277C,
. o N 1))()j i ON
FINAL DRAFT
GeoPentech
September 22, 2004
Mr. William Whittenberg, P.E., DEE
PSOMAS
3187 Redhill Ave, Suite 250
Costa Mesa, CA 92626
SUBJECT: PERCOLATION TESTING — LA QUINTA, CALIFORNIA
Dear Mr. Whittenberg:
This report describes percolation testing that has been conducted by the PSOMAS team for the City
of La Quinta (the City), California. As part of the PSOMAS team, GeoPentech provided
preparation of percolation test procedures, observed and reviewed percolation field testing,
completed data analysis of collected test results, and prepared this report documenting our findings
of this study.
Based on our discussion with PSOMAS and the City, we understand that the City directs storm
water, landscape irrigation runoff and other surface water flows to basins or ponds where the Aater
is allowed to evaporate and percolate into the subsurface. New developments require adequately
sized basins for management of surface water flows. A key element in the design and utilization of
basins or ponds is the percolation rate expected for given areas within the City.
The preferred approach to estimating percolation rates is to test as large an area as possible up to
full -scale for as long as possible in order to minimize unknown subsurface conditions that can
dramatically influence percolation rates. Large -scale tests also provide a measure of clogging
within the basin sediments and future management requirements. However, for this assignment it
was not feasible to use either test basins or ponds to estimate percolation rates, therefore, as an
alternative the approach used the large- diameter infiltrometer test method developed by Herman
Bouwer and his colleagues at Arizona State University. This method has been found to provide
reasonable estimates of the possible range in percolation rates when a sufficient number of careful
tests are completed and the results are combined with an understanding of the sites geologic
characteristics. Results from large- diameter infiltrometer testing are enhanced when coupled with
backhoe test pits of adequate depth to visually inspect subsurface soils for horizons or soil types that
may impede percolation. Results from these tests are used to provide an example of the rate that a
basin may expect to drain following a runoff event where water collects in a basin.
STUDY METHODS
Large diameter infiltrometer tests were conducted at three dry (unsaturated) locations shown on
Figure 1. These locations were at the northern and southern sides of the Hideaway residential
development and at the Andalusia residential development, which are on the east and southeast
601 N. Parkenter Drive, Suite 210, Santa Ana, California 92705
Phone (714) 796 -9100 Fax (714) 796 -9191 Web Site: www.geopentech.com
Mr. William Whittenberg, P.E., DEE
September 22, 2004
Page -2
FINAL DRAFT
sides of the City. In addition, an existing retention basin site with saturated soil conditions was used
to evaluate differences between the percolation rates for soils under "dry" unsaturated and "wet"
saturated conditions. The infiltrometer tests for unsaturated soils were conducted on May 5, 2004 at
the northern Hideaway residential development site and July 22, 2004 at the southern Hideaway and
Andalusia sites. Following infiltrometer testing, several potholes 4 to 5 feet deep were excavated
with a backhoe to observe the subsurface soils to that depth. In addition, two short-term slug tests
were performed July 23, 2004 in saturated sediments at the retention basin at Dune Palms Drive and
Desert Stream Drive (Figure 1).
Large diameter infiltrometer tests in unsaturated soils were conducted in accordance with the
procedures developed by Bouwer, et al., 19971, as follows:
1. Steel cylinders approximately 2 feet in diameter by 2 to 2.5 feet long with a beve led edge were
driven straight down into the ground about 3 to 4 inches and soil was then packed against the
inside and outside of the cylinder to get a good soil - cylinder contact.
2. Water was then poured into the cylinder avoiding soil erosion to fill the cylinder to a depth of
about 12 to 24 inches and time was recorded.
3. The water level was allowed to decline approximately 4 to 5 inches, the water level decline was
measured, clock time was recorded, and the cylinder was filled back up to the starting level.
4. This was repeated until the accumulated water level decline equaled or exceeded 50 inches or
the elapsed time exceeded 5.5 hours.
5. A backhoe was used to dig outside the cylinder and through the total depth of the wetted soil
and the lateral and vertical dimensions of the wet soil was measured.
6. The infiltration rate for the final decline in water level and the measured vertical and lateral
extent of the wetted soils were used to calculate the downward flow rate (i.e. infiltration rate
corrected by removing the effects of lateral divergence in flow), effective soil porosity and the
vertical hydraulic conductivity of the saturated soils.
For the saturated soil test location, the following procedures were used:
1. A test hole was dug with a shovel to a diameter of approximately 8 inches wide and a depth of
approximately 8 -10 inches deep.
