with the applicable codes, agency requirements, the
aforementioned recommendations, and the grading guidelines that accompany this report as mentioned above.
Import Fill Material
The import fill material, if utilized, should meet the following criteria:
1. No particles larger than 4 inches in largest dimension (limit to 2 inches is preferred).
2. Free of perishable material.
3. Plasticity Index of 20 or less and Liquid Limit of 40 or less.
4. Expansion Index of 20 or less.
4.5 Preliminary Foundation Recommendations
General
Minimum criteria for the design of foundations applicable to the project are provided below. The criteria should
not be considered a substitute for design by a structural engineer. The structural engineer should analyze the
1 Relative compaction refers to the ratio of the in-place dry density of soil to the maximum dry density of the same material as obtained by the "modified proctor" (ASTM D1557) test procedure.
File No. 34165-01 May 5, 2020 Page 10
actual soil-structure interaction and consider, as needed, bearing, strength, stiffness, and deflections in the
various slab, foundation, and other elements of the proposed structure to develop appropriate, design-specific
details. Other influences may have to be considered as conditions dictate. The structural engineer should
consider all applicable codes and authoritative sources where needed. If analyses by the structural engineer
result in less critical details than are provided herein as minimums, the minimums presented herein should be
adopted. It is likely that some more restrictive details will be required. If the structural engineer has any
questions or requires further assistance, please do not hesitate to call or otherwise transmit the engineer's
requests.
Foundation Design
The proposed building addition can be supported on a conventional shallow foundation system on compacted
fill. A minimum 2 feet of compacted fill blanket below the bottom of the footing is recommended. Allowable
design parameters for foundations are provided below.
Minimum exterior and interior footings embedment into compacted fill
(measured from lowest adjacent grade) ....................................................... 24 inches Minimum footing width .................................................................................. 18 inches Allowable Bearing pressure
a. Sustained loads (pounds per square foot) .............................................. 2,000 psf b. Total loads (including wind or seismic, increase by one-third)................. 3,000 psf Resistance to lateral loads
a. Passive soil resistance (pounds per cubic foot) within compacted fill .................................................................................. 200 pcf b. Coefficient of sliding friction ............................................................................ 0.45
Subgrade Plate Test Modulus .......................................................................... 100 pci Subgrade Wide Area Modulus ............................................................................ 60 pci The allowable bearing pressures are for dead plus long-term live loads and include a factor-of-safety of at least
3.0. The allowable bearing pressure indicated above can be increased by 500 psf for every additional foot of
embedment, but not to exceed 3,000 psf. It should be noted that a minimum 2 feet of uniform fill blanket below
File No. 34165-01 May 5, 2020 Page 11
the footing bottom is recommended above. As such, if the footing depth is increased, the minimum depth of
removal and recompaction should also be increased accordingly.
Footings can be designed to resist lateral loads by using a combination of sliding friction and passive
resistance. The coefficient of friction should be applied to dead load forces only. The upper 1-foot of passive
resistance should be neglected where the soil is not confined by slabs or pavements.
Footings designed and constructed in accordance with the foregoing criteria are expected to settle less than 1-
inch. Differential settlement of approximately half of the total settlement is expected over a distance of about
50 feet.
Building Slab-on-Grade
The slab-on-grade in the interior of the addition should be a minimum of 6 inches thick and reinforced with
No. 4 bars at 12 inches on center, both ways. The structural engineer should provide final slab detailing as
necessary based on the overall foundation design. The slab should be underlain by 15-mil Stego wrap
membrane. The Stego membrane splices should be staggered between layers. The membrane should be
sealed at all splices, around plumbing, and at the perimeter of slab areas. Every effort should be made to
provide a continuous barrier and care should be taken not to puncture the membrane. Below the membrane and
on top of the subgrade, an approximately 4-inch thick layer of free-draining crushed rock base (e.g., 3/4-inch
rock) is suggested. The crushed rock should have no more than 10 percent passing the 3/4-inch sieve or more
than 3 percent passing the No. 200 sieve. To protect the Stego membrane from the angular corners of crushed
rock, a layer of Mirafi 140N should be placed on the rock subgrade with 8-inch laps at splices.
4.6 Retaining Walls
Wherever retaining walls are planned, they should be designed to resist an equivalent fluid pressure of 45
pounds per cubic foot (pcf) for level backfill. Appropriate allowances should be made for anticipated surcharge
loading. It is assumed that the project engineer will incorporate an appropriately designed wall backdrain
system for the purpose of mitigating potential for hydrostatic and/or seepage forces. It is also assumed that a
predominantly granular, non-expansive backfill is provided. The minimum widths recommended for granular
backfill are 1.5 feet at the base of the wall and 0.6 times that height of the wall at the top. The uppermost 1.0
to 1.5 feet preferably should be backfilled with more cohesive material to minimize surface infiltration.
File No. 34165-01 May 5, 2020 Page 12
If walls are restrained against free movement by structural detailing, the active values given above should be
increased. Although actual increase depends on the degree of restraint, 50 percent is recommended for
design purposes. Walls designed without this restraint-related surcharge should anticipate wall rotation
between about 0.002 to 0.01H.
For walls with retaining height of more than 6 feet, seismic earth pressure should be added to the static earth
pressures given above. The recommended seismic earth pressure for the site is 28 pcf. For simplicity, the
seismic earth pressure can be applied as a uniform pressure equal to 14 times H, where H is the retained
height.
It should be pointed out that the use of heavy compaction equipment in close proximity to the retaining walls
can result in excess wall movement and/or soil loadings exceeding the design values. In this regard, care
should be taken during the backfilling operations.
Groundwater/Waterproofing
Groundwater was encountered within about 6.5 to 7 feet of the ground surface. Groundwater could be higher
at times in the future. We recommend that the designer consider groundwater as high as 2 feet from the
ground surface. Accordingly, any below grade rooms will require design and construction with “boat-like”
waterproofing and waste slab concrete sufficient to offset the buoyant uplift.
If retaining walls form portions of the building interiors, very special consideration should be given to
waterproofing of the walls to prevent damage to the building interior. Unless dampness is acceptable on
exterior wall faces, waterproofing should also be incorporated into the exterior retaining wall design.
Even though groundwater is not expected to be a problem for at grade construction at this site, extreme care
should be exercised in sealing walls against water and water vapor migration. Where retaining walls are
planned against the interior space, continuity should be provided between the aforementioned wall moisture
proofing on the back of the retaining wall and the moisture barrier typically placed under the slab areas. This
waterproofing is necessary to prevent the foundation concrete acting as a wick through which moisture
migrates to the interior space despite the wall moisture proofing. The architect or structural engineer should
develop the actual waterproofing details.
File No. 34165-01 May 5, 2020 Page 13
4.7 Exterior Flatwork
If the exterior flatwork is considered, it should be placed over newly placed compacted fill. The new exterior
flatwork should be at least 6 inches thick with No. 4 bars at 12 inches on center, each way. As recommended for
interior slabs, a four-inch thick crushed rock base under the slab and above the subgrade is also suggested. At
least two No. 4 bars should be planned within the perimeter 6 inches and within 6 inches of planned control
joints. Control joints should be planned at not more than 12-foot spacing for larger concrete areas such as the
driveway and patio areas. Narrower areas of flatwork such as walkways should have control joints planned at
not greater than 1.5 times the width of the walkway. Additionally, it is also recommended that at least 12-inch
deepened footings be constructed along the edges of the patio slab and larger concrete flatwork.
Movement of exterior slabs adjacent to structures can be mitigated by doweling slabs to perimeter footings.
