HomeMy WebLinkAboutCT 94-11; Mar Vista; Tentative Map (CT) (7)12/29/1994 IB: 48 ^IGHTON-SfiN DIEGO «» £ 6192920771 P. 02
LEIGHWH AND ASSOCIATES, INC.
Geotechnical and Environmental Engineering Consultants
February 19, 1990
Project No. 8890860-02
To: BezTak of California
1000 Quail Street, Suite 190
Newport Beach, California 92660
Attention: Mr. Steve Parry
Subject: Supplemental Geotechnical Investigation of Suspect Landslide Area,
Panorama Heights, Carlsbad, California
Introduction
In accordance with your request and authorization, we have performed a
supplemental geotechnical investigation of the suspect landslide area on the
subject site. The purpose of this investigation was to obtain subsurface
information upslope from the suspect slide area and to evaluate the stability
of the proposed adjacent development. One large-diameter bucket-auger boring
was excavated near the previously mapped headscarp area near the property
boundary of Lots 29 and 30 (see Plate 1). The boring was sampled and downhole
logged by a geologist from our firm. The bore hole was subsequently backfilled
prior to leaving the site. The boring was drilled at the rear of the proposed
lots adjacent to the top of slope. No borings were drilled on the slide area
at this time because of environmental concerns.
In addition, we have revised the geotechnical map for the site utilizing the
most recent site development plan. All borings and trenches performed by
Lelghton and Associates are now included on this map.
Jaeot&cJ\n1cal Findings
Based on our observations, the suspect landslide mass does not encroach upon the
pad areas of Lots 29 and 30. However, several claystone beds were observed at
depths of 39 feet, 53.5 feet and 68 feet. The claystone as observed at a depth
of 53.5 feet was highly sheared and plastic with moderate seepage through the
shears and fractures. Because of this weak zone of material and the adjacent
steep natural slope, the proposed lots do not have an adequate factor of safety
against deep-seated failure in their present condition. In addition, this clay
bed, or similar weak material at depth, may coincide with the failure surface
for the possible landslide area to the north. Based upon our interpretation of
the subsurface configuration depicted on Figure 1 (Cross Section A-A')
buttressing of the slope area will be necessary to achieve the minimum factor
of safety of 1.5. A preliminary buttress configuration is depicted on Plates 1
and 2.
5421 AVENIDA ENCINAS, SUITE C, CARLSBAD CALIFORNIA 92008 (619) 931-9953
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12/29/1994 10:49 £-E IGHTON-SAN DI EGO
6192920771 P-03
8890860-02
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• Buttr&ss^v
As Indicated on Plates 1 and 2/the buttress key should be extended to a
minimum elevation of 67 feet and have a minimum key width of 40 feet. The
buttress key backcut and toe cut should be Inclined at an overall Inclination
of no steeper than 1:1 (horizontal to vertical). The buttress key should be
mapped and evaluated by the geotechnical consultant prior to fill placement.
It may ba desirable to drill one additional boring 1n the key area during
construction to verify the actual bottom elevation. The buttress
configuration depicted on Plates 1 and 2 Indicated the worst case scenario.
Based on the results of additional drilling, It may be possible to reduce the
size of the buttress key. This additional drilling 1s not recommended at this
time because of the extensive grading necessary to provide drill rig access
and the sensitive environmental issues related to this slope area.
• Buttress
that the buttress backcut (and toe cut) be observed and
geologically mapped on a full -time basis by the geotechnlcal consultant during
construction of the buttress. The purpose of this mapping 1s to substantiate
the geologic conditions that we have assumed 1n our analysis. In order to
expedite the mapping of these temporary slopes, we recommend that the grading
contractor trim these cuts with a slope board as they are brought downward.
Our analysis Indicates that buttress backcuts will be temporarily stable at
an Inclination of 1:1 (horizontal to vertical). However, because the
temporary backcuts will be excavated Into material with an adverse geologic
structure, backcut failures and surf lei al sloughing are possible. Any loose
soils which may be deposited Into the buttress key areas as a result of such
failures should be removed per the recommendations of the geotechnical
consultant prior to placement of the buttress fill. Where excessive failures
or sloughing are noted during grading, 1t may be necessary to lay slopes back
to a flatter inclination.