2. A 4 -inch diameter 5 -foot long PVC casing was then placed into the hole and tapped into place
and stabilized with metal fence posts driven at approximately 45 degree angles into the ground.
3. A 1 -inch bed of sand was placed at the bottom of the hole and the remaining opening outside
the casing was filled with bentonite chips and hydrated.
4. The bentonite was allowed to hydrate for 15 minutes and the casing was then filled with
approximately 4.8 feet of water. A pressure transducer was placed at the bottom of the casing;
the transducer calibration was checked and it was then used to measure the fall in water level in
the casing with time.
1 Predicting infiltration and ground water mounding for artificial recharge; Bouwer, H., Back, J. and Oliver,
J., October 1997.
9/28/2004
® GeoPentech Final Draft.doc
Mr. William Whittenberg, P.E., DEE
September 22, 2004
Page -3
FINAL DRAFT
The change in water level measured in the casing with time was used to estimate the hydraulic
conductivity of the saturated soils of the retention basin in accordance with the procedures
described by Bouwer and Rice, 19762. Although the slug tests were set up to estimate vertical
hydraulic conductivity, the results represent both horizontal and vertical components of this
parameter. Because horizontal hydraulic conductivity is generally much greater than the
vertical component, the results would tend to overestimate the expected long -term infiltration
rate. In order to account for horizontal flow in the saturated soil beneath the casing that
occurred during the tests, analysis of the test results assumed a horizontal to vertical hydraulic
conductivity ratio of 10 to 1. This assumption is based on professional judgment and literature
that generally reports a horizontal to vertical hydraulic conductivity ratio between 2 and 203.
The reported results and those shown on the charts for the wet basin tests in the attachment are
for vertical hydraulic conductivity.
TEST RESULTS AND ANALYSIS
Percolation data measured during testing is presented in the attachment to this report along with
calculation of the downward flow rate and saturated soil hydraulic conductivities. Analyses of the
wet basin slug tests are also provided in the attachment. Shallow potholes did not identify low
permeability soils that would limit or reduce percolation. The results of the testing along with key
test site features are summarized in the table below.
PERCOLATION TEST RESULTS SUMMARY
Test Site
Soil Type
Downward
Flow Rate
ft/day
Effective
Porosity
%
Vertical
Hydraulic Conductivity
ft/day, (in/hr)
North Hideaway
Sandy Loam
2.9
14
2.0(1.0)
South Hideaway
Fine Sand
7.9
14
5.3 (2.7)
Andalusia
Sandy Loam
1.3
12
0.63 (0.32)
Wet Basin Test 1
Loamy Sand
n/a
n/a
3.2(l.6)
Wet Basin Test 2
Loamy Sand
n/a
n/a
2.0 (1.0)
n/a: Not derived by testing method.
DISCUSSION OF RESULTS
Testing to estimate the infiltration rate at three unsaturated soil sites in La Quinta was conducted
using a large- diameter (approximately 2 feet), single cylinder infiltrometer. Measurements of water
level drop in the cylinder with time and the vertical and lateral extent of wetted soils at the
conclusion of the tests were used to correct the infiltration ate for lateral divergence in the soil
below the infiltrometer to derive a downward flow rate. The downward flow rates were used along
with the soil's water entry value to calculate estimated vertical hydraulic conductivity for the soil at
2 A slug test for determining hydraulic conductivity of unconfined aquifers with completely or partially
penetrating wells; Bouwer, H. and R.C. Rice, 1978.
3 Applied Hydrogeology, Third Ed.; Fetter, Jr., C.W. 1994; Vadose Zone Hydrology; Stephens D.B. 1996.
9/28/2004
® GeoPentech Final Draft.doc
Mr. William Whittenberg, P.E., DEE
September 22, 2004
Page -4
FINAL DRAFT
the test sites. Two falling head slug tests were also conducted in a basin currently receiving surface
water runoff to estimate the vertical hydraulic conductivity of the saturated soils on the floor of the
basin. Because the slug test results are a composite of horizontal and vertical hydraulic
conductivity, the results were corrected assuming a ratio of 10 to 1, horizontal to verticaf. The
vertical hydraulic conductivities estimated from the different testing completed for this study ranged
from 0.63 feet/day (0.32 in/hour) to 5.3 feet/day (2.7 in/hour). These estimates can be used to
assess infiltration rates at the test site locations for retention basins that would be used to capture
and retain surface water runoff without clogging of the surface sediments and without low
permeability, restricting layers at depth.
