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WATER • WASTEWATER • ENVIRONMENTAL
CONSULTING ENGINEERS
0
703 PALOMAR AIRPORT ROAD, SUITE 300 • CARLSBAD, CA 92009 • (760) 438-4422
SEWER STUDY
FOR THE
CANTARINI AND HOLLY SPRINGS PROJECT
IN THE
CITY OF CARLSBAD
October 3, 2002
RECEIVED
OCT 032002
CITY OF CARLSBAD
PLANNING DEPT.
Prepared by:
Dexter Wilson Engineering, Inc.
703 Palomar Airport Road
Suite 300
Carlsbad, CA 92009
Job No. 726-001
DEXTER WILSON ENGINEERING, INC.
DEXTER S. WILSON, P.E.
ANDREW M. OVEN, P.E.
STEPHEN M. NIELSEN, P.E.
MICHAEL J. FILECCIA, P.E.
October 3, 2002 726-001
Ladwig Design Group •
703 Palomar Airport Road, Suite 300
Carlsbad, CA 92009
Attention: Bob Ladwig, President
Subject: Sewer Study for the Cantarini and Holly Springs Projects in the City of
Carlsbad
Introduction
This report provides-an analysis of the offsite sewer service impacts for the Cantarini
and Holly Springs projects. The analyses performed verify that sewer capacity is
available in the gravity sewer lines to which these two projects are proposing to
connect.
Project Overview
The Cantarini and Holly Springs projects are located east of El Camino Real along the
east side of the extension of College Boulevard. These two projects are adjacent to each
other with Holly Springs positioned on the north property boundary of the Cantarini
project. Access to the Cantarini project will be from the extension of College
703 PALOMAR AIRPORT ROAD, SUITE 300 • CARLSBAD, CA 92009 9 (760) 438-4422 • FAX (760) 438-0173
Bob Ladwig
October 3, 2002
Boulevard; the Holly Springs project can only be accessed through the Cantarini
project.
The Cantarini project proposes a total of 105 single family detached residential homes
and 80 multi-family units. The Holly Springs project proposes 39 single family
detached residential homes plus four future single family home lots. Finish grades for
building pads within these two projects range in elevation from a low of 120 feet to the
highest building pad which is 380 feet in elevation.
DesiEn Criteria
Design criteria for the evaluation of the sewer systems for the Cantarini and Holly
Springs projects are in accordance with the Carlsbad Standard Sewer System Design
Criteria and Standard Drawings & Specifications dated May ij, 1993. The main
criteria used for this study are summarized below.
Sewage generation is calculated based upon the number of equivalent dwelling units
(EDUs). The generation factor for each EDU is 220 gpd average flow.
Peak sewage flow is calculated as 2.5 times the average daily sewage flow.
Depth of flow criteria for gravity sewers requires peak sewage flow to be less than half
full for 10-inch and smaller lines, and up to three-quarters full for 12-inch and larger
lines.
Existing Facilities
There are two existing gravity sewer lines in the vicinity of the Cantarini and Holly
Springs projects. To the south of the projects is the South Agua Hedionda Trunk Sewer
DFXER WILSON ENGINEERING, INC. PAGE 2
Bob Ladwig
October 3, 2002
located along the south side of Agua Hedionda Creek. This. s an 18-inch sewer main
which connects to an existing 24-inch gravity sewer line in El Camino Real. Sewer
flow is toward Cannon Road where the flow currently enters the North Agua Hedionda
Trunk Sewer system.
The second existing facility in the vicinity of the Cantarini and Holly Springs projects
is a 10-inch and 12-inch gravity sewer which extends from the Calavera Hills
development and connects to the existing North Agua Hedionda Trunk Sewer at the
intersection of Cannon Road and El Camino Real. This gravity sewer follows the
future alignment of Cannon Road east of El Camino 'Real up to the future intersection
with College Boulevard where the sewer turns north to parallel the future alignment
of College Boulevard.
Exhibit A at the back of this report shows the proposed development projects and the
existing gravity sewer lines in their vicinity.
Overview of Sewer Service
The Cantarini and Holly Springs projects are within the South Agua Hedionda sewer
drainage basin and will be paying the sewer benefit area fees for this basin.