To reduce the potential for backcut failures, we recommend that the buttress
excavation and embankment be done as to minimize the time the backcut stands
open.
gubdralns
To minimize future ground water rise in the buttress, a subdraln should be
provided on the buttress backcut as depicted on Geologic Cross Section A-A'
{Plate 2). The subdrain should have a minimum gradient of 2 percent toward
a suitable drainage outlet. The subdrain should be surveyed for alignment
and grade after installation. Sufficient time should be allowed for the
surveys prior to commencement of filling over subdrain. The buttress subdrain
should be constructed 1n accordance with the General Earthwork and Grading
Specifications presented in Appendix E of our referenced report.
PANORAMA HEIGHTS
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BEZTAK - PANORAMA
CARLSBAD. CAUFORNIA
GEOTECHN1CAL. A_A'
CROSS SECTION M M
T-CT 94 -*mar Vista
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City of Carlsbad
Planning Department
June 6, 1994
Robert Ladwig , . /
Ladwig Design Group CJT^^~' '
1947 Camino Vida Roble, Suite 108
Carlsbad CA 92008
SUBJECT: PRE 94-17, MAR VISTA, McREYNOLDS PROPERTY
APN: 211-040-14
Preliminary review of your project was conducted on May 26, 1994. Listed below are the issues
raised by staff. Please note that the purpose of a preliminary review is to provide you with
direction and comments on the overall concept of your project. The preliminary review does not
represent an in-deptfa analysis of your project. Additional issues of concern may be raised after your
application is submitted and processed for a more specific and detailed review.
Planning Department:
1. The project's proposed density of 3.3 dwelling units per net acre should be reevaluated to
take into consideration the fact that General Plan or proposed open space should not be
deducted from the site's gross acreage of 34.3 acres. Per the requirements of the Local
Facilities Management Plan Zone 20, steep slopes, floodways. riparian habitats, circulation
element roadways, major power transmission easements, permanent bodies of water,
beaches, railroad track beds and wetlands are subtracted from a property's gross acreage.
If applicable, these areas are not permitted to count towards the calculation of the property's
maximum residential density yield and the proposed dwelling units per net acres.
2. The formal application exhibits must illustrate all the offsite utilities and roadway
improvements necessary to serve the residential subdivision, including Hidden Valley Road
and the sewer connection to the east/west sewer trunk line in Encinas Creek.
3. All the potentially significant biological impacts created by on and offsite project
improvements, including the trail, sewer line, drainage maintenance roads, the desUtation
basin, and roadways, etc., must be evaluated per the requirements of Final EIR 90-03. Final
EIR 90-03 requires supplemental environmental review to determine potential biological
impacts and mitigation measures, if necessary related to sewer alignments in the area,
regional desiltation basins in sensitive habitat areas, and the alignment of Hidden Valley
Road north to Palomar Airport Road (See Sambi Tentative Map). The project's biological
impact evaluation should comply with all the mitigation requirements located in the
Biological Resource Section of Final EIR 90-03.
4. The Zone 20 Specific Plan requires that the trail be constructed by the developer of the
underlying property, therefore, the formal project exhibits should illustrate the grading
necessary to accommodate the trail segment. To reduce trail impacts to sensitive biological
habitats, including the riparian areas in the bottom of the canyon and the coastal sage scrub
areas along the steep slopes, the Planning Department recommends that the trail segment
be aligned within the 60 foot buffer area along the top of the natural slopes. See the
attached marked plans for more detail on the recommended location of the trail alignment.
2O75 Las Palmas Drive • Carlsbad, California 92OO9-1576 •(619) 438-1161
Robert Ladwig
Ladwig Design Group
June 6, 1994
Paige 2
5. The Noise Element of the City's General Plan is currently being updated and will be
approved by the City Council in the very near future, therefore, the project's noise study
should comply with the requirements of the updated Noise Element and the associated
Noise Guidelines Manual, (Copies are on file in the Planning Department).
6. The Zone 20 Specific Plan mandates that all property less than 100 acres in size and located
in the Planned Community Zone (PC) must be developed per the requirements of Chapter
21.45 of the Carlsbad Municipal Code. To implement the standards of the Planned
Development Ordinance the appropriate application checklist requires the submittal of
building floor plans and elevations. In addition, the dwelling units should be plotted on the
individual lots to insure adequate future building separation and compliance with required
front yard and 60 foot buffer/building setbacks. An alternative to the requirement to
implement the standards of the Planned Development Ordinance would include a zone
change from PC to R-l Single-Family.