Doweling should consist of No. 4 bars bent around exterior footing reinforcement. Dowels should be extended at
least 2 feet into planned exterior slabs. Doweling should be spaced consistent with the patio reinforcement
schedule. With doweling, 3/8-inch minimum thickness expansion joint material should be provided. Where
expansion joint material is provided, it should be held down about 3/8 inch below the surface. The expansion
joints should be finished with a color matched, flowing, flexible sealer (e.g., pool deck compound) sanded to add
mortar-like texture. As an option to doweling, an architectural separation could be provided between the main
structures and abutting appurtenant improvements.
4.8 Concrete
We recommend that low-permeable concrete be utilized for the project. For this purpose, the water-to-cement
ratio in the concrete should be limited to 0.45 (0.42 preferred). A minimum concrete compressive strength of
4,500 is also recommended. Use of utilizing Type V cement is also preferred. Limited use (subject to approval
of mix designs) of a water-reducing agent may be included to increase workability. The concrete should be
properly cured to minimize risk of shrinkage cracking. One-inch hard rock mixes are recommended. Pea-
gravel mixes are specifically not recommended but could be utilized for relatively non-critical improvements
(e.g., flatwork) and other improvements provided the mix designs consider limiting shrinkage.
Contractors/other designers should take care in all aspects of designing mixes, detailing, placing, finishing, and
curing concrete. The mix designers and contractor are advised to consider all available steps to reduce
cracking. The use of shrinkage compensating cement or fiber reinforcing should be considered. Mix designs
proposed by the contractor should be considered subject to review by the project engineer.
4.9 Corrosion Potential
File No. 34165-01 May 5, 2020 Page 14
In addition to sulfate tests, Chloride, pH, and resistivity tests on near-surface site soil were performed. Results
of these tests are presented in Appendix C. Appropriate design considerations should be made for the risk of
damage from corrosion. The use of STHD style strap anchors should not be permitted unless stainless steel.
Perimeter anchor bolts should be hot-dipped galvanized or epoxy coated. More advice on corrosion risk can
be provided, if needed.
4.10 Plan Review
When detailed grading and structural plans are developed, they should be forwarded to this office for review
and comment.
4.11 Field Construction Review
During construction, a number of reviews by this office are recommended to verify the site geotechnical
conditions and conformance with the intentions of the recommendations for construction. Although not all
possible geotechnical observation and testing services are required by the City, the more site
reviews requested, the lower the risk of future problems. The following site reviews are advised, some of
which will probably be required by the agencies.
Preconstruction/pregrading meeting ............................................................... Advised
Soil and geologic observation and testing during any grading ....................... Required
Foundation excavation .................................................................................. Required
Subgrade preparation for slabs ..................................................................... Required
Reinforcement for slab/foundations ................................................................ Advised
Unless otherwise agreed to in writing, all supplemental consulting services will be provided on an as-needed,
time-and-expense fee schedule basis.
5.0 REMARKS
Only a portion of subsurface conditions have been reviewed and evaluated. Conclusions, recommendations,
and other information contained in this report are based upon the assumptions that subsurface conditions do
not vary appreciably between and adjacent to observation points. Although no significant variation is
anticipated, it must be recognized that variations can occur.
File No. 34165-01 May 5, 2020 Page 15
This report has been prepared for the sole use and benefit of our client. The intent of the report is to advise
our client on geotechnical matters involving the proposed improvements. It should be understood that the
geotechnical consulting provided and the contents of this report are not perfect. Any errors or omissions noted
by any party reviewing this report, and/or any other geotechnical aspect of the project, should be reported to
this office in a timely fashion. The client is the only party intended by this office to directly receive the advice.
Subsequent use of this report can only be authorized by the client. Any transferring of information or other
directed use by the client should be considered "advice by the client."
Geotechnical engineering is characterized by uncertainty. Geotechnical engineering is often described as an
inexact science or art. Conclusions and recommendations presented herein are partly based upon the
evaluations of technical information gathered, partly on experience, and partly on professional judgment. The
conclusions and recommendations presented should be considered "advice." Other consultants could arrive at
different conclusions and recommendations. Typically, "minimum" recommendations have been presented.
Although some risk will always remain, lower risk of future problems would usually result if more restrictive
criteria were adopted. Final decisions on matters presented are the responsibility of the client and/or the
governing agencies. No warranties in any respect are made as to the performance of the project.
File No. 34165-01 May 5, 2020
REFERENCES
California Geological Survey Staff, 1998, Official Seismic Hazard Zone Map, Newport Beach
quadrangle: California Geological Survey, Official Map of Seismic Hazard Zones, scale 1:24,000.
California Division of Mines and Geology staff, 2001, Seismic Hazard Zone Report for the Anaheim and
Newport Beach 7.5-minute quadrangles, Orange County, California: California Division of Mines and
Geology, Seismic Hazard Zone Report 003, scale 1:24,000.
California Geological Survey Staff, 3/15/09, Tsunami Inundation Map for Emergency Planning Newport
Beach Quadrangle, scale 1:24,000.
Morton, P.K., Miller, R.V., and Evans, J.R., 1976, Environmental geology of Orange County, California.:
California Division of Mines and Geology, Open-File Report 79-08, scale 1:48,000.
SITE LOCATION MAP
34165-01MAY 2020N.T.S
PLATEAMERICAN GEOTECHNICAL, INC.122725 Old Canal Road, Yorba Linda, CA 92887
(714) 685-3900 (714) 685-3909
www.amgt.com
TITLE:
1616 West Oceanfront, Newport Beach, CA
FILE NO.:DATE:SCALE:
AERIAL VIEW/ BORING LOCATION MAP
34165-01MAY 2020N.T.S
PLATEAMERICAN GEOTECHNICAL, INC.222725 Old Canal Road, Yorba Linda, CA 92887
(714) 685-3900 (714) 685-3909
www.amgt.com
1616 West Oceanfront, Newport Beach, CA
FILE NO.:DATE:SCALE:
Legend AGSB-2
AGSB-2
Approximate location of boring
AGSB-1
N
1616 West
Oceanfront
File No. 34165-01 May 5, 2020
APPENDIX A
Boring Logs
File No. 34165-01 May 5, 2020
APPENDIX B
Summary of Laboratory Data
File No. 34165-01 May 5, 2020
APPENDIX C
Liquefaction Analysis
File No. 34165-01 May 5, 2020
APPENDIX D
Geotechnical Guidelines for Grading Project
22725 Old Canal Road, Yorba Linda, CA 92887 - (714) 685-3900 - FAX (714) 685-3909
2640 Financial Court, Suite A, San Diego, CA 92117 - (858) 450-4040 - FAX (858) 457-0814
3100 Fite Circle, Suite 103, Sacramento, CA 95827 - (916) 368-2088 - FAX (916) 368-2188
5600 Spring Mountain Road, Suite 201, Las Vegas, NV 89146 - (702) 562-5046 - FAX (702) 562-2457
GEOTECHNICAL GUIDELINES FOR GRADING PROJECTS
22725 Old Canal Road, Yorba Linda, CA 92887 - (714) 685-3900 - FAX (714) 685-3909
2640 Financial Court, Suite A, San Diego, CA 92117 - (858) 450-4040 - FAX (858) 457-0814
3100 Fite Circle, Suite 103, Sacramento, CA 95827 - (916) 368-2088 - FAX (916) 368-2188
5600 Spring Mountain Road, Suite 201, Las Vegas, NV 89146 - (702) 562-5046 - FAX (702) 562-2457
TABLE OF CONTENTS
A. GENERAL ........................................................................................................................................... 1
B. DEFINITIONS OF TERMS .................................................................................................................. 2
C. OBLIGATIONS OF PARTIES ............................................................................................................. 6
D. SITE PREPARATION ......................................................................................................................... 7
E. SITE PROTECTION ............................................................................................................................ 8
F. EXCAVATIONS ................................................................................................................................ 10
F1 UNSUITABLE MATERIALS .................................................................................................. 10
F2 CUT SLOPES ....................................................................................................................... 10
F3 PAD AREAS ......................................................................................................................... 11
G. COMPACTED FILL ........................................................................................................................... 12
G1 PLACEMENT ........................................................................................................................ 12
G2 MOISTURE ........................................................................................................................... 14
G3 FILL MATERIAL .................................................................................................................... 14
G4 FILL SLOPES ....................................................................................................................... 16
G5 OFF-SITE FILL ..................................................................................................................... 19
H. DRAINAGE ....................................................................................................................................... 20
I STAKING .......................................................................................................................................... 21
J. MAINTENANCE ................................................................................................................................ 22
J1 LANDSCAPE PLANTS ......................................................................................................... 22
J2 IRRIGATION ......................................................................................................................... 22
J3 MAINTENANCE .................................................................................................................... 22
J4 REPAIRS .............................................................................................................................. 23
K. TRENCH BACKFILL ......................................................................................................................... 24
L STATUS OF GRADING .................................................................................................................... 25
STANDARD DETAILS NOS. 1-9
1 CANYON SUBDRAIN
2 FILL OVER NATURAL/ CUT SLOPE
3 STABILIZATION/ BUTRESS FILL
4 STABILIZATION FILL
5 FUTURE CANYON FILL
6 TRANSITION LOT OVEREXCAVATION
7 ROCK DISPOSAL
8 MINOR SLOPE REPAIR
9 LOT DRAINAGE
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 1
GEOTECHNICAL GUIDELINES FOR GRADING PROJECTS
A. GENERAL
Al The guidelines contained herein and the standard details attached hereto represent this
firm's standard recommendations for grading and other associated operations on
construction projects. These guidelines should be considered a portion of the project
specifications.
