HomeMy WebLinkAbout66061; Kelly Drive Channel Repairs; Kelly Drive Channel Hydrology Study; 2007-09-17KELLY DRIVE CHANNEL MAINTENANCE PROJECT
PRELIMINARY ALTERNATIVE ANALYSIS
Job Number 15369
September 17,2007
KELLY DRIVE CHANNEL MAINTENANCE PROJECT
PRELIMINARY ALTERNATIVE ANALYSIS
Job Number 15369
R.C.E. # 32838
Exp. 06/08
PREPARED FOR:
City of Carlsbad
1635 Faraday Avenue
Carlsbad, California 92008
PREPARED BY:
Rick Engineering Company
Water Resources Department
5620 Friars Road
San Diego, California 921 10-2596
(619) 291 -0707
September 17,2007
Table of Contents
Project Description ............................................................................................................... 1
Hydraulic Methodology ....................................................................................................... 2
..................... ................................................ Table 1: 6-hr Precipitation Summary .. 2
Existing Condition (No Action Alternative) ....................................................................... 4 . . ......................................................................................................................... Descnptlon 4 . . ........................................................................................................... Antlc~pated Impacts 4
.... Table 2: Existing Condition (No Action Alternative) Anticipated Impact Summary 4
HEC-RAS Results .............................................................................................................. 6
Table 3: Existing Condition WSEL Summary for the 100-year and 2-year Storm
Event ....................................... ; ................................................................................. 6 . . Ant~cipated Benefits ........................................................................................................... 6
Opinion of Probable Cost ................................................................................................... 6
Alternative A . Restore Earthen and Concrete Channel to Construction Plans ........... 7 . . Descript~on ........................... .. ............................................................................................. 7 . . Ant~cipated Impacts ............................................................................................................ 7
.................................................... Table 4: Alternative A Anticipated Impact Summary 8
................................................ ............................................................. HEC-RAS Results ; 8
...... Table 5: Alternative A WSEL Summary for the 100-year and 2-year Storm Event 9 . . Antlc~pated Benefits ........................................................................................................... 9 . . Oplnion of Probable Cost ................................................................................... 10
Table 6: Alternative A . Opinion of Probable Cost Summary ..................................... 10
Alternative B -Restore Earthen Channel North of Concrete Channel Entrance to
Construction Plans ..................................................................................... 11 . . Descr~ptlon ..................................................................................................................... 11 . . .......................................................................................................... Anticipated Impacts 11
.................................................. Table 7: Alternative B Anticipated Impact Summary 12
HEC-RAS Results ......................................................................................................... 12
Table 8: Alternative B WSEL Summary for the 100-year and 2-year Storm Event .... 13 . . Ant~c~pated Benefits ........................................................................................................ 13 . . Opin~on of Probable Cost ................................................................................................ 14
Table 9: Alternative B - Opinion of Probable Cost Summary ..................................... 14
Alternative C . Maintained Concrete Channel with Earthen Low-Flow Channel along
Western Slope Protection (Preferred Alternative) .................................. 15 . . Description ........................................................................................................................ 15
......................................................................................................... Anticipated Impacts 15
................................................ Table 10: Alternative C Anticipated Impact Summary 16
HEC-RAS Results ............................................................................................................ 16
Table 11 : Alternative C WSEL Summary for the 100-year and 2-year Storm Event .. 17
Prepared By: DCB.HM.ns/Reportll5369.001
Rick Engineering Company . Water Resources Division 9-17-07
. . Antlc~pated Benefits 17
Opinion of Probable Cost 18
Table 12: Alternative C . Opinion of Probable Cost Summary ................................... 18
.......... Alternative D . Maintained Concrete Channel and Replaced Slope Protection 19 . . Descr~pt~on ........................................................................................................................ 19 . . Ant~c~pated Impacts .......................................................................................................... 20
Table 13: Alternative D Anticipated Impact Summary ................................................ 20
HEC-RAS Results ........................................................................................................... 21
Table 14: Alternative D WSEL Summary for the 100-year and 2-year Storm Event .. 21 . . ................................................................. Ant~c~pated Benefits .................................... .... 21
Opinion of Probable Cost ............................................................................................... 22
Table 15: Alternative D - Opinion of Probable Cost Summary ................................... 22
Alternative E . Proposed LeveelFloodwall along Kelly Drive Channel ........................ 23 . . Descr~pt~on .............................. 1 ......................................................................................... 23 . . Ant~c~pated Impacts .......................................................................................................... 24
Table 16: Alternative E Anticipated Impact Summary ................................................ 24
HEC-RAS Results ............................................................................................................ 25
Table 17: Altemative E WSEL Summary for the 100-year and 2-year Storm Event .. 25 . . Antlc~pated Benefits ........................................................................................................ 26
Opinion of Probable Cost ............................................................................................... 26
Table 18: Alternative E - Opinion of Probable Cost Summary ................................... 26
Alternative F . Proposed Diversion Culvert under Kelly Drive .................................... 27 . . Descr~pt~on ........................................................................................................................ 27 . . ......................................................................................................... Ant~c~pated Impacts 28
Table 19: Alternative F Anticipated Impact Summary ................................................. 28
