HomeMy WebLinkAbout!Ch 05.11 Hyd 5.11 Hydrology and Water Quality
Otay Ranch Village 8 West EIR
CV EIR 10-03; SCH No. 2010062093 Page 5.11-1
City of Chula Vista
November 2013
5.11 Hydrology and Water Quality
This section describes the hydrological setting of evaluates the potential for changes in drainage, runoff,
and water quality due to implementation of the SPA Plan and TM.
As stated in Section 2.3, Purpose and Legal Authority, this EIR tiers from the 2013 GPA/GDPA SEIR (09-
01). The SEIR did not address hydrology and water quality but relies on analysis in the 1993 Program EIR
for the GDP (EIR 90-01). Section 3.9, Water Resources and Water Quality, of the Otay Ranch GDP
Program EIR (EIR 90-01) analyzed the potential impacts and identified mitigation measures related to
hydrology and drainage for the entire Otay Ranch GDP. The Otay Ranch GDP concluded that
implementation of the GDP would result in significant and mitigable environmental impacts upon
regional hydrology and drainage. The analysis and discussion of hydrology contained in the Otay Ranch
GDP Program EIR are incorporated by reference. The following discussion is also based on the
Preliminary Water Quality Technical Report for Otay Ranch Village 8 West (herein referred to as the
Water Quality Report), revised December 8, 2011; the Preliminary Drainage Study for Otay Ranch Village
8 West (herein referred to as the Drainage Study), revised December 8, 2011; and the Hydromodification
Study for Otay Ranch Village 8 West (herein referred to as the Hydromodification Study), revised August
26, 2011, all prepared by Hale Engineering. These reports are provided as Appendices K1 through K3 in
this EIR and update the applicable information contained in the previously certified EIRs.
5.11.1 Existing Conditions
A. Regulatory Framework
1. Federal
a. National Pollution Discharge Elimination System Permits
In California, the SWRCB and its RWQCB administer the National Pollutant Discharge Elimination System
(NPDES) permit program. The NPDES permit system was established in the CWA to regulate both point
source discharges and nonpoint source discharges to surface waters of the U.S. The NPDES program
characterizes receiving water quality, identifies harmful constituents, targets potential sources of
pollutants, and implements a comprehensive storm water management program. Construction and
industrial activities are typically regulated under statewide general permits that are issued by the
SWRCB. The RWQCB also issues waste discharge requirements that serve as NPDES permits under the
authority delegated to the RWQCBs, under the CWA. In November 1990, under Phase I of the urban
runoff management strategy, the EPA published NPDES permit application requirements for municipal,
industrial, and construction storm water discharges. These requirements are implemented through
permits issued by the SWRCB or the local RWQCB in which the project is located (California RWQCB San
Diego Region, herein San Diego RWQCB), and/or the governing municipality where the project is located
(City of Chula Vista).
2. State
a. California General Construction Activity Permit
Storm water runoff from construction activity that results in soil disturbances of at least one acre of
total land area (and projects that meet other specific criteria) is governed by the SWRCB under Water
Quality Order 2010-0014-DWQ, NPDES Permit #CAS000002. These regulations prohibit discharges of
polluted storm water from construction projects that disturb one or more acres of soil unless the
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November 2013
discharge complies with the general NPDES permit requirements. The nine individual RWQCBs enforce
the general construction permits for projects within their region. The San Diego RWQCB oversees
permits in the project area. It is the responsibility of the landowner to obtain coverage under the
general construction permit prior to commencement of construction activities. To obtain coverage, the
owner must file a NOI with a vicinity map and the appropriate fee to the SWRCB. The general permit
outlines the requirements for preparation of a SWPPP.
SWPPPs are prepared and BMPs identified in the SWPPPs are implemented for construction sites
greater than one acre, which reduce the likelihood of alterations in drainage to result in water quality
impacts. To ensure that the preparation and implementation of the SWPPP is sufficient for effective
pollution prevention, it must be created and implemented by Qualified SWPPP Developer (QSD) and
Qualified SWPPP Practitioner (QSP) that have attended a State Water Resources Control Board
sponsored or approved QSP and/or QSP training course. Typical BMPs include the following:
■ Minimizing disturbed areas. Clearing of land is limited to that which will be actively under
construction in the near term, new land disturbance during the rainy season is minimized, and
disturbance to sensitive areas or areas that would not be affected by construction is minimized.
■ Stabilizing disturbed areas. Temporary stabilization of disturbed soils is provided whenever
active construction is not occurring on a portion of the site, and permanent stabilization is
provided by finish grading and permanent landscaping.
■ Protecting slopes and channels. Outside of the approved grading plan area, disturbance of
natural channels is avoided, slopes and crossings are stabilized, and increases in runoff velocity
caused by the project is managed to avoid erosion to slopes and channels.
■ Controlling the site perimeter. Upstream runoff is diverted around or safely conveyed through
the project and is kept free of excessive sediment and other constituents.
■ Controlling internal erosion. Sediment-laden waters from disturbed, active areas within the site
are detained.