The soils tested were classified as either a sandy loam (North Hideaway and Andalusia sites) or fine
sand (wet basin and South Hideaway sites). Potholes at the Hideaway and Andalusia sites
excavated b 4 to 5 feet below ground surface did not identify low permeability sediments that
would limit or reduce percolation.
Figure 2 shows predicted water level declines in a hypothetical basin with time for the various
vertical hydraulic conductivities estimated for the different test sites within the City. These
examples assume the basin is filled to a level of 10 feet initially and is allowed to percolate into the
subsurface with no additional inflow of water and no mounding of water beneath the basin. The
chart shows that just over 1 week would be required to drain a basin underlain by low conductivity
soils such as at the Andalusia site, whereas areas underlain by more permeable sandy soils would
drain within approximately 1 to 3 days. These infiltration rates would be expected to decrease over
time as organic material and fine - grained sediments build up on the basin soils filling near surface
interstitial pores and/or forming a lower permeability clogging layer.
CONCLUSIONS AND RECOMMENDATIONS
Percolation tests were conducted at three unsaturated soil sites within the City using a large -
diameter infltrometer test method and at one saturated soil site using a slug -test method. Soils
characterized at the test sites were either sandy loam or fine sand. The vertical hydraulic
conductivity estimated for these soils ranged from 0.63 ft/day (0.32 in/hour) to 5.3 feet/day
(2.7 in/hour). We recommend for new developments that a vertical hydraulic conductivity value
(i.e. infiltration rate) of 0.6 ft/day (0.3 in/hour) is used along with the estimated maximum surface
water discharge for an area to design appropriately sized retention basins.
Should a developer desire applying a different infiltration rate, we recommend conducting
additional large- diameter infiltrometer tests at planned retention basin sites. These tests should
account for divergence of flow in the soil due to lateral unsaturated flow consistent with the test
procedures used for the study described in this report. We also recommend completing subsurface
explorations to identify the possible presence of low permeability layers at depth that could limit or
impede the percolation of captured surface flows. As infiltration rates will decrease with time due
to clogging of the surface soils, we further recommend a management plan be prepared for each
retention basin to maintain the maximum percolation rates possible.
9/28/2004
® GeoPentech Final Draft.doc
Mr. William Whittenberg, P.E., DEE
September 22, 2004
Page -5
FINAL DRAFT
We appreciate the opportunity to work with you on this assignment. Please do not hesitate to
contact us should you have any questions regarding this draft letter report.
Sincerely,
GeoPentech
Eric S. Fordham, C.Hg. 283
Principal Hydrogeologist
Figures 1 and 2
Attachments
9/28/2004
GeoPentech Final Draft.doc
®
Figure 1 - Percolation Test Site Locations
W E La Quinta City Boundary
s 3000 0 3000 Feet 0 Percolation Test Site - Dry Condition
Percolation Test Site - Saturated Condition
im
a*
8
w
6
m
5
m
4
3
2
1
v
—0.63 ft/d 2.0 ft/d — 3.2 ft/d —5.3 ft/d
0 1 2 3 4 5 6 7
Time (days)
Predicted Basin Infiltration for Different Hydraulic Conductivities
Figure 2
101
in
M
N 10-�
U
(C3
Q
U)
10-1
10-3
Wet Basin Test 1
0.0 88.2 176.4 264.6 352.8 441.0
Time (sec)
19
E
(D 10-
Ca
Q-
U)
r)
Wet Basin Test 2
10-2 Bouwer & Rice Results
Hydraulic Conductivity 2.0 ft/d
Initial Displacement 4.8 ft
10-3
0.0 164.2 328.4 492.6
Time (sec)
821.0
Psomas Transmittal Form Page 1 of 1
P $ 0 M A $ 3187 Red Hill Avenue, Suite 250 Costa Mesa, CA 92626
Voice: 714-751-7373 Fax: 714 -545 -8883
Date: 09/28/04
Job No. 1LAQ010100
Task
Project: La Quinta Master Drainage Plan
To: Steven Speer, Assistant City Engineer - Public Works Department
(760) 777 -7078
City of La Quinta
78495 Calle Tampico
La Quinta, CA 92253
We Are Transmitting:
Via:
For Your:
Please:
❑ Per Your Request
DJ Mail
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❑ Overnight
❑ Review and
DJ Return Enclosures
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Comment
DJ Respond By:
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Enclosures: .... (If enclosures are not as noted, please inform us immediately)
Qty: Description: Date:
1 Report: Percolation Testing - LA Quinta, California prepared by GeoPentech 5/18/04
Remarks:
We tried to send this via email but the file was too large, so here is a hard copy. Please review and
comment.