HEC-RAS Results ............................................................................................................ 29
Table 20: Alternative F WSEL Summary for the 100-year (Diverted) Storm Event ... 30 . . Ant~c~pated Benefits ......................................................................................................... 30
Opinion of Probable Cost ................................................................................................. 31
Table 21: Alternative F - Opinion of Probable Cost Summary .............................. ..... 31
Summary .................................................................................................................... i ........ 32
Table 22: Anticipated Impact and Anticipated Benefit Comparison Chart .................. 33
Future Considerations ........................................................................................................ 34
Prepared By: DCB.HM.ns/Reportll5369.001
Rick Engineering Company . Water Resources Division 9-17-07
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List of en end ices
Appendix 1 -Vicinity Map
Appendix 2 -Reduced Hard Copies of Construction Plans for Kelly Drive Channel
Appendix 3 -Kelly Drive Channel Maintenance Project Existing Condition (No Action
Alternative)
Kelly Drive Channel Maintenance Project Alternative A HEC-RAS Workmap -
Restore Earthen and Concrete Channel to Construction Plans
Kelly Drive Channel Maintenance Project Alternative B HEC-RAS Workmap -
Restore Earthen Channel North of concrete Channel Entrance to Construction
Plans
Kelly Drive Channel Maintenance Project Alternative C HEC-RAS Workmap -
Maintained Concrete Channel with Earthen Low Flow Channel along Western
Slope Protection (Preferred Alternative)
Kelly Drive Channel Maintenance Project Alternative D HEC-RAS Workmap -
Maintained Concrete Channel and Replaced Slope Protection
Kelly Drive Channel Maintenance Project Alternative E HEC-RAS Workmap -
Proposed Levee along Kelly Drive Channel
Kelly Drive Channel Maintenance Project Alternative F HEC-RAS Workmap -
Proposed Diversion Culvert under Kelly Drive
Appendix 4 -Existing Condition HEC-RAS Model Summary and Output (On enclosed CD)
Appendix 5 - Alternative A HEC-RAS Model Summary and Output (On enclosed CD)
Appendix 6 -Alternative B HEC-RAS Model Summary and Output (On enclosed CD)
Appendix 7 - Alternative C HEC-RAS Model Summary and Output (On enclosed CD)
Appendix 8 - Alternative D HEC-RAS Model Summary and Output (On enclosed CD)
Appendix 9 -Alternative E HEC-RAS Model Summary and Output (On enclosed CD)
Appendix 10 -Alternative F HEC-RAS Model Summary and Output (On enclosed CD)
Appendix 11 -Alternative F WSPGW Model Summary and Output (On enclosed CD)
Prepared By: DCB:HM:nslRepori/l5369.001
Rick Engineering Company - Water Resources Division 9-17-07
Project Description
This document provides preliminary alternatives analyses for the proposed Kelly Drive Channel
Maintenance Project. The proposed project location is east of, and parallel to, Kelly Drive.
Kelly Drive is bounded by El Camino Real to the north and Park Drive to the south, and is within
the City of Carlsbad, California. The existing Kelly Drive Channel outlets into the Agua
Hedionda Lagoon downstream of Park Drive.
Refer to the exhibit titled Vicinifv Mar, located in Appendix 1 for the project location and
approximate project limits.
Between El Camino Real and Park Drive, the existing Kelly Drive Channel consists of
approximately 1100 linear feet of earthen channel and approximately 950 linear feet of concrete
channel. The existing concrete channel begins at the upstream face of Park Drive. The earthen
channel begins approximately 950 feet upstream of Park Drive and extends upstream to the
downstream face of El Camino Real. Portions of the slope along the western channel bank is
lined with concrete to protect existing properties and structures along Kelly Drive.
The concrete channel in its current condition is in fair condition with some accumulated
sediment and vegetation. The existing earthen channel contains accumulated sediment and
vegetation. Concrete slope protection failure along a portion of western earthen channel bank
and riprap slope protection failure at the entrance to the concrete channel has occurred since
construction of the channel circa the early 1970s. The accumulated sediment as well as the slope
protection failure is threatening the private properties and residences adjacent to the channel with
potential for both flooding and erosion.
The main purpose of the Kelly Drive Maintenance Project is to restore the channel's flood
conveyance capacity, and maintain and replace the concrete and riprap slope protection, which
has failed along the western side of the earthen channel, and at the entrance to the concrete
channel. The objective of this alternative analysis is to assess the flood control benefits, identify
potential project footprint, and to assist with determining the potential environmental impacts for
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Rick Engineering Company - Water Resources Division 1 9-1 7-07
this project. Opinions of probable cost for each channel maintenance alternative has also been
included. All calculated flood control benefits, potential project footprint, and opinions of
probable cost are approximate and based on preliminary design. Results are subject to change
during final design of the selected alternative.
Hydraulic Metlrodology
The U.S. Army Corps of Engineers' Hydraulic Engineering Center River Analysis System
(HEC-RAS)(Version 3.1.3) was used to prepare the open channel hydraulic models for Kelly
Drive Channel within the study limits. HEC-RAS calculates water surface elevations (WSELs)
and velocities for natural or engineered channels in supercritical and subcritical flow regimes.
HEC-RAS models existing and proposed hydraulic structures such as culverts and bridges.
Each proposed maintenance alternative models both the 2-year and 100-year flow rates. 100-
year flow rates through all of the Kelly Drive Channel hydraulic models are based on flow rates
from the GIs Based Master Drainage Plan (MDP) for the City of Carlsbad (dated May 4, 2005),
prepared by Rick Engineering Company. Flow rates for the 2-year storm event are estimated as
a percentage of the MDP discharges based on the ratio of the 2-year and 100-year 6-hour
Precipitation Isopluvials from the 2003 San Diego County Hydrology Manual.
Table I: 6-lrr Precipitation Summary
Storm Event Rainfall Depth (in)
2-year
100-year
There are locations along the Kelly Drive Channel where the flow rates, change within the
channel, due to outlets from a brow ditch or storm drain.
Seven HEC-RAS hydraulic analyses were prepared for this alternative analysis. Each of the
HEC-RAS models extends for approximately 830 linear feet downstream of Park Drive and
approximately 560 linear feet upstream of El Camino Real. No maintenance activities are
Prepared By:
Rick Engineering Company - Water Resources Division 2 9-17-07
proposed upstream of El Camino Real or downstream of Park Drive. The following channel
maintenance alternatives are analyzed in this report.
Existing Condition (No Action Alternative)
A) Restore Earthen and Concrete Channel to Construction Plans
B) Restore Earthen Channel North of Concrete Channel Entrance to Construction Plans
C) Maintained Concrete Channel with Earthen Low Flow Channel along Slope
Protection (Preferred Alternative)
D) Maintained Concrete Channel and Replaced Slope Protection
E) Proposed Levee/Floodwall Along Kelly Drive
F) Proposed Diversion Culvert under Kelly Drive
A detailed description of each alternative is included in subsequent sections.
