HomeMy WebLinkAbout; Master Drainage & Storm Water Quality Mgmt Plan; Storm Water; 1994-03-01Table of Contents
CHAPIERl. €!XECTJllS% SUMMARY ..................................................................... 1
A . Goals and Objectives ....................................................................................... 1
B . Report Sxinmaqy ............................................................................................. 2 c . Recomm~dations ........................................................................................... 4
CHAPTER 2. PLANNING- CHARAC3'ERISTCS ................. i ......................... 7
A planning kea Bounda.ries ............................................................................... 7
B . Physical &vimnment ..................................................................................... 7
C . Land Use ......................................................................................................... 9 D . Design Sensitivities ...................................................................................... 10
CEIAPTER 3, METHODOLOGY ............................................................................. 11
A. Study Approach ............................................................................................. 11 B . Hydrologic Deaign Criteria ........................................................................... 11
C . Deaign Runoff Method .................................................................................. 18 D . Design Procedure ......................................................................................... 18
F . Sedimentation Basins .................................................................................... 21
E . Computer Program ........................................................................................ 20
CHAPTER4, FINANCING ....................................................................................... s
A . General .......................................................................................................... 25
B . Source ofhthority ....................................................................................... 26
C . History ........................................................................................................... 26
D . ResentFii status ............................................................................... 28 E . Fiicing Method Alternatives ..................................................................... 29
F . Fiimmcing Recommendatione ........................................................................ 30 G . bed Local Drainage Areas (PISA's) ..................................................... 52
H . Fee Analysis .................................................................................................. 36 I . Fee Adjustments ............................................................................................. 45
J . Fee Credits and Reimbursement for Constructed Facilities ........................ 46
CHAPTER 5, STORM WATER QUALITY MANAGEMENT PROGRAM ................ 47
A . Introduction .................................................................................................. 47
B . Brief History of Actions Leading to City's NPDm Permit ........................... 4.8
C . "Early" =DES Permits ............................................................................... 49
D . Elements of Carlsbad's Storm Water Quality Management Program .......... 50 E . Testing and Monitoring of Storm Water and Urban Runoff ......................... 51
F . Detedion of Illicit Connections and Illegal Discharges ............................... 55
G . Best Management Practices (BMP) .............................................................. 57
H . Program Costs and Funding ......................................................................... 62
Master Drainage and Storm Water Quality Management Plan
Carlsbed. California . March 1994
Tabla of Contsnu
Page i
CHAPTER 6, COST ESTIMATES ........................................................................... 65
A. General .......................................................................................................... 65
B . Unit Costa ...................................................................................................... 65
C . Additional Coats ............................................................................................ 65
D . Comtru& 'on Item Cost Estimates ................................................... : ........... 66 E . Facility Construction Coat %timatea ........................................................... 72
CHAPTER 7, SUMMAlZY OF FIELD INVEsncAnoNS ...................................... 75
A. Introduction .................................................................................................. 75
B . Buena Viata Creek Basin ............................................................................... 75
C . Agua Hedionda Creek Basin ......................................................................... 76
D . Encinaa Creek Basin ..................................................................................... 76 E . San Marcoa Creek Basin ............................................................................... 76 F . Findinga ......................................................................................................... 76
APPENDIX A, PROPOSED DRAINAGE FACILITIES ........................................... 77
A. Introduction .................................................................................................. 77
B . Buena Viata Creek Basin ............................................................................... 78 C . Agua Hedionda Creek Basin ......................................................................... 79 D . Eucinas Creek Basin ..................................................................................... 84 E . San Marcoa Creek Basin ............................................................................... 86 F . Encinitas Creek Basin ................................................................................... 88
APENDIX B. DRAINAGE IMPROVEMENT FACILlTIES MAPS
The following appendices are separately bound .
APPENDIX C. COST ESTIMATES. BY STORM DRAIN LINE
APPENDIX D. DELETED
APPENDIXE. FEMAREVIEW. BUENAVISIACREEK
APPENDIX F. FEMA REVIEW. AGUA HEDIONDA CREEK
APPENDIXG. FEMAREVIEW. SANMARCOS CREEKBASIN
APPENDIX I. CALCULATIONS. AGUA EEDIONDA CREEK BASIN. VOLUMES I &II'
APPENDIX J. CALCULATIONS. ENCrmAs CREEK BASIN
APPENDIX K, CALCULATIONS. SAN MARCOS CREEK BASIN
APPENDIX L. CALCULATIONS. ENCIIUITS CREEK WIN
Table of Content.
Page ii
Master Drainage and Storm Water Qudiry Management Plan
Carlsbd . California. March 1994
C"ER 1
EXECUTIVESUMMARY
A. GoalsandObjectives
This Master Drainage and Storm Water Quality Management Plan was commissioned by City Council in
February of 1988. The purpose of the plan was to:
1. Reassess the storm drainage facility needs ofthe City and to update the 1980 Master Drainage
Plan.
2. Incorporate the drainage facility needs of the southern part of the City which were formerly
included in the County's Zone 1 Flood Control District.
3. Establish drainage facility costs, analyze viability of existing planned local drainage (PLD) fee
areas, recommend changes to existing PLD fee areas, establish new PLD fee areas for the southern
city area, docatecostsinaccordwithStateMap Act andm 1600requirementsandestablishnew
PLD area fees.
4. Provide new topographic mapping of the entire City at two foot contour intervals on printed
mylar sheets and in digital format compatible with our new Geographic Information System (GIs)
on computer.
5. Field review existing facilities for conformity with fie plans and make recommendations on
facity maintenance needs.
6. Review the siitation and water quality requirements ofthe City and make recommendations for
additional measures to protect our sensitive riparian waterways and lagoons.
Over the course of preparing the Master Plan, the Federal Government implemented new regulations
which mandated strict water quality control requirements. These new water quality regulations signifi-
cantly altered the focus of the Master Drainage Plan. Whereas previous master drainage plan studies
focused on storm water flood control measures, the new regulations shifted the focus to preservation and
enhancement of storm water quality. This shift resulted in a significant re-evaluation of our previous
Planned Local Drainage area fee concept. As a result, the numerous localized PLD fsz areas were
combined into four large PLD fee areas which coincide with the four drainage basins within the City. This
reflects the Federal Government emphasis on preserving and protecting the water quality of receiving
waters and not just of a few localized basins. In light of this new focus the title of this report was changed
from Master Drainage Plan to Master Drainage and Storm Water Oualitv Manaeement Plan.
Master Drainags and Storm Water Quality Management Plan
Carlsbad. California. March 1994
Chapter 1
Pago 1
TheMasterDrainage and Storm Water QuaIity Management Plan, herehafIerdedMaster Plan, includes
all drainage areas within the incorporated boundary of the City of CarIsbad covering approximately 39
square des. The Master Plan addresses only those facilities which provide the backbone system to the
City's storm water management hfhtructure. Generally these consist of storm drainage pipes with a
diameter of thirty inches or larger together with concrete and rock lined channels, permanent sediien-
tatiodpollutant control basins and other larger miscellaneous facilities.
The existing and recommended future drainage facilities are shown on the 1 " = 400' maps on file with the
CityEngineerand the 1" = 1000'mapswhichaccompanythisdocument. Eachproposedfacilityhasaletter
designation which begins with the letter A, B, C, or D corresponding with one of the four drainage basins
in the City. The basin designations were assigned consecutively startingfrom the North and moving South
as follows: 'A' for Buena Vista Lagoon drainage basin; 'B' for Agua Hedionda Lagoon drainage basin;
'C' for Encinas Creek drainage basin, and, 'D for Batiquitos Lagoon drainage basin.
A total of 42.9 million dollars in recommended future drainage facilities are identified within the Master
Drainage Plan report. Of this amount, approximately 34.3 million dollars in facility costs are directly
attributable to the needs created by new development. The remaining 8.6 million dollars are attributable
to facility deficiencies created by existing development (Reference Table 6-7).
Thefinancingplanpresentedinthisreportrecommendsthat 1000/oofthedrainagefa~tycostsattributabIe
to new development be financed by developersthrough payment ofplanned Local Drainage kea (PLDA)
fees or by direct construction ofdrainage facilities. Ofthe 34.3 million dollars in facility costs attributable
tonew development, 18.8milliondollarswill becollectedinnewPLDAfeerevenues, 13.7milliondollars
will occur from direct developer construction of drainage facilities and 1.8 million doh will be applied
from previously collected PLDA fee revenues. The 13.7 million dollars in direct developer construction
of facilities occurs in proposed PLDA "D" for reasons discussed below.
The 8.6 million dollars attributable to existing facility deficiencies will be funded through a combiition
of sources as follows: 1.3 million dollars are available from previously collected PLDA fees; 1.6 million
dollars will be generated from PLDA fees charged against existing developments that redevelop or
remodel; 4.3 million dollars in SWAG Transnet funds and 0.5 million dollars in redevelopment tax
increment bond funds are budgeted in the current Capital Improvement Program; and, 0.2 million dollars
has been contributed by the County of San Diego for drainage improvements adjacent to McClellan
Palomar Airport. The remaining 0.7 million dollars is presently udnded and will require hnding from
other non-fee sources such as the general fund, federal and state grants, general obligation bonds, and
assessment districts.
It should be noted that the 1.3 million dollars in existing PLDA funds, allocated to mitigate existing
deficient facilities, will in fact be used to mitigate impacts created by the developments which paid the
PLDA fees, Due to funding shortfalls, many of these impacted facilities were deferred until adequate
funding was available. Since the development was allowed to proceed once the fees were paid, these same
facilities are now categorized as wholly or partly deficient under this plan.
The report recommends establishment of four new Planned Local Drainage Areas (PLDA's) correspond-
ing to the four drainage basins described above. The existing thirteen PLDA's are to be abolished and any
Chapter 1
Page 2
Mester Drainage and Storm Water Quality Maneg-nt Plan
Carlabad. California, March 1994
remaining finds will be transferred into the respective new PLDA With the exception of the PLDA for
basin ‘D’, the fees recommended for each of the PLDA’s are based upon recovery of 100% of the costs
attributable to new development and 200h of the costs attributable to existing development. The 20%
figure wasused because it represents the percentage ofthe existing development base which is estimated
to redevelop or remodel over the life of fee program.
For basin ID’, it is recommended that the primary method of6nancing be direct developer construction
as a condition of development approval. The reasons for using this method of financing over a fee based
programare asfollows: 1)Onlyasmallpercentageofthedrainagefacilityneedsinbasin‘D’areattrhtable
to existing deficiencies; 2) The facilities are located on undeveloped lands which require their installation
inorderto maketheunderlyingproperty suitable for development; 3) Amajority ofthefacilitiesarelocated
within large master plan developments that have the financial capability to find such facilities without
benefitofafeeprogram;and, 4)Thefacilitiesinthesouthernportionofbasin‘D’ areto befinanced through
a proposed Community Facilities District currently under formation.
The report does recommend that a small fee be levied on development within basin ‘D’ in order to
reimburse the City for capital expenses associated withthe Storm Water Testing and Monitoringprogram.
In addition, it may be necessary to establish additional local benefit assessment districts such as the one
proposed in the southern part of basin ‘D’ to reimburse developers on a facility by facility basis.
The PLDA fees recommended in the 1980 Master Drainage Plan were levied only upon developments
which proposed a subdivision of land. Those fees were collected at the time of the approval of the final
map. Pursuant to Section 66483 ofthe Subdivision Map Act fees may be levied upon development only
insofar as they are fairly apportioned within the fee area on the basis ofbenefits conferred or on the need
for such facilities by the proposed subdivision and development of other property within such fee area.
Since some of the recommended facilities serve previously developed areas, their cost could not be fully
recouped through the 1980 Master Drainage Plan PLDA fees. This method of assessment placed the full
burden of hnding needed facilities on the subdivider and allowed non subdivision developers to escape
any obligationto paytheir fair share ofneeded drainagefacilities. Thismethod offee collectionhas resulted
in a shortfall of funds required to build the recommended facilities and thereby delayed construction or
necessitated use of alternate funding sources primarily &om General Fund Revenue.
The Master Plan report recommends that PLDA fees be levied against all new developments within the
City. It hrtherrecommends that PLDAfees be leviedagainst redevelopment projects and remodel building
permits. For building remodels thePLDA fee will be assessed wheneverthe building footprint is increased
by 50% or greater. Such development projects can be found to derive benefit i+om the construction of
needed drainage facilities for the control of storm water flooding or the preservation and enhancement of
the quality of storm water entering the receiving waters of the City. Authority for the levying ofPLDA
fees on non subdivided developments is contained within the provisions ofAB 1600 (Chapter 5 to Division
1 of Title 7 of the Government Code). All drainage area fees are to be paid at the time ofbuildmg permit
issuance or prior to 6nal map approval, whichever comes first. Construction of PLDA facilities and
administration of fee credits will continue to be secured prior to final map approval.
The Master Plan report also recommends a change in the manner in which fees are computed for various
land use types. The existing PLDA fees are computed basedupon property acreage regardless ofland use.
Low density residentially zoned property is charged the same fee on an acreage basis as high density
residential, industrial or commercially zoned property. However, the storm water runoff rate for different
Master Drinags and Storm Water Qualiw Management Ran Chsptsr 1 Catisbad. California. March 1994 Pap. 3
land uses are signScantly different from one another. Therefore, this report recommends adoption of a
varied rate structure in line with average runoff coefficients widely accepted within the Engineering
profession. This will result in higher fees for high density residential, commercial and industrial projects
in recognition ofthe greaterstormwater contribution made by thesetypeuses. Within the Central Business
District, this fee structure will help generate the funds required to construct badly needed facilities in the
downtown area.
An analysis ofthe Land Use maps ofthe City and the aerial photography prepared for this report indicates
approximately 9,2 15 acres of developable land remain in the City exclusive of General Plan designated
open space and constrained lands. Based upon a review of past records, this report projects 20% of the
existing developed properties in the City will remodel or redevelop prior to build out, resulting in an
additional 1,386 acres of property within the City which will be subject to PLDA fees.
The fees proposed in this report were prepared &om the best available records concerning existing and
future land uses and were detumined using a formula which takes into consideration drainage runoff
factors, the various land use types and, existing and fiture development needs. The proposed fee program
excludes all governmental and public school lands, major transportation corridors, and all constrained land
as defined in Chapter21.53.230 ofthe Carlsbad Municipal Code. The proposedfee program provides for
direct fee credits to offset the cost of developer constructed Master Drainage Plan improvements and also
providesfor reimbursement should the fee credit exceed the developers fee obligation. Under the proposed
fee program, new development will pay only for impacts created by such new development. The cost to
mitigate existing deficient facilities will be paid through a combination of drainage area fees charged to
redevelopment and remodel projects, previously collected drainage fee revenues and other City finding
sources. Considering the above, the overall program should easily meet or exceed thevarious requirements
established by State Law for implementation of a facility fee program.
c. Recommendattons
The following is a summary of the recommendations made in this Master Plan report:
1. Adopt this report titledMaster Drainage and Storm Water Quality Management Plan prepared
in March of 1994 in replacement for the previous Master Drainage Plan prepared in June of 1980.
2. Consolidate the existing thirteen Planned Local Drainage fee areas together with the former
Zone 1 Flood Control District into four new Planned Local Drainage Fee Areas coincidmg with
the four major drainage basins in the City as shown on Figure 4-2 on page 32.
3. Make findings that there are no surplus funds in the existing Planned Local Drainage Area
accounts and transfer the current fund account balances into the corresponding account for the
new Planned Local Drainage Fee Area.
4. Make findings that the future drainage facilities identified in the Master Plan report are required
for the proper development of the City, that the facility costs included in the report are fair and
accurate, and that the proposed fees have been fairly apportioned either on the basis of benefits
Chapter 1
Paas 4
Master Drainage and Storm Water Quality Managnmnt Ran
Cadsbad. California. March 1994
conferred on property proposed for development or on the need for such facilities created by the
proposed development and the development of other property within the Planned Local Drainage
Fee Area.
5. Adopt the following fees for the four proposed Planned Local Drainage Areas:
Planned Local Drainage
Area (PLDA)
A
PLDA Fee* PLDA Fee*
Runoff Runoff
($/Acre) ($/Acre)
$1.564 $2,560
For Areas of Low For Areas of High
0
C
$3,362 $5,502
$2,514 $4,114
*See Table 4-3 for Land Use zones included within low and high runoff areas.
D
6. Expand the Planned Local Drainage Area Fee structure to require imposition of the fee to all
non subdivision developments including commercial, industrial and residential remodels which
increase the building footprint a minimum of 50% over the existing structure. Require payment
of the new fees at time of building permit issuance for those developments.
7. Exclude constrained lands from inclusion in the fee program,
$34 $56
8. Maintain the existing fee credit and reimbursement provisions of the existing fee program.
9. Revise existing City Codes and adopt appropriate resolutions to establish a revised drainage
facility fee in accordance with recommendations 1 through 8 listed above.
10. Adopt the sediment and water quality policies included within the report and continue with
the implementation of the water quality control program as required pursuant to the National
Pollutant Discharge Elimination System permit requirements.
Master Drainage and Stom Water Quality Management Plan
Carlsbad. California. March 1994 Chaptar 1
Page 5
Mrter Dranaga and Storm Water Quality Managernem Plan
Carlsbd. California. March 1994 Chapter 1
Page 6
A. PlarmingAreaBoundaries
In 1952theCityofCarlsbadincorporatedwithapopulationof5,000 andanareaof4,781 acres. TheCity
grew slowly at first at a rate of 490 to 850 per year until 1975. Since 1975 the growth rate has doubled
and the 1990 population is 63,126, according to 1990 U.S. Census data.
The City of Carlsbad has annexed all properties with its sphere of intluence covering approximately 39
square miles. The City is bounded on the north by the City of Oceanside. On the east the City is bounded
by the Cities of Vista, San Marcos, and the County of San Diego. To the South the City borders with
Enchitas and a small portion of San Diego County. And finally, Carlsbad has the Pacific Ocean to the
west.
B. F’hydcalE rrpironment
-y Phvsi T h
Carlsbad is a very diverse. city with steep hills to coastal areas. As a result, there are a wide variety of
drainage conditions. New orthophoto mapping was produced withcontours extendingapproximately 200
feet beyond the sphere of influence. This study defined drainage basins up to and beyond this boundary.
San Diego County 1”=200’ mapping was used for supplemental topographic information.
The four major waterways and their tributary canyons have carved valleys floored with alluvial material.
Thus far, construction in the flood plains has not occurred to the extent that it is cause for concern. AU
major drainage basins with the exception of Encinas Canyon terminate in lagoons.
Geograohv and Soils
Soiltypesrangefromalluvialinthelowerfloodplains toweatheredgraniteonthepeaks. Thepredominant
hydrologic soil type in this study was Group D except in the northwest where Group A predominates.
Groups B & C are also represented.’ Soil types are described in Chapter 4.
’ USDA, Soil Conservation SeMce, etal., Soil Sunw. San Dieco Area. California; 1973.
Master Drainage and Storm Watar Quality Management Plan
Carisbad. California, March 1994
Chapter 2
Page 7
Seismicity
Southern California is a seismically active area. An earthquake offshore ofNorth County registered 5.3
Richter Magnitude in July 1986. Active faults in the area include the Elsinore Fault located 20 miles
northeast of Carlsbad and the Rose Canyon Fault located 10 miles west of the City.
Environmental
Drainage basins were characterized by perennial and intermittent stream beds. These stream beds are the
focal point of a sensitive network of riparian corridors. Within the lower portions of the basins, the
drainage channel spreads out to form somewhat narrow flood plains characterized by dense willow and
riparian plant growth and meandering stream channels. These areas generally act as natural siitation
control. At the end of each major drainage basin, with the exception ofEncinas Canyon, is a lagoon which
supports a delicate but rich variety of flora and fauna. It is a stated goal ofthe city to protect and enhance
where possible all riparian and lagoon habitats.
Hydrologic Features
The City ofcarlsbad is divided into four distinct watersheds. Listed below are those basins, starting &om
the north.
a. Buena Vita Creek - “Buena Vista Creek drains an area of 19 square miles. The drainage area is long
and narrow with a distance ofabout 9 miles fiom the Pacific Ocean to its highest peak of 1,671 feet (MSL)
inthe SanMarcosMountainsand awidthofabout2miles. Runofffiomseveraltributariesquicklycombme
into onemainimproved channelwithintheCityoWista. Flowisgenerallyinasouthwestdir~onthrough
the City of Vista. As it leaves the City of Vista, flow becomes more westward and slopes become more
gentle, dischargingintoBuenaVktaLagoonabout3 milesdownstream. BuenaVistalagoonisamanmade
lake with a weir structure at the ocean outlet controlling the discharge. Stream flow eventually enters the
Pacific Ocean some 1.4 miles farther downstream der being temporarily delayed by the considerable
storage volume ofthe lagoon. The stream gradients range fiom 68 feet per’mile in the upper reaches to
32 feet per mile in the lower reaches of the basin. The average gradient within the reach studied is 39 feet
per mile”.2
b. Agua Hedionda Creek - “AguaHedionda Creek and a major tributary, Bum Creek, drain an area
of 29 square miles. Agua Hedionda Creek originates in the hills south of the San Marcos Mountains and
flows in a general southwest direction, confluencing with Buena Creek about 3 miles downstream. From
the confluence, it flows generally westward about 6 miles and enters Agua Hedionda Lagoon, fiom which
it discharges into the Pacific Ocean some 2 miles hrther downstream. The stream gradients along Agua
Hedionda Leek range fiom about 43 feet per mile in the upper reaches of the study area to about 35 feet
per mile in the lower reaches approaching the lagoon. There is an extremely steep canyon reach between
mile 5.2 and mile 6.0 along Agua Hedionda Creek which is called Los Monos Canyon. Stream gradients
in this reach average 180 feet per mile. Buena Creek, with a drainage area of about 6 square miles,
originates in the San Marcos Mountains and flows about 5 miles in a southerly direction before it
confluences with Agua Hedionda Creek. The stream gradient ofBuena Creek through the study reach
is about 5 1 feet per mile”.3
’ Army Corps &Engineers, LAX Angdes Dha, Buena Vista Creek, July 1973. ’ Army Corps of Engineers, Los Angela Distria, Am Hedionda Creek, July 1973.