Issued By: Bill Whittenberg, P. E.
Copies To:
SEP 2,9 2004
qL-
PUBLIC WORKS
https:// intra. psomas.com / project /transmittal/transprint.cf n ?tb id =78995 9/28/2004
PACIFIC ADVANCED CIVIL ENGINEERING, INC.
17520 Newhope Street, Suite 200 • Fountain Valley, California 92708 . tel: 714.481.7300 - fax: 714.481.7299
TECHNICAL MEMORANDUM
Date: March 8, 2004
To: Roy Stephenson - Berryman & Henigar
- Timothy R. Jonasson, P.E. — City of La Quinta
Kory Williams — Palmer Design
Doug Franklin — The Keith Companies
Sonny Sim - PACE
From: Mark E. Krebs, P.E. and Marc Schwering
Re: SilverRock Ranch — Stormwater Runoff Storage
I. GENERAL OVERVIEW:
No. 049292 c/' ,
Exp. 9 -30 - o6
CNk
#7645E
The purpose of this drainage evaluation is to provide a general overview of the
proposed project improvements for conveyance and storage of the 100 -year storm
event at the SilverRock Ranch project. This evaluation provides an overview of the
100 -year storm water and sediment conveyance routes and identifies the onsite storage
areas. The onsite storage areas indicate the limits of maximum ponding of 100 -year
runoff within the lakes, golf course, and open space of the project. In addition to the
identification of the specific stormwater storage areas within the project, it is also critical
to establish suitable stormwater and sediment flow conveyance paths from the toe of
the mountain slope to the storage areas within the golf course. These stormwater
conveyance routes must be integrated into the golf course design to insure minimal
damage to the golf course during a major storm event. It is the intent of this evaluation
to insure that the project storm water conveyance and storage design meets the
requirements of the adopted SilverRock Ranch Water Management Plan. The specific
drainage requirements of the Water Management Plan. are:
1. Maximize water conservation by capturing storm water runoff and routing it to
the project lakes, where it will be retained for lake evaporation and irrigation
make -up water supply.
2. Utilize golf course and open space to convey storm water while minimizing
the disruption and damage to the golf course.
SilverRock Ranch - #7645E 312212004
Technical Memorandum Page 2 of 6
The 525 acre SilverRock Ranch project site will be developed as a golf resort including
two 18 -hole golf courses and various hotel /resort areas. 'Storm water runoff will be
conveyed through the golf course and ultimately into the various lakes throughout the
project.. The majority of storm water runoff and associated sediment comes from the
adjacent mountains to the west. Onsite runoff is also contained in the golf course
stormwater storage areas. However, this amount is minor compared to the offsite
runoff. In general, the onsite and offsite tributary drainage areas are small (less than 30
acres) and. maximum concentrated runoff volumes (stormwater and sediment) and peak
flow rates are small (1 OAF and 38 cfs respectively). Therefore, the. corresponding
design solutions should not-be allowed to impose upon the golf development layout or
design. However, adequate flow paths and storage areas must be provided.
II. STORMWATER AND SEDIMENT RUNOFF DETERMINATION:
As determined in the MDS November 17, 2003 Design Report "Stormwater
Management and Debris Control Plan," the onsite runoff was calculated using the 100 -
year — 24 hour isopluvial and the SCS method. An SCS curve number of 61 was used
for a golf course with a "B" soil type. The Riverside County Flood Control District
Manual 100 -year 24 -hour isopluvial equal to five inches was used. to calculate the
runoff. The result was an effective depth equal to. 0.3 inches. The rainfall depth was
multiplied by the drainage areas which resulted in the total runoff volume that needs to .
be stored. This method accounts for direct percolation and runoff.
In summary, the "Stormwater Management and Debris Control Plan" prepared by MDS
Consulting dated November 17, 2003 has determined offsite. sediment production and
storm water runoff volume and peak flow discharge.