Prepared By:
Rick Engineering Company - Water Resources Division 3
Existing Condition (no Action Alternative)
Description
The existing condition HEC-RAS hydraulic analysis is based on available city wide topography
obtained from the City of Carlsbad (dated 2005) and additional project specific topography
prepared by Melchoir Land Surveying Inc. (dated 2007). Existing culvert information, channel
geometry, and alignments are based on the following plan sets obtained from the City of
Carlsbad.
8 Plan and Profiles for Street Improvements Storm Drain and Water - Laguna Riviera
Unit No. 1, City of Carlsbad (Dwg. 152-8 Sheet 1 through 6)(Proj. 67-3) Approved
March 21, 1967
Grading Plan - Laguna Riviera Tract Unit No. 1, City of Carlsbad @wg. B-4-1 Sheet
1 of 2)(Job 1-67) Dated March 21, 1967
Plan and Profiles for Street Improvements Storm Drain and Water - Laguna Riviera
Unit No. 3, City of Carlsbad (Dwg. 157-4 Sheet 1 through 3)Proj. 68-18) Approved
October 25, 1968
El Camino Real - Road Survey 1800-1 As-built (County of San Diego ~~1800-
l)(Sht. 42 of 128) As Built Date December 13, 1971
Refer to Appendix 2 for reduced scale hard copies of the plan sets listed above.
Anticipated Impacts
The following table summarizes the anticipated impacts associated with the Existing Condition
(No Action Alternative). All quantities are estimates, and are subject to change with more
detailed future studies.
Table 2: Existing Condition (No Action Alternative) Anticipated Impact Summary
Prepared By: DCB:HM:ns/Report/l5369.001
Rick Engineering Company - Water Resources D~vision 4 9-17-07
Approximate Limits of Impact
Approximate Impact Footprint (sq. ft.)
Estimated Export Quantity (cubic yards)
NIA
NIA
NIA
The hydraulic analyses indicate Park Drive is subject to overtopping and flooding with flow
depths of approximately 1.5 feet during the 100-year storm, and approximately 0.5 feet
during the 2-year storm.
The hydraulic analyses indicate El Camino Real is subject to overtopping and flooding with
flow depths of approximatelyl.2 feet during the 100-year storm, and approximately 0.5 feet
during the 2-year storm.
A portion of Kelly Drive between Park Drive and Hillside Drive is subject to flooding with
flow depths of approximately 2.0 feet for the 100-year storm, and 1.0 feet for the 2-year
storm.
Approximately 14 properties along Kelly Drive could be subject to flooding during the 100-
year storm.
Accumulated sediment, debris, and vegetation within the earthen channel results in increased
flooding potential to properties and structures adjacent to the concrete slope protection along
the western earthen channel bank.
Private properties along the western earthen channel bank could be subject to erosion due to
the failed concrete slope protection along the western earthen channel bank and failed riprap
at the entrance to the concrete chamel.
Prepared By:
Rick Engineering Company - Water Resources Division 5
HEC-RAS Results
Water surface elevations for the 100-year and 2-year storm event are summarized below. The
existing condition will be the basis of comparison for each maintenance alternative.
Refer to the exhibit titled Kellv Drive Channel Maintenance Project Existina Condition HEC-
RAS Workmap located in Appendix 3 for the 100-year and 2-year floodplain and profile for the
Existing Condition vo Action Alternative).
Table 3: Existing Condition WSEL Summary for the 100-year and 2-year Storm Event
Anticipated Benefits
No impact to existing wildlife or vegetation habitats within the Kelly Drive Channel.
Opinion of Probable Cost
There are no anticipated construction costs associated with the Existing Condition (No
Action Alternative)
Prepared By:
Rick EngineeriFg Company - Water Resources Division 6
Alternative A -Restore Earthen and Concrete Channel to Construction Plans
Description
Alternative A proposes to maintain the Kelly Drive Channel, between the upstream face of Park
Drive and the downstream face of El Camino Real, to the original channel design shown on the
construction plans. Horizontal alignment, vertical alignment, and channel geometry are based on
information found on the construction plans listed previously, and included in Appendix 2.
The existing concrete channel would be maintained by removing accumulated sediment and
vegetation, and restoring the concrete channel flowline to the original channel design. The
original concrete channel design is a trapezoidal channel with a 5'-6" bottom width and 1.5:l
(H:V) side slopes.
The earthen portion of the channel would be maintained by removing the accumulated sediment
and vegetation, and restoring the channel flowline, and geometry to the original channel design.
The original earthen channel design is a trapezoidal channel with an approximate bottom with of
43' and a varying side slope from 1.5:l (H:V) to 2:l (H:V).
Concrete slope protection along the western channel bank as well as riprap slope protection at
the entrance to the concrete channel would be replaced per the original construction plans.
Anticipated Impacts
The following table summarizes the anticipated impacts associated with Alternative A. All
quantities are estimates, and are subject to change with more detailed future studies.
Prepared By:
Rick Engineering Company - Water Resources Division 7
Table 4: Alternative A Anticipated Impact Summary
The hydraulic analyses indicate Park Drive will remain subject to overtopping and flooding
with flow depths of approximately 115 feet during the 100-year storm, and approximately 0.4
feet during the 2-year storm.
a The hydraulic analyses indicate El Camino Real will remain subject to overtopping and
flooding with flow depths of approximatelyl.3 feet during the 100-year storm, and
approximately 0.5 feet during the 2-year storm.
a A portion of Kelly Drive between Park Drive and Hillside Drive will remain subject to
flooding with flow depths of approximately 2.0 feet for the 100-year storm.
Approximately 1 property along Kelly Drive is could be subject to flooding during the 100-
year storm.
a Proposed channel maintenance within Kelly Drive channel may require processing through
environmental resource agencies and the California Coastal Commission.