Chapter 2
Pago a
~~~
Master Drainage and Storm Water (ludity Management Plan
Carlsbad. Cslifornia. March 1994
c. Enciner Creek - Encinas Creek drains an area of 3.9 square miles. This basin originates 3,000 feet
East of El Camino Real and drains westerly approximately 22,000 feet to the Pacific Ocean. The drainage
course generally parallels Palomar Airport Road along an alignment just south ofthis roadway. The entire
drainage area ranges in elevation 6om sea level to slightly over 440 feet.
d. Batiquitos Lagoon Watershed - TheBatiquitosLagoonwatershed isdividedintotwo majordrainage
basins known as the San Marcos Creek watershed and the Encinitas Creek watershed. San Marcos Creek
originates in the coastal range of mountains north and east of San Marcos and empties into the Batiquitos
Lagoon about 2.6 miles east of the Pacific Ocean. Encinitas Creek, a major tributary, originates in the
mountains southwest of San Marcos and joins San Marcos Creek at the upstream end of Batiquitos
Lagoon. The entire drainage area totals 46 square miles and ranges in elevation 60m sea level to slightly
over 1700 feet in the Merriam Mountain range.
“The stream gradient ranges 6om an average of 10 feet per mile near the mouth to about 600 feet per mile
in headwaters. San Marcos creek has a small and not well defined channel upstream 60m Lake San
Marws. Below that point, the channel is well defined, steep, and rocky to the La Costa development after
whichitbecomessmallandnotwelldefinedagaintoBatiquitosLagoon. The floodplainisbroadupstream
6om Lake San Marcos. From Lake San Marcos Dam to the La Costa development, there is virtually no
flood plain due to the steep, well defined channel. Through the La Costa development to the Batiquitos
Lagoon,thefloodplainis againbroad. Duringlargefloods, flowsexceedthechannelcapacityand inundate
parts of the broad flood plain.”
“Batiquitos Lagoon extends 6om the downstream limit of San Marcos Creek, namely the Pacific Ocean,
as far as El Camino Real Road, some 2.6 miles upstream. It comprises about 600 acres of area and would
provide considerable storage during large floods”.‘
C. Landuse
1. Existing
Existing development in the City is located mainly in the northwest older portion and in the southeast La
Costa area. Existing high-density residential development is located along the coast and at various places
in La Costa. Existing commercial development is centered in the older downtown area in the northwest
quadrant, along Avenida Encinas, and along Palomar Airport Road. There are still large agricultural areas
located in the City. Finally, existing low and medium-density residential development comprise the
majority of the land use in the City.
2. Future
Proposed land use in the City of Carlsbad is varied. The choice of future drainage facilities is dependant
upon future land use designations as determined by the 1987 Citv of Carlsbad General Plan. According
to the 1987 GeneralPlanMap most oftheundeveloped land iszonedfor lowto medium-density residential
land uses. These areas are located in the northeast and southwest portions of the City. Large planned
industrial areas are located around Palomar Airport.
‘ Army Corps of Engineers, Los Angels Did% San Mms Creek, April 1971.
Master Drainage and Storm Water Quality Management Plan Carlsbad. California. March 1994 Chapter 2
Pago 9
Open space zoning is located dong Agua Hedionda, Buena Vtsta, and Batiquitos Lagoons. There is also
a strip of open space running north-south fiom La Costa Avenue to north ofFaraday Avenue. The open
space generally follows the tributary canyons.
D. DesignSensiMtles
Drainage Facilities have been proposed in accordance with the land use constraints of the 1987 Citv pf
Carlsbad General Plm. Underground storm drainlines or concrete channels havegenerally been proposed
in areas slated for fiture development. When such lines empty into canyons expected to remain
undeveloped, enhanced natural channels consisting of drop structures are proposed to decrease erosive
drainage discharge velocities (considered to be above six feet per second). When erosive drainage
discharge velocities occur in open space mned areas, the cost of potential remedial work was estimated.
Chapter 2
Pago 10
~ ~~
Maator Drainage and Storm Water Oudity Management Flan
Caflsbd. California. March 1994
CHAPfER3
METHODOLOGY
A. SkdYApprOach
The approach of this project was to utilize previous hydrology studies for the major water courses and
to analyze m%utary areas where storm drain deficiencies occur. Storm drain facilities are recommended
where existing faciities are inadequate or where projected development will require drainage facilities.
B. Hydrologic Design Criteria
The design criteria, as found in the County of San Diego Department of Public Works Flood Control
Division Hydrology Manual, specifies the design runoff conditions Within the San Diego County Flood
Control District will be based on the 100 year storm frequency as follows:
1. Design for areas over 1 square mile will be based on the 100 year frequency storm
2. For areas under 1 square mile -
a) The storm drain system shall be designed so that the combination of storm drain system capacity and
overtlowbothinsideandoutsidetheright ofway will beabletocarrythe 100yearfrequencystorwithout
damaging adjacent existing buildings or potential building sites.
b) The storm drain system shall be designed so that the combmtion of storm drain system capacity and
allowable street overflow will be able to carry the 50 year frequency storm within the street right-of-way.
c) Where a storm drain is required under headings 1 or 2 above, then as a minimum, the storm drain shall
be designed to carry the 10 year frequency storm.
3. Sump areas are to be designed for a sump capacity or outfall of a 100 year frequency storm.
For this study, existing drainage systems were analyzed with respect to the above criteria and
recommendations made accordingly. In undeveloped areas, where future street alignments and grades
are unknown, the recommended storm drain lines are sized for 100 year flow capacity, based on the grades
of existing flowlines. However, when these area are developed the drainage system may actually carry
the 10 year storm underground, the 50 year storm to top of curb, and the 100 year storm within the street
right-of-way. Drains at sumps should convey 100 year storm flows.
The design flows were computed based on the following assumptions and data:
1. Ground coverwasderivedfromtheSoilConservationService 1969surveymapsupdatedwithultimate
development data corresponding to the 1000 scale city of Carlsbad General Plan Map dated April 1987
and future land use densities projected in the City’s Growth Management Program.
Master Drainage and Storm Water Quality Management Wan
Carlsbad. California. March 1994
Chapter 3
Page 11
2. Hydrologic soil groups were determined firom the 2000 de soil group maps prepared by the Soil
Conservation Service in 1969. Soil types were segregated into groups as a bdon of their probabie
hiltration capacity. The group designations include:
Group A - LOW Runoff Potential:
Soils having high Mtration rates even when thoroughly wetted, consisting chiefly of deep, well to
excessively drained sand andor gravel. These soils have ahigh rate ofwater transmission and would result
in a low runoff potential.
Group B - Moderate Runoff Potential:
Soils having moderate inflitration rates when thoroughly wetted, consisting chiefly of moderately deep
to deep, moderately well to well drained soils with moderately fine to moderately coarse textures. These
soils have a moderate rate of water transmission.
Group c - High Runoff Potential:
Soils having slow infiltration rateswhen thoroughly wetted, consisting chidy of( 1) soils with a layer that
impedes the downward movement ofwater, or (2) soils with moderately he to he texture and a slow
infiltration rate. These soils have a slow rate of water transmission.
Group D - Very High Runoff Potential:
Soils having very slow infiltration rates when thoroughly wetted, consisting chiefly of (1) clay soils with
a high swelling potential; (2) soils with a high permanent water table; (3) soils with clay pan or clay layer
at or near the surface; and (4) shallow soils over nearly impervious materials. These soils have a very slow
rate of water transmission.
Chapter 3
pago 12 Master Drainage end Storm Water Quality Managemant Plan
Caflsbad. California. March 1994
3. The following Manning roughness and rational method runoff coefficients were used:
PIPES
Corrugated Metal Pipe
"U"
0.024
Reinforced Concrete Pipe 0.012 II
Asbestos Concrete Pipe
OPEN CHANNELS
Revetment
Concrete lined
II Cast in Place Concrete Pipe 1 0.015
0.01 1
Wnl.
0.040
0.015
Natural Grass
Reinforced Concrete Box Culverts
0.035
0.01 5
TABLE 3-1
Master Drainage and Storm Water Qualin, Management Plan
Carlsbad, California. March 1994 Chapter 3
Page 13
Rational Method Runoff Coefficients
Coefficient C
Single Family
Multi Units
MediumRowMedium density
HiQh density
MediumHiQh density I Mobile Homes
.50
.50
.55
.40
.ao
.so
.55
.70
.65
.45
.a5
.95
Commercial. Non-residential
Rural
Industrial, Governmental, 11 lndu*fial I public Utilities
Low density, Open Space
-
.40 -
.45 -
.45 -
.30
- -
.70
- -
.ao
.45 -
.50 -
.50
.35 - -
.75
- -
.a5
TABLE 3-2
4. The 100 year 6-hour and 24hour precipitation values were taken from the County of San Diego
Department of Public Works Flood Control Division Hydrology Manual, Section II-A
5. Rainfall intensities for the Rational Method hydrology computations were taken Eom the County of
San Diego Department of Public Works Flood Control Division Hydrology Manual, Appendix XI.
6. Watershed boundaries and grades for proposed storm drains were derived fiom 400 scale orthophoto
maps with 5 foot contours produced photographically from maps prepared by Rick Engineering,
Incorporated, San Diego, California.
7. A number of major creeks have been identified in the City of Carlsbad. Previous hydrologic studies
conducted by Federal, County and privateinstitutions have established 100 year peak flows forthese major
watercourses. Table 3-3 lists the studies available to the Master Drainage Plan Study as follows:
Chapter 3
Page 14 Master Drainage and Storm Water Quality Management Plan Carlabad. California. March 1994
PREYIOUS STUDIES
Encinitas Creek
STREAM I sI!+!QY I Al!I!uR
Watershed HEC-I Model
Analysis Hydrology Rick Engineering
Report August 1988
Watershed Sediment
September 1985
June Applegate
Associates Buena Vista Creek Control Plan
San Marcos Creek
Flood Plain Information
July 1973
Special Flood Plain
Delineation Study Nolte & Associates
Februaw 1978
Corps of Engineers
East Branch of San
Julv 1988
Marcos Creek Boyle Engineering
FEMA I Flood Insurance Study I Auoust 1986
Eocinitas Creek
I ~-~~~ ~~~ I
Corps of Engineers Flood Plain Information
July 1973 Agw Hedionda Creek
San Marcos Creek
Flood Control Imp. Willdan Associates Roiect August 1988
Drainage Study for
Encinitas Creek Dr. Howard H. Chana
Special Flood Plain
Delineation Study Nolte & Associates
Februaw 1978
County of San Diego I Aew Hedionda Creek. Hydrology Report
December 1976 Calavera Lake Inflow
and Outflow I I
San Marcos Creek ' April 1971 corps of Engineers Flood Plain Information
Comprehensive Plan
Zone 1 San Diego Creek' County Flood Control
District
Koebig, Inc. Encinitas Creek
I July 1976 I
Rick Engineering Master Drainage Plan
September 1988 I Poutnay & Associates.
Inc.
Hydraulic and
Encinas Creek Hydrologic Study
September 1987
Northeastern Carlsbad
Agua Hedionda Creek Hydrologic Study Dr. Howard H. Chang
Julv 1989
- May 1991
TABLE 3-3
Master Drainage and Storm Water Clualiry Management Plan
Carlsbd. California. March 1994 Chapter 3
Page 16
The 1OOyearpeakflowsprWiouslyestablished formajorcreeksintheCityofCarlsbadhavebeenanalyzed
for usage in the Master Drainage Plan Study as follows:
a) BUENA VISTA CREEK - The 100 year peak flows have been established in the S~ecial Flood Plain
Delineation Study, Febnmy 1978 by Nolteand Associates. The flow rates to beused inMaster Drainage
Plan are adopted from the 1978 Nolte study.
b) AGUA HEDIONDA CREEK - The 100 year peak flows have been established in the
Plain Delineation Study by Nolte and Associates in February 1978.
AHydroloBcal Study was conducted forNortheastern Carlsbad by Dr. Howard H. Chang in July 1989.
The flow rates used in the Master Drainage plan assumed the discharges listed in the Nolte 1978 study
for the reach upstream of the confluence point east of Oak Lake and the results ofthe Chang 1989 study
downstream of the above mentioned point. The flows in the two studies vary by approximately 1Ph.
c) SANMARCOS CREEK - The 100 year peak flow shave been established intheFlood Plainhfomation
&.& April, 1971 by the U.S. Army Corps of Engineers, Los Angeles District. These flow rates have
been adopted by FEMA for the Federal Insurance Study for San Marcos Creek within the City of San
Marcos. Corps of Engineers peak flows and inundation limits for the 100 year flow have also been used
without modification for the determidon of adequacy of existing structures in the Comprehensive Plan
for Flood Control and Drainage - Zone 1, San Diego County Flood Control District by Koebig,
Incorporated in July 1976.
A hydrologic analysis by Boyle Engineering Corporation in July 1988 on the east branch of San Marcos
Creek generally confirmed the U.S. Army Corps ofEngineers flow rates.
Results of another hydrologic analysis by Wddan Associates in August 1988, for the San Marcos Creek
Flood Control Improvement Project on the main branch of San Marcos Creek upstream of Lake San
Marcoq were within 10 to 15 percent ofthose values in the Corps ofEngineers study. The actual design
dischargevaluesutied forthe floodcontrol channel hydraulics, atthe diectionoftheCityofSanMarcos,
were the values from the Corps of Engineers study.
The 100 year flow rates to be used in the Master Drainage Plan for San Marcos Wiu be adopted fromthe
Corps of Engineers study as follows:
At mouth into Pacific Ocean
Upstream from El Camino Real
Flood
5,000 CFS
12,000
13,000 Upstream from Rancho Santa Fe
d) ENCINITAS CREEK - The 100 year peak flows were established by the U. S. Army Corps of
Engineers, Los Angeles District in April 1971. Koebig, Incorporated developed peak flow rates for the
Encinitas Creek basin in the July 1976 Comprehensive Plan for Flood Control and Drainage -Zone 1, San
Chapfer 3
Page 16
Master Drainage and Storm Water Quality Manaoement Plan
Carlabad. California. March 1994
Diego County Flood Control District. In 1980 the County of San Diego conducted a hydrology study of
Encinitas Creek watershed, establishing peak flow rates for the 100 year flood.
A more recent hydrologic study for Encinitas Creek was completed in August 1988 entitled
comuuter model by Rick Engineering as part of the Master Drainage Plan for the Encinitas Creek
Watershed. Rick Engineering’s study was accepted by the City of Carlsbad.
The 100 year flow rates determined for Encinitas Creek as a result of the 1988 Rick Engineering study
are as follows:
At entrance to Batiquitos Lagoon
Downstream of confluence with tributary
north of Olivenhein 4,210
4,560 CFS
Downstream of El Camino Real 3,430
Downstream of Rancho Santa Fe 1,300
The Rick Engineering Study identified deficiencies with the existing drainage structures crossing El
Camino Real and La Costa Boulevard which result in over topping of these roads in storm events.
Mitigation alternatives for resolution of the deficiencies have been proposed in the recently completed
Drainage Studv for Encinitas Creek prepared by Dr. Howard Chang dated May 1991. The proposed
mitigation involves the construction of a major flood water retention facility just west of Rancho Santa
Fe Road (South) and some berming along La Costa Avenue. The mitigation proposal is undergoing
environmental review as part of the Olivenhain Road widening project.
e) ENCINAS CREEK - The 100 year peak flows were established by the Hvdroloav Studv for the
Determination of the Impact From Runoff in Encinas Creek on the Prouosed Improvements to Palomar
Aimort Road by Poutney and Associates in September 1987.
The 100 year flow rates to be used in the Master Drainage Plan for Encinas Creek are results of the 1987
Poutney study as follows:
Upstream from Interstate 5 1,750 CFS
Downstream from Hidden Valley Road
Upstream from Laurel Tree Road
1,560
1,400
Master DreinaQe and Storm Water Quality Management Plan
Carlsbed. California. Maroh 1994 Chapter 3
Page 17
' C. DesignRmoffMethod
The hydrologic analysis utilized for design of facilities recommended in this report is the Rational Method
for watersheds less than 0.5 square miles and the Modified Rational Method by routing sub-watersheds
for watersheds greater than 0.5 square miles and less than 15 square miles.
The Rational Formula is Q, = CIA where:
C$ = The peak discharge in cubic fdsec.*
* 1 Acre ink. = 1.008 cubic fdsec.
C = Runoff CoefEcient (Dimensionless)
I = Rainfall intensity (iicheshour)
A = Tributary drainage area (Acres)
If rainfall is applied at a uniform rate to an impervious area, the runoff attributed to this area would
eventually reach a rate equal to the rate of precipitation. The time required to reach this equilibrium is
termed the time of concentration.
For small impervious areas one may assume that ifprecipitation persists at a dorm rate for at least as
long as the time of concentration the peak discharge wiU equal the precipitation rate.
D. DesignProceQlre
The following procedure wasu sedin calculating quantity ofstorm flow at variouslocations along the route
ofthe proposed storm drains. Wheneverthe term'TvlanuaI'' isused, it refers to the "County of SanDiego
Department of Public Works Flood Control Division Hydrology Manual" dated January 1985. The
general procedure was developed by Los Angeles County Flood Control District and has been modified
herein for use in San Diego County.
1. Onthedrainagemap, dividetherunoffareaintosubareasoffrom5 to 1OOacres. Thesedivisionsshould,
if possible, be based on the topography, soil type, and the land development. The size of the initial area
should be chosen such that the length of travel for the water from the most remote point to the point of
concentration should not exceed 2,000 feet for natural watersheds and 1000 feet for urban areas and be
of a generally uniform slope.
2. Determine the quantity of water for the initial area.
a) Estimate the initial time of concentration. For natural watersheds this can be obtained from Appendix
X-A of the "Manual". Effective slope of natural watersheds may be estimated from Appendix X-B of
the "Manual". For urban areas overland time of flow can be obtained from Appendix X-C of the
"Manual". Enginering judgement should be used for the validity of the computed initial times. A
minimum of 5 minutes should be used for all basins.
Chapter 3
Page 18
Maater Dranage and Storm Water Quality Managamm Plan
Carlabad. Californie. March 1994
b) Determinethetype ofsoilfrom“Hydrologic SoilGroups-Runoflotential” mapsoftheCounty Soils
interpretation study.
c) Determine the ultimate land use from the Carlsbad General Plan.
d) Obtain the runoff coefficient “C” from Table 3-2.
e) Obtainthe local 6-hour precipitationfrom Section II-A“PrecipitationMaps”ofthe“Manual”. Obtain
the local 24-hour precipitation from Section II- A “Precipitation Maps” of the “Manual”.
f) Obtain the intensity (I) from Appendix X “Intensity - Duration Design Chart” of the “Manual”.
g) Calculate the quantity of water (Q) from the “Rational Equation”, Q = CIA.
3. Determine the quantity ofwater for subsequent subareas as follows:
a) Determine the water route from the point of concentration of the previous subarea to the point of
concentration of the subarea in question.
b) Calculatethetimenecessazyforthequantityofwateranivingat thissubareatopassthroughtoitspoint
of concentration by the above route. The physical properties of this route must be considered and the
velocities obtained from the following:
1) Iftraveling in a street the velocity can be figured from Appendix X-D, “Gutter and Roadway Discharge - Velocity Chart” of the “Manual”.
2) Iftraveling in a ditch, pipe or other regular section calculate the velocity from the actual section.
3) Iftraveling in a natural watercourse the velocity can be derived from the approximation ofthe channel
cross section.
c) Measure the length of flow to the point of inflow of the next subarea downstream. From the velocity
compute the time of flow and add this time to the time for the first area to determine a new time of
concentration.
When determining the time of concentration (Tc), the expected future drainage facility and route is used
to determine velocity and travel time (Tt). Wherever junctions occur, or there is a change in slope or
drainage facility, it is necessary to calculate the velocity and travel time for the precedmgreach. The slope
of the Hydraulic grade line is generally assumcd to be parallel to the grade slope.
d) Calculate Q for the second subarea, using the new time of concentration and continue downstream in
Similar fashion until a junction with a lateral drain is reached.
e) Start at the upper end of the lateral and cany its Q down to the junction with the main line.