Ultimately, all the sewerage generated by .these projects will be conveyed through the
South Agua Hedionda Interceptor System to the Encina Water Pollution Control
Facility which is located between Avenida Enemas the Interstate 5 south of Palomar.
Airport Road.
Based upon the tentative map submitted for these two projects, the proposed
residential dwelling units within the projects fall into two Sewer Benefit Areas: Benefit
Area D and Benefit Area E. All of the Holly Springs project's dwelling units are located
in Sewer Benefit Area E. For the Cantarini project, only the northwest corner of the
project is located in Sewer Benefit Area D; the remainder of the proposed development
DEXTER WILSON ENGINEERING, INC. PAGE 3
Bob Ladwig
October 3, 2002
is within Sewer Benefit Area E. Table 1 below presents a summary of the number of
dwelling units for each project and the Benefit Areas within which they are located.
TABLE 1
CANTARINI AND HOLLY SPRINGS PROJECTS
EDUs BY SEWER BENEFIT AREA
Mgffroj tecl ~1
Sewer Benefit Area D
Cantarini Single Family 13
Cantarini Multi-Family 80
Subtotal 93
Sewer Benefit Area E
Cantarini Single Family 92
Holly Springs Single Family 39
Holly Springs Future 4
Subtotal 135
fUL___TXThL _4.. r2T8O
The dwelling units within Sewer Benefit Area D are proposed to connect to the existing
10-inch and 12-inch gravity sewer line along the future Cannon Road alignment (City
designation: Reach SAHT2C of the South Agua Hedionda Sewer Interceptor). The
dwelling units within Sewer Benefit Area E are proposed to connect to the existing 18-
inch gravity sewer along Agua Hedionda Creek (City designation: Reach SAME of
the South Agua Hedionda Sewer Interceptor).
DEXTER WILSON ENGINEERING, INC. PAGE 4
Bob Ladwig
October 3, 2002
Proposed Sewer System
The proposed sewer service for the Cantarini and Holly Springs projects will be divided
by Sewer Benefit Area. Exhibit A at the back of this report shows the two projects and
the Sewer Benefit Area boundary. The discussion of the sewer analyses performed to
evaluate the ability of the existing sewer system to accommodate the additional sewage
flow generated by the proposed projects will be divided by Sewer Benefit Area.
Sewer Benefit Area D. According to the City of Carlsbad "Updated Fee Study Report
for Sewer Benefit Areas C, D, E, and F (South Agua Hedionda Interceptor Sewer),
dated July 19, 2002 and prepared by the City of Carlsbad Engineering Department, all
of the Cantarini and Holly Springs projects are described to be within Sewer Benefit
Area E. However, based upon the proposed tentative map for the Cantarini project, a
portion of this development more easily gravity sewers to the north and through Sewer
Benefit Area D. Exhibit A at the back of this report shows the proposed adjusted
boundary between Sewer Benefit Areas D and E.
Because a portion of the Cantarini project is proposed to flow through Sewer Benefit
Area D, this report prepared an analysis of the existing 10-inch and 12-inch sewer line
serving Sewer Benefit Area D to ascertain if sufficient capacity existed in this gravity
sewer line for the additional EDUs. Appendix A presents the results of the computer
model of the existing sewer line. Figure A-i in Appendix A shows the computer model
input data including the number of buildout EDUs within Sewer Benefit Area D and
the location at which the buildout EDUs were modeled to enter the existing sewer
system.
The Cantarini project proposes to connect to the existing gravity sewer at the future
intersection of Cannon Road and College Boulevard. This is Access Hole Number 14
of the computer model. At this access hole, the gravity sewer line increases from a
10-inch main to a 12-inch main. Since the design criteria allows the 12-inch main to
DEXTER WILSON ENGINEERING, INC. PAGE 5
Bob Ladwig
October 3, 2002
flow three-quarters full, there are no capacity problems downstream of the proposed
Cantarini connection based upon ultimate buildout for Sewer Benefit Area D plus the
proposed EDUs from the Cantarini project. The greatest depth-to-diameter ratio for
the reach of 12-inch gravity sewer downstream of the proposed Cantarini project
connection is 0.59.