Approximate Limits of Impact
Approximate Impact Footprint
Estimated Export Quantity
HEC-RAS Results
Water surface elevations for the 100-year and 2-year storm event are summarized below.
2050 linear feet
2.3 acres
9500 cubic yards
Refer to the exhibit titled Kellv Drive Maintenance Project Alternulive A HEC-RAS Workrnau
located in Appendix 3 for the approximate 100-year and 2-year floodplain and profile for
Alternative A, Existing Condition (No Action Alternative) 100-year floodplain, and proposed
grading.
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Prepared By:
Rick Engineering Company - Water Resources Division 8
Table 5: Afternative A WSEL Summary for the 100-year and 2-year Storm Event
Anticipated Benefits
The removal of accumulated sediment, debris, and vegetation within the earthen and
concrete channels result in a decrease in flooding potential to properties and structures
adjacent to the concrete slope protection along the western earthen channel bank.
Approximately 13 of the 14 properties currently subject to flooding along Kelly Drive
would be removed from the 100-year floodplain limits.
WSELs decrease up to 4.7 feet within the Kelly Drive Channel between the upstream
face of Park Drive and the downstream face of El Camino Real during the 100-year
storm.
Kelly Drive would no longer be subject to'flooding during the 2-year stonn.
Replacing the concrete slope protection along the western earthen channel bank would
reduce the potential for erosion to the properties along Kelly Drive.
Prepared By: DCB:HM:ns/Report/l5369.001
Rick Engineering Company - Water Resources Division 9 9-17-07
Opinion of Probable Cost
Preliminary opinion of probable construction cost provided within this alternative analysis is
approximate and is based on preliminary channel design. This estimate is based on unit costs
from the San Diego Unit Price List (2006). Opinion of probable cost may be subject to change
during final design.
Table 6: Alternative A - Opinion of Probable Cost Summary
BOND
ITEM DESCRIPTION UNIT QTY UNIT PRICE TOTAL COST
Clearing & Grubbing AC 2.3 $20,000.00 $46,000
Excavate and Export Sediment CY 9500 $16.50 $1 56,750
Remove Concrete Slope Protection CY 80 $135.00 $10,800
114 Ton Rip-Rap CY 100 $60.00 $6,000
Concrete Slope Protection LF 640 $325.00 $208,000
Traffic Control LS 1 $20,000.00 $20,000
SUBTOTAL $447,550
10% Mobilization $44,760
20% Contingency $89,510
TOTAL $582,000
* Based on City of San Diego Unit Price List, January 2006
Prepared By:
Rick Engineering Company - Water Resources Division 10
Alternative B - Restore Earthen Channel North of Concrete Channel Entrance to
Construction Plans
Description
Alternative B proposes to maintain the earthen channel and slope protection between the
entrance to the concrete channel to the downstream face of El Camino Real to the original
channel design shown on the construction plans listed previously, and included in Appendix 2.
Restoring the riprap slope protection at the concrete channel entrance is also proposed.
Horizontal alignment, vertical alignment, and channel geometry are based on information found
on the construction plans listed previously.
The earthen portion of the channel would be maintained by removing accumulated sediment and
vegetation restoring the channel flowline to the original channel design. The original earthen
channel design is a trapezoidal channel with an approximate bottom width of 43' and a varying
side slope from 1.5: 1 (H:V) to 2: 1 (H:V)
Concrete slope protection along the western channel bank as well as riprap slope protection at
the entrance to the concrete channel would be replaced per the original construction plans.
The existing concrete channel would remain in its current condition.
Anticipated Impacts
The following table summarizes the anticipated impacts associated with Alternative B. All
quantities are estimates, and are subject to change with more detailed future studies.
Prepared By:
Rick Engineering Company- Water Resources Division 1 1
Table 7: Alternative B Anticipated Impact Summary
The hydraulic analyses indicate Park Drive will remain subject to overtopping and flooding
with flow depths of approximately 1.5 feet during the 100-year storm, and approximately 0.4
feet during the 2-year storm.
The hydraulic analyses indicate El Camino Real will remain subject to overtopping and
flooding with flow depths of approximatelyl.3 feet during the 100-year storm, and
approximately 0.5 feet during the 2-year storm.
A portion of Kelly Drive between Park Drive and Hillside Drive will remain subject to
flooding with flow depths of approximately 2.0 feet for the 100-year storm, and 1.0 feet for
the 2-year storm.
Approximately 5 properties along Kelly Drive could remain subject to flooding during the
100-year storm.
Proposed channel maintenance within Kelly Drive channel may require processing through
environmental resource agencies and the California Coastal Commission.
Approximate Limits of Impact
Approximate Impact Footprint
Estimated Export Quantity
HEC-RAS Results
Water surface elevations for the 100-year and 2-year storm event are summarized below.
1 160 linear feet
1.7 acres
9300 cubic yards
Refer to the exhibit titled KeNv Drive Maintenance Project Alternative B HEC-RAS Workmaa
located in Appendix 3 for the approximate 100-year and 2-year floodplain and profile for
Alternative B compared to the Existing Condition (No Action Alternative) 100-year floodplain,
and proposed grading.
Prepared By:
Kick Engineering Company - Water Resources Division 12
Table 8: Alternative B WSEL Summary for the 100-year and 2-year Storm Event
Anticipated Benefits
a The removal of accumulated sediment, debris, and vegetation within the earthen channel
results in a decrease in flooding potential to properties and structures adjacent to the
concrete slope protection along the western earthen channel bank.
a Approximately 9 of the 14 properties currently subject to flooding along Kelly Drive
would be removed from the 100-year floodplain limits.
WSELs decrease up to 4.7 feet within the Kelly Drive Channel between the upstream
face of Park Drive and the downstream face of El Camino Real during the 100-year
storm.
Replacing the concrete slope protection along the western earthen channel bank would
reduce the potential for erosion to the properties along Kelly Drive.