Master Drainage and Storm Water Quality Management Plan
Carlsbad. California. March 1994 Chapter 3
Page 19
4. Compute the peak Q at each junction. Let Q., T,, I,, corresponding to the tributary areawith the longer
timeofconcentration. LetQb, Tp I, correspond tothetributaryareawiththeshortertimeofconcentration
and Q@ T, correspond to the peak Q and time of concentration when the peak flow occurs.
a) Ifthetributaryareashavethesametimeofconcentration, thetributary Q'sareadded to obtainthePeak
Q. &=Q,+Qb
b) If the ttiiutary areas have different times of concentration, the smaller of the tributary Q's must be
corrected as follows:
1) The usual case is where the tributary area with the longer time of concentration has the larger Q. In
this case, the smaller Q is corrected by a ratio ofthe intensities and added to the larger Q to obtain the peak
Q. The tabling is then continued downstream usig the longer time of concentration.
2) In some cases, the tributary area with the shorter time of concentration has the larger Q. In this case,
the smaller Q is corrected by a ratio of the times of concentration and added to the larger Q to obtain the
peak Q. The tabling is then continued downstream using the shorter time of concentration.
E. ComputerProgram
In this project the Rational Method Hydrology Program version 1.2 by Advanced Engineering Soilware
has been used to compute and design the drainage systems for the different watersheds. The San Diego
County hydrologic design criteria has been incorporated in the software. The program develops anode-
link model of the watershed and in the process estimates the conduit and channel sues needed to
accommodate the design storm peak flow rate. The designer then reviews the hydrologic results as to
acceptability and options whether to proceed with the designor investigate an alternate hydrologic process
in the subject subarea.
With respect to the Urban Area Overland Time of Flow Chart in Appendix X-C of the "Manual" the
computer program has been designed to accurately compute initial flow times for urban areas with slopes
ofup to 2.5%. For slopes steeperthan 3% the estimated initial times start to deviate from theFAA curve;
T,= l.S(l.1 -ClfL)m
[S(lOO)]'"
In such cases the designer manually computes the initial time and run-off and inputs the values into the
computer model.
Chapter 3
Page 20
Master Drainage and Storm Water auality Management Pien
Cwlsbad. California. Maroh 1994
E SedimedaticmBasins
Sedimentation basins have been proposed near where drainage discharges into the four major channels.
Their fimction is to decrease the amount of sit and other fine particulate matter deposited into the three
lagoons and major natural channels. Ifthese sedimentation basins are not at 111 capacity at the time the
design storm occurs, they will also function as storm water detention basins, attenuating discharge into
major channels, thus decreasing channel erosion. However, for Master Drainage Plan purposes, both
existing and proposed sedimentation and detention basins are assumed to be at 111 capacity. Any lines
proposed downstream have been sized accordingly.
sedimentation basin calculations are first approximations only. They are found in the back of the
hydrology calculation volumes for the basin or basin portion in which they om. The method used was
based upon “The Erosion and Sediment Control Handbook”’, The San Diego Hydrology Manual, and
the City of Carlsbad Standards. Basin volume was sized to retain annual sediment load (calculated using
the universal soil loss equation) with a five foot settling depth, exceeding the two foot minimum
recommended.2 Basin surface area was sized using the surface area formula in the following example.3
The settling velocity used was 0.00096 fps.4
In order to lit Citation of lagoons receiving runoff from the City of Carlsbad, the design particle size
used was 0.02mm (medium silt).’ Since basin surface area is inversely proportional to settling velocity,
and settling velocity is directly proportional to particle size, a smaller design particle will result in
sedimentation basins requiring more land. However, the effective length ofparticle trajectory inthe basin
may be increased using baftles, decreasing the surface area required for particle settling. Sedimentation
basins in major channels (such as Buena Vista and Agua Hedionda Creeks) were sized using estimates of
available land only.
The calculation method requires assumptions of areas that will remain natural and areas that will be
subjected to construction activity. These areas have been estimated using the 1987 Carlsbad General Plan
and land use projections (densities) assumed in the City’s Growth Management Program. The universal
soil loss equation also requires the estimation ofpercentages of sand, fine sand, sit and clay. In this study,
these estimates were based upon SCS Soil Survey Documents.6
Special Note: Basin design for the purpose of drainage fee estimation was purposehlly calculated fiom
conservative design criteria. This was done because basin costs may flucuate significantly due to land
values and environmental mitigation requirements. For most basins a particle size approaching fine sand
or 0.074 mmwill be acceptable provided the design allowsfor adequate storagevolume and has protection
against resuspension of settled particles in a 10 year storm.
Erosion and sed^ ’ment Control Handbook Goldman et al., McGraw HiIl, 1986.
a Erosion and Sediment Control Handbook Section 8.2, Goldman et. al., McGraw Hill, 1986. ’ Erosion and Sediment Control Handbook Section 8.2% Goldman et al, ~VcGraw Hill, 1986.
‘Erosion and Sediment Control Handbook Figure 8.12, Goldman et. al, McGraw Hill, 1986.
’Erosion and Sediment Control Handbook Section 8.2~. Goldman et. al., McGraw HiIl, 1986.
Master Dranags and Storm Water Clualitv Management Pten
Carlsbd. California. March 1994
Soil Swev. San Dieeo Area. California; USDA, SCS, et. al., 1973.
Chapter 3
Pogo 21
In the example which follows, variables and formulas used are the following.
The Universal Soil Loss Equation:
Sed. Vol. = Rx K xLS x C XP
where:
R = rainfall erosion index in 100A.tondacre x in/hr.
K = soil erodabiity factor in todacre per unit of R
LS = slope length and steepness factor, dimensionless (see below)
C = vegetative cover factor, dimensionless
P = erosion control practice &or, dimensionless
c and nc refer to developed and undeveloped areas respectively.
LS = r(65.41 x $9 + 4.56 x s
L = slope length in feet
s = slope steepness, dimensionless
m = exponent dependant on slope steepness
0.2 for slopes < 1%,
0.3 for slopes 1% to 3%,
0.4 for slopes 3.5 % to 4.5%,
0.5 for slopes > 5%
+ 0.065](1/72.5)"', where
(s+ 10,000) (s+ 10,000)'"
The Surface Area Formula:
Sur. Area = 1.2 Q,,N, in sf
where:
V, = settling velocity for the design particle, in fps
d = design particle size, in mm
Page references noted in the margins ofthe following calculation example refer to pages in "The ErosiQn
and Sediment Co ntrol Handbo OK'.
EXAMPLE SEDIMENTATION BASIN AFB @ CONC. PT. 209.00
%GRAV %SAM) %F.s. %SILT %CLAY (acres)
209.00 9.93 100.00
m.00 7255 20.00
205.00 36.36 F.00 50.00
203.00 66.57 10.00 45.00 20.00
201 .OO 21.66 80.00 20.00
80.00
45.00
25.00
202.00 29.31 100.00
200.10 250 100.00
TOTAL 238.97
AVERAGE 3.55 40.75 13.46 0.00 4225
Chapter 3
Page 22 Master Drainage and Storm Water Quality Managmnt Plan
Carisbad. California. March 1994
P 8.16
P8.11
P 6.7
P 6.14
P 6.20
P 6.20
P 6.22
P 6.24
P 6.6
P 6.22
P 6.24
P 6.6
P 6.6
P 8.16
P 8.16
p 8.19
Avg Dahs
d
V.
R
K
a
L
m
LS
cc
Pc
AC
Area c
CK
Pnc
Am:
Area K
sed VOl
C
P6-10
Ilo-ava
Qlhva
Sur Area
Sur Area
Vol water
Vol total
109.12 pcf
0.02 m
0.00086 fp8
60.00
0.10
6.93 9c
64oQ.00 fl
0.60
4.86
0.60
0.90
10.94 tonlac-yr
1137.28 ac
0.30
0.90
6.67 tonlac-yr
71.89 ac
1662.38 CY
0.64
1 .EO
0.60 in/hr
38.63 cfa
48286.04 sf
1.11 ama
8941.87 cy (6' depth1
10604.06 cy
Since ideal basin efficiency corresponds to the percentage ofsoil equal to or greaterthanthe design particle
size', an alternate method ofbasin size calculation could be to specify the required basin efficiency. (Fii
to seventy-five percent is recommended by Goldman et. al.) Given a detailed determination of particle
sue eequency, the design particle necessary to achieve the specifled basin efficiency may be determined.
This method is recommended for final design in areas where silt and clay particles constitute a high
percentage of total soil particulates and basin size calculated using a design particle of 0.02mm results in
unreasonably high areas of land required.
Because the surface area required for sedimentation can vary greatly depending upon soil particle sue
distribution, soil composition should be determined by field testing at the time of final design. At that time
more accurate information should be available, and Sedimentation basinsmay be reliably sized for sediment
removal efficiency as dictated by City of Carlsbad design standards.
'Erosion and Sediment Control Handbook: Seaion 8.26, Goldman et. al., McGraw Hill, 1986.
Meatar Drainage and Stonn Watar (lualiw Management Plan Chwtar 3 Cadsbd. California. March 1994 Paas 23
Chapter 3 Mutar Drainow and Storm Watw adiw Mmagumnt PIm
Page 24 Carlsbd. California. Wrch 1994
CmR4
FINANCING
AGeneral
The purpose ofplanned Local Drainage Area (PLDA) fees is to design and construct storm drainage and
storm water quality enhancement facilities. The guidingtheme of apportioning the fees recommended by
this study is fairness. Fee recommendations are based on the concept that development creating the need
for enlarging or adding drainage facilities should bear the primary responsibility for providing the means
to satisfy the need. The study also recognizes worth of storm drain facilities already in place and the value
of the existing facilities to properties proposed to be developed. The study recommends a procedure to
reimburse fee amounts to developers who build Master Plan drainage facilities which meet the
requirements for the use of drainage area fees. This study anticipates a “build-out” condition for the City
per the presently adopted General Plan and land use projections in the City’s Growth Management
Program. The study concludes that there are both specific and general benefits that have and will exist to
all development within the City as the result of well-fhctioning drainage facilities.
The criteria used in determining the fees and requirements established in this report are: . Does it make sense? . Is it fair?
More specifically the following tests were used: . Do the value of the benefits of the drainage facility exceed the cost of constructing it?
Do the benefits kom the drainage project accrue to those who are paying for it? .
These criteria must be aEnnatively satisfied. The Carlsbad City Council must make the preceding findings
to satisfy the mandates of law in establishing the PLD area fees and requirements recommended by this
study. The fees recommended by this study are summarized in Table 4-1.
Mastar Drainapa and Storm Water cluality Managernant Plan
Carlsbad. California, March 1994 Chaptar 4
Page 25
A
0
$1,564 $2.560
$3.362 $5,502
TABLE 4-1
C
D
*See Table 4-3 for Land Use zones included within low and high runoEareas.
$2,514 $4,114
$34 $56
B. SourceofArrthority
The legislation providing authority for, and specifying the methodology of improvement exaction and
establishing fees are found in sections 65800 et seq., 66000 et seq. and 66410 et seq. ofthe Government
Code ofthe State of California. These sections impose numerous restrictions on the establishment and use
of facility fees.
Generally, fees must be reasonable and fairly apportioned within the fee benefit area based upon benefits
conferred to the developing property or on the needs created by the development. Funds collected through
such facility fees must be kept in separate fee area accounts and expended solely for the construction or
reimbursement of specified facilities within the appropriate fee area. In addition, facility fee funds must
be expended or committed within five years oftheir payment, otherwise, they are subject to refund. For
this reason, the study recommends that the City include within its annual Capital Improvement Program
budgetary process a mechanism to budget and/or appropriate the fees collected during the prior year to
the various facilities for which the fees were collected.
c. History
The City of Carlsbad commissioned and approved two previous master drainage plans. The first,
completed in April of 1971 had no provision for drainage fees and recommended that facilities be
constructed by developers, the City, the County or by funds from theFederal Government. The 1971 plan
failed to anticipate the taxpayer revolt that resulted in the passage ofProposition 13 and that has continued
to make the passage of general obligation bonds unlikely. The second plan, completed in June of 1980,
recognized the difficulty of passing bonds and increasing property taxes and established a fee program that
had the levy of Planned Local Drainage Area (PLDA) fees triggered when land was subdivided.
Chapter 4
page 26 Master Drainage end Stonh Water Quality Managernem Plan
Cadsbed. California. March 1994
The fee system established in 1980 was based upon the cost ofneeded facilities divided by the number of
acres within the Planned Local Drainage Area. The resulting fee was charged against subdivided property
on an acreage basis regardless oftype of development proposed. The fee program had several weaknesses
which have been addressed in this proposed Master Plan.
The following list identifies the weaknesses of the existing fee structure together with a discussion on how
the weakness is addressed within the proposed fee program :
1. The 1980 Planned Local Drainage Areas (PLDA) distributed the cost ofdrainage facilities over
properties that were already developed or that were used for schools, parks, streets, heways, utility right-
of-way, open space and other uses that had no new development potential and would never contribute
PLDA fees. This had the effect of inflating the potential developable area thereby reducing the fee
collectionforthePlannedLocalDrainage Areas. The GrovithMiwagement Program developed numerous
land use and constraints maps which have been incorporated into the preparation ofa more rehed analysis
of developable areas within this study.
2. The 1980 PLDA fees were only assessed against property being subdivided under authority of
the SubdivisionMap Act(Section66410et seq. oftheGovenunent Code). Thisgreatlylimitedtheabiity
of the City to collect adequate fees within drainage areas that were relatively built out or had been
previously subdivided. Under the 1980 Master Drainage Plan three Planned Local Drainage Areas had a
zero dollar fee rate. Several other areas were seriously constrained in their abiity to generate adequate
fees to pay for needed facilities.
New state law under AB 1600 (Government Code Section 66000 et seq.) provides the City with added
authority to establish facility fees which may be imposed upon all development and not just subdivisions.
This study recommends the use of AB 1600 to increase the base of development responsible for provision
of needed drainage facilities to include all new development, including subdivisions, and all redevelop-
ment, remodels and building alterations which contribute to the increase of drainage runoff With these
additions, the City will be able to collect fees in an amount approaching eighty five percent of the cost of
the drainage facilities proposed in this Master Plan.
3. Until recently, most drainage master plans, including the City’s 1980 Master Plan, primarily
focused on the quantitative nature of storm water flows and not the qualitative nature. However, Section
402@) of the Water Quality Act of 1987 alters this fundamental perception by mandating an increased
emphasis on the qualitative nature of storm water runoff It is no longer considered acceptable to design
drainage facilities solely to transport water from one place to another. It is now required to include
measures assuring that water quality is maintained or enhanced in some environmentally sound manner
during its transport.
This shiflinemphasisnowrequireslocalagenciesto reviewand considerstormdrainagefacilitiesinamuch
broader context. Whereas the previoushkter Planmainly addressed the issue offlood control ona facility
by facility basis, this study further considersthe overall nature and protection ofthe watershed as a whole.
The importance ofthis new emphasis is reflected in the title change ofthis report study to Carlsbad Master
Drainape and Storm Water Oualitv Management Plan.
Maater Drainage and Storm Water Quality Management flm
Carlsbd. California. March 1994 Chapter 4
Page 17
D. PresentFinandalStatns
1
2
3
4
The Planned Local Drainage Area (PLDA) fee accounts presently contain approximately $1,872,000 in
undesignated funds and $1,220,000 in designated funds. The account balances correspond to ten of the
thirteenPLDA'sestablishedinthe 1980MasterDrainagePlan. ThreeofthePLDA's hadno feeandthus
an account balance of $0.00. It should be noted that there are no outstanding developer reimbursement
obligations within any of the fee areas. There is one outstanding obligation within PLDANo. 7 to repay
monies to the City General Fund in the amount of $185,860 for monies advanced to construct the James
Drive storm drain. Table 4-2 shows the current balances forthe PLDAaccounts together with atabulation
of account expenditures for the previous 10 years. All funds collected to date are needed to construct
facilities identified in both the 1980 Master Drainage Plan and this report. There are no surplus funds
available.
NIA so so NIA NIA WA
NIA so so NIA NIA NIA
35081 0-1 8-70-874 $3,808 $33.128 $968 so $32,160
350-810-18-71-874 $1,686 $35.786 5968 so 534.818
Theestimatedconstru~oncostsforthenewstormdrainagefacilltiesid~tifiedinthereportis42.9 million
dollars. Only about one half of this amount was to be generated through collection of the drainage area
fees under the existing drainage fee program. An additional 5.0 million dollars has been allocated towards
II EXISTING PLDA FEE ACCOUNTS L\s OF FEBRUARY 17.1994 I
11 5 135G810-18-72-8741 52.658 I $72.350 I 510.643 I $0 I $61.707 11
U I
350-810-18-73-874
11 13 1350-810-18-79-874/ $2.858 I so I $0 I so I so II
Chapter 4
Page 28 Maater Drainage and Storm Water Quality Management Plan
Cdsbd. California, Maroh 1994
construction ofMaster Drainage Plan fadties 6om the following funding sources - 4.3 million dollars
in SANDAG Transnet funds, 0.5 million dollars in Redevelopment Tax Increment bond money and 0.2
million dollars 60m the County of San Diego. This leaves the City with an unfunded obligation of
approximately 18 million dollars. This remaining 18 million dollars in unfunded improvements would
presumably be constructed as a condition of development approval or require additional contributions by
the City. As will be seen the revised fee program substantially addresses the existing funding deficiency.
E. Fiaancing Method Alternatives
Several sources of funds were considered to finance the drainage facilities proposed by this plan. The
categories reviewed were:
Development Exactions
Assessment District Proceedings
General Fund Contniutions
Federal and State Funding
Special Benefit District Fees
Development exactions are requirements to construct and/or to pay for faciiities. They are applied to
developments at the time that various types of permits or approvals are sought. This type of requirement
is equitable to the Developer sice the construction or fee is required when the need for the facility is
triggered by the development being proposed. The 1980 Master Storm Drainage Plan incorporated this
approach. With carem attention to the drainage impacts, project specific and cumulative, at the
discretionary approval stage development exactions work well.
Assessment District proceeding sallow facilities to beconstructedwithfundsobtained bythesaleofbonds.
They are typically used by land owners who wish to construct large public works facilities. The City of
Carlsbad has determined that assessment district proceedings should be used only for large projects that
provide facilities which benefit the general population of the City.
GeneralFundmoniesaregeneral fUnd contributionswithdrawn6omtheoperatingfundsoftheCity. Since
the adoption of the 1980 Master Storm Drain Study, General Fund monies have typically been used for
storm drain projects only when reimbursement was expected to offset their use within a short time. In the
present financial climate, this type ofuse for General Fundswill be increasingly difficult to accommodate.
Federal and State appropriations, grants and loans are available at Limited times withvarying requirements
of application procedures, qualification criteria, matching funds, use restrictions and accounting regula-
tions. Ihe lack of reliability in obtaining grants and loans effectively removes them 6om consideration
in any long-term planning. The City should remain poised to take advantage of opportunities to obtain
federal and state funds. It is recommended that any federal and state fUnds be used in areas of the City
that have low development potential, are more densely developed and that have storm drainfaCiiity needs
that are significant. An example of this approach is the City Council approval of43 million dollars 6om
SANDAG Transnet Local Funds to improve drainage of streets in PLDA “A”.
Master Drainage and Storm Water Qudity Management Plan
Cadrbsd. California. March 1994 Chapter 4
Paw 29
Special Benefit Districts are established under Section 54700 et seq. of the Government Code, titled the
Benefit Assessment Act of 1982. The Districts may be formed to provide for the maintenance and
operation costs of drainage, flood control or street lighting. The districts may also impose assessments
to 6nance the cost ofinstallation and improvement of drainage and flood control facilities. The act allows
fees for flood control purposes to be determined onthe basis ofthe propodonate storm water runoff&om
each parcel. A special benefit district would be initiated by the City Council and approved by the
landowners within the proposed district in a simple majority vote. The City presently has one special
benefit district for drainage purposes, the Buena Usta Channd Maintenance District.
F. Finandng Rsunnmada~cma
This report recommends development exaction as the primary source of funding for new storm drainage
facilities. Development exactions would take the form of both payment of fees and construction of
facilities. This method is consistent with past practice and the City’s Growth Management Program.
Historically, the financing of storm drainage facilities has been considered the responsliity of those
wishing to develop their property. This is because the need for new or upgraded facilities can be directly
linked to land development practices. The City’s Growth Management Program recognizes this fact by
inclusion of a facility standard which requires that “Drainage facilities must be provided as required by
the City concurrent with development”.
In general, developers are My responsible forthe construction ofboth onsite and offsite drainage facilities
whicharenecessarytomitigatetheirprojectimpactsandlortoprovideforthe orderlydevelopment oftheir
property. In some cases, it is necessary or desirable to construct facilities which are in excess ofthe need
of a single developer and provide a benefit to the community as a whole. To handle these cases, the City
established, and this report recommendsthe continued use o$ Planned Local Drainage Area (PLDA) fees.