3. Local
a. Development Storm Water Manual
New development and redevelopment projects in the city are subject to the requirements of the Chula
Vista Development Storm Water Manual (January 2011). The development storm water manual meets
the hydromodification control requirements of the NPDES Municipal Permit issued to Chula Vista by the
San Diego RWQCB. New development and redevelopment projects are to minimize impacts on receiving
water quality and habitat by incorporating construction and post-construction BMPs in their project
design. Construction BMPs typically include erosion control, sediment control, non-storm water
management, and material management practices. The applicant is required to prepare a SWPPP which
identifies all applicable construction BMPs. Post-construction BMPs include low impact development
site design, source control, treatment control, and hydromodification control practices. The manual
provides guidance and establishes standards and criteria to meet those requirements.
According to Section 3.6.1.b of the manual, pollutants generated by a project that exhibit one or more
of the following characteristics are considered pollutants of concern:
■ Current loadings or historical deposits of the pollutant are impairing the beneficial uses of a
receiving water;
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■ Elevated levels of the pollutant are found in water or sediments of a receiving water and/or
have the potential to be toxic to or bioaccumulate in organisms therein; and
■ Inputs of the pollutants are at a level high enough to be considered potentially toxic.
This section of the manual also states that any anticipated pollutants to be generated by the project,
which also are on the 2006 CWA Section 303(d) List of Water Quality Limited Segments (303(d) list) of
impairments for the receiving waters of the project site, shall be considered as pollutants of concern.
b. City of Chula Vista Municipal Code Section 14.20, Storm Water Management and Discharge
Control
The purpose of this ordinance is to promote the health, safety, and general welfare of the citizens of
Chula Vista by prohibiting non-storm water discharges to the storm water conveyance system,
preventing discharges to the storm water conveyance system from disposal of materials other than
storm water, reducing pollutants in storm water discharges to the maximum extent practicable, and
reducing pollutants in storm water discharges in order to achieve applicable water quality objectives for
surface waters in San Diego County. This ordinance states that it is unlawful for any person to cause,
either individually or jointly, any discharge into or from the storm water conveyance system that results
in or contributes to a violation of any NPDES permit. Any person engaged in activities that may result in
pollutants entering the storm water conveyance system shall, to the maximum extent practical,
undertake all measures to reduce the risk of illegal discharges. The following requirements apply:
■ Best Management Practices Implementation. It is unlawful for any person not to comply with
BMPs and pollution control requirements established by the city or other responsible agency to
eliminate or reduce pollutants entering the city storm water conveyance system. BMPs shall be
complied with throughout the life of the activity.
■ Storm Water Pollution Prevention Plan. When the enforcement official determines that a
business or business-related activity causes or may cause an illegal discharge to the storm water
conveyance system then the enforcement official may require the business to develop and
implement a SWPPP. Businesses which may be required to prepare and implement a SWPPP
include, but are not limited to, those which perform maintenance, storage, manufacturing,
assembly, equipment operations, vehicle loading, and/or cleanup activities partially or wholly
out of doors.
■ Coordination with Hazardous Materials Response Plans and Inventory. Any activity subject to
the hazardous materials inventory and response program, pursuant to Chapter 6.95 of the
California Health and Safety Code, shall include provisions for compliance with this chapter in its
hazardous materials response plan, including prohibitions of unlawful non-storm water
discharges and illegal discharges, and provisions requiring the use of BMPs to reduce the
discharge of pollutants in storm water.
■ Impervious Surfaces. Persons owning or operating a parking lot or an impervious surface
(including, but not limited to, service station pavements or paved private streets and roads)
used for automobile-related or similar purposes shall clean those surfaces as frequently and as
thoroughly as is necessary, in accordance with BMPs, to prevent the discharge of pollutants to
the city storm water conveyance system. Sweepings or cleaning residue from parking lots or
impervious surfaces shall not be swept or otherwise made or allowed to go into any storm water
conveyance, gutter, or roadway, but must be disposed of in accordance with regional solid
waste procedures and practices.
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■ Compliance with NPDES Permit for Storm Water Discharges. Each discharger subject to any
NPDES permit for storm water discharges shall comply with all requirements of such permit.
The Chula Vista Development Storm Water Manual is incorporated into this ordinance by reference. The
ordinance states that no land owner or development project proponent in Chula Vista shall receive any
city permit or approval for land development activity or significant redevelopment activity unless the
project meets or will meet the requirements of the manual.
c. City of Chula Vista General Plan
The Chula Vista General Plan Public Facilities and Services and Environmental Elements address reliable
drainage facilities and the protection of water quality. The Public Facilities and Services Element includes
objectives to increase efficiencies in handling storm water runoff through use of alternative technologies
(Objective PFS 2). Additionally, Objective E 2 in the Environmental Element is to protect and improve
water quality within surface water bodies and groundwater resources within and downstream of Chula
Vista.
d. Zoning Code and Growth Management Ordinance
Zoning Code Section 19.80.030 is intended to ensure that new development would not degrade existing
public services and facilities below acceptable standards for storm water collection and other public
services. The preparation of the PFFP is required in conjunction with the preparation of the SPA Plan for
the project to ensure that the development of the project is consistent with the overall goals and
policies of the General Plan. Similarly, Section 19.09 (Growth Management) provides policies and
programs that tie the pace of development to the provision of public facilities and improvements.