Prepared By: DCB:HM:ns/Repon/l5369.001
Rick Engineering Company - Water Resources Division 13 9-17-07
Opinion of Probable Cost
Preliminary opinion of probable construction cost provided within this alternative analysis is
approximate and is based on preliminary channel design. This opinion of probable cost is based
on unit costs from the San Diego Unit Price List (2006). Opinion of probable cost may be
subject to change during final design.
Table 9: Alternative B - Opinion of Probable Cost Summary
* Based on City of San Diego Unit Price List, January 2006
Prepared By: DCB:HM:ns/Reportll5369.001
Rick Engineering Company - Water Resources Division 14 9-17-07
Alternative C - Maintained Concrete Channel with Earthen Low-Flow Channel along
Western Slope Protection (Preferred Alternative)
Description
Alternative C proposes to maintain the concrete channel located upstream of Park Drive by
removing accumulated sediment and debris, and replacing the riprap slope protection at the
concrete channel entrance to the original channel design shown on the construction plans listed
previously, and included in Appendix 2. A portion of the earthen channel would also be
maintained upstream of the concrete channel entrance (approximately HEC-RAS cross-section
2010) and adjacent to the concrete slope protection located along the western bank
(approximately HEC-RAS cross-section 2580).
The concrete channel would be maintained by removing accumulated sediment and vegetation,
restoring the concrete channel flowline to the original channel design. The original concrete
channel design is a trapezoidal channel with a 5'4" bottom width and 1.5:l (H:V) side slopes.
A proposed low-flow earthen channel is proposed in this alternative which involves removing a
portion of the accumulated sediment located upstream of the concrete channel to improve
drainage. The proposed low-flow earthen channel would be aligned adjacent to the western
slope protection, with an approximate bottom width of 20' and a 1.5:l (H:V) side slopes. The
proposed low-flow channel begins at the concrete channel entrance and extends upstream at
approximately 2% and daylights with the existing ground approximately 5 10 linear feet upstream
of the concrete channel entrance.
Concrete slope protection along the western channel bank as well as riprap slope protection at
the entrance to the concrete channel would be replaced per the original construction plans.
Anticipated Impacts
The following table summarizes the anticipated impacts associated with Alternative C. All
quantities are estimates, and are subject to change with more detailed future studies.
Prepared By: DCB:HM:nslReport/l5369.001
Rick Engineering Company - Water Resources Division 15 9-17-07
Table 10: Alternative CAnticipated Impact Summary
Approximate Limits of Impact
Approximate Impact Footprint
The hydraulic analyses indicate Park Drive will remain subject to overtopping and flooding
with flow depths of approximately 1.5 feet during the 100-year storm, and approximately 0.4
feet during the 2-year storm.
The hydraulic analyses indicate El Camino Real will remain subject to overtopping and
flooding with flow depths of approximatelyl.2 feet during the 100-year storm, and
approximately 0.5 feet during the 2-year storm.
A portion of Kelly Drive between Park Drive and Hillside Drive will remain subject to
flooding with flow depths of approximately 2.0 feet for the 100-year storm.
Approximately 7 properties along Kelly Drive could remain subject to flooding during the
100-year storm.
. Proposed channel maintenance within Kelly Drive channel may require processing through
environmental resource agencies and the California Coastal Commission.
1540 linear feet
1.2 acres
Estimated Export Quantity
HEC-RAS Results
Water surface elevations for the 100-year and 2-year storm event are summarized below.
1700 cubic yards
Refer to the exhibit titled Kellv Drive Maintenonce Project Alternative C HEC-RAS Workmar,
located in Appendix 3 for the approximate 100-year and 2-year floodplain and profile for
Alternative C compared to the Existing Condition (No Action Alternative) 100-year floodplain,
and proposed grading.
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Prepared By:
Rick Engineering Company - Water Resources Division 16 9-17-07
Table 11: Alternative C WSEL Summary for the 100-year and 2-year Storm Event
Anticipated Benefits
The removal of accumulated sediment, debris, and vegetation within a portion of the
earthen and concrete channel results in a decrease in flooding potential to properties and
structures adjacent to the concrete slope protection along the western earthen channel
bank.
Approximately 7 of the 14 properties currently subject to flooding along Kelly Drive
would be removed from the 100-year floodplain limits.
WSELs decrease up to 1.6 feet within the Kelly Drive Channel between the upstream
face of Park Drive and the downstream face of El Camino Real during the 100-year
storm.
w Kelly Drive would no longer be subject to flooding during the 2-year stom.
Prepared By: DCB:HM:nsReport/l5369.001
Rick Engineering Company - Water Resources Division 1 7 9-17-07
Replacing the concrete slope protection along the western earthen channel bank would
reduce the potential for erosion to the properties along Kelly Drive.
Opinion of Probable Cost
Preliminary opinion of probable construction cost provided within this alternative analysis is
approximate and is based on preliminary channel design. This opinion of probable cost is based
on unit costs from the San Diego Unit Price List (2006). Opinio'n of probable cost may be subject
to change during final design.
Table 12: Alternative C- Opinion of Probable Cost Summary
* Based on City of San Diego Unit Price List, January 2006
Prepared By:
Rick Engineering Company - Water Resources Division 18
Alternative D -Maintained Concrete Channel and Replaced Slope Protection
Description
Alternative D proposes to maintain the concrete channel located upstream of Park Drive to
remove accumulated sediment and debris, and replace the riprap slope protection at the concrete
channel entrance to the original charinel design shown on the construction plans listed
previously, and included in Appendix 2. The slope protection along the western channel bank
upstream of the concrete channel entrance would also be replaced per the original construction
drawings listed previously, and included in Appendix 2.
The concrete channel would be maintained by removing accumulated sediment and vegetation,
restoring the concrete channel flowline to the original channel design. The original concrete
channel design is a trapezoidal channel with a5'-6" bottom width and 1.5:l (H:V) side slopes.
The slope protection along the western channel bank would be replaced between the concrete
channel entrance (approximately HEC-RAS cross-section 2010) and upstream edge of the slope
protection (approximately HEC-RAS cross-section 2580). Horizontal alignment, vertical
alignment, and channel geometry are based on information found on the construction plans listed
previously.