The offsite gravity sewer required from the Cantarini project north in College
Boulevard to the existing 10-inch and 12-inch gravity sewer is expected to be an 8-inch
line. In addition to serving the 13 single family homes and 80 multi-family homes from
the Cantarini project, this line will also serve the future 80 multi-family units at the
southeast intersection of Cannon Road and College Boulevard. All the EDUs
connecting to the 12-inch gravity sewer will be subject to paying the Sewer Benefit
Area Fee for Zone D.
Sewer Benefit Area E. The majority of the Cantarini project and all of the Holly
Springs project will sewer to the existing 18-inch South Agua Hedionda Interceptor
Sewer Reach SAME. This gravity sewer is located on the south side of the Agua
Hedionda Creek. It is proposed that an 8-inch gravity sewer line will be constructed
in College Boulevard to convey sewage from the two projects south to the interceptor
sewer.
Capacity is available in the 18-inch South Agua Hedionda Interceptor Sewer since all
of the EDUs within Sewer Benefit Area E have been accounted for in the City of
Carlsbad sewer study titled, "Updated Fee Study Report for Sewer Benefit Areas C, D,
E, and F (South Agua Hedionda Interceptor Sewer)." All the EDUs connecting to the
18-inch gravity sewer will be subject to paying the Sewer Benefit Area Fee for Zone E.
DEXTER WILSON ENGINEERING, INC. PAGE 6
Bob Ladwig
October 3, 2002
Downstream Sewer System
As mentioned earlier in this report, the sewage generated by the Cantarini and Holly
Springs projects will be conveyed by the South Agua Hedionda Interceptor Sewer
system to the wastewater treatment plant. At this time, the South Agua Hedionda
Interceptor Sewer system is not entirely constructed. The main portion of the system
which is not yet constructed is the Cannon Road Lift Station. The final design for this
facility was initiated at the end of September 2002; it is expected that the design and
construction of this lift station will take two years. This time line fits the expected
timing of the Cantarini and Holly Springsprojects. The approval and construction
time for the development projects will put the first occupancies near the same time
frame as the completion of the Cannon Road Lift Station. Thus, sewer facilities are
expected to be available for these projects in time for their first occupancies.
Recommendations
The following recommendations and conclusions are made based on the sewer system
analyses performed for the Cantarini and Holly Springs projects.
The Cantarini and Holly Springs projects are within the South Agua Hedionda
Sewer Drainage Basin and will contribute flow to the South Agua Hedionda
Interceptor Sewer system.
The Cantarini project is split between Sewer Benefit Area D and E. The Holly
Springs project is entirely within Sewer Benefit Area E.
There is sufficient capacity in the existing 12-inch gravity sewer serving Sewer
Benefit Area D and located along the future alignment of Cannon Road east of
El Camino Real for the EDUs within the Cantarini project which are proposed
to gravity sewer through Sewer Benefit Area D.
DEXTER WILSON ENGINEERING, INC. PAGE 7
Bob Ladwig
October 3, 2002
Within Sewer Benefit Area E, the existing 18-inch gravity sewer line along Agua
Hedionda Creek has been sized to accommodate all the EDUs proposed by both
projects.
The proposed dwelling units for both the Cantarini and Holly Springs projects
will pay the Sewer Benefit Area Fee for Zone D or Zone E depending upon which
zone they are in.
Though not all of the South Agua Hedionda Interceptor Sewer facilities are
currently constructed, it is anticipated that by the time the Cantarini or Holly
Springs project is ready for occupancy (approximately two years) the facilities
left to be constructed will be completed. The main portion of the system that
needs to be completed is the Cannon Road Lift Station which is currently under
final design.
Thank you for the opportunity to prepare this report. If you have any questions on the
enclosed information, please do not hesitate to call.
Dexter Wilson Engineering, Inc.
ak
Andrew Oven
NO. 1015 AO:clr d( Exp1o3
010.
l*
Appendix
DEXTER WILSON ENGINEERING, INC. PAGE 8
APPENDIX A
SEWER SYSTEM ANALYSIS
FOR
SEWER BENEFIT AREA D
For Access Manhole Number designations, EDU inputs, and for sewer
system layout for Sewer Benefit Area D, refer to Figure A-i within this
Appendix.