Thefundsgenerated bythecollectionofPLDAfeescanthenbeused bythecityto either construct needed
facilities or to reimburse developers for the construction of facilities.
A total of 42.9 million dollars in recommended future drainage facilities are identified within the Master
Drainage Plan report. Of this amount, approximately 34.3 million dollars in facility costs are directly
attributable to the needs created by new development. The remaining 8.6 million dollars are amiutable
to facility deficiencies created by existing development.
Thefinancingplanpresentedinthisreportrecommendsthat 100%ofthedrainageficilitycostsattriiutable
to new development be financed by developers through payment ofplanned Local Drainage Area fees or
by direct construction of drainage facilities. Ofthe 34.3 million dollars in facility costs attributable to new
development, 1 8.8 million dollars will oe collected in new PLDA fees, 13.7 million dollars will occur &om
direct developer construction of drainage facilities and 1.8 million dollars wiU be applied from previously
collectedPLDAfeerevenues. The 13.7 million dollarsin direct developer constructionoffacilitiesoccurs
in proposed PLDA “D” for reasons discussed below.
The 8.6 million dollars attributable to existing facility deficiencies will be funded through a combiition
of sources as follows: 1.3 million dollars are available from previously collected PLDA fees; 1.6 don
dollars will be generated eom PLDA fees charged against existing developments that redevelop or
Chapter 4
Page 30
Master Drainage and Storm Water Oudiw Ma~ganwnt Plan
Carlebsd. California, March 1994
remodel; 4.3 million dollars in SANDAG Transnet limds and 0.5 million dollars in redevelopment tax
increment bond finds are budgeted in the current Capital Improvement Program; and, 0.2 million dollars
has been contributed by the County of San Diego for drainage improvements adjacent to McClellan
Palomar Airport. The remaining 0.7 million dollars is presently unfunded and will require finding 60m
other non fee sources such as the general fund, federal and state grants, general obligation bonds, and
assessment districts.
It should be noted that the 1.3 million dollars in existing PLDA funds, allocated to mitigate existing
deficient facilities, will in fact be used to mitigate impacts created by the developments which paid the
PLDA fees. Due to funding shortfalls, many of these impacted fadties were deferred until adequate
funding was available. Since the development was allowed to proceed once the fees were paid, these same
facilities are now categorized as wholly or partly deficient under this plan.
The report recommends establishment of four new Planned Local Drainage Areas (PLDA’s) correspond-
ing to the four drainage basins described above. The existing thirteen PLDA’s are to be abolished and any
remaining finds will be transferred into the respective new PLDA With the exception of the PLDA for
basin ‘D’, the fees recommended for each of the PLDA’s are based upon recovery of 100% of the costs
attributable to new development and 20% of the costs attributable to existing development. The 20%
figure was used because it represents the percentage of the existing development base which is estimated
to redevelop or remodel over the life of fee program.
For basin ‘D’, it is recommended that the primary method of Snancing be direct developer construction
as a condition of development approval. The reasons for using this method of financing over a fee based
programareasfollows: 1)Onlyasmallpercentageofthedrainagefadtyneedsinbasin ‘D’ areattriiutable
to existing deficiencies; 2) The facilities are located on undeveloped lands which require their installation
inorderto maketheunderlyingproperty suitable for development; 3) Amajority ofthe facilitiesarelocated
within large master plan developments that have the financial capability to find such facilities without
benefit ofafeeprogram, and, 4)Thefadtiesinthemthemportionofbasin‘D’ areto behanced through
a proposed Community Facilities District currently under formation.
The report does recommend that a small fee be levied on development within basin ‘D’ in order to
reimbursetheCityforcapitalexpensesassociatedwiththe StormWaterTestingandMonitoringprogram.
In addition, it may be necessary to establish additional local benefit assessment districts such as the one
proposed in the southern part of basin ‘D’ to reimburse developers on a facility by facility basis.
The existing drainage fee program requires payment ofPLDA fees only upon the subdivision of land. This
practice was the result of State legislation which only provided authorization for the levy of such fees on
subdivisions. Recent State legislation in the form of- 1600 (Government Code Section 66000 et seq.)
now provides the Citywith the authority to levy such facility fees on all developments that impact theneed
for such public facilities The ability to charge a PLDA fee to all developers eliminates an inherent inequity
with the old fee structure and allows the City the opportunity to collect a greater percentage ofthe fiture
cost of the Master Plan drainage facilities.
This report recommends that any person who constructs or causes to be constructed any building or finals
a subdivision map should pay a PLDA fee as listed in Table 4-1. This requirement would apply to new
construction as well as all remodeling, enlargement or alteration to any building where additional
impermeable surface area is added. For residential remodels, enlargement or alterations it is suggested that
Master Drunage ad Storm Water auahty Management Uan
Carlsbsd. Califorma, March 1994 Chapter 4
Page 31
the fee be required only where the building footprint is expanded by 5Vh or greater over the existing
condition. This arrangement will help prevent the fee fiom exceediig the value ofthe potential benefit to
such projects.
PLDA fees should be levied for all lands subdivided prior to October 16,1980, the effective date for the
1980PLDAfees, and for any projectwhichhasnot previously paid or received credit for payment ofPLDA
fees. Fees would not be charged for projects constructed upon property which have paid or received credit
for PLDA fees prior to the effective date of this fee program and which property is not subject to an
agreement to pay increased PLDA fees pursuant to a condition of project approval. PLDA fees should
be paid by all who increase the drainage burden. The sum of all PLDA fees levied against any one property
should not exceed the total of the fees recommended in this report.
Fees should be computed on the basis of each acre or fraction thereof of the lot or parcel of land on which
the construction is located plus the area equal to one-halfthe width of public and private street fronting
the lot or parcel. Projects located adjacent to arterial stree-ts would compute their fee on the basis of lot
area exclusive of the arterial street plus an area equal to a thirty foot strip of the arterial frontage.
The following types of land uses or ownerships should be exempted from inclusion in the area for fee
computation:
1. Any portion of an arterial street in excess of thirty foot halfwidth.
2. Zoned open space under public ownership.
3. Lands owned by governmental agencies that are used for public purposes.
4. Railroad right of way.
5. Public utility right-of-way when owned by the utility in fee title.
6. Property which paid PLDA fees prior to the effective date of the new fee program and which
is not subject to an agreement to pay for increased drainage area fees pursuant to a condition of
approval.
7. Constrained lands as they are defined in Chapter 21.53.230 ofthe Carlsbad Municipal Code.
G. Planned Local Drainage Areas (€‘IDA’S)
The 1980 Drainage Master Plan diGded the City into thirteen independent PLDA’s for the purpose of fee
collection as shown on Figure 4-1. A large portion of the southern part of the City was not included in
aPLDAbecauseatthe timeitwasincludedwithinZone 1 oftheSanDiego CountyFlood ControlDistrict.
The Zone 1 Flood Control District was dissolved in July of 1985 and the responsibility for flood control
was turned over to each of the respective jurisdictional agencies.
This study recommends consolidation of the existing thirteen PLD Areas and the City portion of the old
Zone 1 Flood Control District into four new PLD Areas. The PLD Areas would correspond to each of
the four major drainage basins within the City as shown on Figure 4-2. The few small areas which drain
to sumps or directly into the oceanwould be included into the basinwhich surrounds them. The four basins
are labeled “A” through “D” in ascending order fkom north to south as follows :
Chaptsr 4
Pags 32
Mastar Drainage and Storm Water Quality Managwmm Plan
Carlabud, California. March 1994
. Buena Vista, PLDA “A” which includes all areas within the City which drain in the Pacific
Ocean via Buena Vista Lagoon. . AguaHedionda, PLDA“B which includes all areas within the City which drain into the
Encinas Creek, PLDA “C“ which includes all areas within the City which drain into the
Pacific Ocean via Agua Hedionda Lagoon. .
Pacific Ocean via Encinas Creek. . San Marms Creek, PLDA “D which includes all areas within the City which drain into
the Pacifk Ocean via Batiquitos Lagoon.
There are several reasons for consolidation of the existing fee areas and incorporation dthe previously
undesignated drainage areas into four Planned Local Drainage Areas. The reasons are as follows:
1. Master drainage facilities provide benefit to the City beyond the benefit provided to property
owners in any one sub-basin. Most of the Master Plan facilities are needed to protect circulation
element roads used by all residents and emergency services. Also Master Plan facilities reduce the
potentialforthespreadofwaterbomediseasewhichimprovestheoverall healthofthe community.
2. Improving water qualitywithin the lagoons provides a general benefit to all Carlsbad residents.
New federal regulations included within Section 402@) of the 1987 amendment to the Water
Quality Act require the City to improve water quality within the City’s lagoons and tributary
creeks. This must be accomplished by balancing the water quality levels of each of the subbasins
throughout the overall lagoon basin. Therefore, advanced construction or increased facilities may
be needed in one basin to make up for deficiencies in another due to a lack of available land or
environmental constraints.
3. Fewer basins are easier to administer and will provide the City greater flexibility in generating
finds necessary to construct needed facilities in a timely manner.
Upon City Council action establishing the four new PLDA’s, it will be necessary to transfer hds fiom
the existing PLDA accounts ts new PLDA accounts. To assure that the collected hnds are used for the
same purpose for which they were collected, the existing finds should be transferred to the respective
account for the new PLDA which encompasses the old existing PLDA as follows:
Existing PLDA Proposed PLDA
1,3,4,5,6 A
2,7,8,9,10,12,13 B
11 C
None D
Master Drainage and Storm Water Quality Management Plan
Carlsbad. California. March 1994 Chapter 4
Page 33
PLANNEDL@CAL
DRAINAGEFEEAREAS
Master Drainage and Storm Water Quality Managamem Plan
Carlsbad. California. March 1994
Chapter 4
Page 35
In determining fee amounts the primary consideration is to effectively and fairly apportion fees in relation
to the development’s demand on required drainage facilities. In the 1980 Master Plan this was
accomplished by simply dividing the total cost of needed drainage facilities by the total number of acres
ofremaining developableland. Though easy to understand and to calculate, the inherent problemwith this
method is that it assumes the drainage burden is uniform for all land use types which is certainly not the
case. Drainage runoff is directly related to the permeability or absorption characteristics of the land upon
which the rainfall occurs. Permeability is measured by a value known as the “runoff coefficient” and can
be statistically related to land use. The values ofvarious runoff coefficients for different soil types and land
uses is shown on Table 3-2. They range from a low of .30 for Open Space and rural areas to high of .95
for industrial lots.
To simplifythe fee structure, this studygroupedlandusesintothreegend categories. Theseincludeland
with high runoff potential, land with low runoff potential and land that is non developable or which is
governmentally owned. The non-developabldgovernmentally owned category was excluded from the fee
analysis. Table 4-3 shows the breakdown of the three groups by City land use designation. An average
runoff coefficient factor of .55 was assumed for land uses with low runoff potential and .90 for land with
high runoff potential. These figures represent a weighted average of the various land uses and soils types
and take into account the various land constraints identified in the growth management ordinance.
The next step in computing the fee was to determine the total amount of land within each of the four
proposed PLD Areas which would ultimately contribute to the construction of the Master Planned
facilities. Two categories of development were considered - new development and redevelopment/
remodeling. For the first category all undeveloped parcels of land were identified and included within the
fee analysis. To determine the potential acreage which could be redeveloped it was necessary to review
past redevelopmenthemodel rates and to set a time in the fhre at which point all knds would need to
be collected to construct the Master Planned facilities. A time period ofthirty years corresponding to time
for City buildout was selected. Given a review of past records on redevelopment and remodel rates, it was
assumed thit within this time he approximately twenty percent of the existing developments will
remodel and or redevelop. Tables 4-4 through 4-7 list the total amount of developable and redevelopable
acreage for each of the four PLD Areas by runoff potential category.
In determining the amount of low and high runoff areas the formula at the bottom of Tables 44 through
4-7 was used. The formula computes the low and high runoff areas by adding the respective undeveloped
area with 20% ofthe developed area. The resultant sum is then multiplied by 0.85 to account for the area
excluded due to the presence ofconstrained lands. The 85% figure was obtained by averaging the amount
of unconstrained lands reported in the various approved zone plans throughout the City.
Chapter 4
Paue 36 Master Drainage and Storm Water Qualiw Managanwnt Plan
Carlsbad. California. March 1994
GENERAL PLAN
LOW RUNOFF
POTENTIAL GOVERNMENTAL
C
N
4
+ 4
I I I
SBD I I + I n
I Y
TS 4
RC 4
RL
RLM
II
4
4
RM
RMH 4
RH 4
1
+ II
Master Dr~i~ge and Stom Water Qudiw Managamnt Plan
Cerlsbd. California. March 1994 Chapter 4 Pago 37
LAND
Low High Runoff Runoff
Area Area
(Acres) (Acres)
LAND AREA
Low High
Area Area (Acres)
Runoff Runoff Area
(Acres) (Acres)
19.9
I 10.0
I 13.5 6.9
15.0
25.2
3.7
0.8
I 41.2 9.7
398.8
160.0
~ ~~ 541.5
53.4
138.9 60.4
DEVELOPED I UNDEVELOPED I EXCLUDED GENERAL PLAN
LAND USE
DESIGNATION
E
J
H I 2.4
HC
P 17.4 1
0
PI I I I
8.6 G
U
os 636.0
NRR
TC
RRI
40.1
124.8
RRE
RS
C
N
TS I 24.6 I I 116.8 I
RC
CBD I I I I I 24.0 RL
RLM
RM
RMH
FIU I 18.6 1 I I ....
TOTAL 576.2 I 401.8 I 618.9 1 198.3 1 717.0
4. = (618.9 + 0.2 X 576.2) X 0.85 = 624.0 4 = (198.3 + 0.2 X 401.8) X 0.85 = 236.9
TABLE 4-4
LAND USE ACREAGE TOTALS FOR PLD AREA "A"
Chapter 4
PSQS 38
Master DrainaQe end Stom Watar aUaliry Menagmnt Plan
Carlabad. California. March 1994
RM
RMH
RH
TOTAL
4 = (2791.9 + 0.2 X 1297.8) X 0.85 = 2593.7 &= (1162.8 + 0.2 X 1233.7) X 0.85 = 1198.1
TABLE 4-5
LAND USE ACREAGE TOTALS FOR PLD AREA "B"
Master Drainage and Stom Water Quality Management Plan
Catisbad. California. March 1994 Chapter 4
Page 39
276.0 220.4
105.3 87.4
186.2 22.7
1297.8 1233.7 2791.9 11 62.8 2431.5
PLDA FEE CATEGORY
DEVELOPED UNDEVELOPED EXCLUDED
LAND LAND AREA GENERAL PLAN
LAND USE
DESlGNATlON Low HiQh Low High
Area Area Area Area (Acresl Runoff Runoff Runoff Runoff Area
(Acres) (Acres) (Acres) (Acres)
E
J
H
HC
P
0 17.6
PI 943.1 25.3
G I I I I I 139.7
U 16.2
OS I 153.1
NRR I I I
TC 67.5
RRI
RRE 35.3
RS
C
N 8.1
TS 32.9 22.4
RC 18.0 4.0
RL 19.4
RLM 323.5
RM 178.2 257.6
I RMH I I I I RH
TOTAL I 178.2 I 1074.9 1 600.5 I 351.8 I 376.5
.4d = (600.5 + 0.2 X 178.2) X 0.85 = 540.7 4 = (351.8 + 0.2 X 1074.9) X 0.85 = 481.8
TABLE 4-6
LAND USE ACREAGE TOTALS FOR PLD AREA "C"
Chapter 4
Page 'la Mastar Drainage and Stonn Water Quality M~M~WIOI~~ Plan
Carlsbd, California. March 1994
GENERAL PLAN
LAND USE
DESIGNATION
RM 503.0 982.0
RMH 320.4 21 3.2
RH 65.4 15.0
TOTAL 2874.1 491.0 4261.6 861.6 2439.9
4=(4261.6+0.2 X2874.1)XO.SS =4111.0 4 = (861.6 + 0.2 X491.0) X 0.85 = 515.8
TABLE 4-7 LAND USE ACREAGE TOTALS FOR PLD AREA "D"
Master Drainage and Storm Water (lusrity Manaesment Ran
Cadsbad. California. March 1994 Chapter 4 Pago 41
In establishing the appropriate formula for the determination of the per acre fee for each planned local
drainage area, two basic criteria were utilized. First the ratio of the per acre fee for low and high runoff
areas must equal the ratio ofthe weighted runoff coefficients for the low end high runoffareas as follows:
where FL = per acre fee for low runoff areas
F, = per acre fee for high runoff areas
C, = 0.55 = weighted average runoff coef6cient for areas with low runoff potential
C, = 0.90 = weighted average runoff coefficient for areas with high runoff potential
Secondly, theproductoftheperacrefeeforlowrunoffareasmultipliedbythetotalrmmberofundeveloped
acres with low runoff potential plus the product of the per acre fee for high runoff areas multiplied by the
total number of undeveloped acres with high runoff potential must equal the total recoverable cost of
drainage facilities within each respective planned local drainage area as foUows:
where 4 = number of undeveloped acres with low runoff potential
4, = number of undeveloped acres with high runoff potential
ZS = total recoverable cost of unfunded drainage facilities subject to the fee program
By solving for these two equations a fee fonnula for low and high runoff areas was established as follows:
Th
F, =
F, =
ifvariable
CL Z$
CL4 + C"
- :th 4,kandZSforeachofthefourPLDAre -with the fees recommender.
to be levied on an acreage basis are contained in Table 4-8. For PLD Areas "A", "B" and "C" the value
of XS is the total recoverable cost ofthe facilities as determined in Table 6-7. The value of Z$ for PLDA
"D" represents the recoverable costs for facilities necessary to implement the Storm Water Testing and
Monitoring Program. The remaining facility costs in PLDA "D" will be funded through direct developer
construction of the facilities.
Chapter 4
Paga 42
Muter Drainaga and Storm Water hdity Managamant Ran
Carllbd. California. Marah 1994
The due of the variable CS used in the fee computation formula is an estimate ofthe percentage of total
fdty costs that is permissibly recoverable through the proposed facility impact fee program. Essentially,
the figure represents the cost required to mitigate 20% of the existing facility deficiencies and 100% of
the costs required to mitigate impacts caused by future development less the existing PLDA fee balance
attributable to new development. (See Table 4-8). The 20% figure corresponds with the anticipated
percentage of the existing development base that will be subject to fee payment as redevelopment and
remodelsocar overthekfe ofthe fee program. Amore detailed explanation andanalysisoftherecoverable
facility costs is presented in Chapter 6 of this report.
State law precludes establishment of a faciity fee unless it can be shown to be reasonably related to the
impacts created by the development. The proposed program meets the intent of this law by requiring
existing development to pay their prorata share to mitigate existing deficiencies while new development
is required to pay the fiU costs to mitigate their impacts. The remaining 80% ofthe cost needed to mitigate
existing deficiencies will be funded through previous drainage fee contributions and other City funding
sources
In order to maintain the relevance of the fees to the cost of the storm drain facilities recommended by this
study the fees should be adjusted on an annual basis. This study recommends that the ENR (formerly
Engineering News-Record) Construction Cost Index (CCI) for Los Angeles be used to provide the basis
for PLDA fees adjustment. The fee adjustment should be made in conjunction with the City Budget
approval. Since the Los Angeles CCI is published on a quarterly basis in them it is recommended that
the March value of the CCI be used as a basis for determining fee increases. The January 1994 ENR CCI
for Los Angeles was 549.13 based on the 1967 average = 100. The ENR index is widely accepted in the
construction and engineering professions.
Master Drainage and Storm Water (lualiw Management Plan
Carlsbsd. California. March 1994
Chapter 4
Page 43
w
1
TABLE 4-8
Chapter 4
Page 44
Master Drainage and Storm Water Qusliry Managemant Plan
Carlsbad. Cslifornia. March 1994
I. FeeAcl.tments
This study recommends that an administrative variance procedure be established to allow waiver of
payment of PLDA fees. Requests for relief would be limited to the following circumstances:
1. When portions of the project have slopes greater than 25 percent and less than 40 percent as
defined in Chapter 21.95 CMC one-halfthe fee for those portions may be waived. The criteria for waiver
should be that the slope is undisturbed and has a flourishing cover of native vegetation, that the owner
irrevocably convents with the City or another public agency to maintain the slope as open space and that
the sloped area has not been used to compute more than one-half of an area equal to the sloped area used
to establish the maximum development density of the project.
2. The increment of a project that is replacing a building destroyed by accidental fire or natural
disaster may be considered to be deducted kom the valuation of the project PLDA fee.
3. Structures that will not be in place kom November 16 through April 14 of any year are
considered temporary €or the purposes of this report. Temporary buildings may have the payment of
PLDA fees reimbursed without interest when they have been removed and when the areas under and
appurtenant to them are restored to their natural hydrologic condition. Appurtenant areas include parking
areas, w&s, activity areas and other areas accessory to theuse ofthe building. Structures and appurtenant
areas that have not been or are not removed between any November 16 through April 14 period during
their existence are not eligible for reimbursement of any portion of the PLDA fee.