A2 All plates attached hereto shall be considered as part of these guidelines.
A3 The Contractor should not vary from these guidelines without prior recommendation by the
Geotechnical Consultant and the approval of the Client or his authorized representative.
Recommendations by the Geotechnical Consultant and/or Client should not be considered to
preclude requirements for approval by the controlling agency prior to the execution of any
changes.
A4 These Standard Grading Guidelines and Standard Details may be modified and/or
superseded by recommendations contained in the text of the preliminary geotechnical report
and/or subsequent reports.
A5 If disputes arise out of the interpretation of these grading guidelines or standard details, the
Geotechnical Consultant shall provide the governing interpretation.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 2
B. DEFINITIONS OF TERMS
Bl ALLUVIUM - unconsolidated detrital deposits resulting from flow of water, including
sediments deposited in river beds, canyons, flood plains, lakes, fans at the foot of slopes and
estuaries.
B2 AS-GRADED (AS-BUILT) - the surface and subsurface conditions at completion of grading.
B3 BACKCUT - a temporary construction slope at the rear of earth retaining structures such as
buttresses, shear keys, stabilization fills or retaining walls.
B4 BACKDRAIN - generally a pipe and gravel or similar drainage system placed behind earth
retaining structures such as buttresses, stabilization fills and retaining walls.
B5 BEDROCK - a more or less solid, relatively undisturbed rock in place either at the surface or
beneath superficial deposits of soil.
B6 BENCH - a relatively level step and near vertical rise excavated into sloping ground on which
fill is to be placed.
B7 BORROW (Import) - any fill material hauled to the project site from off-site areas.
B8 BUTTRESS FILL - a fill mass, the configuration of which is designed by engineering
calculations to stabilize a slope exhibiting adverse geologic features. A buttress is generally
specified by minimum key width and depth and by maximum backcut angle. A buttress
normally contains a backdrain system.
B9 CIVIL ENGINEER - the Registered Civil Engineer or consulting firm responsible for
preparation of the grading plans, surveying and verifying as-graded topographic conditions.
B10 CLIENT - the Developer or his authorized representative who is chiefly in charge of the
project. He shall have the responsibility of reviewing the findings and recommendations
made by the Geotechnical Consultant and shall authorize the Contractor and/or other
consultants to perform work and/or provide services.
B11 COLLUVIUM - generally loose deposits usually found near the base of slopes and brought
there chiefly by gravity through slow continuous downhill creep (also see Slope Wash).
B12 COMPACTION - is the densification of a fill by mechanical means.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 3
B13 CONTRACTOR - a person or company under contract or otherwise retained by the Client to
perform demolition, grading and other site improvements.
B14 DEBRIS - all products of clearing, grubbing, demolition, contaminated soil material
unsuitable for reuse as compacted fill and/or any other material so designated by the
Geotechnical Consultant.
B15 ENGINEERING GEOLOGIST - a Geologist holding a valid certificate of registration in the
specialty of Engineering Geology.
B16 ENGINEERED FILL - a fill of which the Geotechnical Consultant or his representative, during
grading, has made sufficient tests to enable him to conclude that the fill has been placed in
substantial compliance with the recommendations of the Geotechnical Consultant and the
governing agency requirements.
B17 EROSION - the wearing away of the ground surface as a result of the movement of wind,
water and/or ice.
B18 EXCAVATION - the mechanical removal of earth materials.
B19 EXISTING GRADE - the ground surface configuration prior to grading.
B20 FILL - any deposits of soil, rock, soil-rock blends or other similar materials placed by man.
B21 FINISH GRADE - the ground surface configuration at which time the surface elevations
conform to the approved plan.
B22 GEOFABRIC - any engineering textile utilized in geotechnical applications including
subgrade stabilization and filtering.
B23 GEOLOGIST - a representative of the Geotechnical Consultant educated and trained in the
field of geology.
B24 GEOTECHNICAL CONSULTANT - the Geotechnical Engineering and Engineering Geology
consulting firm retained to provide technical services for the project. For the purpose of
these guidelines, observations by the Geotechnical Consultant include observations by the
Soil Engineer, Geotechnical Engineer, Engineering Geologist and those performed by
persons employed by and responsible to the Geotechnical Consultants.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 4
B25 GEOTECHNICAL ENGINEER - a licensed Civil Engineer who applies scientific methods,
engineering principles and professional experience to the acquisition, interpretation and use
of knowledge of materials of the earth's crust for the evaluation of engineering problems.
Geotechnical Engineering encompasses many of the engineering aspects of soil mechanics,
rock mechanics, geology, geophysics, hydrology and related sciences.
B26 GRADING - any operation consisting of excavation, filling or combinations thereof and
associated operations.
B27 LANDSLIDE DEBRIS - material, generally porous and of low density, produced from
instability of natural or man-made slopes.
B28 MAXIMUM DENSITY - standard laboratory test for maximum dry unit weight. Unless
otherwise specified, the maximum dry unit weight shall be determined in accordance with
ASTM Method of Test D 1557-78.
B29 OPTIMUM MOISTURE - test moisture content at the maximum density.
B30 RELATIVE COMPACTION - the degree of compaction (expressed as a percentage) of dry
unit weight of a material as compared to the maximum dry unit weight of the material.
B31 ROUGH GRADE - the ground surface configuration at which time the surface elevations
approximately conform to the approved plan.
B32 SITE - the particular parcel of land where grading is being performed.
B33 SHEAR KEY - similar to buttress, however, it is generally constructed by excavating a slot
within a natural slope in order to stabilize the upper portion of the slope without grading
encroaching into the lower portion of the slope.
B34 SLOPE - is an inclined ground surface the steepness of which is generally specified as a
ratio of horizontal:vertical (e.g., 2:1).
B35 SLOPE WASH - soil and/or rock material that has been transported down a slope by mass
wasting assisted by runoff water not confined by channels (also see Colluvium).
B36 SOIL - naturally occurring deposits of sand, silt, clay, etc. or combinations thereof.
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B37 SOIL ENGINEER - licensed Civil Engineer experienced in soil mechanics (also see
Geotechnical Engineer).
