29889 La Quinta Professional Plaza�#7 -),° ?
BANK
PAS a NATID�, '
January 23, 2001
Marshall Italiano, President
Lake La Quinta Board of Directors
c/o J & W Management Co.
P.O. Box 1398
Palm Desert, California 92261
Subject: Palm Desert National Bank Drainage Plan as it relates to the Lake La Quinta
Master Drainage Plan
Dear Mr. Italiano,
This letter is in response to your January 19, 2001 memo, specifically clarifying drainage issues. The
project site is approximately 4.96 acres, of which 3.67 acres was not included in the 1989 Lake La Quinta
Master Drainage Plan. Based upon the attached drainage analysis, it can be concluded that
development of the Palm Desert National Bank site to be known as La Quinta Professional Plaza as
proposed will have a less than significant impact on the existing drainage improvements and the Lake La
Quinta development, and that the additional 100-year runoff volume added by the development over the
riir1en} natu'rui state vriii 4111VUIIL to an inircaSc ill the VYatel IeVel Vf aUVIJt V. IV Inch dlstri'u'eo over t le
surface of the lake.
Interest has been raised by the residents of the Lake La Quinta community concerning the nuisance
runoff as well as that of 100-year runoff volume. To address the nuisance water, a combination catch
basin/dry well will be located in the landscaping adjacent to the Caleo Bay access. Grading will be
performed in such a way as to insure that runoff will be directed towards this point, and away from Caleo
Bay. The purpose of this dry well will be to retain as much nuisance water onsite as possible during
normal rain events. This is being done with the understanding that water above and beyond the capacity
of this well during such events as a 100-year storm will be allowed to flow off site and be addressed per
the Lake La Quinta Drainage Plan.
With regard to the water that will run offsite into Caleo Bay Street, property owners of the La Quinta
Professional Plaza development will share some of the costs associated with clean up of the affected dry
wells, the details of which are to be worked out as the development proceeds, and ultimately be
incorporated into the Covenants, Conditions and Restrictions of the La Quinta Professional Plaza.
Based on this arrangement, the Lake La Quinta Homeowner's Association endorses the drainage plan
described above in regards to the 3.67 acres not included in the 1989 Lake La Quinta Master Drainage
Plan. And, under significant rain events, including the 100-year runoff volume, consent is given to allow
the project to drain onto Caleo Bay and ultimately into Lake La Quinta as it is now being drained.
Ver my yours,
Randal D. Miller, President/ COO
Palm Desert National Bank
Colin Mc e'rmott
Palm Desert National Bank
Approved:
Marsha , President
Lake La Quinta Homeowner's Association
Board of Directors
73-745 El Paseo, Palm Desert, California 92260-4328 (760) 340-1145 • 70-390 Highway 111, Rancho Mirage, California 92270-5100
k.
Engineering, Planning,
& ASSOCIATES, INC.
Professional Teams for Complex Projects
January 15, 2001
Environmental Sciences and
Management Services
Mr. Colin McDermott
Palm Desert National Bank
73-745 El Paseo
Palm Desert, California 92260
Subject: Pain: Desert National Bank (PDNB)
Comments: Neu, Site on Washington and 47`'
Dear Colin:
75-150 Sheryl Avenue
Suite C
Palm Desert, California 92211
760.341.6660
Fax 760.346.6118
# 2432-05
As per our discussion with the City and you, Dudek & Associates has evaluated the drainage situation for
the proposed PDNB facility to be located at the southeast corner of Washington Street and 47'h Avenue.
The project site is approximately 4.96 acres and is located at the southeast comer of Washington Street and
47' Avenue. The entire area is vacant and it naturally drains from the northwest to the southeast direction.
This site is part of the large drainage area contributing to Caleo Bay Street and ultimately into Lake La
Quinta through catch -basins, storm drains and dry -wells already in place. Lake La Quinta is relatively large,
covering almost 25 acres.
111OW4111721FAX►►'
The project site is approximately 4.96 acres. The portion of the site excluded from the Lake La Quinta
drainage study is about 3.67 acres (see attached map). The total area included in the drainage study is
approximately 151 acres, thus, the 3.67 acres that was excluded makes up less than 2.5% of the total area.
The PDNB site naturally drains to the southeast corner of the property into Caleo Bay. With the
development of the site, there will be a marginal increase in the amount of How that will go into the Caleo
Bay storm drain system.
The following is an estimate of incremental drainage due to the development of PDNB site:
A.
I:
Area = 3.67 acres
100-year/24 hour precipitation = 4.5"
Runoff coefficient = 0.73
100-year runoff volume - undeveloped state = 3.67 x 4. x 0.73 = 1.01 acre foot
12
Area = 3.67 acres
100-year/24 hour precipitation = 4.5"
Runoff coefficient = 0.88
100-year runoff volume - undeveloped site = 3.67 x 4.5 x 0.73 = 1.21 acre foot
12
Mr. Colin McDermott
Palm Desert National Bank
January 15, 2001
Page 2
#2432-05
As a result, the 100-year runoff volume created by the development will only increase by 0.20 acre foot over
its natural undeveloped state. This volume represents a relatively small increase (approximately 0.54%)
compared to the total volume of -runoff from 151 acres at the 100-year runoff volume, which is
approximately 37.28 acre foot'.
Another method to illustrate this small increase is to measure its impact on the water surface elevation of
the lake. Lake La Quinta is about 25 acres in size, and with 0.20 acre foot distributed over the surface it
amounts to about 0.10 inch elevation difference. Thus, the PDNB project will have an insignificant effect
on the existing drainage system.
Based upon this drainage analysis, it can be concluded that development of the PDNB site as proposed will
have a less than significant impact on the existing drainage improvements and the Lake La Quinta
development.
We request that the Lake La Quinta Homeowners' Association endorse the PDNB project and give their
consent to the project draining onto Caleo Bay and ultimately into Lake La Quinta.
Lake La Quinta Drainage Report, August 1989.
Dudek & Associates, Inc.
75-150 Sheryl Avenue ■ Suite C a Palm Desert ■ California 92211 r (760)341-6660 ■ (760)346-6118 fax