PAGE 1
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10/ 1/82 2 439
SEWER ANALYSIS GEOMETRY
Cantarirti/Holiy Springs Sewer Analysis - LFNP 14 EDUs
NH NH --- Design Criteria
Down Slope Up n or C Diac d/D Flow Veio
100 .032200 110 .013 15 .75 6.8 10.7
44Th .102800 120 7 .01 ., 6.7 16.5
120 .007000 1 .013 12 .73 1.8 4.3
1 .006700 2 .013 12 .75 1.7 4.2
f .106718 113 . .75 1.7 4.2
7 . .006000 4 .013 L ., 1.6 4.0
4 .004600 5 .013 12 1.4
.05200 6 .013 12 .75 1.5 3.7
6 .004500 7 .013 12 .75 1.4 3.4
7 .006300 8 .013 12 .75 1.7 4.1
8 .004200 9 .013 12 .75 1.4 3,3
9 .004000 10 .013 12 .75 1.3 3.3
10 .004000 11 .@17 12 .7 47 7
11 .004000 12 .013 12 .75 1.3 3.3
12 .004000 47 .013 12 .75 1.3 3113
13 .007600 14 .013 12 .75 1.8 4.5
14 .017600 IC .013 10 .50 .9 5.3
+++++++++++++++++4++++++++++++++ END OF AREA ++++++++++++++++++++++++++++++++
SEWER ANALYSIS UNITS
Cartarini/Ho11y Springs Sewer Analysis - LFI4F 14 EDLJs
DISTANCE DIAMETER FLOW ELEVATION AREA
FEET INCHES MOD FEET ACRES
1/ 1/02 2: 4:42 PAGE I
SEWER ANALYSIS LOAD SUMMARY
Caritarini/Holly Springs Sewer Analysis - LFMP 14 EDUs
Manhole Total Contributed Point
Area Flow Source
I
'
7 5i 641 .14 .88
4 321.05 .07 .08
13 200,00 .04 Be.
15 908.35 .20 .50
It/ 1/82 2 442 PAGE 2
SEWER ANALYSIS SANITARY LOAD APPLICATIONS
Cantarini/Hoily Springs Sewer Anaiysis - LFNP 14 EDUs -
NH NH Slope Diac Capa- Area Flow Point Average Peak Vel- Depth Under Capacity
Up Down city input Source Flow Flow ocity Ratio Replace Relief Identification
15 14 .01760 10 .94 988.30 .20 .00 .20 .50 4.5 .35
14 13 .80768 12 1.83 .88 .80 .88 .20 .58 3.3 .34
13 12 .80400 12 1.33 200.00 .04 as .24 .61 2.7 .45
12 11 .88408 12 1.33 .88 .80 .88 .24 .61 2.7 .45
11 11 10 .00400 12 1.33 .80 .80 .00 .24 .61 2.7 .45
18 9 .00400 12 1.33 .00 .00 .00 .24 .61 2.7 .45
9 8 .00420 12 1.36 .00 .08 .00 .24 iM 2.8 .44
8 7 .00630 12 1.67 .00 .00 .00 ..24 .61 3.2 .40
7 6 .00458 12 1.41 .00 .00 .00 .24 .61 2.9 .44
6 5 .00520 12 1.51 .88 .00 .00 .24 .61 3.0 .42
5 4 .00460 12 1.42 .00 .00 .00 .24 .61 2.9 .44
4 3 .80600 17 1.63 321.00 .07 .00 .31 .79 3.4 .47
3 2 .00670 12 1.72 641.30 .14 .00 .46 1.14 3.9 .56
2 1 .00670 12 1.72 .00 .00 .00 .46 1.14 3.9 .56
1 120 .00700 12 1.76 .00 .00 .00 .46 1.14 4.0 .55
120 110 .10288 17 6.73 .00 .00 .00 .46 1.14 10.8 .27
110 180 .03220 15 6.83 .00 .00 .00 .46 1.14 6.9 .27
4 + 4 + + + + + + + + 4 + + + + + 4 4 + + + + + + ++ + + END OF AREA• + + + + + + 4 + + + + + + + + + + + + + + + + + + + + + +
4Th! 1/ 82 U!! IOh h. 7.2Q
SEWER ANALYSIS GEOMETRY
Cantariiii/Holly Springs Sewer Analysis - Add LFNP 15 -
NH NH --- Design Criteria