B38 STABILIZATION FILL - a fill mass, the configuration of which is typically related to slope
height and is specified by the standards of practice for enhancing the stability of locally
adverse conditions. A stabilization fill is normally specified by minimum key width and depth
and by maximum backcut angle. A stabilization fill may or may not have a backdrain system
specified.
B39 SUBDRAIN - generally a pipe and gravel or similar drainage system placed beneath a fill in
the alignment of canyons or former drainage channels.
B40 SLOUGH - loose, noncompacted fill material generated during grading operations.
B41 TAILINGS - non-engineered fill which accumulates on or adjacent to equipment haul-roads.
B42 TERRACE - relatively level step constructed in the face of a graded slope surface for
drainage control and maintenance purposes.
B43 TOPSOIL - the presumably fertile upper zone of soil which is usually darker in color and
loose.
B44 WINDROW - a string of large rock buried within engineered fill in accordance with guidelines
set forth by the Geotechnical Consultant.
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C. OBLIGATIONS OF PARTIES
C1 The Geotechnical Consultant should provide observation and testing services and should
make evaluations to advise the Client on geotechnical matters. The geotechnical Consultant
should report his findings and recommendations to the Client or his authorized
representative.
C2 The Client should be chiefly responsible for all aspects of the project. He or his authorized
representative has the responsibility of reviewing the findings and recommendations of the
Geotechnical Consultant. He shall authorize or cause to have authorized the Contractor
and/or other consultants to perform work and/or provide services. During grading the Client
or his authorized representative should remain on-site or should remain reasonably
accessible to all concerned parties in order to make decisions necessary to maintain the flow
of the project.
C3 The Contractor should be responsible for the safety of the project and satisfactory
completion of all grading and other associated operations on construction projects, including,
but not limited to, earth work in accordance with the project plans, specifications and
controlling agency requirements. During grading, the Contractor or his authorized
representative should remain on-site. Overnight and on days off, the Contractor should
remain accessible.
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D. SITE PREPARATION
D1 The Client, prior to any site preparation or grading, should arrange and attend a meeting
among the Grading Contractor, the Design Engineer, the Geotechnical Consultant,
representatives of the appropriate governing authorities as well as any other concerned
parties. All parties should be given at least 48 hours notice.
D2 Clearing and grubbing should consist of the removal of vegetation such as brush, grass,
woods, stumps, trees, roots of trees and otherwise deleterious natural materials from the
areas to be graded. Clearing and grubbing should extend to the outside of all proposed
excavation and fill areas.
D3 Demolition should include removal of buildings, structures, foundations, reservoirs, utilities
(including underground pipelines, septic tanks, leach fields, seepage pits, cisterns, mining
shafts, tunnels, etc.) and other man-made surface and subsurface improvements from the
areas to be graded. Demolition of utilities should include proper capping and/or rerouting
pipelines at the project perimeter and cutoff and capping of wells in accordance with the
requirements of the governing authorities and the recommendations of the Geotechnical
Consultant at the time of demolition.
D4 Trees, plants or man-made improvements not planned to be removed or demolished should
be protected by the Contractor from damage.
D5 Debris generated during clearing, grubbing and/or demolition operations should be wasted
from areas to be graded and disposed off-site. Clearing, grubbing and demolition operations
should be performed under the observation of the Geotechnical Consultant.
D6 The Client or Contractor should obtain the required approvals from the controlling authorities
for the project prior, during and/or after demolition, site preparation and removals, etc. The
appropriate approvals should be obtained prior to proceeding with grading operations.
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E SITE PROTECTION
El Protection of the site during the period of grading should be the responsibility of the
Contractor. Unless other provisions are made in writing and agreed upon among the
concerned parties, completion of a portion of the project should not be considered to
preclude that portion or adjacent areas from the requirements for site protection until such
time as the entire project is complete as identified by the Geotechnical Consultant, the Client
and the regulating agencies.
E2 The Contractor should be responsible for the stability of all temporary excavations.
Recommendations by the Geotechnical Consultant pertaining to temporary excavations
(e.g., backcuts) are made in consideration of stability of the completed project and, therefore,
should not be considered to preclude the responsibilities of the Contractor.
Recommendations by the Geotechnical Consultant should not be considered to preclude
more restrictive requirements by the regulating agencies.
E3 Precautions should be taken during the performance of site clearing, excavations and
grading to protect the work site from flooding, ponding or inundation by poor or improper
surface drainage. Temporary provisions should be made during the rainy season to
adequately direct surface drainage away from and off the work site. Where low areas cannot
be avoided, pumps should be kept on hand to continually remove water during periods of
rainfall.
E4 During periods of rainfall, plastic sheeting should be kept reasonably accessible to prevent
unprotected slopes from becoming saturated. Where necessary during periods of rainfall,
the Contractor should install checkdams, desilting basins, rip-rap, sand bags or other devices
or methods necessary to control erosion and provide safe conditions.
E5 During periods of rainfall, the Geotechnical Consultant should be kept informed by the
Contractor as to the nature of remedial or preventative work being performed (e.g., pumping,
placement of sandbags or plastic sheeting, other labor, dozing, etc.).
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E6 Following periods of rainfall, the Contractor should contact the Geotechnical Consultant and
arrange a walkover of the site in order to visually assess rain related damage. The
Geotechnical Consultant may also recommend excavations and testing in order to aid in his
assessments. At the request of the Geotechnical Consultant, the Contractor shall make
excavations in order to evaluate the extent of rain related-damage.
E7 Rain-related damage should be considered to include, but may not be limited to, erosion,
silting, saturation, swelling, structural distress and other adverse conditions identified by the
Geotechnical Consultant. Soil adversely affected should be classified as Unsuitable
Materials and should be subject to overexcavation and replacement with compacted fill or
other remedial grading as recommended by the Geotechnical Consultant.
E8 Relatively level areas, where saturated soils and/or erosion gullies exist to depths of greater
than 1.0 foot, should be overexcavated to unaffected, competent material. Where less than
1.0 foot in depth, unsuitable materials may be processed in-place to achieve near-optimum
moisture conditions, then thoroughly recompacted in accordance with the applicable
specifications. If the desired results are not achieved, the affected materials should be
overexcavated, then replaced in accordance with the applicable specifications.
E9 In slope areas, where saturated soil and/or erosion gullies exist to depths of greater than 1.0
foot, they should be overexcavated and replaced as compacted fill in accordance with the
applicable specifications. Where affected materials exist to depths of 1.0 foot or less below
proposed finished grade, remedial grading by moisture conditioning in-place, followed by
thorough recompaction in accordance with the applicable grading guidelines herein may be
attempted. If the desired results are not achieved, all affected materials should be
overexcavated and replaced as compacted fill in accordance with the slope repair
recommendations herein. As field conditions dictate, other slope repair procedures may be
recommended by the Geotechnical Consultant.
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F. EXCAVATIONS
F1 UNSUITABLE MATERIALS
F1.1 Materials which are unsuitable should be excavated under observation and
recommendations of the Geotechnical Consultant. Unsuitable materials include, but
may not be limited to, dry, loose, soft, wet, organic compressible natural soils and
fractured, weathered, soft bedrock and nonengineered or otherwise deleterious fill
materials.
F1.2 Material identified by the Geotechnical Consultant as unsatisfactory due to it's
moisture condition should be overexcavated, watered or dried, as needed, and
thoroughly blended to a uniform near optimum moisture condition prior to placement
as compacted fill.
F2 CUT SLOPES
F2.1 Unless otherwise recommended by the Geotechnical Consultant and approved by
the regulating agencies, permanent cut slopes should not be steeper than 2:1
(horizontal: vertical).