III. PROPOSED DEVELOPMENT CONVEYANCE AND STORAGE:
With the total runoff volumes (sediment and stormwater) determined, the proposed
grading plan was verified to confirm that the stormwater would be conveyed to the lakes
and stored within the golf course. The summary of Table 1 illustrates that the entire
runoff of 86.8 AF (sediment and runoff) can be contained in the SilverRock Ranch
project area which has a storage capacity in excess of 1.60 AF. Table 1 also evaluates
the (12) offsite and '(7) onsite tributary drainage areas, the column labeled "Golf Course
Available Storage" first shows the storage available at a elevation chosen to best meet
the specific drainage requirements of the Silverrock Ranch Water Management Plan for
a specific storage basin. The column then shows the minimum storage required to
contain the 100 -year storm event and the corresponding elevation. This latter storage is
also illustrated in Figure 1. For example, Golf course retention /detention basin "A" is
able to store 19.1 AF at elevation 20 however for a 100 -year storm event, only 9.1 AF
would be needed and this corresponds to an elevation of 16.
' . SilverRock Ranch - #7645E 312212004
Technical Memorandum Page 3 of 6
Figure 1 identifies the lakes and adjacent stormwater storage areas, tributary drainage
areas and the locators of the concentrated stormwater runoff coming from the
mountains. In most cases the storage areas hold the entire runoff amount.. However, in
some cases the inflow volume is larger than the capacity of the individual storage area.
This excess runoff is directed toward another storage basin as in D -1, D -2, and D -3.
Figure 1 also shows the seven main stormwater storage areas in the SilverRock Ranch
project area. These are labeled A through G with storage area D being divided into
three (3). sub - basins. There are twelve (12) tributary drainage areas offsite and seven
(7) onsite which deliver stormwater and sediment to these seven storage areas. Each
tributary drainage area is labeled and includes drainage area size (AC), 100 -year flow
(cfs), and 100 -year sediment and stormwater volume (AF).
This evaluation clearly indicates the required 100 -year total required storage volume
can easily be retained within the golf course basin areas and routed to the lakes for
irrigation use. It is important to note that the calculations for the required storage area
are conservative as they do not include'any of the golf course area percolation. In
addition, there is significantly more storage area (Volume) within the golf course than is
required.
Based upon the largest drainage area, 100 -year peak flow of 38 cfs and a (majority of
the 100 -year peak flows of less than 10 cfs) calculations show that formal drainage
conveyance infrastructure (pipes, catch basins, lined channels, etc. are not required).
Scour and erosion from major storm events is not a substantial concern given the low
flow rates (max 38 cfs). However, it is critical that the final grading of the area between
the toe of the mountain and the golf course storage areas include stormwater
conveyance paths (graded channel or swale) to direct the stormwater to the storage
areas. The simplified design criteria for these channels (swales) indicates maximum
channel slopes of 3% side slopes may vary, and the channel bottom width should be set
based on a maximum of 3 cfs per foot of channel width. Thus, for the 38 cfs condition,
the channel width should be 13 feet (38 T 3) and the resulting maximum flow depth of
0.5 feet and velocity of 5 fps (see attachments 1 and 2, normal depth Manning's
hydraulic data). It is important to note that the channel section does not have to be a
Uniform trapezoidal section; this section can (and should) be an undulate and vary to
match the golf grades.
SilverRock Ranch - #7645E 312212004
Technical Memorandum Page 4 of 6
Table 1
SilverRock Ranch Runoff Analysis
(Available Storage vs. 100 Year Storm Storage)
Trib ary Watershed
Golf Course
Golf Course
Det. / Ret.
Basin
#
Area
(AC)
Runoff Vol.
100 yr
AF
Sediment
Vol. 100 yr
AF
Total
Req'd
Storage
AF )
Peak
Flow
Rate
(cfs)
Storage
Available Storage
Volume
(AF
Elev.
A
Onsite Storage
Available 19.1 20
Offsite
1
5.8
1.3
0.9
2.2
9
Offsite
2
12.4
2.8
1.9
4.7
18
Req'd for 9.1 16
100 yr
Onsite
12
7.9
1.3
0
1.3
N/A
5.4 2.8
Total Tributary to Basin "A" = 8.2 AF (Sediment & Runoff)
Required
<< Than Available Storage
Volume
B
Onsite Storage
Available 11.4 20
Offsite
3 .