Section 19.09 H specifically requires that: 1) storm water flows and volumes shall not exceed city
engineering standards as set forth in the subdivision manual and 2) the GMOC shall annually review the
performance of the city storm drain system to determine its ability to meet the goals and objectives of
the subdivision manual. Section 19.09 also requires a PFFP and the demonstration that public services
meet the GMOC quality of life threshold standards. The analysis of storm drain systems provided in this
section, along with the PFFP to ensure funding for any needed expansion of services, confirm that storm
drain systems will be provided commensurate with development and demand.
B. Hydrological Setting
The project is located within the Otay Hydrologic Unit, which encompasses the Otay River watershed.
The Otay River watershed encompasses approximately 160 square miles in southwest San Diego County
and is one of the three hydrologic units that discharge to San Diego Bay. The watershed consists largely
of unincorporated areas in the County of San Diego, but also includes portions of the cities of Chula
Vista, Imperial Beach, Coronado, National City, and San Diego. From east to west, the watershed is made
up of the Coronado, Otay Valley, and Dulzura hydrologic areas. Village 8 West is within the Otay Valley
hydrologic area (Basin #910.20). The major inland hydrologic features, Upper and Lower Otay Lakes, are
two water supply reservoirs that also provide important habitat and recreational opportunities. Village 8
West is located downstream of the Otay Lakes. San Diego Bay, located west of Village 8 West, and Otay
River, located south of Village 8 West, are the other major water bodies in the watershed.
Approximately 36 square miles of the watershed are within MSCP conservation areas (Project Clean
Water 2011).
The receiving waters of Village 8 West are Wolf Canyon, Otay River, and the San Diego Bay. Drainage
from Village 8 West flows to either Wolf Canyon or directly to Otay River. Wolf Canyon is a tributary to
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Otay River, which is a tributary to San Diego Bay. Wolf Canyon is located approximately 0.4 mile west of
Village 8 West. Otay River is located approximately 0.6 mile south of Village 8 West. San Diego Bay is
located approximately 8.6 miles west of Village 8 West.
1. On-site Hydrology
The site is currently composed of three drainage areas with three distinct discharge points. The three
drainage areas are shown in Figure 5.11-1. Drainage areas A and B, which encompass the southern and
northeastern areas of Village 8 West, drain southwesterly toward outlet points along the southern
boundary of the project. Drainage Area A is an 83.9-acre drainage area and Drainage Area B is a 127.1-
acre drainage area. Drainage Area B receives off-site flow from Village 7. Flow through these drainage
areas consists of natural channel flow. The flow from Drainages Areas A and B exit the project boundary
by way of natural channel flow and continues southwesterly along the natural channel to Otay River.
Drainage Area C, which encompasses the northwest area of Village 8 West, drains westerly toward an
outlet point along the western boundary of the project. Drainage Area C is a 183.6-acre drainage area
composed of 89.6 acres of off-site flow and 94.0 acres of on-site flow. This basin receives off-site flow
from Otay Ranch Village 7. Flow through the drainage area consists of natural channel flow. This flow
exits the project boundary and continues southwesterly along the natural channel to Wolf Creek, which
is a tributary to Otay River.
2. Water Quality
a. Surface Water Quality
The Porter-Cologne Act establishes a comprehensive program for the protection of beneficial uses of the
waters of the state. California Water Code Section 13050(f) describes the beneficial uses of surface and
ground waters that may be designated by the state or regional board for protection as follows:
“Beneficial uses of the waters of the state that may be protected against quality degradation include,
but are not necessarily limited to, domestic, municipal, agricultural and industrial supply; power
generation; recreation; aesthetic enjoyment; navigation; and preservation and enhancement of fish,
wildlife, and other aquatic resources or preserves.” Twenty-three beneficial uses are now defined
statewide and are designated within the San Diego Region. The complete list of the beneficial uses and
their definitions for Otay River, Wolf Canyon, and San Diego Bay are provided in the water quality report
in Appendix I1. On October 25, 2006, the SWRCB approved the 303(d) list. Subsequently on November
30, 2006, the EPA approved the SWRCB’s inclusion of all waters and pollutants identified for the San
Diego region in its 2006 List of Water Quality Limited Segments. Within the Otay Hydrologic Unit, the
San Diego Bay is impaired for pollution from organic compounds. Wolf Canyon and Otay River are not on
the 303(d) list.
b. Groundwater
Groundwater in the Otay Valley hydrologic area has been identified for the following beneficial uses:
municipal and domestic water supply, agricultural water supply, and industrial service water supply.
However, active springs or surface seeps have not been observed on Village 8 West. It is possible that
seasonal groundwater associated with precipitation intermittently occurs in on-site drainages or trapped
along joints or rock beds, especially in the Santiago Peak Volcanics rock formation (Advanced
Geotechnical Solutions, Inc. 2010). This rock formation occurs in the southwest portion of the project
site.
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Thresholds of Significance
Based on Appendix G of the CEQA Guidelines, impacts regarding hydrology and water quality would be
significant if the project would:
■ Threshold 1: Violate any water quality standards or waste discharge requirements, including
City of Chula Vista engineering standards for storm water flows and volumes.
■ Threshold 2: Substantially deplete groundwater supplies or interfere substantially with
groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of
the local groundwater table level (e.g., the production rate of pre-existing nearby wells would
drop to a level which would not support existing land uses or planned uses for which permits
have been granted).