An application for waiver or refund ofPLDA fees should be submitted in writing by the owner of the land
involved. The request should be accompanied by:
1. Written statement citing the reason(s) why the refund is justified.
2. Proof of ownership of the land should be provided when fees have been previously paid. A
preliminary title report, dated within 30 days ofthe request for refund, that names the requestor as fee title
ownerofthelandwillbesatisfactoryproof. Proofofownership shouldnotberequiredwhenfeesarebeing
waived prior to their payment.
3. The current fee for an administrative variance (may be waived subject to City Engineer
determination).
Master Drainage and Storm Water Qualiw Management Plan Carlsbsd. California. March 1994 Chqmr 4 Paw 45
J. Fee Credits and Reimbursement for Gmstxucted Facilities
A developerwho constructs all or a portion of one or more ofthe drainage facilities identified inthis Master
Plan study may be eligible for reimbursement from funds accumulated through collection of PLDA fees
insofar as the facility cost was included within the fee computation formula. No fee credits or
reimbursements are allowed for facility costs not included in the fee program. The maximum reimburse-
ment is limited to the actual cost ofinstalling the facilities. The form and manner in which reimbursements
aregivendbedeterminedatthetimethedeveloperentersinto areimbursement agreementwiththecity.
AU reimbursement agreements are approved by City Council. Whenever the actual cost of installation of
a drainage facility exceeds the cost estimate in this report adjusted for inflation, a revised fee schedule
should be adopted to ensure that adequate funds are collected to cover the reimbursement payments.
Any request for reimbursement should be made as early as possible (preferably during the planning
approval stage) to ensure adequate lead time for the allocation of available funds for reimbursement.
Fee credits will be given for all developments which construct onsite master planned drainage facilities
up to the maximum amount of PLDA fee paid by the development. Fee credits will be determined at the
time PLDA fees are due and will in all cases be based upon the value ofthe facility as it is estimated in this
report adjusted for inflation unless a revised fee schedule is approved in advance. of the fee payment.
Chapter 4
Page 46
Mastar Drainaga and Storm Water Ouality Menagemem Plan
Carlabad, California. March 1994
C"ER5
STORM WATER QUALITY
"AGEMEN" PROGRAM
At this time, pollutants in storm water discharges arc largely uncontrolled not only in the City of Carlsbad,
but in most cities in the United States. The U.S. Environmental Protection Agency determined that
pollutants in runoff from urban areas and from construction sites are a leading cause of water quality
impairment. In recognition of this problem, recent Federal Legislation was enacted which now requires
that the City of Carlsbad establish a Storm Water Quality Management Program.
The majority of storm water runoff from urban areas and construction sites contain pollutants which find
their way into the surface waters of the United States and are therefore subject to the provisions of the
Clean Water Act (CWA). Studies have shown that many storm drains receive illicit discharges which
include a wide variety ofwastes from sources such as illegal sewage connections and waste dumping of
industrial and automotive by-products. In addition there are numerous"non point" sources ofpollutants
which hd their way into the storm drainage system such as fertilizers, pesticides, grease, oils, automotive
and power plant soot, trash, human and animal excrement, etc. Storm water discharges from industrial
facilities may also contain toxins and other noxious pollutants. In urbanizing areas such 83 Carlsbad and
the surrounding communities, soil erosion and sedimentation caused by construction activities together
with increased runofffrom developed property contribute significantly to the degradation ofsurface water
quality. Removal of these wastes and sediment materials from storm water discharges presents an
opportunity for dramatic improvements in the quality of water found in our local creeks and lagoons.
The Environmental Protection Agency WA) tried a variety of approaches since 1972 to address storm
water based pollutants under the National Pollutant Discharge Elimination System (NPDES). Their past
effort met with little success; therefore, when the Clean Water Act was reauthorized pursuant to the Water
Quality Act of 1987, Section 402(p) to the Clean Water Act was amended to require EPA issuance of
regulations establishing permit application requirements for:
1) storm water discharges associated with large municipal jurisdictions being served by separate
storm drain systems; and,
2) stcim water discharges from any jurisdiction whose storm water discharged into receiving
waters found to be in violation of established water quality objectives.
WithinCarisbadall threelagoons have been foundto beinviolationofestablishedwaterqualityobjectives.
The task of administering the Water Quality Act in California was delegated by the EPA to the Regional
Water Quality Control Boards. In the past, the Regional Boards pursued regulation of non storm water
discharges from discrete "point" sources, such as an industrial or sewer outfall pipes, through issuance
and enforcement ofNational Pollutant Discharge Elimination System (NPDES) permits. These "point"
Master Drainage and Storm Water Quality Management Plan Chapter 5 Carlsbad. California. March 1994 Pago 47
sourceNPDES permitsrequiredtechnologybasedorwaterqualitybasedeffluent limitationsandcontrols
for the reduction and/or elimination of pollutants in discharges to surface waters. Today, the majority of
“point” source discharges have been curtailed or are effectively regulated to protect the beneficial uses
of surface waters.
Duringthepastdecade, agreatdeaIofinformationwasleamedabout“nonpoint”stormwaterdischarges
and urban runoff through the National Urban Runoff Program (”). By monitoring runoff and
receiving waters, NURP and other studies indicate that 40 to 80 percent of pollutants currently found in
our lakes, streams, rivers, and other surface waters are a result of runoff from urban areas. Urban areas
are normally covered with structures and asphalt upon which a variety of pollutants settle or are spilled.
These impermeable surface areas prevent absorption of both water and pollutants into the ground thus
allowing more pollutants and storm water runoff to find their way into the receiving waters. The increased
storm water runoff subsequently results in increased potential for downstream erosion.
Pollutants found in the greatest frequency and concentration are metals (cadmium, copper, lead, zinc),
sediments, oil and grease, and polyaromatic hydrocarbons (combustion products of petroleum). In the
San Diego area, nutrients such as nitrogen and phosphorus fiom fertilizer are also significant pollutants
in estuaries, lagoons, and ephemeral streams. Nutrients are responsible for increased algal blooms with
their subsequent decreases in dissolved oxygen. Most fish kills in the region are probably due to dissolved
oxygen depletion as a consequense of nutrient loading. Organic priority pollutants, such as pesticides and
herbicides, are found at lesser eequencies dependent upon the type of land use found in the basin and
application techniques used by the land owners.
Inaneffort to contro1thedischargeofthese“nonpoht” sourcesofpollutants, theRegionalWataQuality
ControlBoard forthe SanDiego Region, issued asiigleNPDES permit tothe City ofcarlsbad, the County
of San Diego, the S.D. Port District and all other Cities in San Diego County pursuant to Order No. 90-
42 dated July 16,1990. A single permit was issued to all municipalities, the County and the Port District
because it was found by the Regional Board that essentially all surface and ocean waters in San Diego
County fail to meet minimum water quality control objectives. Because water quality management must
be effective throughout the basin and sice established jurisdictional boundaries do not coincide with
drainage basin boundaries, the Regional Board opted to include all agencies within the County under one
permit as co-permittees. Through issuance of the NPDES permit, the Regional Water Quality Control
Board is requiring Carlsbad and other San Diego jurisdictions to develop and implement Storm Water
Quality Management Programs to eliminate and/or reduce storm water pollutants fiom reaching the
streams, lakes, lagoons, bays, ocean and other surface waters within the County.
B. Brief Histmy of Adions Leading to City’s NPDI33 Permit
1. Clean Water Act of 1972 amended theFederalPollution Control& to prohibit “point” source
discharges without a National Pollutant Discharge Elimination System (NPDES) permit.
2. Water Quality Act of 1987 amended the Clean Water Act by addition of Section 402(p) which
established NPDES permit requirements for “non point” source discharges fiom municipally
owned storm drainage systems.
Chapter 5
Page 48
Ma8ter Drai~p. and Storm Water auality MaMg.nwm Plan
Cadsbd. California. hoh 1994
3. On December 7, 1988, EPA published draft regulations governing permit application
requirements. Due to litigation with environmental groups, the regulations were not finalized.
4. CarIsbad City Council on July 10,1990, adopted Resolution No. 90-235 noticing City’s intent
to apply for a NPDES permit pursuant to Order No. 9042 of the San Diego Regional Water
Quality Control Board.
5. The Regional Water Quality Control Board for the San Diego Region issued Order No. 90-
42 on July 16,1990, naming the City of Carlsbad as a co-permittee on a National PoIIutant
Discharge Elimination System (NPDES) permit.
6. The final regulations for NPDES permit requirements promulgated by the Environmental
Protection Agency were published in the Federal Register on November 16, 1990.
7. Carlsbad City Council on July 16,1991, adopts Resolution No. 91228 authorizing Mayor to
sign Implementation Agreement with other co-permittees listed under the NPDES permit.
C. “Early” NPDES Permits
As written, the proposed federal regulations governing storm water discharges are compleq burdensome,
costly, and require tight time schedules for compliance. Seeing the complexity and potential costs
associated with the federal regulations, a number of municipalities in the State, including Carlsbad,
requestedtheirlocalRegionalWaterQualityControlBoardto issue”ear1y” permits(astormwaterpe&t
issued prior to promulgation of the final federal regulations). ‘’Early” permits are exempt from some of
the stricter requirements of the EPA for a period of five years. The intent of issuing “early” permits was
to:
1. Establish reasonable permit conditions and requirements specific to the local agency and its
hydrological characteristics;
2. Allow flexibility and a working relationship between local governments and the permit dter
(Regional Board staff);
3. Establish reasonable time schedules for compliance;
4. Establish area-specific monitoring programs;
5. Allow for prioritizing programs for impacted waters; and
6. Avoid costly and burdensome federal regulations.
Within San Diego County it was determined by the Regional Water Quality Contrc Board (Region;
Board) that all municipalities including Carlsbad togetherwith the County of SanDiego and the SanDiego
Port District were subject to NPDES permitting requirements. In July of 1990 the Regional Board issued
Maatar Drainage and Storm Water aualitv Management Man
Carlsbd, Cdifornia. March 1994 Chapier 5
Page 49
Order Number 9042, titled Waste D ischarne Reauirements for Storm Water and Urban Runoff fiom the
CountvofSanD iefio. the Incorpo rated Cities of San Dieso Co untv. an d The San Dieao Unified Port
District, which mandated Carlsbad‘s participation ss a co-permittee on an “early” NPDES permit.
D.
gram
Elements of Gwlsbad’s Storm Water Quality Management Pro-
The basic elements required to complete the proposed Storm Water Quality Management Program for
Carlsbad are outlined within the text of Order No. 90-42 of the Regional Board. The following is a brief
synopsis of the required elements together with the implementation or submittal dates contained in Order
No. 90-42. Much ofthe inventory work needed to complete the elements was completed by virtue of the
completion of this Master Drainage Plan. The basic elements of the proposed Storm Water Quality
Management Plan for Carlsbad are as follows:
1. Enter into a cooperative ”implementation” agreement with the co-permittees on the NPDES
permit defining the roles and fiscal responsibilities of each party to the agreement.
2. Inventory existing stormwater pollutioncontrol programs, illicit discharge detection programs,
monitoring programs and data, storm water conveyance system maps, land use maps, and existing
laws, ordinances, and codes which provide the City authority to implement and enforce storm
water pollution control measures.
3. Develop and implement a storm water, urban runoff and receiving water monitoring program
to evaluate the type and characteristics of pollutant loading in order to target priority pollutants
and evaluate the efficiency of pollutant control programs.
4. Develop and implement an illicit connectiodiegal discharge detection program to identify and
eliminate non storm water discharges to storm water conveyance systems.
5. Develop a fiscal analysis of the capital and operating expenditures necessary to accomplish the
activities of the proposed Storm Water Quality Management Program.
6. Develop and implement best management practices (BMPs) to control discharges ofpollutants
to and 6om stonn water conveyance systems to the maximum extent practicable (MEP). The
BMP’ s shall address structural and non-structural techniques for the control of pollutants inurban
runoff and storm water discharges 60m industrial, commercial and residential areas. Where
necessary codes, ordinances and standards shall be enacted to ensure implementation of the
program.
7. Inventory and compile data regarding existing programs and data. Prepare report on adequacy
of data relevant to the EPA promulgated requirements and recommend actions necessary to
correct any program deficiencies.
8. Conduct an annual analysis of the effectiveness of the overall storm water pollution control
management program in Carlsbad. If the water quality objectives of the receiving waters are
Chapter 5
peg. 90 Master Drainage and Stonn Water Oualiw Management Plan
Carlsbd. Californle. March 1994
violated asaresult ofsto~water/urbann~harges, thenidentify proposedprograms which
will result in the attainment of the water quality objectives, and a time schedule to implement the
new programs.
E. Testing and MdtmIng of Storm Water and Urban Runoff
A major task necessary to establish the Storm Water Quality Management Program is implementation of
a program for the testing and monitoring of storm water flows. Testing and monitoring is necessary to
determine the type, quantity and characteristic of the pollutants within the various conveyance systems
and within the receiving waters in the City. Testing should be conducted on dry weather flows to detect
illegal dumping or connection of non storm water into the conveyance system, and during storm events
to determine the residual pollutant loads from all non point sources within the drainage basin.
The testing and monitoring program should be coordinated with other cities and agencies having
jurisdiction over the portion of the drainage basins which extend beyond Carlsbad‘s city limits. The faa
that basins cross jurisdictional boundaries was a primary motivation for including all Cities, the County
and the Port District as co-permittees under oneNPDES permit. It has been suggested by RegionalBoard
&that the North County cities and the County of San Diego join together via some form of cooperative
agreement to establish a coordinated testing and monitoring program for the North County drainage
basins. Such cooperation would produce greater consistency in the test data and result in lower costs to
each of the individual cities and the County. As of this report date, the staffs from Carlsbad, other North
County Cities and the County have generally agreed to work together to formulate such a cooperative
arrangement.
In the development of the testing program and the later evaluation of test data it will be necessary to
consider the physical characteristic, ecology and beneficial uses of the receiving waters. As noted
previously in the report, Carlsbad contains four separate and distinct drainage basins. Each of these basins
extend in a general eastward direction through the City and contain perennial or intermittent flowing
streams. Ofthe four basins only one, Encinas Creek, which parallels Palomar Airport Road and discharges
directly into the Pacific Ocean, is located entirely within the Carlsbad city lits. The other three basins
originate outside of Carlsbad and terminate at “lagoons” within Carlsbad prior to discharging into the
Pacific Ocean. In addition to the three “lagoons”, there is afresh water reservoir, known as CalaveraLake.
located along the north fork of Agua Hedionda Creek.
The term lagoon is used parenthetically above because in reality only Agua Hedionda Lagoon is subject
to tidal innuences. Buena Vista Lagoon is a fresh water reservoir created by the installation of a weir
structure near the discharge point at the ocean. Batiquitos Lagoon is a brackish water estuary essentially
closed to tidal influences except during major storm events, at which time the sand and cobble deposits
which block the outlet are washed away. Each ofthe lagoons, their tributary streams, CalaveraLake and
the Pacific Ocean has different capabilities to absorb and handle storm water pollutants. In addition, each
of these bodies ofwater has different beneficial uses as defined in the various water quality control plans
and reports produced by the Regional Board. A listing ofthe beneficial uses is presented in Tables 5-1 and
5-2.
The testing and monitoring program would be conducted on dry weather flows and during storm events.
The dry weather testing is used primarily to detect illicit connections and will be discussed in more detail
in SectionF ofthischapter. Themethodologyfor stormwatertestingshouldbeworked out incooperation
Master Orainaga and Storm Watar cluditv Manapemant Plan
Catisbad. California. March 1994
Chaptar 5
Paga 51
with the other North County co-permittees and must be approved by the Regional Board. The Regional
Board has indicated a willingness to consider a graduated testing program which begins at the receiving
waterand progressesup streamuntiltherearenofUrtherwaterqualityviolations. Giventhelimited amount
of rainfall in the North County the co-permittees may wish to select initial upstream test sites to more
quickly define the extent and nature of the pollutant loading.
The following is a recommended strategy for completing the storm water testing program:
1. Meet with other North County NPDES co-permittees to develop a strategy for storm water
testing, stream flow and rainfall measurement, consultant selection and hiring, cost sharing and
cooperative agreement if necessary.
2. Submit the strategy for storm water testing and monitoring to the Regional Board for approval.
3. Finalize a cooperative agreement with other North County co-permittees and submit for
Council approval.
4. Prepare request for proposals &om consulting firms specializing in water quality testing and
monitoring.
5. Form a committe of co-permittees to review proposals and make recommendation on
consultant selection.
6. Negotiate a contract with the selected consultant for the required testing and monitoring
program. Verify fbndmg sources and prepare an agenda bill for Council approval. Scope of work
should at a minimum include:
A) Research and review of available records regarding previous water quality testing done
within the basins, existing stream gauging stations, rainfall stations, topographic mapping
of the basins, land use mapping, and hydrologic studies.
B) Prepare comprehensive topographic maps delineating each of the basin boundaries
which clearly identify the major hydrologic features such as streams, lined and unlined
channels, major dams and retention structures, lakes and lagoons. Prepare land use overlay
maps at the same scale. The City of Carlsbad has the mapping data recommended by this
item.
C) Analyze the existing data and make recommendations on location of proposed new
stream gauges, rainfall measurement stations, and storm water test sites.
D) Upon City approval, obtain and install the necessary automatic flow samplers, flow
meters, rain gauges and other testing equipment.
E) Provide all technical support necessary to actuate and maintain the automatic samplers
and other test equipment during runoff producing rain storms.
Chapter 5
PaQe 52
Master Drainage and Storm Weer (ludity Managernant Plan
Carlsbed. Cdifornia. March 1994
F) Accomplish the required testing and analysis within laboratories and utilizing test
methods approved by the Regional Board.
G) Reduce and collate the data into report form acceptable to the Regional Board. Dehe
the type ,magnitude (concentration and mass load) and sources of pollutants in the storm
water system. Provide pollutographs or other suitable graphic representations ofthe data.
H) Maintain hII written records of all sampling and testing in accordance with Regional
Board requirements. Provide City with copies of aU reports, test data and field notes.
I) Develop andor utilize a suitable pollutant monitoring program on a P.C. based
computer system for delivery to the City.
J) Evaluate the effectiveness of pollution control measures and compliance with water
quality objectives as established by the Regional Board. Make recommendations on the
need for Mher testing and proposed mitigation programs
7. Council approval of consultant contract.
8. Consultant implementation of testing program.
Mastor Drainaga and Storm Water Qualiry Manapamant Plan
Carlsbd, California. March 1994
Chaptar 5
P6ga 53
H BENEFICIALUSESFORINLANDWATERSOFCARISBAD
BUENAVLWAIACOON
(Icold hsh water habitat
BUENAVLWACREEK
Resavation of rere and endangered spacies
WJ~~R Habitat
AGUA HEDlOMU CREEK
Cold fresh water habitn
llWddlifa habitat
WJdlifO hebitat
BATIQ~tXLACOON
Fmah and bmckieh water habitat
llWildlifa habitat
(/Cold h8h water habitat
IIWildlife habitat
llCold fresh water habitat
IlWiIdlifa habita
TABLE 5-1
Chapter 5
Page 54 Master Drainage and Storm Water Quslity Managamant Plan
Caflsbd. California. March 1994
BENEFICIAL USES FOR MARINE WATERS OF CARLSBAD I
F.
II PACIFICOCEAN ll
SheWih hrvening
TABLE 5-2
Detection of Illicit cOrmecttons and Illegal Mscharges
A m+r focus of-the Regional Water Quality Control Board (Regional Board) and the En%_ xunentd
Protection Agency @PA) has been placed on the detection of illicit connections and illegal discharges of
non storm water waste into storm water conveyance systems. EPA sponsored studies have shown that
severe and widespread contamination problems have resulted fiom these two waste discharge sources.
It is not expected that illicit connections will be a major factor within Carlsbad because ofthe arid climate
and lack of significant natural water flows which can be used to disguise illicit waste streams. However,
the illegal discharge ofwastes into storm conveyance systems does occur with considerable frequency in
Carlsbad.
Sources ofdeLal discharges are numerous and varied. Significant waste contributions originate from gas
stations and other automotive businesses that lack recycling systems, grease and oil separators, and proper
sewer discharge systems. At many of these facilities, surfaces are washed down with degreasing agents
and discharged directly into storm drainage conveyance systems. Another source ofillegal waste discharge
results fromimproperly stored or disposed wastes at commercial and industrial facilities whichare exposed
to rainfall or storm water flows.
Not all illegal discharges originate fiom commercial or industrial uses. Individual residentsfiequently drain
motor home holding tanks, radiator coolants, crankcase and other engine fluids into storm drains or upon
Chapter 5
Page 55
Master Drainage and Storm Water Quality Management Man
Carlebd, California. March 1994
hard SurfaceswhichultimatelyWashintostormdrainS. Inadditionresidentswashout containersor directly
pour unused portions of pesticides, household cleaners, detergents, paints, solvents and other hard3
wastes into storm drains or onto surfaces which drain into storm drains. A recent study conducted in San
Diego indicated that 90% of the residents believed that storm drains flowed directly to the sewer plant.