The maintenance of the slope protection along the western channel bank will require removal of
some material within the channel, due to the required key down depth. However, this alternative
assumes the material removed from the earthen channel would be reused to return the earthen
channel to its current geometry.
Concrete slope protection along the western channel bank as well as riprap slope protection at
the entrance to the concrete channel would be replaced per the original construction plans.
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Rick Engineering Company - Water Resources Division 19
Anticipated Impacts
The following table summarizes the anticipated impacts associated with Alternative C. All
quantities are estimates, and are subject to change with more detailed future studies.
Table 13: Alternative D Anticipated Impact Summary
The hydraulic analyses indicate Park Drive will remain subject to overtopping and flooding
with flow depths of approximately 1.5 feet during the 100-year storm, and approximately 0.4
feet during the 2-year storm.
The hydraulic analyses indicate El Camino Real will remain subject to overtopping and
flooding with flow depths of approximately 1.2 feet during the 100-year storm, and
approximately 0.5 feet during the 2-year storm.
A portion of Kelly Drive between .Park Drive and Hillside Drive will remain subject to
flooding with flow depths of approximately 2.0 feet for the 100-year storm.
Approximately 11 properties along Kelly Drive could remain subject to flooding during the
100-year storm.
Accumulated sediment, debris, and vegetation within the earthen channel will remain, which
currently results in increased flooding potential to properties and structures adjacent to the
concrete slope protection along the western earthen channel bank.
Proposed channel maintenance within Kelly Drive channel may require processing through
environmental resource agencies and the California Coastal Commission.
Approximate Limits of Impact
Approximate Impact Footprint
Estimated Export Quantity
- ~
Prepared By:
Rick Engineering Company - Water Resources Division 20
1540 linear feet
1.2 acres
200 cubic yards
HEC-RAS Results
Water surface elevations for the 100-year and 2-year storm event are summarized below.
Refer to the exhibit titled Kellv Drive Maintenance Proiect Alternative D HEC-RAS Workmau
located in Appendix 3 for the approximate 100-year and 2-year floodplain and profile for
Alternative D compared to the Existing Condition (No Action Alternative) 100-year floodplain,
and proposed grading.
Table 14: Alternative D WSEL Summary for tlre 100-year and 2-year Storm Event
Anticipated Benefits
The removal of accumulated sediment, debris, and vegetation within the concrete channel
results in a decrease in flooding potential to properties and structures along the concrete
slope protection along the western earthen channel bank.
Prepared By: DCB:HM:ns/Repo~t/l5369.001
Rick Engineering Company - Water Resources Division 2 1 9-1 7-07
Approximately 3 of the 14 properties currently subject to flooding along Kelly Drive
would be removed from the 100-year floodplain limits.
WSELs decrease up to 0.7 feet within the Kelly Drive Channel between the upstream
face of Park Drive and the downstream face of El Camino Real during the 100-year
storm.
Kelly Drive would no longer be subject to flooding during the 2-year storm.
Replacing the concrete slope protection along the western earthen channel bank would
reduce the potential for erosion to the properties along Kelly Drive.
Opinion of Probable Cost
Preliminary opinion of probable construction cost provided within this alternative analysis is
approximate and is based on preliminary channel design. This opinion of probable cost is based
on unit costs from the San Diego Unit Price List (2006). Opinion of probable cost may be
subject to change during final design.
Table IS: Alternative D - Opinion of Probable Cost Summary
Clearing & Grubbing
Excavate and Fill
Excavate and Export Sediment
Remove Concrete Slope Protection
* Based on City of San Diego Unit Price List, January 2006
Prepared By: DCB:HM:ns/Report~l5369.001
Rick Engineering Company - Water Resources Division 22 9-17-07
Alternative E - Proposed Levee/Floodwoll along Kelly Drive Channel
Description
Alternative E proposes to maintain the concrete channel located upstream of Park Drive by
removing accumulated sediment and debris, and replace the riprap slope protection at the
concrete channel entrance to the original channel design shown on the construction plans listed
previously, and included in Appendix 2. The slope protection along the western channel bank
upstream of the concrete channel entrance would also be replaced per the original construction
drawings listed previously, and included in Appendix 2. In addition, a proposed levee/floodwall
would also be constructed along the Kelly Drive Channel to prevent inundation of Kelly Drive
and properties adjacent to the channel. The leveelfloodwall would begin at approximately 100
feet upstream of Park drive along the western edge of Kelly Drive Channel and extend upstream
for approximately 1400 linear feet.
The concrete channel would be maintained by removing accumulated sediment and vegetation,
restoring the concrete channel flowline to the original channel design. The original concrete
channel design is a trapezoidal channel with a 5'-6" bottom width and 1.5: 1 (H:V) side slopes.
The slope protection along the western channel bank would be replaced and the remaining
portions of the earthen channel would remain in its current condition.
Concrete slope protection along the western channel bank as well as riprap slope protection at
the entrance to the concrete channel would be replaced per the original construction plans.
For purposes of this analysis, the proposed levee is assumed to be a concrete floodwall rather
than an earthen berm due to footprint co~straints from the existing roadway and the existing
properties located along Kelly Drive Chamel. The levee/floodwall will protect the properties
along Kelly Drive but will not prevent flows from overtopping Park Drive.
Prepared By: DCB:HM:ns/Report/l5369.001
Rick Engineering Company - Water Resources Division 23 9-17-07
Anticipated Impacts
The following table summarizes the anticipated impacts associated with Alternative E. All
quantities are estimates, and are subject to change with more detailed future studies.
Table 16: Alternative E Anticipated Impact Summary
The hydraulic analyses indicate Park Drive will remain subject to overtopping and flooding
with flow depths of approximately 1.4 feet during the 100-year storm, and approximately 0.5
feet during the 2-year storm.