■ Threshold 3: Substantially alter the existing drainage pattern of the site or area, including
through the alteration of the course of a stream or river, in a manner, which would result in
substantial erosion or siltation on or off the site or City of Chula Vista Engineering Standards for
storm water flows and volumes.
■ Threshold 4: Substantially alter the existing drainage pattern of the site or area, including
through the alteration of the course of a stream or river, or substantially increase the rate or
amount of surface runoff in a manner which would result in flooding on or off the site.
■ Threshold 5: Create or contribute runoff water, which would exceed the capacity of existing or
planned storm water drainage systems or provide substantial additional sources of polluted
runoff.
■ Threshold 6: Otherwise substantially degrade water quality.
■ Threshold 7: Place housing within a 100-year flood hazard area as mapped on a federal Flood
Hazard Boundary or Flood Insurance Rate Map or other flood hazard delineation map.
■ Threshold 8: Place structures within a 100-year flood hazard area which would impede or
redirect flood flows.
■ Threshold 9: Be inconsistent with General Plan, GDP or other objectives and policies regarding
water quality thereby resulting in a significant physical impact.
■ Threshold 10: Expose people or structures to a significant risk of loss, injury or death involving
flooding, including flooding as a result of the failure of a levee or dam.
■ Threshold 11: Result in a substantial increase in risk of exposure to inundation by seiche,
tsunami, or mudflow.
0 225 450
Feet ±Source: Hale Engineering 2012
OTAY RANCH VILLAGE 8 WEST EIR
EXISTING DRAINAGE AREAS
FIGURE 5.11-1
Off-site Facilities
Corridor/Greenbelt
Trail Connection
Off-site Facilities
Corridor/Greenbelt
Trail Connection
No Scale
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5.11.2 Impact Analysis
A. Threshold 1: Violate any water quality standards or waste discharge
requirements, including City of Chula Vista Engineering Standards for storm
water flows and volumes.
1. Construction
The project would result in sources of polluted runoff during construction which would have short -term
impacts on surface water and groundwater quality through activities such as demolition, clearing and
grading, excavation of undocumented fill materials, stockpiling of soils and materials, concrete pouring,
painting, and asphalt surfacing. Construction activities would involve various types of equipment such as
dozers, scrapers, graders, loaders, compactors, dump trucks, cranes, water trucks, and concrete mixers.
Additionally, soils and construction materials are typically stockpiled outdoors.
Pollutants associated with construction would degrade water quality if they were washed by storm
water or non-storm water into surface waters. Sediment is often the most common pollutant associated
with construction sites because of the associated earth-moving activities and areas of exposed soil.
Sediment that is washed off site can result in turbidity in surface waters, which can impact aquatic
species. In addition, when sediment is deposited into receiving water it can smother species, alter the
substrate and habitat, and alter the drainage course. Hydrocarbons such as fuels, asphalt materials, oils,
and hazardous materials such as paints and concrete slurries discharged from construction sites could
also impact aquatic plants and animals downstream. Debris and trash could be washed into existing
storm drainage channels to downstream surface waters and could impact aquatic wildlife, wetland or
riparian habitat and aesthetic value. Construction activities would potentially result in a significant
change in local receiving water quality if BMPs are not put in place to prevent polluted runoff from
entering the Wolf Canyon or Otay River.
The NPDES General Construction Permit program requires a SWPPP to be prepared for the project prior
to construction. For coverage by the General Construction Permit, the applicant is required to submit to
the SWRCB a NOI and develop a SWPPP describing BMPs to be used to prevent discharge of sediment
and other pollutants. The BMPs may include, but are not limited to, silt fences, fiber rolls, gravel bags,
temporary desilting basins, velocity check dams, temporary ditches or swales, storm water inlet
protection, or soil stabilization measures such as erosion control mats. Prior to the issuance of grading
permits, the SWPPP would be required to be prepared to the satisfaction of the City Engineer and the
Director of Public Works.
Additionally, all construction activities would comply with the Chula Vista Development Storm Water
Manual. In addition to the requiring compliance with a project-specific SWPPP and General Construction
Permit, the manual requires proper inspection, monitoring, and maintenance of construction BMPs
during dry and wet weather conditions. A qualified person who is trained and competent in the use of
BMPs shall be on site daily, although not necessarily full time, to evaluate the conditions of the site with
respect to storm water pollution prevention.
In accordance with the manual, the City of Chula Vista will evaluate the adequacy of the owner’s/
contractor’s site management for storm water pollution prevention, inclusive of BMP implementation
on construction sites based on performance standards for storm water BMPs. Ineffective BMPs would
be replaced with more effective BMPs. The manual lists specific BMPs that must be implemented
seasonally during wet and dry season. Additionally, the manual sets limitations specific to grading
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activities. The area that can be cleared or graded and left exposed at one time is limited to the amount
of acreage that the owner/contractor can adequately protect prior to a predicted rainstorm. At no time
shall the disturbed soil area on the site be more than 100 acres for an individual grading permit or a
combination of grading permits under an associated TM. Construction sites that pose an exceptional
threat to water quality from sediment are required to implement advanced treatment to eliminate or
minimize the discharge of sediment from the construction site to storm drainage systems and/or
receiving waters. The project would be considered an exceptional threat to water quality because it
would disturb more than five acres; therefore, advanced treatment would be implemented for the
project in accordance with the manual requirements.
