HomeMy WebLinkAboutCT 15-08; CARLSBAD RANCH PLANNING AREA 5; HYDROLOGY & SWQMP MEMORANDUM; 2019-08-21.,
HYDROLOGY & SWQMP MEMORANDUM
ECEJVE
ii.US 2 '! 20!:J
LAND CEVE.LOPMENT t=Nr• , ...... ,_.)I ~ ....;, .. __ ,. G
PROJECT ID: 15-08 I~ ----
DRAWING NO: 428-9J RECORD COPY
PERMIT NO: ~-019-0027 1).tftft,g1 _2_ ,2_ ,,
L Initial Date
PREPARED FOR:
GRAND PACIFIC CARLSBAD, L.P .
5900 PASTEUR COURT, SUITE 200
CARLSBAD, CA 92008
(760) 431-8500
PREPARED BY:
l:J:<!41
ENGINEERING
LAND Pi~ rHG •fNaNEIR/iVC • 9./RlflWC
44{) STA l[ Pt),(I, [SCOiW"lW, CA 92029
PH {76,9)745--8118 FAK (760)745-1890
EXCEL ENGINEERING
440 STATE PLACE
ESCONDIDO, CA 92029
(760)745-8118
ENGINEER OF WORK :
ROBERT D. DENTINO
RCE 45629
DATE:
August 21, 2019
·-
MEMORANDUM
Thi s memo is in support of a new pool slide being proposed within the Carlsbad Ranch PAS, Phase II
project. The project proposes to disturb an existing area of 5,920 sqft that consists of 1,585 sqft of
impervious and 4,335 sqft of landscaped area.
The existing site condition contains an already constructed pool with a concrete deck surrounding it. The
concrete deck contains area drains that convey storm water to a water quality and detention pond from
the pool decking and surrounding landscape areas.
The project proposes to build a slide within the adjacent landscaped area. The slide will require
construction of a staircase with a concrete footprint of 289 square feet. The increase of impervious area
is offset by the removal of 475 square feet of concrete decking. The decking will be replaced by more
landscaped area. Additionally, the burden to the area drain system and water quality basin is further
reduced due to the slide conveying any precipitation that falls within its 359 square foot footprint to the
pool. This runoff is then treated with the pool water and conveyed to the sanitary sewer system.
Roughly 1110 sqft of pool decking will be removed and replaced to support the relocation of area drains.
After construction of the slide, the impervious area will be reduced to 1,399 sqft and landscaped area
increased to 4,521 sqft. Ultimately, the site proposes to reduce the impervious surface by 186 square
feet and removes 359 square feet of surface runoff (see exhibit for clarification and calculations). The
reduction of impervious area combined with the removal of surface area reduces the runoff potential of
the site. Thus, no analysis of the existing storm drain network and detention pond capacity is needed.
Since a previously approved BMP is currently treating the project site area and the impervious area of
the project site is reduced by 186 sqft, no additional BMP area will be required to effectively treat the
runoff.
~ ~
~ ~
~ ~ ls
~
~ .:..: ....
~ ~ ~ ~ ~
~ "\'i
-~ -~ t (.3
1 V)
~ ~ ~
~
~
I ~=~
?
\ 'C /
_./
t... ... _____
✓
✓
0
0
.______;
475 SF CONCRETE '---
TO BE /fEI.IOJ/EO-"<
\
cP
\ . 0
./
i
~
~ ~
~ :::::,,
I.. ~· ~ ~~ ~ •. -~~ ~
~...:.;..;.:---~~~~~~~_f59 SF 0/RECTEO TO SANITARY
~o__B£ REI../Ol~O ::~I.I SURF~CE CALCULA llONS
I
t _ l
~ ~ q:
~
~
~ ~ -I
------.,0 hf/ -20 0 ~ ~ ~ ~
c-,: .. . '
'
CONCRETE REI/OVAL =
NEfff.. Y CREA TEO CONCRETE =
/1../PERWO/JS S/JRFACE REOUCllON =
475 SF
289SF
!86 SF
IMPERVIOUS AREA
REDUCTION EXHIBIT