7.4
1.7
1.1
2.8
11
Req'd for
100 yr 4.5 17
Onsite
13
6.2
1
0
1
N/A
2.7 1.1
<< Than Available Storage
Total Tributary to Basin "B" = 3.8 AF Sediment & Runoff) Required Volume
C
Onsite Storage
Available 48.7 20
Offsite
4
26.6
6
4.1
10.1
38
Req'd for
100 yr 28.6 18
Offsite
5
17.1
3.8
2.6
6.4
24
Offsite
6
4.7
1.1
0.7
1.8
8
Onsite
14
34.9
5.6
N/A
5.6
N/A
16.5 7.4
<< Than Available Storage
Total Tributary to Basin "C" = 23'.9 AF (Sediment & Runoff Required Volume
SilverRock Ranch - #7645E 312212004
Technical Memorandum Page 5 of 6
Table 1 (continued)
SilverRock Ranch Runoff Analysis
(Available Storage vs. 100 Year Storm Storage)
Total runoff and sediment 86.8 AF
Tributary Watershed
Golf Course
Golf Course
Det. / Ret.
Basin
#
Area
(AC)
Runoff Vol.
100 yr
(AF)
Sediment
Vol. 100 yr
(AF)
Total
Req'd
Storage
I (AF)
Peak
Flow
Rate
I (cfs)
Storage
Available
Storage
Volume
(AF)
Elev.
D
'Onsite Storage _
Sub -Basin
D -1
D -2
D -3
Available
4
3.6
24.7
32
30
25
32.3
Offsite
7
16.7
3.7
2.6
6.3
24
Sub -Basin
D -1
D -2
D -3
Req'd for 100 yr
4
.3.6
16
32
30
24
Offsite
8
6.8
1.5
1.1
2.6
10
Offsite
9
8.1
1.8
1.3
3.1
12
Offsite
10
5.9
1.3
0.9
2.2
9
Onsite
15
43
6.9
N/A
6.9
N/A
23.6
15.2
5.9
Total Tributary to Basin "D" = 21.1 AF Sediment & Runoff) Required
<< Than Available Storage Volume
E
Onsite Storage
Available 21.9
32
Offsite
11
5.9
1.3
0.9
2.2
9
Used for
100 yr
21.9
32
Offsite
11-
1
N/A
17
N/A
17
N/A
Onsite
16
16
2.6
N/A
2.6
N/A
20.9
0.9
Total Tributary to Basin "E" = 21.8 AF. Sediment & Runoff Required
< Than Available Storage Volume
F
Onsite Storage
Onsite
17
23
3.7
N/A
3.7
N/A
Available 18.7
30
Req'd for
1 100 yr 3.7
26
3.7
Total Tributary to Basin "F" = 3.7 AF Sediment & Runoff) Required
<< Than Available Storage Volume
G
Onsite Storage
Onsite
18
27
4.3
N/A
4.3
N/A
Available 7.6
20
Req'd for
1 100 yr 4.6
19
4.3
Total Tributary to Basin "G" = 4.3 AF (Sediment & Runoff ) Required
<< Than Available Storage Volume
Total runoff and sediment 86.8 AF
SilverRock Ranch - #7645E 312212004
Technical Memorandum Page 6 of 6
IV. CONCLUSION:
Table 1 shows that 86.8 AF of runoff and sediment produced can be retained by the
159.7 AF of storage areas and lakes. Figure 1 illustrates the location of the drainage
areas; storage basins, and the runoffs produced by a 100 -year storm event. Consistent
with the Water Management Plan, the runoff volume produced by .a 100 -year storm
event can be retained and.the majority used for irrigation while minimizing golf course
disruption and damage-.
The final part of this effort will be for the Palmer Design Group to incorporate drainage
flow paths from the toe of the mountain at-each primary discharge point to the golf
storage area. The grading design solutions for these conveyance flow paths are flexible
in location and section.
In summary, the drainage system for conveyance and storage of the offsite generated
runoff can easily be accommodated within the golf course design without disturbing the
golf playability or aesthetics. For major rainfall events one should expect any sediment
or debris deposition, to be concentrated at the toe of the mountain (and as history has
shown, there is little sediment generated) and only minor erosion or scour within the
conveyance channels to the golf storage areas.
ij
i
LEGEND
DRAINAGE AREA BOUNDARY - - ---
STORMWATER FLOW PATH -- -
100 YR. STORAGE I—I
V w Co em STORMM lm t smmwr vouff OF
fm ME w Tmw Srom mu
LAKE AREA
NATIVE VEGETATION
LANDSCAPE
GOLF TURF AREA
OFF -SITE DRAINAGES BASIN
BASIN DESIGNATION
�E
�
... x°v
BASIN DESIGNATION
GOLF COURSE /00
DRAINAGE EXHIBIT
Fla RF Of
a NON
MARCH 03, 2004
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CIVIL ENGINEERING
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