HomeMy WebLinkAboutMP 139A; Rancho Carrillo Master Plan; Master Plan (MP) (22)louo ua \J<LJ VJL/ U U LJ UaUn
LEEDS, HILL AND JEWETT.IHC.
Thomas A. Lang
B. Hungell. CEO
Richard H. Gllman
James S. Jenks
John A. Blschoff
Thomas C. MacDonald
Philip L. Wagner
1275 MARKET STREETSAN FRANCISCO. CALIFORNIA 94103TELEPHONE <41S) 626-2070
Cable: LEEOSHILL
6 August 1981
CONSULTING ENGINEERS
AUG101981
Mr. Barry C. Bender
Rick Engineering Company
365 So. Rancho Santa Fe Road
San Marcos, CA 92069
Dear Barrys
On July 31 you asked LEEDSHILL to review and comment on the drainage
control impacts of a new development concept for Rancho Carrillo that
was prepared by The Planning Center in July and August, 1981.. In
this new concept, essentially all of the major stream channels through,
the property will be left in their existing natural condition as
opposed to the former concept which was to fill most of the stream
channels and provide storm drains through the property. We have com-
pleted our review of the new concept and have the following comments
regarding drainage control.
From a drainage control viewpoint, the nev; development concept is not
significantly different from the concept that we analyzed for our .
March 3, 1981 report, "Rancho Carrillo Drainage Study". In our March
report, two alternative drainage control plans, involving five deten-
tion basin sites, are described to illustrate how drainage control
might be achieved. The new development concept allows provision of
detention basins at approximately the same five locations described
in the March report and the amounts of development upstream from the
five sites are approximately the same. Thus, the illustrative drainage
control plans presented in the March report are applicable to the new
development concept.
From a theoretical viewpoint, use of the natural stream channels in
lieu of stormdrains will increase the time of concentration of storm-
water runoff and thereby reduce the peak rate of runoff. However,
the predominant factor influencing the size of drainage control facil-
ities for Rancho Carrillo is runoff volume and not the rate of runoff.
Thus, the sizes of the detention basins and appurtenant works needed
under the new development concept will be essentially the same as
those presented in the March report.
The new development concept offers nn additional alternative for the
control of drainage that was not available under the former concept.
With the new concept, a detention basin could be provided on the
IXEOS.HIU.AKDJEWETT,INC.
Mr. Barry C. Bender
6 August 1981
Page 2
main drainage channel just upstream of the.major roadway that traverses
the property in the southeast-northwest direction. There appears to
be space available at this location and provision of a basin at this
site could reduce the size of the basin needed at the outlet from the
de ve lopment-..
The foregoing comments are based on qualitative analyses of the new
development concept and not detailed quantitative analyses using our
computer program. Detailed new analyses are not necessary at this
time because the drainage control plans presented, in our March report,
which were prepared for.illustrative purposest are applicable to the
current development concept.
We suggest that you use this letter as an amendment to our March report
to obtain permits and approvals that are needed at this stage of the
development. Should you have any questions, please call.
Very truly yours, .'.-...
Thomas C. MacDonald
TCMrcd
cc: Terry Teeple
Arne Kama la
Don Woodward /
.Peter Temple t on \-