F2.2 If excavations for cut slopes expose loose, cohesionless, significantly fractured or
otherwise unsuitable material, overexcavation and replacement of the unsuitable
materials with a compacted stabilization fill should be accomplished as
recommended by the Geotechnical Consultant. Unless otherwise specified by the
Geotechnical Consultant, stabilization fill construction should conform to the
requirements of the Standard Details.
F2.3 The Geotechnical Consultant should review cut slopes during excavation. The
Geotechnical Consultant should be notified by the contractor prior to beginning slope
excavations.
F2.4 If, during the course of grading, adverse or potentially adverse geotechnical
conditions are encountered which were not anticipated in the preliminary report, the
Geotechnical Consultant should explore, analyze and make recommendations to
treat these problems.
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F2.5 When cut slopes are made in the direction of the prevailing drainage, a non-erodible
diversion swale (brow ditch) should be provided at the top-of-cut.
F3 PAD AREAS
F3.1 All lot pad areas, including side yard terraces, above stabilization fill or buttresses
should be overexcavated to provide for a minimum of 3 feet (refer to Standard
Details) of compacted fill over the entire pad area. Pad areas with both fill and cut
materials exposed and pad areas containing both very shallow (less than 3 feet) and
deeper fill should be overexcavated to provide for a uniform compacted fill blanket
with a minimum of 3 feet in thickness (refer to Standard Details). Cut areas exposing
significantly varying material types should also be overexcavated to provide for at
least a 3-foot thick compacted fill blanket. Geotechnical conditions may require
greater depth of overexcavation. The actual depth should be delineated by the
Geotechnical Consultant during grading.
F3.2 For pad areas created above cut or natural slopes, positive drainage should be
established away from the top-of-slope. This may be accomplished utilizing a berm
and/or an appropriate pad gradient. A gradient in soil areas away from the top-of-
slopes of 2 percent or greater is recommended.
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G. COMPACTED FILL
All fill materials should be compacted as specified below or by other methods specifically
recommended by the Geotechnical Consultant. Unless otherwise specified, the minimum degree of
compaction (relative compaction) should be 90 percent of the laboratory maximum density.
G1 PLACEMENT
G1.1 Prior to placement of compacted fill, the Contractor should request a review by the
Geotechnical Consultant of the exposed ground surface. Unless otherwise
recommended, the exposed ground surface should then be scarified (six inches
minimum), watered or dried as needed, thoroughly blended to achieve near optimum
moisture conditions, then thoroughly compacted to a minimum of 90 percent of the
maximum density. The review by the Geotechnical Consultant should not be
considered to preclude requirement of inspection and approval by the governing
agency.
G1.2 Compacted fill should be placed in thin horizontal lifts not exceeding eight inches in
loose thickness prior to compaction. Each lift should be watered or dried as needed,
thoroughly blended to achieve near optimum moisture conditions then thoroughly
compacted by mechanical methods to a minimum of 90 percent of laboratory
maximum dry density. Each lift should be treated in a like manner until the desired
finished grades are achieved.
G1.3 The Contractor should have suitable and sufficient mechanical compaction
equipment and watering apparatus on the job site to handle the amount of fill being
placed in consideration of moisture retention properties of the materials. If
necessary, excavation equipment should be "shut down" temporarily in order to
permit proper compaction of fills. Earth moving equipment should only be
considered a supplement and not substituted for conventional compaction
equipment.
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G1.4 When placing fill in horizontal lifts adjacent to areas sloping steeper than 5:1
(horizontal: vertical), horizontal keys and vertical benches should be excavated into
the adjacent slope area. Keying and benching should be sufficient to provide at least
six-foot wide benches and a minimum of four feet of vertical bench height within the
firm natural ground, firm bedrock or engineered compacted fill. No compacted fill
should be placed in an area subsequent to keying and benching until the area has
been reviewed by the Geotechnical Consultant. Material generated by the benching
operation should be moved sufficiently away from the bench area to allow for the
recommended review of the horizontal bench prior to placement of fill. Typical
keying and benching details have been included within the accompanying Standard
Details.
G1.5 Within a single fill area where grading procedures dictate two or more separate fills,
temporary slopes (false slopes) may be created. When placing fill adjacent to a false
slope, benching should be conducted in the same manner as above described. At
least a 3-foot vertical bench should be established within the firm core of adjacent
approved compacted fill prior to placement of additional fill. Benching should
proceed in at least 3-foot vertical increments until the desired finished grades are
achieved.
G1.6 Fill should be tested for compliance with the recommended relative compaction and
moisture conditions. Field density testing should conform to ASTM Method of Test
D1556-64, D2922-78 and/or D2937-71. Tests should be provided for about every
two vertical feet or 1,000 cubic yards of fill placed. Actual test interval may vary as
field conditions dictate. Fill found not to be in conformance with the grading
recommendations should be removed or otherwise handled as recommended by the
Geotechnical Consultant.
G1.7 The Contractor should assist the Geotechnical Consultant and/or his representative
by digging test pits for removal determinations and/or for testing compacted fill.
G1.8 As recommended by the Geotechnical Consultant, the Contractor should "shut down"
or remove grading equipment from an area being tested.
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G1.9 The Geotechnical Consultant should maintain a plan with estimated locations of field
tests. Unless the client provides for actual surveying of test locations, the estimated
locations by the Geotechnical Consultant should only be considered rough estimates
and should not be utilized for the purpose of preparing cross sections showing test
locations or in any case for the purpose of after-the-fact evaluating of the sequence
of fill placement.
G2 MOISTURE
G2.1 For field testing purposes, "near optimum" moisture will vary with material type and
other factors including compaction procedure. "Near optimum" may be specifically
recommended in Preliminary Investigation Reports and/or may be evaluated during
grading. As a preliminary guideline "near optimum" should be considered from one
percent below to three percent above optimum.
G2.2 Prior to placement of additional compacted fill following an overnight or other grading
delay, the exposed surface or previously compacted fill should be processed by
scarification, watered or dried as needed, thoroughly blended to near-optimum
moisture conditions, then recompacted to a minimum of 90 percent of laboratory
maximum dry density. Where wet or other dry or other unsuitable materials exist to
depths of greater than one foot, the unsuitable materials should be over excavated.
G2.3 Following a period of flooding, rainfall or overwatering by other means, no additional
fill should be placed until damage assessments have been made and remedial
grading performed as described under Section E6 herein.
G3 FILL MATERIAL
G3.1 Excavated on-site materials which are acceptable to the Geotechnical Consultant
may be utilized as compacted fill, provided trash, vegetation and other deleterious
materials are removed prior to placement.
G3.2 Where import materials are required for use on-site, the Geotechnical Consultant
should be notified at least 72 hours in advance of importing, in order to sample and
test materials from proposed borrow sites. No import materials should be delivered
for use on-site without prior sampling and testing by the Geotechnical Consultant.
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G3.3 Where oversized rock or similar irreducible material is generated during grading, it is
recommended, where practical, to waste such material off-site or on-site in areas
designated as "nonstructural rock disposal areas". Rock placed in disposal areas
should be placed with sufficient fines to fill voids. The rock should be compacted in
lifts to an unyielding condition. The disposal area should be covered with at least
three feet of compacted fill which is free of oversized material. The upper three feet
should be placed in accordance with the guidelines for compacted fill herein.
G3.4 Rocks 12 inches in maximum dimension and smaller may be utilized within the
compacted fill, provided they are placed in such a manner that nesting of the rock is
avoided. Fill should be placed and thoroughly compacted over and around all rock.
The amount of rock should not exceed 40 percent by dry weight passing the 3/4-inch
sieve size. The 12-inch and 40 percent recommendations herein may vary as field
conditions dictate.
G3.5 During the course of grading operations, rocks or similar irreducible materials greater
than 12 inches maximum dimension (oversized material), may be generated. These
rocks should not be placed within the compacted fill unless placed as recommended
by the Geotechnical Consultant.