In addition to a Planned Development Permit the project requires a Carlsbad Tract Map,
Hillside Development Permit, and approval by the California Coastal Commission. Any
impacts to coastal sage scrub and riparian habitats, or wetland areas will require the
approval of the appropriate State and Federal resource agencies.
7. The Zone 20 Specific Plan requires the developer of the McReynolds property to adequately
buffer future residents from the impacts of future Poinsettia Community Park. The Planning
Department recommends that the large open space lot be extended further east along the
southern property line and that the Lot 9 (panhandle lot) be eliminated. Another
alternative in providing a buffer from the park would be to extend "B" Street south and east
along the southern property, thus eliminating the cul-de-sac.
8. All residential projects with a requirement to produce inclusionary housing units on the
ground must illustrate how this inclusionary obligation is proposed to be fulfilled as part
of the application for the market rate residential project.
Engineering Department:
1. The existing roadway configuration design is very circuitous, please redesign this
configuration to conform to a less circuitous pattern, as is shown on the attached redlined
check print.
2. Please relocate the proposed City trail to the top of the existing ridge and continue the trail
in the direction as shown in the City's Master Trail Plan.
3. Lot #27 cannot share the drainage access easement roadway. What is intended for this lot
(dwelling unit, RV lot, open space, etc.)?
4. Why is a desiltation basin proposed, is it to reduce the "Q" for off-site runoff, is it to meet
National Pollutant Discharge Elimination (NPDES) requirements, is it for grading
desiltation? Is this basin a requirement of the Specific Plan?
5. What will be proposed on the Kelly parcel? Please supply a letter of intent/recognition,
from Kelly, indicating their future plans and that they are aware of this proposed project.
Robert Ladwig
Ladwig Design Group
June 6, 1994
Page 3
6. Please supply invert elevations or a sewer line profile indicating that gravity flow can be
maintained for the proposed sewer, from the future City park through the proposed project
to Palomar Airport Road (PAR). Please supply documentation on this item, i.e. Abada CT
plan's/improvement plan's, City park improvement plan's, etc.
7. Please provide a preliminary striping plan for the future Hidden Valley Road intersection.
This is needed to show what will be proposed regarding the intersection offset.
8. Please indicate all easement's, in accordance with a Preliminary Title Report (PTR) for the
project, and indicate the future disposition of these easement's.
9. Not providing sidewalk on the non loaded side of a street is potentially acceptable. This
item will be more formally reviewed upon a formal application submittaL
10. Reducing the right of way to 51' on a single loaded street is potentially acceptable. This
item will be more formally reviewed upon a formal application submittaL
11. At sump conditions in roadways, please provide a fail safe overflow/easement between
property lines (Example: See Lots 28 and 29).
12. Depending on the time frame for development, a cul-de-sac issue may become evident with
regards to Hidden Valley Road. If access has not been previously provided to PAR and
Camino De Los Ondas, from the intersection of Hidden Valley Road, then roadway
infrastructure to PAR and Camino De Los Ondas will have to be provided, to meet the City's
cul-de-sac standard. This issue will be more formally reviewed upon a formal application
submittal.
13. Please indicate a gated emergency access lining up with the City park driveway aisle and
the on-site roadway system.
14. Upon formal application submittal, and upon further project review, additional issues may
arise for this project. A redlined check print is attached to aid in making the recommended
revisions.
Please contact Jeff Gibson at (619) 438-1161, extension 4455 if you have any questions.
Since
WAYNE'
Assistant Planning Director
c: Bobbie Hoder
File Copy
Data Entry GEW:JG:lh
3 PRE9417.LTR
MEMORANDUM
May 31, 1994
TO: ASSOCIATE PLANNER - JEFF GIBSON
From: Assistant Engineer - LUR
Via: Principal Civil Engineer - LUR
APN 211-040-14; MCREYNOLDS PROPERTY - MAR VISTA
PRELIMINARY REVIEW
A preliminary review was conducted on the above referenced project. Prior to formal
project submittal, the following item's must be addressed:
1 . The existing roadway configuration design is very circuitous,
please redesign this configuration to conform to a less
circuitous pattern, as is shown on the attached redlined check
print.