Compliance with applicable regulatory requirements described above, which is prescribed as mitigation
for the project, would ensure that potentially significant water quality impacts during on-site
construction would be reduced to a less than significant level.
2. Operation (Post-Construction)
Equipment and hazardous materials associated with construction activities would be removed from the
project site after buildout is complete, which would reduce the potential for pollutants to be discharged.
However, there are multiple pollutants associated with operations of land uses proposed in Village 8
West. The pollutants of concern for the project are listed in Table 5.11-1 and are described below.
Table 5.11-1 Pollutants Potentially Generated by the Project
Priority Project Categories
General Pollutant Categories(1) Sediments Nutrients Heavy Metals Organic Compounds Trash & Debris Oxygen Demanding Substances Oils & Grease Bacteria & Viruses Pesticides Detached Residential X X X X X X X
Attached Residential X X X P(2) P(3) P X
Commercial (> 1 ac) P(2) P(2) P(3) X P(6) X P(4) P(6)
Auto Repair Shops X X(5)(6) X X
Restaurants X X X X
Hillside Development (>5,000 S.F.) X X X X X X
Parking Lots P(2) P(2) X X P(2) X P(2)
Gasoline Outlets X X X X X
Streets X P(2) X X(5) X P(6) X
(1) X = Anticipated Pollutants, P = Potential Pollutants
(2) A potential pollutant if landscaping exists on site
(3) A potential pollutant if the project includes uncovered parking areas
(4) A potential pollutant if land use involved food or animal waste products
(5) Including petroleum hydrocarbons
(6) Including solvents
Source: Hale Engineering 2011a.
Sediment. Sediments are soils or other surface materials eroded and then transported or deposited by
the action of wind, water, ice, or gravity. Sediments can increase turbidity, clog fish gills, reduce
spawning habitat, lower young aquatic organisms survival rates, smother bottom dwelling organisms,
and suppress aquatic vegetation growth.
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Nutrients. Nutrients are associated with landscaping, which would occur throughout the project site.
Nutrients are inorganic substances, such as nitrogen and phosphorus. They commonly exist in the form
of mineral salts that are either dissolved or suspended in water. Primary sources of nutrients in urban
runoff are fertilizers and eroded soils. Excessive discharge of nutrients to water bodies and streams can
cause excessive aquatic algae and plant growth. Such excessive production, referred to as cultural
eutrophication, may lead to excessive decay of organic matter in the water body, loss of oxygen in the
water, release of toxins in sediment, and the eventual death of aquatic organisms.
Heavy Metals. Metals are raw material components in non-metal products such as fuels, adhesives,
paints, and other coatings. Primary sources of metal pollution in storm water are typically commercially
available metals and metal products. Metals of concern include cadmium, chromium, copper, lead,
mercury, and zinc. At low concentrations naturally occurring in the soil, metals are not toxic. However,
at higher concentrations, certain metals can be toxic to aquatic life. Humans can be impacted from
contaminated ground water resources, and bioaccumulation of metals in fish and shellfish.
Organic Compounds. Organic compounds are carbon-based, commercially available or naturally
occurring, and are found in pesticides, solvents, and hydrocarbons. Organic compounds can, at certain
concentrations, indirectly or directly constitute a hazard to life or health. When rinsing off objects, toxic
levels of solvents and cleaning compounds can be discharged to storm drains. Dirt, grease, and grime
retained in the cleaning fluid or rinse water may also absorb levels of organic compounds that are
harmful or hazardous to aquatic life.
Trash and Debris. Trash (such as paper, plastic, polystyrene packing foam, and aluminum materials) and
biodegradable organic matter (such as leaves, grass cuttings, and food waste) are general waste
products. The presence of trash and debris may have a significant impact on the recreational value of a
water body and aquatic habitat. Excess organic matter can create a high biochemical oxygen demand in
a stream and thereby lower its water quality. In addition, in areas where stagnant water exists, the
presence of excess organic matter can promote septic conditions resulting in the growth of undesirable
organisms and the release of odorous and hazardous compounds such as hydrogen sulfide.
Oxygen Demanding Substances. This category includes biodegradable organic material as well as
chemicals that react with dissolved oxygen in water to form other compounds. Proteins, carbohydrates,
and fats are examples of biodegradable organic compounds. Compounds such as ammonia and
hydrogen sulfide are examples of oxygen-demanding compounds. The oxygen demand of a substance
can lead to depletion of dissolved oxygen in a water body and possibly the development of septic
conditions.
Oil and Grease. Oil and grease are characterized as high-molecular weight organic compounds. The
primary sources of oil and grease are petroleum hydrocarbon products, motor products from leaking
vehicles, esters, oils, fats, waxes, and high molecular-weight fatty acids. Introduction of these pollutants
to the water bodies are very possible due to the wide uses and applications of some of these products in
municipal, residential, and commercial areas. Elevated oil and grease content can decrease the aesthetic
value of the water body, as well as the water quality.