Carisbad is requiredunder the NPDES permit to develop and implement a program to detect and eliminate
illicit connections to storm drains and illegal discharges of non storm water wastes into storm water
conveyance systems. A primary component of the program is field screening and testing of dry weather
flows at storm drain discharge points for priority pollutants (commonly found pollutants which indicate
illegaldischargemay have occurred). Should anyprioritypollutantsbefound, amoredetailedinvestigation
would be conducted upstream of the test point to determine the source of the discharge.
It is proposed that initial testing be accomplished by an outside consulting h. Continued testing in fbture
years would be conducted by City staffwho would receive training from the consultant. The dry and wet
weather testing programs may be combiied into one contract and conducted by the same consultant;
however, this may not be practicable due to timing constraints and the need to coordinate the wet weather
testing with other agencies
The following is a proposed strategy for a separate program for the detection and elimination of illicit
COM~O~S and illegal discharges:
1. Prepare request for proposal 60m qualified consultants.
2. Review submittals and select consultant.
3. Negotiate a contract for the required testing and detection program. Obtain fUnding source and
prepare an agenda bill for Council approval. Scope of work should at a minimum include;
A) Review of City Master Drainage and Storm Water Quality Management Plan and Land
Use maps to determine appropriate test sites.
B) Field review pipe discharge points and perform appropriate tests in accordance with
Regional Board requirements. Tests should generally be conducted at all discharge points
for pipes 36 inches'in diameter or greater where dry weather flows exist.
C) Mer initial field screening and testing is complete, plot test results on a City map.
Prepare a strategy to conduct &her testing or site visits to determine the source of
pollution. Conduct the necessary secondary testing and field review to determine the
source of the pollutant discharge.
D) Prepare a report which includes maps, field notes, test results and written opinion on
the possible sources of pollutant discharges discovered through the testing and field
inspections.
E) Provide City with appropriate test kits together with field test manuals and train two
or more City staffmembers in appropriate test methods and reporting requirements
Chapter 5
Page 58
Masrer Drainage and Stoim Water (lualiw Managanent Plan
Carlsbad. California. March 1994
4. Once an illicit connection or iuegd discharge has been discovered, City should begin an
abatement process with the owner ofthe property in violation. Abatement should begin by written
notification to the owner of the property upon which the violation exists identifying the violation
together with a request to cease and desist the discharge activity and to begin clean up measures
ifappropriate. For violators with minimally toxic discharges a phased program of abatement may
be considered. Non responsive violators should be referred to City Cound for initiation of
abatement proceedings and possible legal actioa
5. Develop a program of public education on the nature of storm drains and the harmful
environmental effects which can result from the improper use and disposal ofcommon household,
yard and automotive products. Possible suggested elements of the program are as follows:
A) Prepare a public information pamphlet explaining the problem, why it is important to
Carlsbad and suggesting ways individuals can contribute to the solution. The pamphlets
could be mailed to residents or made available at public information counters throughout
the City.
B) Create a public service video on storm water quality issues for showing on local cable
T.V.
C) Develop a student awareness program within the local schools
D) Create public awarenessin storm drains by stenciling water birds, fish, turtles and frogs
on storm drain manhole covers. Such a program was used successfully in a Washington
State community to raise the publics’s level ofunderstanding regarding the consequence
of discharging harmful materials into the storm drain. Stenciling may be accomplished by
students as part of the student awareness program suggested above.
G. Best Management Practices (BMP)
The Water Quality Act requires municipalities to control discharges containing storm water pollutants to
the maximum extent practicable (MEP). Generally it has been held by the Environmental Protection
Agency that MEP means the use ofBest Management Practices (BMP) for the control ofpollutants. This
approachwas chosenin lieu of amore stringent program based on quantitative effluent limitations because
there are no generally accepted effluent limits.
Best Management Practices include implementation of structural and non-structural controls. Structural
controls are physical improvements made to the storm water conveyance system which remove or reduce
storm water pollutant levels. Non-structural controls are programs and practices which tend to eliminate
or reduce pollutants at their source before they enter the storm water conveyance system. Table 5-3 lists
potential structural and non-structural controls which could be utilized in Carlsbad.
Althoughmany ofthe elements ofBMP have beenin usein Carlsbad and other communities formany years,
the concept of an integrated program implementing BMP is new. To prevent propagation ofnumerous
community standards regarding BMP, the State has budgeted hnds for the preparation of a statewide
guidelines manual for Best Management Practices. When this manual becomes available, the City will need
to review the contents and incorporate all or portions of it into the City’s proposed Best Management
Maetor Drainago and Storm Water Quality Managemsnt Plan Chaprer 5 Carisbad. California. March 1994 Pago 57
Practices program. The following is a brief discussion of some of the more important elements of BMP
which will need to be addressed in the proposed BMP manual.
Land Use Restrictions
Land Use restrictions and regulations can play a crucial role in the control of storm water pollutants. It
has generally been found that preservation Of natural streams and drainage courses enhance water quality
by providing a natural filtering m&hanism to remove urban pollutants. Collecting and combining urban
runoff in concrete lined conveyance systems for direct discharge into receiving waters provides little
opportunity for the reduction or control of storm water based pollutants.
Land Use policies which preserve natural water courses or provide ~turali~ed drainage channels are to
be encouraged within the City. Additionally, Open Space policies should be reviewed to coordinate the
needs of storm water pollution management with habitat presemation, aesthetics and other Open Space
needs. Naturalized channels and pollution management basins should be landscaped with native plant
species which balance the needs offire suppression, habitat values, maintenance, aesthetics and pollution
absorption. Appropriate buffer zones should be maintained between lot lines and major storm water
management features to enhance their pollution control value and to reduce potential negative impacts
on adjacent development.
Other Land Use regulations which affkct storm water quality and should be considered when preparing
the BMP manual are : zone code enforcement to eliminate unauthorized uses which may contribute to
pollutant loading; rezoning of property which is incompatible with the preservation ofwater quality; and,
density reductions.
Maintenance and Ouera tion
Good maintenance and operation ofthe storm water conveyance system is an essential component ofBest
Management Practices. This includes the sweeping of streets and parking lots, removal of accumulated
silt and debris kom inlets, pipes, channels and tiltratioddesiltation basins, cleaning ofgrease and oil traps
and, other maintenance hnctions which generally remove or reduce pollutant loads before they can be
discharged to the receiving waters. Carlsbad’s municipally owned storm drainage system is maintained
by the Streets Division of the Utilities and Maintenance Department. Street sweeping activities are
accomplished through private contract with the Oceanside Disposal Company.
Maintenance functions need to be reviewed to assure maximum effectiveness for pollutant removal. Street
sweeping schedules should be accelerated prior to predicted storm events which occur after long dry
periods. Since oil and grease bind to fine particulate materials, new street sweeping equipment which
capture, these fine particles are to be investigated and utilized when practicable. Desiltation basins and
other urban pollutant facilities should be designed to accommodate necessary maintenance activities in
both dry and wet weather.
Maintenance of privately owned storm drainage and pollutant control facilities is also important for the
overall control and reduction of storm water pollurants. Adequate provisions should be included within
the various homeowners associations to properly maintain private facilities and to assure that adequate
hnds are available for maintenance.
Chaptar 5
Page 58
Master Drainage and Storm Water (lualiry Management Plan
Carlsbad. California. March 1994
Private Deve looment Restrictions and Conditions
State laws regarding the conditioning of subdivisions and other land development projects currently
provide the City with sui3icient latitude to restrict andor condition developments to comply with the BMP
Program. In addition, the California Environmental Quality Act (CEQA) provides added authority to
require pollutant mitigation measures together with monitoring programs designed to evaluate the
effectiveness of the installed mitigation. AU new development projects within Carlsbad should be
conditioned to comply with currently established BMP as well as any new BMP established prior to
issuance of the respective building permits.
Construction Sites
Construction activities generate numerous types of pollutants detrimental to water quality such as engine
and diesel oils, hydraulic fluids, paints and solvents, herbicides and, fertilizers; however, the most
significant pollutant originating froomconstruction sitesis soil. In small quantities soil does not impair water
quality or degrade riparian habitat. In fact soil deposition is a natural process vital to the long term survival
of marine and riparian habitats. However, soil loss at construction sites can significantly exceed natural
levels and overwhelm both habitats and drainage facilities located downstream. Excessive sedimentation
can clog vital storm drains, disturb natural stream flows, suffocate bottom dwelling plantsand animals and,
create impediments to boating in the lagoon areas. In the long term, excessive sedimentation can
prematurely impair the vitality of water based habitats as exemplified by the Batiquitos Lagoon.
Carlsbad has exhibited a strong commitment to reduce construction site sedimentationinorderto preserve
its lagoons and riparian habitats. The 1980 Drainage Master Plan included a model erosion control
ordinance which formed the basis ofthe subsequent erosion control program within the City. During the
past eleven years, substantial advancements in erosion control methods and practices have OCCUH~~ and
been incorporated into the City’s Engineering Standards and Inspection Manuals. These erosion control
methods and practices should be reviewed and consolidated into the proposed comprehensive manual of
BMP for the City.
Waste Minimization Collection and Recvcling
A key feature of Best Management Practices is to eliminate the source of environmental pollutants prior
their introduction into the drainage system. To this end, the City and other agencies are being encouraged
by the Regional Board to establish effective programs for the reduction of waste, collection of common
household hazardous wastes and recycling ofmotor oils. The City has implemented many aspects ofthese
programs and is in the process of expanding their role in this regard. Several times a year the City notifies
residents and establishes local collection points for household hazardous wastes. Numerous handouts on
the subject ofwaste collection, reduction and recycling are available at public offices throughout the City.
In the future, the City4 need to expand the circulation ofthe handouts and to establish convenient year
round hazardous waste collection centers within the City.
Comuliance and Enforcement
Presently the only effective enforcement carried out on a regular basis within the City is conducted by the
Engineering Inspection Division with regard to land development and construction activities and, the Fire
Department with regard to hazardous waste storage, disposal and cleanup. Enforcement of Zoning
Master Drainage and Storm Water Quality Management Plan
Carlabad. California. March 1994 Cheptsr 5
Page 59
violations and homeowner association maintenance requirements are carried out ona complaint basis only.
The City does not presently have an effective program to reduce or prevent the illegal dumping and
discharge of prohibited materials ftom sources such as automotive wrecking and repair facilities, gas
stations, industrial facilities, recreational vehicle holding tanks or home mechanics.
No policy, condition, faciity or standard will properly control storm water pollution Without effective
complianceand enforcement. Akey component ofFJestManagementPracticesis to obtainthe cooperation
of individuals, companies, homeowners associations, developers, departments and others in complying
withBest Management Practices. In addition, appropriate City staffmust be assigned and properly trained
to enforce those elements ofsest Management Practices required by Municipal Code, City Standards and
conditions of approval.
The City will need to carefully review the enforcement requirements and staeing levels necessary to
comply with the proposed Best Management Practices program to be submitted to the Regional Board
as part of the NPDES permit.
Chapter 5
Pegs so hbstar Drainage and Storm Watar Quality Managsment Plan Carlsbd. California. March 1994
I1 STRUCITJRAL AND NON-Sl'RlJCITJRAL CONTROLS
S~COntmlc
Filtration Basins
IlDesiltation Basins
Wet Ponds
Grassy SwalesMer Strips
Porous Pavement
Pomus Channel Linings
~
Check Dams
Silt Fences; Hay Bales. Sand Bags. Jute Matting, Hydroseeding and Other Erosion
Control Measures
Channel Ranting and Naturalization
Nowtd Cootroi~
PuMi Education - About use and disposal of household, automotive and yard products - About storm drains discharging to streams and lagoons
Spill prevention and Cleanup Response Programs
Household Hazardous Waste Collection
Crankcase Oil Recycling
Street and Parking Lot Cleaning
Pesticide and Fertilizer Application Reduction Programs 11 Wastxization and Reduction Programs
Storm Drain Inlet and Conveyance System Maintenance and Operation
lmpmved hazardous Waste Storage, 7 ransport and Disposal Programs
Land Use Restrictions - Zone Code Enforcement - Density Reduction - Compatible Zoning - Buffer Areas
TABLE 5-3
Master Drainage end Storm Water Quality Management Plan
Carlabad. Cdifornia. March 1994
Chapter 5
Page 61
H. ProgramCostsandFundjng
The iU cost to implement the Storm Water Quality Management Program is not known at this time;
however, the major capital costs of the program have been estimated and are included in the proposed
drainage fee structure. This includes costs for the proposed sedimentation basins and the monitoring
equipment required to sample dry and wet weather drainage flows. These costs were included in the fee
structure because they represent capital costs to the City and as such may be factored into the Planned
Local Drainage Area fee calculation. Total capital cost figure for the sedimentation basins is $9.2 1 million
dollars and for the test equipment $900,000.00. A more complete breakdown of these cost estimates is
included within Appendix C of this report.
Funding for non-capital elements of the Storm Water Quality Management Program will come from
sourcesotherthanPlannedLocalDrainage Areafees. TheproposedFiscalYear91-92budgetfortheCity
includes $30,000 in General Fund monies for program implementation to be used primarily to bd
consultant contracts to perform testing and monitoring functions. This figure may increase significantly
in future years depending upon the testing requirements imposed by the Regional Board.
In addition to testing and monitoring, General Fund monies will be expended for statftime spent on
program development, &orcement activities and administration. Other program costs such as implemen-
tation of erosion control measures and construction of localized filtration and sedimentation basins will
be funded directly by developers. Ifneeded, low inters loans and grant monies are available fromthe State
Water Resources Control Board for non point source pollution control facilities.
A significant program cost which has received little attention in the past but will increase in importance
as a result of this program is the maintenance and operation of storm drainage facilities. This is especially
true for inlet structures, filtration basins and sedimentation basins. Without proper maintenance,
accumulated silts and debris can reduce the effectiveness ofpollutant control facilities or be washed down
the drainage system and degrade surface andor receiving waters. Presently, drainage maintenance
functions within the City are almost completely bded from General Fund monies. A small portion ofthe
drainage maintenance budget is derived through a special Drainage Maintenance District formed in
cooperation with adjacent property owners for the maintenance of the Buena Vista Creek Channel
between El Camino Real and Jefferson Street.
The City may wish to investigate alternatives to General Fund financing of the drainage maintenance
operations. Alternative financing mechanisms would free Geneml Fund monies for other City uses and
provide a stable source of funds for continued maintenance operations. Two alternative sources of funds
which deserve careful consideration are:
I) To form a Drainage Utility and establish a monthly service charge similar to the charges paid
for water and sewer service; and,
2) To establish a citywide drainage maintenance district and assess maintenance fees similar to
the City’s Street Light and Landscape Maintenance District.
Both alternatives place the financial burden for drainage facility maintenance directly upon the users of
the system. Each alternative requires that a rate structure be established which equitably distributes costs
based upon the demand created by the use of the property. Generally the rate structure would be based
Chapter 5
Page 62 Maeter Drainage and Storm Water Quality Management Ran
Carlsbad. California. March 1994
upon current land use,'acreage and amount ofimpermeable surfacing (usually reflected as an average for
the property's zoning designation). In each caseamechanism to review individual charges upon property
owner appeal would need to be established. The following is a brief discussion of each of the two
alternatives.
pr ' ainaee Maintenance Distriq
The City may form a drainage maintenance district pursuant to the Benefit Assessment Act of 1982
(Government Code Sections 54703 - 54719). A maintenance district formed under this act may include
a few parcels, as in the case of the City's existing Buena Vista Channel Maintenance District, or it may
include all parcels within the City. A maintenance district formed under this Act requires a simple majority
vote of the voters included within the proposed district. Assessments would be collected on the property
owners tax bill in the same manner as the existing Street Light and Landscape Maintenance District. This
methodavoidstheneed to establishanewbiUingmechanismortoincludeadditionalcostsonexistingwater
biilS.
Drainage maintenance districts may impose a benefit assessment to finance maintenance and operation of
the drainage conveyance system, including storm water monitoring, as well as the cost for installation and
improvement of facilities. Given that the proposed Planned Local Drainage Area Fees will finance the
construction of new and upgraded facilities the City would need only to finance the maintenance and
operation costs for the foreseeable future. In later years, replacement costs for aging facilities may be
factored into the assessment.
Drainaee Ut ility
Altqnative bdmg for drainage maintenance and storm water monitoring may be provided through the
formation of a Drainage Utility. ADrainage Utility would function in a similar manner to a water or sewer
utility. A majority vote of the voters within the City would be required to implement a Drainage Utility.
Once formed fees may be imposed to pay for drainage maintenance and operation hctions as well as
installation of new facilities, upgrades or replacement facilities. A disadvantage of this method is that the
City would be required to establish a new billing system or include the fee within the existing water billing
system. Inclusion of the fee on the existing water bills would be impractical given that the City Water
District does not cover the entire City. For areas within the City that are outside the City Water District
boundaries a separate b&g system would still be required.
Master Drainage and Storm Water Quality Management Ann
Carlsbad. California, March 1994 Chapter 5
Pags 63
Chapter 5
PSQS 64
Master Drainage and Storm Water Quality Managanwnt Plan
Carlsbed, California. March 1994
CHApfER 6
In this section, the basis of the unit prices used for the construction cost estimates are developed and
presented. Theseunit prices provide ameans ofbudgeting for proposed improvement projects, comparing
alternative projects and for developing drainage assessment fees for proposed Planned Local Drainage
(PLD) Areas. Except in the case of sedimentation basins, land costs are not included in cost estimates,
since. all right of way containing Master Drainage Plan facilities shall be dedicated to the City.
B. Unitcosts
The unit costs used in this study are presented in the following tables. Sources of information for the
development of these costs include local contractors, material suppliers, data from professional journals
and local municipality bonding estimate costs.
To accommodate the additional costs of field construction contingencies, engineering fees, legal fees and
contract administration costs, an allowance of 38% was added to all calculated construction costs. This
38% represents an estimate of the sum ofthese variables and is included in the costs shown in Tables 6-
1 through 6-4 thereby obtaining the drainage facility totals given in this report.
Construction Contingencies
An allowance for construction contingencies is made for unavoidable uncertainties in the project design.
Items such as conflictswith existing underground utilities and variations in depths of pipelines may increase
construction costs and should be planned for. A contingency allowance of 15% was assumed for this
report.
Engineering Fees
Some ofthe costs included in the engineering of construction projects are special site investigations, field
surveys, preparation of construction plans and specifications, special site investigations, and materials
testing. For this report, engineering fees were assumed to be 10% of the construction costs.
Master Drainage and Storm Water Quality Management Plan
Carlabad. California. March 1994 Chapter 6 Paw 65
The following section presents the construction item cost estimates utilized in the preparation of the
construction costs for the facilities identified in this study.
Future construction costs are expected to change with the fluctuations in the economy. A means to index
the costs to a baseline is required. The most widely referenced construction cost reference is the
Engineering News Record Construction Cost Index (ENR-CCI) which is computed from prices of
constructionmaterialsandlabor. TheENR-CCIisbasedonavalueof 100 in 1913. Theindexhassteadily
increased since 1913, with a current value of 6348.44 for Los Angeles in January, 1993.
Storm Drain Piping
Included in the prices for drainage pipe are excavation, shoring, bedding, pipe installation,
compactionand siteclean-up. Thecostsforpipedi30" through48" assumeameaninstalled depth
of 8 feet. The costs for pipe diameters 60" through 96" assume a mean installed depth of 13 feet All pipe
is assumed as jointed RC.P.
Enhanced Natural Channels
Based upon typical channel sections, the number of two foot high drop structures necessary to achieve
a slope giving a design flow rate less than 6 feet per second was estimated. Using Manning's equation
for channel flow velocity in typical sections, it was noted that for Q > 150 ds, a slope ofless than 0.015
fpf was necessary to achieve velocities of 5 fps. Therefore the number of drop structures in any given
channel was determined by the following formula.
no. of drop structures = L(S-.Ol)
2
where:
L = length of the channel in feet
S = slope of the channel in feetlfoot
The length ofeach drop structure was based upon typical channel sections and associated Q,,values. This
relationship is shown in Table 6-3.
-4 unit cost of $44.00 per lineal foot was based on a two foot high masonry wall with a two foot cutoff
wdandriprapextendmgfivefeetoutfrornthe baseofthewall. Anadditionaltwentypercentwasincluded
in the estimate to cover difficult working conditions and access problems.
Potential Remedial Work
.h estimate of the cost of erosion damage to natural channels in areas zoned open space was made. The
costing procedure for enhanced natural channels was used.
Chapter 6
Page 50 Mastar Drainage and Storm Water (ludity Management Plan Cadsbad. California. March 1994
Open Channels
Concreteorearthenchannelcostestimateswere basedonearthworkexcavationandexportcostsof$5.50
per cubic yard. In the construction of a channel in an area classiied as "rural" the excavation quantity
was reduced by 20% to account for the existing ~tuml channel condition. For channels in river beds or
stream beds, calculated excavation quantity was reduced by 50%. In "undeveloped" areas with no
appreciable existing watercourse, 90% of the calculated excavation quantity was used.