G3.6 Where rocks or similar irreducible materials of greater than 12 inches but less than
four feet of maximum dimension are generated during grading, or otherwise desired
to be placed within an engineered fill, special handling in accordance with the
accompanying Standard Details is recommended. Rocks greater than four feet
should be broken down or disposed off-site. Rocks up to four feet maximum
dimension should not be placed in the upper 10 feet of any fill and should not be
closer than 20 feet to any slope face. These recommendations could vary as
locations of improvements dictate.
Where practical, oversized material should not be placed below areas where
structures or deep utilities are proposed. Oversized material should be placed in
windrows on a clean, overexcavated or unyielding compacted fill or firm natural
ground surface. Select native or imported granular soil (S.E. 30 or higher) should be
placed and thoroughly flooded over and around all windrowed rock, such that voids
are filled. Windrows of oversized material should be staggered so that successive
strata of oversized material are not in the same vertical plane.
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The Contractor should be aware that the placement of rock in windrows will
significantly slow the grading operation and may require additional equipment and/or
special equipment.
G3.7 It may be possible to dispose of individual larger rock as field conditions dictate and
as recommended by the Geotechnical Consultant at the time of placement.
G3.8 Material that is considered unsuitable by the Geotechnical Consultant should not be
utilized in the compacted fill.
G3.9 During grading operations, placing and mixing the materials from the cut and/or
borrow areas may result in soil mixtures which possess unique physical properties.
Testing may be required of samples obtained directly from the fill areas in order to
verify conformance with the specifications. Processing of these additional samples
may take two or more working days. The contractor may elect to move the operation
to other areas within the project, or may continue placing compacted fill pending
laboratory and field test results. Should he elect the second alternative, fill placed is
done so at the Contractor's risk.
G3.10 Any fill placed in areas not previously reviewed and evaluated by the Geotechnical
Consultant, and/or in other areas, without prior notification to the Geotechnical
Consultant may require removal and recompaction at the Contractor's expense.
Determination of overexcavations should be made upon review of field conditions by
the Geotechnical Consultant.
G4 FILL SLOPES
G4.1 Unless otherwise recommended by the Geotechnical Consultant and approved by
the regulating agencies, permanent fill slopes should not be steeper than 2:1
(horizontal: vertical).
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G4.2 Except as specifically recommended otherwise or as otherwise provided for in these
grading guidelines (Reference G4.3), compacted fill slopes should be overbuilt and
cut back to grade, exposing the firm, compacted fill inner core. The actual amount of
overbuilding may vary as field conditions dictate. If the desired results are not
achieved, the existing slopes should be overexcavated and reconstructed under the
guidelines of the Geotechnical Consultant. The degree of overbuilding shall be
increased until the desired compacted slope surface condition is achieved. Care
should be taken by the Contractor to provide thorough mechanical compaction to the
outer edge of the overbuilt slope surface.
G4.3 Although no construction procedure produces a slope free from risk of future
movement, overfilling and cutting back of slope to a compacted inner core is, given
no other constraints, the most desirable procedure. Other constraints, however,
must often be considered. These constraints may include property line situations,
access, the critical nature of the development and cost. Where such constraints are
identified, slope face compaction on slopes of 2:1 or flatter may be attempted as a
second-best alternative by conventional construction procedures including
backrolling techniques upon specific recommendation by the Geotechnical
Consultant.
Fill placement should proceed in thin lifts, (i.e., six to eight-inch loose thickness).
Each lift should be moisture conditioned and thoroughly compacted. The desired
moisture condition should be maintained and/or re-established, where necessary,
during the period between successive lifts. Selected lifts should be tested to
ascertain that desired compaction is being achieved. Care should be taken to extend
compactive effort to the outer edge of the slope.
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Each lift should extend horizontally to the desired finished slope surface or more as
needed to ultimately establish desired grades. Grade during construction should not
be allowed to roll off at the edge of the slope. It may be helpful to elevate slightly the
outer edge of the slope. Slough resulting from the placement of individual lifts should
not be allowed to drift down over previous lifts. At intervals not exceeding four feet in
vertical slope height or the capability of available equipment, whichever is less, fill
slopes should be thoroughly backrolled utilizing a conventional sheepsfoot-type
roller. Care should be taken to maintain the desired moisture conditions and/or
reestablishing same as needed prior to backrolling. Upon achieving final grade, the
slopes should again be moisture conditioned and thoroughly backrolled. The use of
a side-boom roller will probably be necessary and vibratory methods are strongly
recommended. Without delay, so as to avoid (if possible) further moisture
conditioning, the slopes should then be grid-rolled to achieve a relatively smooth
surface and uniformly compact condition.
In order to monitor slope construction procedures, moisture and density tests should
be taken at regular intervals. Failure to achieve the desired results will likely result in
a recommendation by the Geotechnical Consultant to overexcavate the slope
surfaces followed by reconstruction of the slopes utilizing over-filling and cutting back
procedures and/or further attempt at the conventional backrolling approach. Other
recommendations may also be provided which would be commensurate with field
conditions.
G4.4 Where placement of fill above a natural slope or above a cut slope is proposed, the
fill slope configuration as presented in the accompanying Standard Details should be
adopted.
G4.5 For pad areas above fill slopes, positive drainage should be established away from
the top-of-slope. This may be accomplished utilizing a berm and pad gradients of at
least 2 percent in soil areas.
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G5 OFF-SITE FILL
G5.1 Off-site fill should be treated in the same manner as recommended in these
specifications for site preparation, excavation, drains, compaction, etc.
G5.2 Off-site canyon fill should be placed in preparation for future additional fill, as shown
in the accompanying Standard Details.
G5.3 Off-site fill subdrains temporarily terminated (up canyon) should be surveyed for
future relocation and connection.
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H. DRAINAGE
H1 Canyon subdrain systems specified by the Geotechnical Consultant should be installed in
accordance with the Standard Details.
H2 Typical subdrains for compacted fill buttresses, slope stabilizations or sidehill masses,
should be installed in accordance with the specifications of the accompanying Standard
Details.
H3 Roof, pad and slope drainage should be directed away from slopes and areas of structures
to suitable disposal areas via non-erodible devices (i.e., gutters, downspouts, concrete
swales).
H4 For drainage over soil areas immediately away from structures, (i.e., within four feet) a
minimum of 5 percent gradient should be maintained. Pad drainage of at least 2 percent
should be maintained over soil areas.
H5 Drainage patterns established at the time of fine grading should be maintained throughout
the life of the project. Property owners should be made aware that altering drainage patterns
can be detrimental to slope stability and foundation performance.
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I STAKING
I1 In all fill areas, the fill should be compacted prior to the placement of the stakes. This
particularly is important on fill slopes. Slope stakes should not be placed until the slope is
thoroughly compacted (backrolled). If stakes must be placed prior to the completion of
compaction procedures, it must be recognized that they will be removed and/or demolished
at such time as compaction procedures resume.
12 In order to allow for remedial grading operations, which could include overexcavations or
slope stabilization, appropriate staking offsets should be provided. For finished slope and
stabilization backcut areas, we recommend at least a 10-foot setback from proposed toes
and tops-of-cut.
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J. MAINTENANCE
J1 LANDSCAPE PLANTS
In order to enhance surficial slope stability, slope planting should be accomplished at the
completion of grading. Slope planting should consist of deep-rooting vegetation requiring
little watering. Plants native to the southern California area and plants relative to native
plants are generally desirable. Plants native to other semi-arid and arid areas may also be
appropriate. A Landscape Architect would be the best party to consult regarding actual
types of plants and planting configuration.
J2 IRRIGATION
J2.1 Irrigation pipes should be anchored to slope faces, not placed in trenches excavated
into slope faces.