The hydraulic analyses indicate El Camino Real will remain subject to overtopping and
flooding with flow depths of approximatelyl.2 feet during the 100-year storm, and
approximately 0.5 feet during the 2-year storm.
A portion of Kelly Drive near Park Drive will remain subject to flooding with flow depths of
approximately 2.2 feet for the 100-year storm.
Proposed channel maintenance within Kelly Drive channel may require processing through
environmental resource agencies and the California Coastal Commission.
Proposed levee could create a new public safety hazard by blocking visibility into the
channel.
Further structural calculations would be required to design the levee/floodwall to qualify as a
flood control structure, and to comply with design requirements set forth by applicable state
andlor federal agencies.
Local drainage issues may need to be addressed with the construction of the proposed
levee/floodwall, and further hydraulic analysis may be required during final design.
Approximate Limits of Impact
Approximate Impact Footprint
Estimated Export Quantity
Prepared By: DCB:HM:ns/Report/l5369.001
Rick Engineering Company - Water Resources Division 24 9-17-07
1540 linear feet
1.2 acres
200 cubic yards
HEC-RAS Results
Water surface elevations for the 100-year and 2-year stom event are summarized below.
Refer to the exhibit titled Kelly Drive Maintenance Project Alternative E HEC-RAS Workmap
located in Appendix 3 for the approximate 100-year and 2-year floodplain and profile for
Altemative E compared to the Existing Condition (No Action Altemative) 100-year floodplain,
and proposed grading.
Table 17: Alternative E WSEL Summary for the 100-year and 2-year Storm Event
Prepared By:
Rick Engineering Company - Water Resources Division 25
Anticipated Benefits
All 14 of the properties currently subject to flooding along Kelly Drive would be
removed from the 100-year floodplain limits.
Changes in WSELs range from an increase of 0.2 feet to a decrease of 0.5 feet within the
Kelly Drive Channel between the upstream face of Park Drive and the downstream face
of El Camino Real, however the increases in WSELs are within the proposed
leveelfloodwall and do not negatively affect private properties or structures adjacent to
Kelly Drive Channel.
Replacing the concrete slope protection along the western earthen channel bank would
reduce the potential for erosion to the properties along Kelly Drive.
Opinion of Probable Cost
Preliminary opinion of probable construction cost provided within this alternative analysis is
approximate and is based on preliminary channel design. This opinion of probable cost is based
on unit costs from the San Diego Unit Price List (2006). Opinion of probable cost may be subject
to change during final design.
Table IS: Alternative E - Opinion of Probable Cost Summary - BOND
ITEM DESCRIPTION UNIT QTY UNIT PRICE TOTAL COST
Clearing & Grubbing AC 1.2 $20,000.00 $24,000
Excavate and Export Sediment CY 200 $27.50 $5,500
Levee wall SF 16000 100.00 $1,600,000
Remove Concrete Slope Protection CY 80 $135.00 $10,800
114 Ton Rip-Rap CY 100 $60.00 $6,000
Concrete Slope Protection LF 640 $325.00 $208,000
Traffic Control LS 1 $30,000.00 $30,000
SUBTOTAL $1,884,300
10% Mobilization $188,430
20% Contingency $376,860
L
TOTAL $2,450,000
Based on City of San Diego Unit Price List, January 2006
Prepared By:
Rick Engineering Company - Water Resources Division 26
Alternative F - Proposed Diversion Culvert under Kelly Drive
Description
Alternative F proposes to maintain the concrete channel located upstream of Park Drive by
removing accumulated sediment and debris, and replacing the riprap slope protection at the
concrete channel entrance to the original channel design shown on the construction plans listed
previously, and included in Appendix 2. The slope protection along the western channel bank
upstream of the concrete channel entrance would also be replaced per the original construction
drawings listed previously, and included in Appendix 2. The remaining portions of the earthen
channel would remain in its current condition.
The concrete channel would be maintained by removing accumulated sediment and vegetation,
restoring the concrete channel flowline to the original channel design. The original concrete
channel design is a trapezoidal channel with a 5'4" bonom width and 1.5:l (H:V) side slopes.
To prevent inundation of Kelly Drive and properties adjacent to Kelly Drive Channel during
large storm flows, a proposed diversion culvert, consisting of a 9'W x 3'H triple-box culvert
would be constructed under Kelly Drive Channel. The box culvert inlet would be located at the
upstream side of El Camino Real and the outlet would be located at the downstream side of Park
Drive. The horizontal alignment would be similar to the horizontal alignment of Kelly Drive.
Based on the flowlines of the existing terrain at the inlet and outlet locations, the longitudinal
slope of the culvert was assumed to be 1.2%.
Water Surface Pressure Gradient for Windows (WSPGW) was used to model the proposed
diversion culvert under Kelly Drive Channel within the study limits. WSPGW is intended for
calculating WSELs and velocities for natural or engineered channels in addition to closed
conduits such as culverts. The proposed diversion box would be designed to only intercept high
flow. Low flows would remain in the existing channel. This alternative will also involve
modifications to the existing storm drain outlet at Hillside Drive to discharge to the box culvert,
and not the channel.
Prepared By:
Rick Engineering Company - Water Resources Division 27
Concrete slope protection along the western channel bank as well as riprap slope protection at
the entrance to the concrete channel would be replaced per the original construction plans.
Anticipated Impacts
The following table summarizes the anticipated impacts associated with Alternative F. All
quantities are estimates, and may be subject to change with more detailed future studies.
The hydraulic analyses indicate Park Drive is subject will remain overtopping and flooding
with flow depths of approximately 1.0 feet during the 100-year storm.
Table 19: Alternative F Anticipated Impact Summary
The hydraulic analyses indicate El Camino Real will remain subject to overtopping and
flooding with flow depths of approximately 0.3 feet during the 100-year storm.
Proposed channel maintenance within Kelly Drive channel may require processing through
Approximate Limits of Impact *
Approximate Impact Footprint *
Estimated Export Quantity *
environmental resource agencies and the California Coastal Commission.