The cost of earthen channels with rip rap along one side was based on a rip rap thickness of3 feet at $5.50
per square foot. The rip rap runs from the top of the channel to 2 feet below the channel bottom.
For both concrete and earthen channels, chain link fence (on both sides of the channel) was estimated at
$25 perlineal foot. Fordchannelsa 12footwidedecomposedgraniteaccessroadwasestimatedat $9.50
per lineal foot of channel. Concrete channel costs include a four inch concrete lining cost of $225 per cubic
yard.
Box Culverts
Box culvert estimated costs are based on earthwork and structural concrete volumes. Earthwork
excavation and subsequent backfill costs were assumed at $7.00 per cubic yard. Excavation and export
costs were assumed at $5.50 per cubic yard. Excavation quantities were based on vertical trench walls
for the lower 5 feet and 1:l side slope to daylight points. The bottom of the trench was assumed to be
2 feet wider than exterior box dimensions. A 15% allowance was added for miscellaneous appurtenances.
Structural concrete costs included bedding, formwork, steelwork and site clean up and were estimated
at $525 per cubic yard. Repaving cost was based on a repaving width equal to the excavation width plus
4 feet. New pavement section was 4 inches of A.C. over 12 inches of aggregate base.
Catch Basins
Unit prices of $7,O40.00 for catch basins assume a 14 foot curb inlet opening and includes an 18 inch by
30footlongRC.P. lateralandaconcretelug-inat themainline. Thenumber ofcatchbasinsfor anygiven
line was based upon the hydrologic flow rate (Q) ofthe area through which the proposed storm drain line
passes. If more than one line passes through a basin, the Q of that basin is apportioned to each line
proportionally by length. A flow rate into each of 0.5 cfs per lineal foot of curb inlet opening is assumed.
Cleanouts
Unit prices for cleanouts assume type 'B'. Spacing for cleanouts for pipe up to 48" diameter will be every
300 feet. For pipes greater than 48" diameter, spacing wiU be wery 500 feet.
Junction Structures
Unit prices for junction structures are based on a modified type D-9 cleanout, $3,750.00 is used for each
junction structure.
Master Drainage and Storm Watar Qudiw Management Plan
Carlsbed. California. March 1994 Chapter 5
Page 67
Sedimentation Basins
A unit price for each sedimentation basin was calculated as a lump sum based on typical design features
shown in Figure 8.1 of “The Erosion and Sediment Control HandbooK”.
The channel (iany) into and out ofthe basin was assumed to be lined with 4“ thick concrete at $520.00
per cubic yard (the City of Carlsbad unit cost for drainage channel concrete). Major creek channels (such
as Buena Vista Creek and Agua Hedionda Creek) were assumed to be 40 feet wide by 20 feet high with
one to one side slopes. At the entrance, 50 lineal feet of lining was used and 75 lineal feet at the outlet.
Smaller channel entrances were assumed to be 20 feet wide by 8 feet high and 30 feet long with one to
one side slopes.
Basin shape was estimated to be eight times as long as wide. As recommended by Goldman et. al., one
batne was estimated for each basin not in a major channel. The batne was estimated to be equal in length
to one halfofthe basinwidth. Its height is that ofthe outlet riser crest. Eight bdes ofthe same size were
estimated for major channels in order to increase the effective basin area in these locations where available
land is the factor limiting sediment removal eliiciency. The Carlsbad unit price of $550 per cubic yard for
a cast in place wall 8 inches thick (12 inches thick for major channels) was used for these batnes.
The City of Carlsbad grading unit price ($3.50 per cubic yard of embankment or excavation) was used
to calculate the earthwork cost for each basin. This volume was estimated to be approximately three
quarters sedimentation basin total volume plus the height of the weir.
Wing Quantity = 3/4 [basin volume + (weir height x basin surface area)]
Eight (8) inch perforated PVC pipe surrounded by 6 inches of pvel in a 20 inch wide trench running the
length of the basin for each outlet was estimated at $20.00 per lineal foot. Where outlet RCP sized 48
inches and greaterwas required, 12 inch perforated PVC pipe in atrench surrounded by 8 inches ofgravel
at $35.00 per lineal foot was used. Weighted standpipe drainage structures were estimated at $1,000.00
each for tributary basins and $3,500.00 each for outlet pipe sizes 48 inches or greater in diameter.
Reinforced concrete pipe draining these structures was sized to pass the 100 year storm excepting those
in major channels which were sized to pass the ten year storm. A fifty foot minimum length for each pipe
was used. Two antiseep collars were estimated at $4,000.00 for each RCP outlet less than 48 inches in
diameter. For RCP outlets 48 inches or greater in diameter, each pair was estimated at 35,000.00.
Emergency weir spillway cost was estimated by using the unit cost for 4 inch drainage channel concrete
for a weir 20 feet wide (30 feet wide in major channels) and a length such that the design flow is able to
flow over a2.5 foot high weir (5 foot high in major channels and basins with a design Q greater than 2000
cfs). Rip rap was used for the first 20 lineal feet of tributary outlet channel. For major channels 50 lineal
feet of rip rap was used.
Si foot high chain link fence surrounding the basin was estimated at $13.00 per lineal foot.
Land acquisition costs are estimated at $1 per square foot for sedimentation basin bottom land.
It should be recognized that sedimentation basin sizes are first approximations only. At the time of final
Chapter 6
Page a8 Master Drainape and Stom Watar auality Management Plan
Carlabad, California. March 1984
design, soil composition should be detemined by field testing. It wiU then be possible to reliably design
basins with sediment removal e5ciencies in accordance with City of Carlsbad Design Standards.
However, only those items included in sedimentation basin cost estimates which are dependant on basin
surface area would be expected to fluctuate greatly with soil composition. These items are perimeter
fencing, perforated drain pipe with gravel and land costs.
'Fa pip dim 30" tboysh 48'. a mc.ll &pib of pip = 8- slllmcd
'Fa pip dim €4" tkw& 96". ofpip = 13' WI lumod
TABLE 6-1
Maater Drainage and Storm Water Quality Management Plan
Cedsbad. Cslifornia. March 1994 Chapter 8
Page 69
N& d B8rroll
2
2
2
2
I 1 I 10x4 I 802 I 09.00 II
Size C0.l Ilrpnil-
(fi) (YM rm) (YM rm)
OX2 307 36.00
Or4 338 48.00 1
OXO 024 00.00
oxo 736 00.50
I 4 I 12x4 I 4990 I 105.00 il
3
I 1 I 12x6 I 584 1 62.00 11
~~~ ~~~
12x8 4479 260.00
2
2
1
4
1
3
TABLE 6-2
axe 024 00.00
OX8 735 66.50
10x4 802 69.00
12x4 4898 ie5.00
12x5 584 52.00
12x8 4479 250.00
I 2 0x2 307 35.00
2 I 0x4 I 339 I 49.00
TABLE 6-3
Chaptar 6 Page 70 Master Drainage and Storm Water (luslity Management Plan
Cadsbad. California. March 1994
TABLE 6-4
TABLE 6-5
Master Drainage and Storm Water Quality Management Plan
Cadsbed. California. March 1994
Chapter 6
Page 71
I Unitcod-- II
JUnaionSt~ch~m
WRaP
3750.001ea
I 1 14 ton grouted with 6' gravel filter I blanket
1 ton grouted with 6' gravel filter
blanket
analwtr
cach Bscir.
5.50ls.f.
6.051s.f.
3050.001ea
7040.001ea
ll
Headwalr
Pipe -49' 2000.00lea
I Film -542' I 2500.001ea II
TABLE 6-6
The itemized cost estimates for each of the facilities identified within this report are contained within
-4ppendix 'C' entit1ed"CostEstimates by StormDrainLme Item". Oncethebasic cost estimate had been
established it was necessary to make a determination on the percentage of costs attributable to existing
and future development on a facility by facility basis. This was done to ensure that the hal cost estimate
utilized inthedeterminationofthedrainageareafeesdidnot includecostswhichareattributableto existing
deficiencies except insofar as they may be charged to existing developments that remodel or redevelop.
The determination ofhow much of any particular faciity is attributable to existing and future development
impacts is not easily quant5ed and requires a good deal ofjudgement on the part of the person making
the determination. The factorsthat must be considered include the relative percentage ofdevelopedversus
undeveloped property upstream of the improvement, the percentage of low and high runoff land uses,
whether the property underlying the proposed improvement is developed or undeveloped, the extent of
existing erosion or public nuisance, whether the proposed improvement serves a general public need and,
whether ornot theproposedimprovment allows adeveloperto expand the development potential ofthek
property.
' Erosion and Sediment Control Handbook Goldman et. al., McGraw Hill, 1986.
Chapter 6 Master Drainage and Storm Water (lualiw Menaoement Plan
Carlabad, California. kroh 1994 Page 72
To simplify the process, the following rules were applied. Where more than one rule applied, an
approximate estimate was made weighing the relative values of the contlicting rules.
1. When the proposed improvement is located on undeveloped property and there is no existing
erosion or public nuisance associated with the site, then loOO? of the cost of the facility is attributed to
future development.
2. When the proposed improvement is located on undeveloped property and there is evidence of
serious erosion potential or the site is a public nuisance, then 20% of the facity costs are attributed to
existing development.
3. Whentheproposedfacilityislocated onpreviouslydevelopedlandorlandthat isundevelopable,
then the costs shall be apportioned in relation to relative percentages of developed versus undeveloped
land upstream of the improvement.
4. The cost of future testing and monitoring stations and equipment necessary to comply with
future storm water quality improvements is to be apportioned in relation to the relative percentage of
developed versus undeveloped land within the boundaries of the respective drainage fee area.
A facility by facility analysis of costs attributable to existing and hture development needs is presented
in Appendiv 'C' of this report. A summary of the results for each of the four basins is presented in Table
6-7. Since this study assumes that 20% of the existing development base will pay a drainage fee as a
condition of remodeling or redevelopment, the total recoverable facility costs included within the fee
program is found by adding all ofthe costs attributable to future development activity together with 20??
ofthe costs attributable to existing development. The remaining 80% ofthe costs attributable to existing
development, forwhichfeeswillnotbecoUeaed,mustbefundedthroughsourcesotherthantheproposed
fee program.
A $3,022,945 $1,383,893 $1,639,053 $1.71 1,704
B $21,256.41 6 $1 5.480.973 $5,775,443 $16,636,061
C $3.989.850 $3.580.51 4 $409,336 $3,662,381
D $14.603.823 $13,801,948 $801.875 $13,962,323
Totals $42.873.034 $34.247.328 $8.625.707 $35.972.469
potmtial Recoverable mts =New development costs + 0.2 (E* development costs)
TABLE 6-7
Master Drmnaga and Storm Water Quality Management ?Ian
Carlsbad. California. March 1994
Chapter 6
Page 73
Chapter 6
Paga 74 Master DrainaQe end Storm Water Quality ManaQement Plan
Corlsbed. California. March 1994
CHApfER7
SUMMARY OF FIELD INVESTIGATIONS
Before making recommendations for drainage improvements a field investigation was conducted. The
goal of this investigation was to document conditions and problems associated with existing storm drain
structures. Plans of existing storm drain structures were obtained from the City of Carlsbad, adjoining
city and Cdtransrecords. Drainage facilities were plotted on worksheetsin orderto determinethe location
of major drainage lines. These existing drainage facilities and surrounding conditions were investigated
during the months of October, November and December of 1988. Caltrans and adjoining city plans were
transmitted to the City of Carlsbad for their records.
The entire City of Carlsbad was inspected to check for general conformance to the record drawings. No
detailed measurements were taken to verify slope, invert elevations and outlet elevations. Instead Fraser - Cooper verified the location of the storm drain facility as shown on record improvement plans and
examined their condition.
The limits of the investigation were those portions of Buena Vista Creek Basin, Agua Hedionda Creek
Basin, Encinas Creek Basin and San Marcos Creek Basin within the City of Carlsbad sphere of influeace.
The investigation was conducted by driving near the locations of possible interest and walking to those
not visible &om the road. Photographs were taken of sigdcant conditions, noting the time of day,
direction and location ofthe photograph. Photographs were mounted in two albums and delivered to the
City of Carlsbad in December of 1988.
Facilities were found to be in generally good condition. Some, however, were poorly maintained, their
effectiveness hindered by vegetation overgrowth, siltation andor pondmg. Some structures are in danger
due to erosion.
B. Buena Vista Creek Basin
Drainage structures inthe Buena Vista CreekBasin showing evidence ofvegetation overgrowth, sitation
or pondmg are seen in photograph numbers 8,9,10,11,18,26,27,28,30,3 1,32,34,35,39,40 and41
of the Buena Vista creek section of Album 1. Damage or potential damage from erosion can be seen in
photographs number 1, 14 and 25.
Some storm drain lines such as line AC are incomplete and need improvements discussed in other sections
ofthis report. The current conditions ofline AC are shown in pictures 12,13 and 14 ofthe Buena Vista
Creek section of Album 1. Vandalism can influence the effectiveness of storm drain lines as can be seen
in picture number 42.
Master Drainage and Storm Warsr Quality Manapemant Man
Carlsbd. California. March 1994
Chapter 7
Page 75
C. Agua Hedionda Creek Basin
Drainage structures in the Agua Hedionda Creek basin showing evidence of vegetation overgrowth,
siltationorpondingareseeninpiaurermmbersS,lO, 11,12,15,16,19,20,27,28,29,30,31,34,35,
36,37,38,39,40,41,43,47, 50, 51, 52,53, 54, 55, 56, 57, 58, 59,60, 61,64, 65,66, 67,68, 69,70,
71,72,73,74,76,80,8 1,82,82,, 84,85,89,95,96,97,98,99 and 100 of the Agua Hedionda Creek
Basin section of Album 1. Damage or potential damage fiom erosion can be seen in pictures 6 and 14.
Obstruction due to littering can be seen in photographs 13,33 and 70.
Drainage StNctures in the Encinas Creek Basin showing evidence ofvegetation overgrowth, siltation or
ponding are seen in photograph numbers 4,13,22,23,27,31,33,39,44,46,47,50,54 and 55 of the
EncinasCreeksectionofAlbum2. Incompleteconstructioncanbeseeninphotographs 1 and5 Damage
or potential damage fiom erosion can be seen in photographs 2,3,11 and 16.
E. San Marcm Creek Basin
Drainage Structures inthe SanMarcos Creek Basin showing evidence ofvegetation overgrowth, siltation
or ponding are seen in photograph numbers 2,5,8,9, 11, 14, 15, 18, 19,, 20,21,22,24,25,27,29,33,
34,35,36,37,38,39,47and48oftheSanMarwsCreekportionofAlbumZ. Damageorpotentialdamage
fiom erosion can be seen in photographs 12, 17 and 23. Obstruction due to littering can be seen in
photographs 3 and 30.
E Findings
In summary, the field investigation located.many areas of vegetation overgrowth, siltation and ponding.
These areas can be seen in the photographs accompanying this document. Areas of erosion damage as
well as areas of severe littering or vandalism were also noted and photographed.
General conformance to record improvement plans was found. Storm drain facilities which were
damaged, covered by vegetation and filled with silt were documented by the photographs submitted to
the City of Carlsbad in December of 1988. It is recommended that the City of Carlsbad clean silted pipes,
trim brush and repair damaged storm drain facilities.
Chapter 7
Page 78 Master Drainage and Storm Water Quality Msnapmwnt Plan
Cadsbad. Californie. March 1994
APPENDIXA
PROPOSED DRAILVAGE FACE-
In the descriptions which follow, it will be noted that several existing facilities, some of which were
constructed relatively recently, are considered undersized. This is primarily because the 1985 revised
Intensity-Duration Design (I-D-D) Chart was used for this study. The onginal1-D-F (Intensity-Duration-
Frequency) wes (developed in about 1965) were based on extremely limited data f?om the San Diego
National Weather Service (NWS) and the Mount Laguna rain gauges. The new I-D-D Chart is based on
up-to-date precipitation data and statistical analysis which makes the results much more reliable and
consistent with Federal and State studies and reports. The I-D-D Chart is applicable to short duration
hydrology procedures such as the rational method.
Since the City of Carlsbad desires that natural channels in canyon areas remain as natural as possible,
“enhanced natural channels” are proposed in these areas when drop structures are necessary to reduce
the flow velocity to less than 6 feet per second. However, if channel areas having a design flow velocity
of greater than 6 feet per second are located in areas zoned open space, the cost of potential remedial work
was estimated, <ice the construction of drop structures may not conform to land use requirements.
Recommendations are limited to proposed pipe Sizes of 30” (inches) or greater in diameter. RCP refers
to reinforced concrete pipe. The following general procedures were used to determine the adequacy of
existing lines and to recommend improvements if necessary.
1. If computations indicate a new replacement pipe line sue is not more than 6 inches in diameter larger
than the existing facility no improvements are deemed necessary.
2. Ifcomputations indicate a new replacement pipeline sue is more than 6 inches in diameter larger than
the existing facility and the additional capacity- be conveyed in the street, no improvements are deemed
necessary.
3. If computations indicate a new replacement pipeline size is more than 6 inches in diameter larger than
the existingfacilityandtheadditionalcapacitywbe conveyedinthestreet, therequiredimprovements
are shown on the maps as the new size required. Cost estimates generally reflect the construction of new
facilities to replace the existing undr sized facilities. However, in some locations, a parallel pipe to the
existing pipe line may be provided. In these cases cost estimates reflect the construction of these parallel
lines. Generally, where existing pipeline diameters are 48 inches and larger, new parallel pipelines are
considered to be most likely and hence are shown on themaps. For smaller existing pipelines, replacement
with larger diameter is considered more feasible. In all cases, whether shown as replacing existing with
larger sizes or providing parallel pipelines to secure the additional capacity, the final determination as to
the most cost effective method should be left to a detailed analysis during final design.
Appendix A
Page 77
Master Drainaga and Storm Water (ludity Managamant Plan
Carlsbld. California. March 1994
4. Other alternatives to reducing peak flows and hence reducing size ofnew facilities include on-site storm
detention facities. These should be evaluated on a case by case basis during detailed design.
B. BuenaVistaCreekBash
FadlltyA
Sedimentation Basin A1 is proposed along Buena Vista Creek in the Vicinity ofthe South Coast Asphalt
Plant as recommended by the Buena Vista Lazoon Sed iment Contro I Plan prepared by June Applegate
and Associates in September of 1985 and adopted by the City of Carlsbad. Preliminary estimates of
sedimentation basin size are based on approximations of available land only. The second basin
recommended within the Buena Vista Creek just east of Jefferson Street was excluded due to limitation
in available land and environmental considerations.
This is an extension eastward along Carlsbad Viage Drive fiom the end ofthe existing Central Business
storm drain system. This 30" RCP line will connect to an existing 24" RCP line which ends at Jefferson
Street. This system receives drainage orighathg east ofiterstate 5 and connects to the CentralBusiness
District storm drain line becoming 36" RCP for the last 200 feet. The sizes used for this line are fiom City
approved plans.
FadlltyAAA
Drainage facilities are needed for the residential areas north of Laguna Drive west of Interstate 5 which
drain into the down line end ofthe Central Business District storm drain system. New 33" RCP is needed
along Jefferson Street and existing 24" and 30" RCP along Laguna Drive should be upgraded to 45" RCP
as indicated on plans.
FadlityAAAA
This 24" RCP line is smaller than the standard 30" minimum otherwise used as the lower limit of facilities
in this study. It is needed to cany drainage north to Laguna Drive along Monroe Street correcting local
pondmg conditions.
FadlityAC
Along the northernmost section of Highland Drive in a residential arca, 36" RCP is required to route
drainage to an existing AC channel in an area zoned open space.
Appendix A
Pegs 7%
Master Drainage and Storm Water Oualitv Managenwnt Plan
Carlsbad, California. March 1884
FadlltyAD
Two portions of existing storm drain lines in Monroe and Canyon Street residential areas should be
upgraded to conform to current standards, since streets are unable to carry the remainder of the drainage
flow. These portions are shown in the plans. The currently disconnected sedimentation basin at the
southwest comer of the intersection of Monroe Street and Marron Road should be reconnected if
calculations show it is of adequate size to use as a detention basin.
FdtyAFA
An enhanced natural channel is proposed to route drainage from the existing residential area drainage
system ending east ofAvenida de Louisa to Buena Vista Creek through an area designated for residential
development.
FdtyAFB
Anatural channel carries drainage through an area designated as open space to a proposed sedimentation
basin facility. From this facility northwest to Buena Vista Creek, potential remedial work has been
estimated where natural channel velocities exceed 6 feet per second.
FadlityAG
This facility wiU carry drainage under the fiture College Boulevard from proposed development in
Caiavera Ws. The drainage facility will extend approximately 600 feet into Oceanside and connect into
an existing storm drain which discharges into Buena Vista Creek.
C. Agua Hedionda Creek Basin
FadlityBA
In the commercially zoned area north ofPalomar Airport Road adjacent to Interstate 5, one 27" RCP line
should be upsized to 45".