J2.2 Slope irrigation should be minimized. If automatic timing devices are utilized on
irrigation systems, provisions should be made for interrupting normal irrigation during
periods of rainfall.
J2.3 Though not a requirement, consideration should be given to the installation of near-
surface moisture monitoring control devices. Such devices can aid in the
maintenance of relatively uniform and reasonably constant moisture conditions.
J2.4 Property owners should be made aware that overwatering of slopes is detrimental to
slope stability.
J3 MAINTENANCE
J3.1 Periodic inspections of landscaped slope areas should be planned and appropriate
measures should be taken to control weeds and enhance growth of the landscape
plants. Some areas may require occasional replanting and/or reseeding.
J3.2 Terrace drains and downdrains should be periodically inspected and maintained free
of debris. Damage to drainage improvements should be repaired immediately.
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J3.3 Property owners should be made aware that burrowing animals can be detrimental to
slope stability. A preventative program should be established to control burrowing
animals.
J3.4 As a precautionary measure, plastic sheeting should be readily available, or kept on
hand, to protect all slope areas from saturation by periods of heavy or prolonged
rainfall. This measure is strongly recommended, beginning with the period of time
prior to landscape planting.
J4 REPAIRS
J4.1 If slope failures occur, the Geotechnical Consultant should be contacted for a field
review of site conditions and development of recommendations for evaluation and
repair.
J4.2 If slope failures occur as a result of exposure to periods of heavy rainfall, the failure
area and currently unaffected areas should be covered with plastic sheeting to
protect against additional saturation.
J4.3 In the accompanying Standard Details, appropriate repair procedures are illustrated
for superficial slope failures (i.e., occurring typically within the outer one foot to three
feet of a slope face).
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K. TRENCH BACKFILL
K1 Utility trench backfill should, unless otherwise recommended, be compacted by mechanical
means. Unless otherwise recommended, the degree of compaction should be a minimum of
90 percent of the laboratory maximum density.
K2 As an alternative, granular material (sand equivalent greater than 30) may be thoroughly
jetted in-place. Jetting should only be considered to apply to trenches no greater than two
feet in width and four feet in depth. Following jetting operations, trench backfill should be
thoroughly mechanically compacted and/or wheel rolled from the surface.
K3 Backfill of exterior and interior trenches extending below a 1:1 projection from the outer edge
of foundations should be mechanically compacted to a minimum of 90 percent of the
laboratory maximum density.
K4 Within slab areas, but outside the influence of foundations, trenches up to one foot wide and
two feet deep may be backfilled with sand and consolidated by jetting, flooding or by
mechanical means. If on-site materials are utilized, they should be wheel-rolled, tamped or
otherwise compacted to a firm condition. For minor interior trenches, density testing may be
deleted or spot testing may be elected if deemed necessary, based on review of backfill
operations during construction.
K5 If utility contractors indicate that it is undesirable to use compaction equipment in close
proximity to a buried-conduit, the Contractor may elect the utilization of light weight
mechanical compaction equipment and/or shading of the conduit with clean, granular
material, which should be thoroughly jetted in-place above the conduit, prior to initiating
mechanical compaction procedures. Other methods of utility trench compaction may also be
appropriate, upon review by the Geotechnical Consultant at the time of-construction.
K6 In cases where clean granular materials are proposed for use in lieu of native materials or
where flooding or jetting is proposed, the procedures should be considered subject to review
by the Geotechnical Consultant.
K7 Clean granular backfill and/or bedding are not recommended in slope areas unless
provisions are made for a drainage system to mitigate the potential build-up of seepage
forces.
GEOTECHNICAL GUIDELINE FOR GRADING PROJECTS
Page 25
L STATUS OF GRADING
Prior to proceeding with any grading operation, the Geotechnical Consultant should be notified at
least two working days in advance in order to schedule the necessary observation and testing
services.
L1 Prior to any significant expansion or cut back in the grading operation, the Geotechnical
Consultant should be provided with adequate notice (i.e., two days) in order to make
appropriate adjustments in observation and testing services.
L2 Following completion of grading operations and/or between phases of a grading operation,
the Geotechnical Consultant should be provided with at least two working days notice in
advance of commencement of additional grading operations.
Geofabric
Minimum
15% open
area;
EOS = 40 - 70
1ft. min. overlap.
24"
min.
Nominal 2-3"
24"
min.
Geof abric Alternative
Geofabric Alternative
Backhoe Trench
Dozer Trench
Filter Material
9ft. / ft.3
24"
min.
12" min.
3
, , etc. or 1 "
open graded
rock; 6 ft. /ft.
38 12 12 Filter
material - 9ft. /ft.3
6" min.*
12" min.
**
CANYON SUBDRAIN
Drains along canyon walls
as recommended by the
geotechnical consultant.
Install as - needed per
buttress backdrain detail.
Removal ofunsuitablematerial
Proposed Grading
Bedrock
Bench:Vertical 4ft. min.
Horizontal 6ft. min.Canyon
Subdrain
Compacted FillNatu
r
a
l
G
r
o
u
n
d
Notes:
1- Pipe be 4" min. diameter, 6" min. for runs of 500ft to 1000ft, 8" min. for runs of 1000ft. or greater.
2- Pipe should be schedule 40 PVC or similiar. Upstream ends should be capped.
3- Pipe should have 8 uniformly spaced 3/8" perforations per foot placed at 90 oset on underside
of pipe. FInal 20 foot of pipe should be nonperforated.
4- Filter material should be Calif. Class 2 Permeable Material.
5- Appropriate gradient should be provided for drainage; 2% minimum is recommended.
6- For the Geofabric Alternatives and gradients of 4% or greater, pipe may be omitted from the upper
500ft. For runs of 500, 1000, and 1500ft or greater 4", 6", and 8" pipe, respectively, should be provided.
o
Nominal 2-3"
Separation
6" min.
STANDARD DETAIL NO. 1
H/2 or 15ft min
H/2 or 15ft min
HRecontour, slope
to drain or
provide paved
drainage swales
and down drains
Fill Slo
p
e
Fill Slo
p
e
Remove uns
u
i
t
a
b
l
e
m
a
t
e
r
i
a
l
Remove
u
n
s
u
i
t
a
b
l
e
m
a
t
e
r
i
a
l
H
Backcut not steeper
than 1:1
Backcut not steeper
than 1:1
1 - If overfilling and cutting back to
grade is adopted, 15ft. min. fill
width may be reduced to 12ft. min.
In no case should the fill
width be less than 1/2 the
height of fill remaining.
2 - Backdrain as recommended by
geotechnical consultant per
buttress backdrain detail.
Bench: Vertical 4ft min.
Horizontal 6ft min.
Bench: Vertical 4ft min.
Horizontal 6ft min.
Notes:
STANDARD DETAIL NO. 2
cut slope
FILL OVER NATURAL SLOPE
slope
Natural
FILL OVER CUT SLOPE2 ft. min.
key depth at toe;
tip key 1ft. nominal
or 4% into slope
*
*
*
Backcut 1:1 max.
maintain 15ft. min. width
Fill Slope 2:1
or flatter
Dt
Compacted
Fill
3ft. min. cap
HFill Slope 2:1
or flatter (1)
Compacted
Fill
Backcut 1:1 max.
maintain 15ft. min.
fill width
15ft.
min.
H/2 or 15ft.
min.
Bench: Vertical 4 ft. min.
Horizontal 6 ft. min.
Backdrain system if
recommended by geotechnical
consultant.3 ft. min.2 ft. min.
H
3ft. min. cap (2)
STABILIZATION FILL
BUTTRESS FILL
W
Dh
Bench: Vertical 4ft. min.
Horizontal 6ft. min.
Backdrain System per
Standard Details
15ft.
min.
Bedding planes or other
adverse geological
condition.