WSELs increase up to 0.4 feet at the'downstream side of Park Drive as a result of the
diversion culvert outlet location.
Based on the results fiom the HEC-RAS analysis, to remove Kelly Drive and existing
1540 linear feet
1.2 acres
200 cubic yards
properties along the Kelly Drive Channel from the 100-year floodplain, approximately 60%
of the 100-year flow rate, approximately 1090 cfs would need to be diverted at the upstream
side of El Camino Real.
Based on the preliminary WSPGW analysis, to convey this diverted flow rate under Kelly
Drive it would require a triple 9' by 3' (WxH) box culvert.
Additional grading would be required upstream of El Camino Real and downstream of Park
Drive to accommodate construction of the diversion culvert.
*excludes impact limits within Kelly Drive
The proposed diversion box would require special structural design considerations due to the
size of the box culverts required.
- --
Prepared By:
Rick Engineering Company - Water Resources Division 28
The proposed diversion box would follow the alignment of Kelly Drive, which is an existing
street with existing utilities underlying the roadway. There is a high potential for utility
conflicts with the proposed diversion alternative.
The proposed diversion box would directly discharge to Agua Hedionda Lagoon.
HEC-RAS Results
Water surface elevations for the 100-year storm event are summarized below. Due to the impact
of the diversion culvert proposed with this alternative, the 100-year flow rates between El
Camino Real and Park Drive would be reduced to lower than the existing flow rates for the 2-
year storm event, therefore the 2-year storm event has been excluded from the proposed
condition hydraulic analysis for this alternative.
Refer to the exhibit titled Kelly Drive Maintenance Project Alternative F HEC-RAS Workmau
located in Appendix 3 for the approximate 100-year floodplain and profile for Alternative F
compared to the Existing Condition (No Action Alternative) 100-year floodplain, and proposed
grading.
Prepared By:
Rick Engineering Company - Water Resources Division 29
Table 20: Alternative F WSEL Summary for the 100-year (Diverted) Storm Event
Anticipated Benefits
The removal of accumulated sediment, debris, and vegetation within the earthen and
concrete channels result in a decrease in flooding potential to properties and structures
along the concrete slope protection along the western earthen channel bank.
All 14 properties ciurently subject to flooding along Kelly Drive would be removed from
the 100-year floodplain limits.
WSELs decrease up to 3.1 feet within the Kelly Drive Channel between the upstream
face of Park Drive and the downstream face of El Camino Real.
Replacing the concrete slope protection along the western earthen channel bank would
reduce the potential for erosion to the properties along Kelly Drive.
Prepared By:
Rick Engineering Company - Wafer Resources Division 30
HEC-RAS
Cross-section
100
360
560
710
940
Park Drive
I100
1190
1360
1500
1670
1790
1890
2010
2220
2370
2580
2720
2880
3070
El Camino Real
3590 1770
3790 53.2 1770 56.0
Min. Channel
Elev. (A)
10.0
12.0
14.0
15.0
16.0
14.8
15.8
17.5
19.0
20.6
21.2
22.0
24.5
29.7
33.6
36.1
39.2
41.2
42.0
100-year
Q (cfs)
205 1
205 1
2051
2051
2037
887
887
887
887
887
887
864
864
864
864
864
864
725
725
(Diverted)
WSEL (ft)
16.0
16.1
16.6
18.2
21.0
22.2
21.7
23.3
24.7
26.3
26.9
27.7
29.3
33.7
37.5
40.0
42.1
44.0
45.4
Opinion of Probable Cost
Preliminary opinion of probable construction cost provided within this alternative analysis is
approximate and is based on preliminary channel design. This opinion of probable is based on
unit costs from the San Diego Unit Price List (2006). Opinion of probable cost may be subject to
change during final design.
Table 21: Alternative F - Opinion of Proboble Cost Summary
BOND
ITEM DESCRIPTION UNIT QTY UNIT PRICE TOTAL COST
Clearing & Grubbing AC 1.2 $20,000.00 $24,000
Excavate and Export Sediment CY 200 $27.50 $5,500
Relocate existing Sewer, Water Mains & Lateral: LF 2200 400.00 $880,000
Triple box culvert LF 2400 $1,000.00 $2,400,000
Remove Concrete Slope Protection CY 80 $135.00 $10,800
114 Ton Rip-Rap CY 100 $60.00 $6,000
Concrete Slope Protection ' LF 640 $325.00 $208,000
Pavement SF 84000 $2.00 $168,000
Traffic Control LS 1 S50,OOO.OO $50,000
SUBTOTAL $3,752,300
10% Mobilization $375,230
20% Contingency $750,460
TOTAL $4,878,000
* Based on City of San Diego Unit Price List, January 2006
Prepared By:
Rick Engineering Company - Water Resources Division 3 1
Summary
The concrete channel portion of the Kelly Drive Channel is currently in fair condition, based on
visual inspection of the channel, with some accumulated sediment and vegetation. The existing
earthen channel contains accumulated sediment and vegetation. Concrete slope protection
failure along a portion of western earthen channel bank and riprap slope protection failure at the
entrance to the concrete channel has occurred since construction of the channel circa the early
1970s. The accumulated sediment as well as the slope protection failure is threatening the
private properties and residences adjacent to the channel with potential for both flooding and
erosion.
Based on hydraulic analysis performed within this preliminary alternatives analysis, the 100-year
flow rate within the Kelly Drive Channel exceeds the capacity of the concrete channel and
portions of the earthen channel based on current geometry, resulting in an increased potential for
flooding to properties and structures along Kelly Drive Channel, and Kelly Drive. The failure of
the existing slope protection has resulted in increased exposure to erosion for the adjacent private
properties.
Seven alternatives were explored within this preliminary alternative analysis, each having unique
combination of flood control, impacted area, and cost benefits, to address the erosion potential
and the flooding impacts associated with each maintenance alternative. A summary of
anticipated impacts and anticipate benefits is located below.
Prepared By:
R~ck Engineering Company - Water Resources Division 32