2. Please relocate the proposed City trail to the top of the
existing ridge and continue the trail in the direction as shown
in the City's Master Trail Plan.
3. Lot #27 cannot share the drainage access easement
roadway. What is intended for this lot (dwelling unit, RV lot,
open space, etc.)?
4. Why is a desiltation basin proposed, is it to reduce the "Q" for
off-site runoff, is it to meet National Pollutant Discharge
Elimination (NPDES) requirements, is it for grading desiltation?
Is this basin a requirement of the Specific Plan?
5. What will be proposed on the Kelly parcel? Please supply a
letter of intent/recognition, from Kelly, indicating their future
plans and that they are aware of this proposed project.
6. Please supply invert elevations or a sewer line profile
indicating that gravity flow can be maintained for the
proposed sewer, from the future City park through the
proposed project to Palomar Airport Road (PAR). Please
supply documentation on this item, i.e. Abada CT
plan's/improvement plan's, City park improvement plan's, etc.
MCREYNOLDS; MAR VISTA - PRELIM. REV. PAGE: 2
MAY 31, 1994
7. Please provide a preliminary striping plan for the future
Hidden Valley Road intersection. This is needed to show
what will be proposed regarding the intersection offset.
8. Please indicate all easement's, in accordance with a
Preliminary Title Report (PTR) for the project, and indicate the
future disposition of these easement's.
9. Not providing sidewalk on the non loaded side of a street is
potentially acceptable. This item will be more formally
reviewed upon a formal application submittal.
10. Reducing the right of way to 51' on a single loaded street is
potentially acceptable. This item will be more formally
reviewed upon a formal application submittal.
11. At sump conditions in roadways, please provide a fail safe
overflow/easement between property lines (Example: See lot's
28 & 29).
12. Depending on the time frame for development, a cul-de-sac
issue may become evident with regards to Hidden Valley
Road. If access has not been previously provided to PAR
and Camino De Los Ondas, from the intersection of Hidden
Valley Road, then roadway infrastructure to PAR and Camino
De Los Ondas will have to be provided, to meet the City's cul-
de-sac standard. This issue will be more formally reviewed
upon a formal application submittal.
13. Please indicate a gated emergency access lining up with the
City park driveway aisle and the on-site roadway system.
Please advise the applicant that upon formal application submittal, and upon further
project review, additional issues may arise for this project. To aid the applicant in making
the recommended revisions, a redlined check print is attached.
If you or the applicant have any questions, please either see or call me at extension 4388.
Attachment
Ladwig Design Group, Inc.
May 23, 1994
Mr. Brian Hunter
Planning Department
CITY OF CARLSBAD
2075 Las Palraas Drive
Carlsbad, California 92009
SUBJECT: MCREYNOLDS PROPERTY (MAR VISTA) ZONE 20, CITY OF CARLSBAD
(LADWIG DESIGN GROUP JN# L-1015)
Dear Brian:
Enclosed for your review and written comments is our Study #1 for
Mar Vista. As we discussed earlier, we would like to request
deletion of the PD Plan as required for theP.C. Zoned property in
Zone 20. I would think the Specific Plan would satisfy that
requirement. Also, we have designed this subdivision to meet the
standards for 7,500 square foot lots, so the need for the PD is
diminished. Your answer on this questions would be appreciated.
The project is served by one (1) street and meets the criteria of
the City cul-de-sac policy. We have also met with Kelly to the
east and the two (2) owners are willing to work together to share
grading rights and access. Also, Mar Vista will provide access to
a drainage and sewer system for Kelly. The City park" can also
sewer into Mar Vista, eliminate a pump station and solve the
ultimate offsite sewer system for the park. We followed the grades
on the park plan and the current rest room location. I would
suggest your staff look at our plan to satisfy the City sewer
needs.
Thank you for reviewing our plan. We look for your written
comments.
Sincerely,
LADWIG DESIGN GROUP
Robert C. Ladwig
RCL:lw.008
Enclosures
cc: Mrs. Christa McReynolds
Mr. Alan McReynolds
7347 Cam/no Vida Roble, Suite 108, Carlsbad, CA 92008
(619) 438-3182 FAX (619) 431-2205