Bacteria and Viruses. Bacteria and viruses are ubiquitous microorganisms that thrive under certain
environmental conditions. Their proliferation is typically caused by the transport of animal or human
fecal wastes from the watershed, such as pet waste. Water, containing excess bacteria and viruses can
alter the aquatic habitat and create a harmful environment for humans and aquatic life. Also, the
decomposition of organic waste causes increased growth of undesirable organisms in the water.
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Pesticides. Pesticides (including herbicides) are chemical compounds commonly used to control
nuisance growth or prevalence of organisms. Excessive application of a pesticide may result in runoff
containing toxic levels of its active component.
Generally, these constituents can be referred to as non-point source pollutants. As stated in the
Development Storm Water Manual, any anticipated pollutants potentially generated by the project that
are on the 303(d) list are considered pollutants of concern. The San Diego Bay is impaired for organic
compounds. Therefore, organic compounds are a pollutant of concern associated with the project.
Increased runoff from the development of future land uses as designated in the project area, and an
associated increase in impervious surfaces, would potentially result in the contribution of non-point
source pollution, including organic compounds, into Wolf Canyon and Otay River, and ultimately San
Diego Bay, that would degrade water quality.
3. Operational Best Management Practices
As required by the development storm water manual, implementation of the project would minimize
impacts on receiving water quality by incorporating post-construction BMPs into project design,
including low impact development site design, source control, and treatment control BMPs.
Implementation of the SPA Plan and TM is subject to site design and source control BMPs that apply to
the entire project area, as outlined in Section 3.6.2 of the Development Storm Water Manual.
Additionally, individual land uses types are subject to additional requirements specific to the activities
associated with that land use.
Impervious surfaces and associated runoff would increase with urban development of Village 8 West.
However, development of the project would be designed to minimize directly connected impervious
surfaces and to promote infiltration using low impact development techniques. The BMPs identified in
the water quality report would also minimize, to the maximum extent practicable, the introduction of
pollutants and conditions of concern into the storm water conveyance system. The water quality report
identifies the following low impact development and site design BMPs that would be implemented for
the project:
■ Minimize the Impervious Footprint
Incorporate alternative street layouts to reduce road networks. La Media Road, a 4-lane
major road is designed with a 94 feet right-of-way rather than the typical 100 foot right-of-
way.
Provide public safety and a walkable environment for pedestrians is not compromised,
constructing streets and sidewalks to the minimum widths. All sidewalks are constructed to
the minimum width.
Whenever practical, preserve existing native trees and shrubs to maximize canopy
interception and water conservation. A total of 21.1 acres of Village 8 West is to remain
undeveloped and set aside as a combination of open space and MSCP.
Plant native or drought tolerant trees and large shrubs to maximize canopy interception and
water conservation.
Minimize the use of impervious surfaces, such as decorative concrete, in the landscape
design. Landscaping within the parkways throughout the project also serve as bioretention
BMPs and contain minimal use of impervious surfaces.
5.11 Hydrology and Water Quality
Otay Ranch Village 8 West EIR
CV EIR 10-03; SCH No. 2010062093 Page 5.11-13
City of Chula Vista
November 2013
■ Conserve Natural Resources and Areas
Utilize natural drainage systems to the maximum extent practicable. The site shall outlet to
three existing discharge points. Two of the three points discharge directly to the Otay River;
the third point discharges to an existing drainage path in Wolf Canyon that ultimately
outlets to the Otay River as well.
Minimize soil compaction.
■ Minimize Directly Connected Impervious Areas
Where landscaping is proposed, drain impervious sidewalks, pathways, and trails into
adjacent landscaping prior to discharging to the storm drain. Specifically, all sidewalks within
the proposed parkways are designed to drain to the adjacent landscaped areas prior to
discharging to the storm drain.
■ Protect Slopes and Channels
Minimize disturbances to natural drainages. The project utilizes existing discharge points to
minimize impacts to natural drainages. A regional analysis for the overall Otay development
directly tributary to the Otay River is being undertaken to demonstrate that an increase in
peak 100-year event flows will not have a negative effect on the downstream receiving
waterway. This regional analysis will also investigate hydromodification impacts upon the
Otay River to address current hydromodification management plan criteria.
Convey runoff safely from the tops of slopes. Runoff is collected within concrete drainage
ditches located at the tops of the proposed slopes and transported safely to the proposed
storm drain system.
Vegetate slopes with native or drought tolerant vegetation
Control and treat flows in landscaping and/or other controls prior to reaching existing
natural drainage systems. The project incorporates bioretention BMPs in the median along
La Media Road and parkways throughout the site. These BMPs shall treat flows prior to their
entrance to the proposed storm drain system and subsequent discharge to the existing
natural drainage systems.
Install energy dissipaters, such as rip rap, at the outlets of new storm drains, culverts, or
conduits that enter unlined channels in accordance with applicable specifications to
minimize erosion. Energy dissipaters shall be installed at each of the three outlet points in
such a way as to minimize impacts to receiving waters.
■ Use natural site design features to the maximum extent practicable
Incorporate alternative street layouts to reduce road networks. La Media Road, a 4-lane
major road is designed with a 94 foot right-of-way rather than the typical 100 foot right-of-
way.
Whenever practical, preserve existing native trees and shrubs to maximize canopy
interception and water conservation. A total of 21.1 acres of Village 8 West is to remain
undeveloped and set aside as a combination of open space and MSCP.