FdtyFL4A
New facilities begin with a double 66" RCP culvert (or box equivalent) conveying drainage under the AT
& SFRailroadtrackstoCannonLake. Theexisting 30"DPisinadequate, andthe areaiscurrentlypoorly
dlained. The line continues north of Cannon Lake with a 51" RCP parallel to an existing undersized
66"RCP.
FadlityBB
This facility begins at the intersection of Pine Avenue and Harding Street and receives drainage fiom
residential areas east of Interstate 5. New 30" RCP is proposed nonh along Harding Street, then42" RCP
westalongOakStreettoRooseveit Street. New51"RCP isrequiredfromthispointwest alongoakstreet
to discharge into what is currently an earthen channel parallel to the AT & SF Railroad. This earthen
Master Drainage and Storm Water Quality Management Plan
Carlsbad. California. March 1994 Page 79
Appendix A
channel which has only 0.1% slope is unable to carry drainage flow and should be replaced by underground
drainage facilities. A reinforced concrete box of increasing size is shown on the plans. The existing 63"
RCP at the southern (downstream) end of the eastern channel is undersized. A parallel 72" is required
to carry drainage as shown.
Alternatively, the 63" RCP as well as downline 72" RCP could be removed. The discharge point of this
line could be lower. A replacement line would then have significantly greater slope and could be a smaller
size. This alternative should be examined for the entire line at the time of detailed design.
FadlityBBA
This 30" RCP along Chinquapin Avenue in a residential area is needed to carry drainage west ofinterstate
5 to the improvements of line BB.
Facility BBB
This line through a residential neighborhood currently consists of 24", 27" and 30" RCP which should
be upgraded to 33" and 45" RCP to conform to current standards, since Chestnut Avenue is marginally
unable to carry the portion of the drainage flow which existing pipes will not carry. This line currently
discharges into existing earthen channel BB.
FacilityBBC
This 30" RCP in a residential neighborhood is needed to carry drainage originating east of Interstate 5,
west and north along Palm and Madison Streets to line BBB at Chestnut Avenue. Along Madison Street,
this line replaces an existing 18" RCP line.
FdtyBC
This facility extends from Sandalwood Lane south to Park Drive before discharging to Agua Hedionda
Lagoon. The facility was constructed in FY 89-90. Due to a shortfall in drainage area fee funds the city
borrowed $300,000 from the General Fund to be repaid from drainage area fees. This amount is included
in the cost estimate for reimbursement of the General Fund.
FacilityBCA
This 24" RCP line collects drainage from the residential areas surrounding Park Drive and Tamarack
Avenue directing flow to James Drive where this line connects to facility BC. This facility is necessary
to correct'local ponding and floodLig conditions.
FdtyBCB
This facility extends from the James Drive storm drain east along Magnolia Avenue to Valley Street. The
facilitywiU be extendedby adjacent land developmentto drainlow areasofvalley Street northofMagnolia
Street.
A~pendix A
Page 80
Master Drainape and Storm Water OualiW Management Am
Carlsbad, California. March 1994
FadlilyBCC
This facility extends fiomthe JamesDrive storm drain east along Chestnut Avenue to Valley Street. The
facility is needed to accommodate drainage flows which presently flood portions of Chestnut Avenue
during storm events.
FaciliiyBD
Currently, positive drainage does not exist fiom the end ofthe existing line. The existing condition includes
siltation and cattail overgrowth and can be seen in photograph 26 of Album 1. Sedimentation basin BD
is proposed to decrease the deposition of silt into Agua Hedionda Lagoon.
FadlityBE
The improvements contemplated in this area ofMarcario Canyon consist ofremedial work to enhance the
natural channel by provision of drop structures and other features to reduce erosive drainage flows.
FadIilyBEA
Natural channel velocities exceed 6 feet per second in this open space zoned area near Agua Hedionda
Lagoon. The cost of potential remedial work has been estimated.
FadlilyBF
North ofTamarack Avenue immediately east of Sierra More& Avenue, where channel velocities exceed
6 feet per second, an enhanced natural channel has been proposed. Drainage from existing residential
development storm drains north of Tamarack Avenue and east of El Camino Real currently discharges
into an open field south of Tamarack Avenue and west of El Camino Real. New 75" RCP is proposed
to carry drainage water south to proposed sedimentation basin BF immediately north ofEl Camino Real.
The size of this basin was estimated omitting the amount of suspended soil material calculated to be
drainingintothe existing sedimentation basin at PontiacDrive and Tamarack Avenue. Drainagethen flows
in a proposed double 8' x 4' RCB under El Camin0 Real.
Special Note: The proposed 75" RCP east ofEl Camino Real may be replaced with an enhanced natural
channel to mitigate riparian loss and to accommodate Habitat Management Plan goals. This decision it
to be made at time of development application.
Fadlily BFA
This 42" RCP line south of El Camino Real is proposed to carry drainage fiom an area designated for
residential develooment north and west to the concrete channel of facilitv BF south of sedimentation basin
BFl
Mastar Drsinaoe end Storm We181 Qudiw Management Plan Appendix A
Carlsbsd. California. March 1994 P.0.81
FadlltyBFB
North of Tamarack Avenue immediately east of El Camino Red, where channel velocities exceed 6 feet
per second, an enhanced natural channel has been proposed. Drainage east and west of El Camino Real
&om Chestnut to Tamarack currently drains into an earthen channel and undeveloped lot at the southeast
comer ofEl Camino Real and Tamarack Avenue. A 48" RCP pipe is proposed to route this water to line
BF north of sedimentation basin BFl .
FaciliiyBG
This proposed facility will carry drainage &om future development areas located along the west side of
El Camino Real opposite the Rancho Carlsbad Mobile Home Park
FadlilyBH
These 36", 57" and 72" RCP lines are proposed to carry drainage from an area designated for residential
development south and west of Carlsbad Viage Drive and future College Boulevard south to Agua
Hedionda Creekjust northEl Camino Real and hture Cannon Road. The facilities include a 10,600 cubic
yard sedimentation basin just prior to discharge into Agua Hedionda Creek.
FadlityBJ
This line travels along future Cannon Road through an area zoned for residential development. It begins
at the City of Carlsbad boundary and carries watex fiom existing lines in the City of Oceanside's Leisure
Viage south and west to Agua Hedionda Creek just west of Rancho Carlsbad Mobile Home Park. It
begins as large (63" and 66")RCP and becomes anenhanced naturalchannel asit isjoined by various branch
lines. A sedimentation basin is proposed immediately upstream ofRancho Carlsbad Mobile Park. From
this point, an 80 foot wide earthen channel is proposed to carry drainage to Agua Hedionda Creek The
City of Carlsbad does not choose to construct a narrower concrete channel in this area. It is possible that
detailed design studies using other methods could determine a narrower section for this earthen channel.
FadlltyBJA
This is a 33" RCP line carrying drainage along the hture College Boulevard to the enhanced natural
channel of line BJ.
FadlityBJB
An entaced natural channel canies drainage through a portion of an area designated for residential
development to a proposed sedimentation basin northeast offuture CannonRoad and College Boulevard.
This proposed sedimentation basin drains into an earthen channel of line BJ.
Facilities BJBA, BJBB & BJBC
Potential remedial work has been estimated in these open space zoned areas south of Calavera Lake where
natural channel flow velocities exceed 6 feet per second.
Appendix A
Page 82
MZIS~OI Drainage and Storm Wat01 Quality Managamant Plan
Carlsbd. California. March 1994
FacilityBJC
These 33" and 42" RCP lines carry drainage through an area designated for residential development to
the enhanced natural channel of line BJ.
Facilityl3JD
This mhanced natural channel carries drainage originating in the City of Oceanside west through an area
designated for residential development to the upstream end of the enhanced natural channel of line BJ.
FacilityBL
This line carries drainage from south and east of El Camino Real and College Boulevard north across El
Camino Real and through areas designated for commercial and residential development to Agua Hedionda
Creek. This is a new storm drain line except that one segment of existing 54" RCP should be paralleled
by new 57" RCP, and the existing 60" RCP under El Camino Real should be replaced by 78" RCP or a
parallel pipe to conform to current standards. The 60"RCP through thecarlsbad Research Center (CRC)
is currently guaranteed for construction as a condition ofthe CRC project. Credits and fees for this line
were accounted for at time of Final Map approval for CRC Unit 5. The cost estimate for this facility
includes provision for a potential bridge structure on College Boulevard across Agua Hedionda Creek.
Theneed fora bridgestructureversusa boxculvertwillbe determinedat thetimeofdevelopment approval.
FdtyBM
An enhanced ~hual channel is proposed to carry drainage through an area designated for residential
development to Agua Hedionda Creek. Within this channel, there currently exists a lake which it is
expected will remain for scenic or recreational purposes.
This is a long (7330') natural channel carrying City of Oceanside drainage from the city boundary along
future Cannon Road and receiving additional drainage from areas designated for or currently built as
industrial park developments. Since most ofthe area containing this channel is zoned open space, the cost
of potential remedial work is estimated where design storm velocities exceed 6 feet per second. A
sedimentation basin is proposed upstream of Agua Hedionda Creek in an area zoned for industrial park
development. The cost estimate for this facility includes provision for a potential bridge structure on
Faraday Road across Agua Hedionda Creek. The need for a bridge will be determined at time of
development approval.
Facility BPA
This enhanced natural channel connects existing industrial park drainage facilities to natural channel BP.
Facility BPB
These proposed 36" and 45" RCP lies run through an area designated for industrial park development
and empty into naturai channel BP.
Master Orainaos and Storm Watar Quality Management Plan
Carlsbd, California. March 1994
Appendix A
Pag. 83
FacilityBPC
Storm water attenuation is required to bring existing 36" RCP lines into conformity with current design
standards. A proposed brow ditch, directs the discharge of this industrial park line into ~tural channel
BP.
FacilityBPD
Storm water attenuation is required to bring existing 24" and 30" RCP industrial park storm drains into
conformity with current design standards. An enhanced natural lined channel is also proposed to co~ect
outflow 60m an existing sedimentation basin to natural channel BP.
Facility BPDA
Storm water attenuation is required to bring an existing 42" RCP industrial park storm drain into
conformity with current design standards.
Facility BPDB
Storm water attenuation is required to bring an existing 48" RCP line in an industrial park into conformity
with current design standards.
FdtYBQ
Potential remedial work was estimated in this area zoned open space where channel velocities exceed 6
feet per second.
D. EndnasCreekBasin
FadlityC
Thisproposed facilitywill completethemajor drainage systemintheEncinasBasin. Theproposedchannel
andenhancednaturalchannelconnectstheexisting 12'xS'RCB westofPalomarOaks WaytotheEncinas
Creek natural channel downstream ofFaciIity CC 22OO'West ofCoUegeBouIevard. Afterthe coduence
of Facility CC the natural channel of the creek will carry runoff though a designated open space. The
existing facility between the coduence of proposed facility CI and CH south of Palomar Airport Road
was found inadequate with the current standards and should be replaced by this proposed facility to handle
the projected discharges. The existing facilities across Paseo Del Norte and Carlsbad Boulevard are also
found inadequate with the current standards and additional 10' x 4' RCB and 12' x 5' RCB should be
constructed along with those existing facilities, respectively, to handle the projected discharges.
Appendix A
PE~O a4
Master Ordnwe and Storm Water QudiV Management Man
Carlsbd. California. Much 1984
FadlltyCA
The proposed facility CA is a concrete trapezoidal channel which will complete a drainage system by
connecting to an existing concrete channel just east of the AT & SF Railroad. The upstream area is
undeveloped and high density fbture development will aggravatethe drainage deficiency unless this facility
is built. This facility will also mitigate the erosion problem along the railroad.
FadUQCB
Facility CB is comprised of 39" and 60" RCP's which will carry runoff from a mostly undeveloped area
north ofPalomar Airport Road and drain into Encinas Creek after crossing Palomar Airport Road. The
upstream area is mostly undeveloped and higher density fbture development will require the construction
of this facity.
FadlltyCC
Facility CC is a storm drain proposed to be constructed and will carry runoff &om an undeveloped area
north ofPalomar Airport Road with an outfall to the proposed channel offacility C through a 72" diameter
pipeunderPalomar Airport Road. Construction ofthis facilitywillbe required along withthe development
of the undeveloped upstream areas.
FadlityCE
This faciity will drain future residential areas along the proposed Hidden Valley Road to Encinas Creek.
FadlityCF
This facility will convey drainage along the fbture Alga Road and empty into basin CFA
FadlityCFA
Drop structures and other enhancements will be made to the existing natural drainage course to reduce
erosion potential. Additionally, a desiltation basin will be installed just upstream of the proposed
Cobblestone Viage access road. An enhanced natural channel will then convey drainage on down to
Encinas Creek.
FadlityCJ
Facility CJ will extend an existing 36" RCP iystream. This improvement will alleviate nuisance pondmg
and reduce the potential for mosquito breediig. The upstream area is mostly undeveloped and higher
density fbture development will aggravate the drainage problems unless this facility is built.
FadlityCK
Facility CK will improve the existing drainage facility along Camino Vida Robles, north of Las Palmas
Drive. The downstream 550' ofthe existing 24" RCP in this system was found inadequate by the current
standards and should be upgraaed by'the addition of a retention basin.
Master Drainage and Storm Wetar Qualitv Managamant Plan
Carlsbd. Cdifornia. March 1994
Appendix A
Page 85
FaciliiyCM
Facility CMisproposedto beconstructed tocarryrunoffalongPalomarAirportRoadandElCaminoReal
northwest ofthe intersection ofthe two roads. It will outfall to the natural swale through the golf course
just south of Palomar Airport Road. The streets provide the only conveyance for drainage and are of
inadequate capacity by current standards. The upstream area is partially undeveloped and high density
future development will aggravate the drainage deficiencies unless this facility is built.
FadYityCMA
This proposed 51" RCP will join proposed Facility CM and it will carry runoff across Palomar Airport
Road. The upstream area is partially undeveloped and high density fbture development will aggravate the
drainage deficiencies unless this facility is built.
E. San Marcos Creek Bash
FacilityDA
Facility DAis comprisedof48", 54", 60", 72", and 81"RCP'sthatwillcarryrunofffiombothdeveloped
and undeveloped areas with an outfall to Batiquitos Lagoon. Most ofthe upstream portion ofthis facility
runs parallel to the AT & SF Railroad and the most downstream portion along Carlsbad Boulevard.. The
existing24" RCPfromPoinsettiaLanetotheconfluence ofproposedlineDAAwasfoundinadequatewith
the current standards and needs to be replaced to carry the projected discharges. The upstream area is
mostly undeveloped and higher density future development will aggravate the drainage deficiency unless
this facility is constructed. One debris basin is also proposed at the downstream ofthis facility to mitigate
the impact of siltation and storm water pollutants on Batiquitos Lagoon due to grading and new
development inthe future. An alternate proposal may be to route the storm drain from its point of crossiig
at the AT & SF Railroad line southeast along the Avenida Encinas right of way to the existing siltation
basin adjacent to the Rosalina subdivision. The existing basin would require relocation and enlargement
to accomodate the new flows. This alternative should be throughly reviewed prior to new development
within zone 9.
FadliiyDAA
Facility DAA, proposed to be constructed, will be required to upgrade or replace the existing 24" RCP
by a proposed 39" RCP sice the existing facility is inadequate with the present standards. This facility
will drain into the facility DA The upstream area is undeveloped and future development will aggravate
the drainage deficiency unless this facility is built.
FadUtyDBA
Facility DBA is a storm drain line proposed to be constructed and will complete a drainage system by
connecting upstream and downstream existing facilities. The upstream area is mostly undeveloped and
future development will require construction of this facility.
Appendix A
Page 86 Master Drainage and Storm Water Quality Management Plan
Carlabad, California. March 1994
Fadliw DBB
This proposed 30" RCP to be constructed to connect existing 30" RCP across Interstate 5 to the existing
60" RCP across Avenida Encinas. The System has found to be deficient for fiture development.
FadUtyDF
This facility collects drainage &om the Aviara development and discharges into the Batiquitos Lagoon.
The facilitywas constructed as an offsite requirement for the Aviara project and may potentially be subject
to reimbursement as part of the drainage fee program.
Fadlity DFA
This permanent sedimentation basin is located at the lower end ofFacility DF and discharges directly to
the Batiquitos Lagoon. When installed, the temporary basin located upstream in the Aviara project may
be removed. Ifthis basin is eliminated and the Aviara basin is made permanent the Aviara developer will
be eligible for reimbursement for this facility.
Facility DH
Facility DH comprises an enhanced natural channel to prevent erosion along the natural channel due to
high velocity. The enhanced mal channel will consist of drop structures at points along the channel
to reduce the slope of the stream flow.
FadlityDI
This facility is comprised of a 42" RCP connecting with the existing 42" RCP at upstream just west of
AvenidaDel Para and Unicornio Street with an outfall to the existing swale passing through agolfcourse.
The area at the downstream portion of the two basins is undeveloped and fiture development in this area
will require the construction of both facilities.
FacilityDIB
Facility DIB is a debris basin at the downstream northerly of Alga Road. It is proposed to be constructed
to mitigate the impact of siltation as part of the fiture development in the area.
FacilityDM
FaciLry DM comprises of an enhanced ~tural channel to prevent erosion along the natural channel due
to highvelocity. The enhanced natural channel will consist of drop structures at points along the channel
to reduce the slope of the dtrearn flow.
Master Drainage and Stom Water Clualitv Management Man Appendix A Carlsbd, California, March 1994 page a7
Facility DMA, DMB, DMD BDME
These future facilities are located within undeveloped arm of zones 10 and 17. As such, there are no
definite or proposed plans for the development of the included drainage basins except for the future
extension of Carrillo Way. The estimates for these facilities were based upon channel construction and
enhancement as well as culvert crossings under the future Carrillo Way.
FacilityDMF
This facility will handle drainage along the extension of El Fuerte Street to enhanced natural channel DM.
E EndnitasCreekBasin
FadutyDQ
Facility DQ is a storm drain proposed to be constructed and is comprised of 33", 36" and 45" RCP's
carryingrunofffromandthroughundeveloped areaeast ofRancho SantaFeRoad drainingintothenatural
swale at the downstream end. The upstream area is undeveloped and high density future development will
require the installation of the facility.
FadlltyDQA
This proposed storm drain will join proposed facility DQ at its most downstream end. It will carry runoff
through an undeveloped area and should be constructed as part of the future development.
Fadlity DQB & DQC
These two facilities are needed to drain runoff from the proposed realignment of Rancho Santa Fe Road
through future development and empty into the northeast fork of Encinitas Creek.
FaciliWDR, DRA, DRB &DRC
These comprise the Master Plan facilities for the proposed Arroyo La Costa project. They include
enhancement of the natural channel, installation of a sedimentkention basin, and extension of existing
concrete culverts to handle the existing and proposed drainage.
FacilityDS
Facility DS is a storm drain proposed tc oe constructed along Camino Alvaro and Rancho Santa Fe Road
replacing the existing 36" RCP. The system has found to be deficient between the existing 2'x 4' RCB
across Rancho Santa Fe Road and the existing 30" ACP on Alvaro.
Appendix A
Page aa Master Drainage end Storm Water Quality Management Plan
Carfsbad. California. March 1994
FadlityDTA
The Encinitas Creek study prepared by Howard Chang indicates that the existing triple box culvert under
La Costa Avenue is inadequate to handle the 100 year flood flows. By ktabg retention basin DTB and
addition of a berm along La Costa Avenue, the flooding and overtopping of La Costa Avenue will be
prevented.
FadlltyDTB
This retentiodsedimentation basin is needed to retain drainage in order to mitigate flooding and
overtopping of El Camino Real and La Costa Avenue located downstream of the proposed facility.
FadlityDTC
This proposed facility is a 15k 4'RCB across Rancho Santa Fe Road along the course ofEncinitas Creek.
The existing 2-10k 4' RCB was found inadequate with the current standards and the proposed facility
should be added to the existing to trade properly the projected discharges. This wiU eliminate flooding
on both sides of the creek upstream of Rancho Santa Fe Road.
FndU@M'D
This facility includes two culvert crossings ofEncinitas Creek beneath the future Calle Acwvo and some
remedial work to enhance the natural drainage courses.
FacUityDU
This sedimentation basin will work in combination with the existing basin at the southwest comer of
Batiquitos Lane and Poinsettia Lane to reduce erosion potential for existing and proposed developments
in the respective basin.
FadliWDV
Facility DV is a 60" RCP proposed to be constructed across the El Camino Real to replace the existing
60" CMP draining into Enchitas Creek.
FadIityDW
FaciiityDWisa33"RCPproposedto beconstructedacrossOlivenhainRoadandreplacesthetwo existing
24"CMP's.
FacilityDZ
This facility will carry drainage along Rancho Santa Fe Road &om new development within Carisbad and
&om existing development in Encinitas.
Maatar Drainage and Storm Water Quality Menagemant Ran Cadsbad. California. March 1994 Appan(ix A Pago 88
Appendix A
Page 90 Master Drainage and Storm Water (ludiw Manag.men1 Plan
Carl.bed, California. March 1994