Down Slope tip n or C Dim diD Flow Veluc
188 .032200 118 .813 15 .75 6.8 10.7
118 .182800 128 .813 12 .75 6.7 16.5
120 .007000 1 .013 12 .75 1.8 4.3
1 .086780 2 .013 12 .75 1.7 4.2
2 .006708 3 .013 12 .75 1.7 4.2
3 .006808 4 .813 12 .75 1.6 4.0
4 .004600 5 .013 12 .75 1.4 3.5
5 .005280 6 .013 12 .75 1.5 3.7
6 .804508 7 .013 12 .75 1.4 3.4
7 .006300 8 .813 12 .75 1.7 4.1
8 .084200 9 .013 12 .75 1.4 3.3
9 .884008 18 .013 U .75 1.3 3.3
It .804800 11 .813 12 .75 1.3 3.3
11 .804880 12 .013 12 .75 1.3 3.3
12 .004000 13 .013 12 .75 1.3 3.3
13 .087600. 14 .013 12 .75 1.8 4.5
14 .017608 15 .013 18 .50 .9 5.3
++i+++++++++++++++++++++++++++++ END OF AREA ++++++++++++++++++++++++++++++++
PAGE 1
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SEWER ANALYSIS UNITS
CantariiiHuiIy Springs Sewer Analysis - Add LFt4P 15
DISTANCE DIAMETER FIlM ELEVATION AREA
FEET INCHES NOD FEET ACRES
1/ 1/82 2 928 PAGE 1
SEWER ANALYSIS LUAU SUMMARY
Cantarini/Holly Springs Sewer Analysis - Add LFNP 15
Manhole Total Contributed Point
Area Flow Source
3 641,3 .14 .11
4 321.80 .7 .11
13 28J1 .114 .1111
14 173.1111 .114 .1111
15 9118.311 .211 .1111
10/ 1/82 2 929 PAGE 2
SEWER ANALYSIS SANITARY LOAD APPLICATIONS
Cantarini/Holly Springs Sewer Analysis - Add LFNP 15
NH NH Slope Diaa Capa- Area Flow Point Average Peak Vel- Depth Under Capacity
Up Down city Input Source Flow Flaw ocity Ratio Replace Relief Identification
15 14 .81768 18 .94 908.30 .28 .00 .28 .50 4.5 .35
14 13 .00768 12 1.83 173.00 .84 .00 .24 .59 3.4 .37
17 '1 ir1rr 1'1 I 7 '1ThTh ThTh A ir fl. 7Th '1 i i. .i,,thj i. 211. 80 .r, .0 .o .iI .
12 11 .88488 12 1.33 .00 .88 .80 .28 .70 2.9 .49
11 18 .00488 12 1.33 .88 .88 .88 .28 .78 2.9 .49
18 9 .88488 12 1.33 .88 .08 .88 .28 .70 2.9 .49
9 8 .08428 12 1.36 .08 .88 .88 .28 .78 2.9 .49
8 7 .88638 12 1.47 .88 .88 .08 .28 .18 3.3 .43
7 6 .08450 12 1.41. .08 .8 .08 .28 .78. 3.8 .47
6 5 .88528 17 1.51 .80 .08 .00 is .70 3.1 .46
5 4 .88460 12 1.42 .00 .00 .88 .28 .70 3.0 .47
4 3 .00608 12 1.83 321.08 .87 .08. .35 .88 3.5 .49
7 '1 I1fII7Th '1 * 1'1 11* 7Th *1 11Th r * '17 '1 3 h .UlIOIS S £.IL Oti.33 .Jt .VII .ti £.L3 t.Th .3
2 1 .88678 12 1.72 .08 .80 .00 .49 1.23 4.8 .59
1 120 .80788 12 1.76 .80 .0 .00 .49 1.23 4.0 .58
120 118 .18280 12 6.73 .00 .80 .00 .49 1.23 10.8 .28
110 180 .03220 15 6.83 .80 .00 .00 .49 1.23 6.9 .27
+ + + + + + + + + + ... + + + + + + + + + + + + + + + + + END OF AREA + + + + + + + + + + # + + + + + + + + + + + + + + + + + +
U
CANTARINI AND HOLLY SPRINGS
SEWER BENEFIT AREA D ANALYSIS
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