Plant native or drought tolerant trees and large shrubs to maximize canopy interception and
water conservation.
Minimize soil compaction.
5.11 Hydrology and Water Quality
Otay Ranch Village 8 West EIR
CV EIR 10-03; SCH No. 2010062093 Page 5.11-14
City of Chula Vista
November 2013
Utilize natural drainage systems to the maximum extent practicable. The site shall outlet to
three existing discharge points. Two of the three points discharge directly to the Otay River;
the third point discharges to an existing drainage path in Wolf Canyon that ultimately
outlets to the Otay River as well.
Where landscaping is proposed, drain impervious sidewalks, pathways, and trails into
adjacent landscaping prior to discharging to the storm drain. Specifically, all sidewalks within
the proposed parkways are designed to drain to the adjacent landscaped areas prior to
discharging to the storm drain.
Source-control BMPs are activities, practices, and procedures that are designed to prevent urban runoff
pollution. These measures either reduce the amount of runoff from the site or prevent contact between
potential pollutants and storm water. Source-control BMPs are often the best method to address non-
storm (dry-weather) flows. The following source-control BMPs would be required for implementation of
the SPA Plan and TM.
■ Provide Storm Drain System Stenciling and Signage. Storm drain stencils are highly visible
source control messages, typically placed directly adjacent to storm drain inlets. The stencils
contain a brief statement that prohibits the dumping of improper materials into the urban
runoff conveyance system. Graphical icons, either illustrating anti-dumping symbols or images
of receiving water fauna, are effective supplements to the anti-dumping message. The project
design shall include the following requirements:
- Provide stenciling or labeling of all storm drain inlets and catch basins with the project area
with prohibitive language (such as "NO DUMPING - I LIVE DOWNSTREAM") and/or graphical
icons to discourage illegal dumping.
- Maintaining legibility of stencils and signs.
■ Use Efficient Irrigation Systems and Landscape Design, and Employ Integrated Pest
Management Principles. The project shall design the timing and application methods of
irrigation water to minimize the runoff of excess irrigation water into the storm water
conveyance system. In compliance with the Water Conservation in Landscaping Act, the
following methods to reduce excessive irrigation runoff shall be considered, and incorporated
and implemented where determined applicable and feasible by the City of Chula Vista:
- Employ rain shutoff devices to prevent irrigation after precipitation.
- Design irrigation systems to each landscape area's specific water requirements
- Use flow reducers or shutoff valves triggered by a pressure drop to control water loss in the
event of broken sprinkler heads or lines.
■ Incorporate Requirements Applicable to Individual Priority Project Categories
The project shall meet all applicable BMP requirements identified in Section 3.6.2 of the
Chula Vista Development Storm Water Manual.
The project shall select a single or combination of storm water BMPs that maximize
pollutant removal efficiency for the particular primary pollutants of concern, which are
organic compounds. BMPs with a high efficiency for organic compound removal are
bioretention facilities, setting basins (dry ponds), wet ponds and wetlands, low impact
development, and media filters.
5.11 Hydrology and Water Quality
Otay Ranch Village 8 West EIR
CV EIR 10-03; SCH No. 2010062093 Page 5.11-15
City of Chula Vista
November 2013
Post-construction treatment control BMPs provide treatment for storm water emanating from Village 8
West. These BMPs are also known as structural BMPs. Implementation of NPDES General Permit
requirements include the use of post-construction BMPs that will remain in service to protect water
quality throughout the life of the project. Structural BMPs are an integral element of post-construction
storm water management and include storage, filtration, and infiltration practices. BMPs have varying
degrees of effectiveness versus different pollutants of concern. The pollutant of concern for the project
is organic compounds. Other anticipated pollutants for the project are sediments, nutrients, heavy
metals, trash and debris, and oil and grease. Bioretention facilities are a BMP that has a high pollutant
removal efficiency for organic compounds, meets the maximum extent practicable standard for all other
anticipated pollutants, is relatively inexpensive to construct and maintain, can be incorporated into the
proposed landscaping, has a low probability of ground water contamination, and requires a relatively
small footprint for treatment. Therefore, bioretention facilities would be incorporated into the project in
the form of bioretention tree wells and bioretention swales. The bioretention integrated management
practices would be designed to meet the area-based treatment control BMP standards as set forth in
Section 3.6.2.C of the Chula Vista Development Storm Water Manual.
Bio-retention areas would be incorporated into all single-family, detached residential lots and
bioretention tree wells would be located along roadways. The bioretention tree wells necessary to
provide treatment for runoff from the small portion of Otay Valley Road that drains easterly to Village 8
East would treat runoff from Village 8 West prior to the confluence with the Village 8 East storm drain
system. The bioretention areas on the residential lots would be tied to the bioretention swales within
the roadways via perforated pipe. Each bioretention BMP shall be fully operational prior to the use of
any dependent phase of development. In the event that interim storm water BMPs are deemed
necessary, said interim BMPs shall proved equivalent or greater treatment than is required per the
design criteria set forth in the development storm water manual. Such interim BMPs shall remain in use
until the permanent structural BMPs are operational.