- If overfilling and cutting back to grade is adopted,
15ft. may be reduced to 12ft. In no case should
the fill width be less than 1/2 the fill height remaining.
- A 3ft. blanket fill shall be provided above stabilization
and buttress fills. The thickness may be greater as
recommended by the geotechnical consultant.
- W = designed width of key.
- Dt = designed depth of key at toe
- Dh = depth of key at heel; unless
otherwise specified, Dh = Dt + 1ft.
Notes:
STANDARD DETAIL NO. 3
2
1
34 5
2
1
3
4
5
Conventional Backdrain
STABILIZATION FILL
STANDARD DETAIL NO. 4
3ft.
nominal
4in. min.
3ft.
nominal
H
4%
2 ft. nominal
1ft. nominal 12.5 ft. nominal
interval *
* For H 18 ft.
additional upper
drain may be
omitted.
<_
Horizontal spacing of
outlets should be
limited to about
100 ft.
Geofrabic Alternative
Geofabric: Minimum
15% open area
EOS = 40 - 70; 1ft.
min. overlap.
See details below
Blanket Fill, 3ft. min.
Notes:
1 - Pipe should be 4 inch diameter
Schedule 40 PVC or similiar.
2 - Gradients should be 4% or greater.
3 - Cap all upstream ends
4 - Trenches for outlet pipes
should be backfilled with
compacted native soil.
5 - Backdrain pipe should have
8 uniformly spaced perforations
per foot placed 90 offset on
underside of pipe. Outlet pipe should
be nonperforated.
6 - For the geofrabric alternative the
backdrain pipe may be omitted
provided at least 20 feet (i.e. 10 ft
each side of outlet) of perforated
pipe is provided to lead into
each outlet.
7 - At each outlet the geofabric
should be appropriately overlapped
(1ft.) at cuts in fabric or otherwise
sealed or taped around the pipe.
o
2ft. min.
4in. min.
2ft. min.
Clean, open graded rock; pea gravel
3/8, 1/2, 3/4 or 1-inch; 3ft /ft. min.3
Calif. Class 2 Permeable
material 3ft 3/ft. min.
View Along Canyon
Proposed Future Grade
FUTURE CANYON FILL
STANDARD DETAIL NO. 5
View of Canyon Sidewall
Future limit of
engineered fill
Future limit of
engineered fill
Future Benching
Natur
al grade
up ca
n
y on
Bedro
c
k
Futur
e
r
e
m
o
v al of
unsui
t
a
b
le ma
t
e
r
ial
Survey end of subdrainsubdrain trench
Bedrock
Proposed Future Grade
Future
Removal
Current limit of
engineered fill
Tempory Grade to Provide Drainage Natur al g r ade
up can y on
Future extension
of subdr ain
Unsuitable
material (e.g.
alluvium, topsoil,
colluvium)
Bedrock
Existing
Engineered Fill
Existing
Engineered Fill
1
1 1
1
1 1
TRANSITION LOT OVER-EXCAVATION
STANDARD DETAIL NO. 6
Cut Lot
Cut-Fill Lot
Or iginal Gr ade
Fir m Natur al Groun
d
per grading
plan
Removal, of topsoil,
colluvium, weathered
bedrock
Engineered
Fill
per grading
plan.
Engineered Fill pergrading plan.
Overexcavate and replace asengineered fill.6 inch. min. scarificationin place and recompaction
Finished Grade
Bench: Vertical 4ft. min. Horizontal 6ft. min.
Removal ofunsuitable
materials
6 inch. min. scarificationin place and recompaction
Finished Grade
3ft. min.
Overexcavate and replace asengineered fill.
Bench: Vertical 4ft. min. Horizontal 6ft. min.
5ft.
min.
Or iginal Gr
ade
Fir m Natur al Grou
n
d
1 - Topsoil, colluvium, weathered bedrock and otherwise unsuitable materials
should be removed to firm natural ground as identified by the geotechnical
consultant.
2 - The minimum depth of overexcavation should be considered subject to review
by the geotechnical consultant. Steeper transitions may require deeper
overexcavation.
3 - The lateral extent of overexcavation should be 5 feet minimum, but may
include the entire lot as recommended by the geotechnical consultant.
4 - The contractor should notify the geotechnical consultant in advance of
achieving final grades (i.e. within 5 ft.) in order to evaluate overexcavation
recommendations. Additional staking may be requested to aid in the
evaluation of overexcavations.
Notes:
5ft.
min.
ROCK DISPOSAL
STANDARD DETAIL NO. 7
Windrow Section
Windrow Profile
Fill Slope
Place
m
e
n
t
Limit
o
f
r
o
c
k
Utility
Finished Grade
Stagger Locations
of rock windrows
20ft. nominal spacing
Bedrock or Firm Natural Ground
Fill surface during grading
Fill surface during grading
Compacted Fill
Rock should be placed end to end.
Rock should not be nested.
5ft. Vertical Separation
3ft. min.
10ft.
10ft.
20ft.
Dozer V-ditch or fill thoroughly
compacted to a smooth unyielding
condition (e.g. by wheel rolling.)
Place rock on 3 to 6 inches granular
as recommended for flooding *
1 - Following placement of rock, flooding of granular material, and
placement of compacted fill adjacent to windrow, each windrow
should be thoroughly compacted from the surface.
2 - The contractor should provide to the geotechnical consultant plans
prepared by survey documenting the location of buried rock.
3 - Disposal in streets may be subject to more restrictive
requirements by the governing authorities.
Notes:
3ft. max.20ft. nominal spacing
* clean grandular material
(S.E. 30) should be
thoroughly flooded to
fill voids around rock.
>_
MINOR SLOPE REPAIR STANDARD DETAIL NO. 8
Tensar CE3 Erosion Control Grid
pinned on slope face; 4ft. each way;
Gr id of 12in. min. galvanized anchor pins
Keep chimney
drains 2 - 3ft.
below grade.
Slope
4 M Tensar SS-2 geog rid at 2ft.
vertical spacing; tip at 10%
roll out along slope to
provide continuous layers.
Chimney drain system
30ft. O.C.
Typical backdrain: 12.5ft. max.
vertical spacing; tip out of slope
at 4%; place at as low an elevation
as possible to allow for outletting.
Existing firm natural ground
or compacted fill
2ft. min.
key depth
Soil slump
1ft. min.
Bench 4ft.+_
Key width
controlled
by geogrid
(14ft. )+_
2
1
3
4
5
1
3
2Overfill slope and
cut back to compacted
core exposing edge
of geogrid.
*
*
MINOR SLOPE REPAIR STANDARD DETAIL NO. 8A
Tensar CE3 Erosion Control Grid
pinned on slope face; 4ft. each way;
Grid of 12in. min. galvanized anchor pins
Keep geofabric
drains 2 - 3ft.
below grade.
Slope
4 M Tensar SS-2 geogrid at 2ft.
vertical spacing; tip at 10%
roll out along slope to
provide continuous layers.
Geofabric drainagesystem, 15ft. o.c.
Typical backdrain: place at as low anelevation as possible to allow for
outletting through curb.
Existing firm natural ground
or compacted fill
2ft. min.
key depth
Soil slump
1ft. min.
Bench 4ft.+_
Key width
2
1
3
4
5
1
3
2Overfill slope and
cut back to compacted
core exposing edge
of geogrid.
*
*
LOT DRAINAGE
2%
2%
2%
2%
2%
2%
2%
2%
2%
2%
2%
Alternative A
Gutters and downspouts
to yard drains where
roof sections slope
to side yards.
Yard drains at 1% or greater
4 inch minimum pvc pipe
or similiar to suitable
disposal area (e.g. curb outlet.)
1 - Drainage into swale areas should be at 2% gradient.
Directly away from buildings drainage should be at 5%.
Notes:
STANDARD DETAIL NO. 9