HomeMy WebLinkAboutCT 03-01; LA COSTA RESORT; DRAINAGE STUDY; 2010-11-05PLANNING
ENGINEERING
SURVEYING
IRVINE
LOS ANGELES
RIVERSIDE
SAN DIEGO
ARIZONA
9707 Waples Street
San Diego, CA 92121
(858) 558-4500 PH
(858) 558-1414 FX
www.HunsakerSD.com
Info@HunsakerSD.com
HUNSAKER
&ASSOCIATES
5 AND lEG 0, INC.
DRAINAGE STUDY
for
LA COSTA RESORT & SPA
GOLF COURSE RENOVATION
City of Carlsbad, California
Prepared for:
KSL Development Corporation
2100 Costa Del Mar Road
Carlsbad, CA 92009
W.O. 2833-1
November 5, 2010
Hunsaker & Associates
San Diego, Inc.
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Drainage Study for La Costa Resort and Spa
Golf Course Renovation
Introduction
The La Costa Resort and Spa is proposing to renovate the golf course, which includes minor
site grading for 22 of the 36 existing holes. The goal is to reduce maintenance costs while
increasing play on the course, including attracting professional level tournaments. Primarily,
this will be achieved by an aggressive turf replacement program that places new, healthy
turf over a sand cap within the fairways to establish a healthier root zone. Turf area
reduction is included both outside existing fairways and reducing the size of some fairways.
These areas will be replaced with native plant materials In order to reduce mowing and
maintenance costs. Golf course irrigation will also be upgraded to a more efficient system
which combined with the reduction in turf, will decrease water usage and frequency of
watering. While performing the turf replacement, bunkers, tee boxes and other golf features
will be adjusted to improve aesthetics and overall playability of the course. This drain~ge
report accompanies grading plans for the proposed golf course renovation.
Existing Conditions
The La Costa Resort and Spa is located in the City of Carlsbad, east of EI Camino Real and
north of La Costa Avenue. The resort consists of approximately 392 acres, and includes
golf course, driving range, clubhouse, ballroom, tennis courts, hotel, spa, and commercial
dwelling units. The resort is bordered by eXisting residential development on the north and
east. The resort operates in conformance with Master Plan 03-02. There are seven
planning areas, the golf course being #7 and the largest, making up 360 acres of the resort.
Generally the site topography slopes southerly and westerly. An un-named tributary collects
water from Poinsettia Lane at the north, conveys southerly under Alga Road and continues
southerly toward the southwest corner of the project. There, this un-named tributary
discharges into San Marcos Creek, which drains the eastern portion of the resort, as well as
a large area of southeastern Carlsbad. San Marcos Creek then flows under EI Camino Real
to the 8atiquitos Lagoon and eventually drainsjo-the..F.?acific.Ocean ... The .. cur.r~nt golfcour.se .....
includes 11 lakes, 4 of which are jurisdictional and will not be touched during construction of
this plan.
There is a network of subsurface area drains that collect runoff within the golf course and
outlet into the existing creeks. Runoff from the surrounding residential areas are collected in
a series of ditches and placed in storm drain systems that also drain to the creeks. All drain
outlets within the creek limits will remain in place and not be disturbed by the proposed
renovation, due to the sensitive nature of the creeks. The current golf course includes 11
lakes, 4 of which have been identified as valuable environmental resources and are in-line
with the un-named tributary. Since alteration of jurisdictional waters would require resource
agency permitting, this plan avoids any impacts by not touching any sensitive habitat during
construction of this plan.
Much of the golf course at the La Costa Resort is currently within the 100 year floodplain
established by FEMA. There has·been a history of flooding within portions of the golf
course. The project site soil consists primarily of a surface layer of silty clays 'and cI~yey
sands overlaying native silty sands. These current soil conditions make it difficult to
maintain healthy turf; so existing conditions cause much of the course to require regular use
of fertilizer and herbicides.
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Drainage Study for La Costa Resort and Spa
Golf Course Renovation
Proposed Project
The proposed L~ Costa Golf Course renovation will include minor grading to reconfigure
greens, tees, and sand traps in order to improve golf experience and attract PGAILPGA
tournaments. Of the 360 acres that make up the golf course, proposed grading operations
will disturb approximately 57 acres and be confined to 22 of the 36 existing holes.
Fairways in 16w.Jying .. ;ar~as will be raised in order to reduce the frequency of inundation
when creeks crest.t IT)\'o lakes and other low lying areas outside of play will be created to
compensate for fill placem.ent in order to provide no net fill within the regulated flood plain.
Redundant and unnecessary cart paths will be removed thus reducing impervious surfaces.
Also, turf areas will be replaced with native plant species which may improve infiltration over
heavily trafficked turf surfaces currently existing on the course.
These site improvements will have a significant positive impact on the ability of the course to
drain during small storm events, due to a healthier turf and root structure, as well as reduce
many storm water quality issues that currently exist. Run-off generated on-site or passing
through the project will have a better ability to infiltrate into the soil, due to the 7" sand cap
that will be placed on top of the clayey soils that currently exists as part of the turf
replacement. By eliminating surface area of cart paths, the proposed design will also
decrease the total percentage of impervious area. The proposed grading associated with
this project does not have an overall impact on the limits of floodplain, as cuts and fills are
balanced within the floodplain area. The goal is to raise playable areas outside of the
floodplain, and lower other areas to collect storm runoff in a major storm event.
Conclusions and Recommendations
Renovation of the golf course will have an overall positive impact on site drainage during
small storm events. Turf areas will have better infiltration rates and overall imperviousness
of the golf course will·be. reduced., Drainage.pattems . .will remain.the.same .as.tl:le.site . .wiIL .. ,
continue to drain into San Marcos Creek and its tributary through current drainage outlets
and surface "sheet" flow patterns. The site area remains the same as existing, and the
small reduction in impervious area will reduce the runoff coefficient, no increase in runoff is
expected. This project will not cause an increase in runoff during the 1 DO-year storm, and
therefore we recommend approval of this report and issuance of permits allowing the
proposed renovations to proceed.
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