Lot-specific structural BMPs would also be implemented as lots are developed that would meet the
numeric sizing standards set forth in the Chula Vista Development Storm Water Manual. The proposed
off-site utility access road consists of a 12-foot wide asphalt paved roadway edged on either side with
permeable gravel. Given the minimal traffic expected on this roadway and the lack of run-on onto the
roadway, no bioretention BMPs are necessary or proposed along this portion of project roadways.
Rather, the permeable gravel shall provide adequate infiltration of the minor runoff due to the access
roadway. BMP design calculations are provided in the water quality report, provided as Appendix I1 to
this EIR. The report also includes an inspection, operation, and maintenance plan for the BMPs to ensure
their effectiveness during operation of the project. Implementation of the BMPs outlined in the water
quality report would ensure that mass grading of Village 8 West and development of infrastructure
would comply with the manual.
In conclusion, with implementation of the proposed storm water BMPs, including the BMPs identified in
the water quality report that are prescribed as mitigation measures for the project, potentially
significant impacts to downstream drainage facilities identified as conditions of concern in this analysis
would be reduced to a less than significant level.
5.11 Hydrology and Water Quality
Otay Ranch Village 8 West EIR
CV EIR 10-03; SCH No. 2010062093 Page 5.11-16
City of Chula Vista
November 2013
B. Threshold 2: Substantially deplete groundwater supplies or interfere
substantially with groundwater recharge such that there would be a net
deficit in aquifer volume or a lowering of the local groundwater table level
(e.g., the production rate of pre-existing nearby wells would drop to a level
which would not support existing land uses or planned uses for which permits
have been granted).
Groundwater on Village 8 West is seasonal and results from rainwater or runoff that is trapped along
joints or rock beds. The project does not propose to use groundwater during construction or operation.
Operation is anticipated to result in an increase in groundwater because runoff from watering for
landscaping and other activities would seep into groundwater through infiltration basins and low impact
development BMPs. This increase would be beneficial by raising the water table slightly. Increased
groundwater would be expected to improve the quality of water slightly in the watershed because
runoff from the project site would be treated by the basins and BMPs and would dilute existing
pollutants in groundwater (Advanced Geotechnical Solutions, Inc. 2013). Therefore, development of
Village 8 West would not interfere with groundwater recharge or deplete groundwater supplies such
that there would be a net deficit in aquifer volume of lowering of the local groundwater table. This
impact would be less than significant.
C. Threshold 3: Substantially alter the existing drainage pattern of the site or
area, including through the alteration of the course of a stream or river, in a
manner, which would result in substantial erosion or siltation on or off the site
or Chula Vista Engineering Standards for storm water flows and volumes.
As shown in Figure 5.6-3, Jurisdictional Delineation Results, several natural drainages traverse the
project site. Otay River is located approximately one-quarter mile south of the project site. However,
there are no streams or rivers on the project site or immediately adjacent to Village 8 West. No
alteration of the course of a stream or river would result from implementation of Village 8 West.
However, natural channel flow occurs on site and development of Village 8 West would alter the
existing drainage pattern of the site, as discussed below.
1. Post-Project Drainage Conditions
A drainage study has been prepared to determine the drainage system requirements to support the
proposed development. As discussed above under the discussion of On-site Hydrology, Village 8 West is
currently composed of three drainage areas that flow either directly to Otay River or to Wolf Creek,
which is a tributary to Otay River. Following implementation of the project, the site would be divided
into five drainage basins. The proposed drainage system is shown in Figure 3-12, Hydrologic Basins and
Proposed Drainage System. The northern portion of the site would drain to Wolf Canyon via two of five
proposed storm drain systems. The other three storm drain systems would drain the remainder of the
site south to the Otay River. The remaining project areas that are not included in one of these five
drainage areas consist of areas that would remain as open space, including the Preserve. No change in
the existing natural drainage pattern is proposed for the open space areas; therefore, the project would
not alter the existing drainage pattern in these areas.
a. Post-Project Drainage Area 1
Post-project Drainage Area 1 is a 37-acre drainage area in the southwest corner of Village 8 West in the
Neighborhood Edge Zone. Proposed improvements within this drainage area include mass grading of
5.11 Hydrology and Water Quality
Otay Ranch Village 8 West EIR
CV EIR 10-03; SCH No. 2010062093 Page 5.11-17
City of Chula Vista
November 2013
pads and roadways within Planning Area P for future development. Development proposed for Planning
Area P consists of detached single-family homes. Runoff in this drainage area would be transported to
the proposed storm drain system via proposed catch basins and curb inlets located at intervals within
the proposed roadways. This storm drain system would ultimately confluence with areas Drainage Areas
2 and 3 and flows would be conveyed southerly through the storm drain system that follows the Otay
Valley Regional Park trail connection alignment to drain directly to the Otay River.
b. Post-Project Drainage Area 2
Post-project Drainage Area 2 is a 42-acre drainage area in the southeast corner of Village 8 West in the
Neighborhood General, Neighborhood Edge Zones, and the Neighborhood Park. Proposed
improvements within this area include mass grading of building pads and roadways within Planning
Areas T, U, and V. Future development proposed for these planning areas consists of detached and
attached single-family homes and a neighborhood park that would include amenities such as small-scale
multi-purpose play fields, sport courts, playgrounds, and picnic areas. Runoff in this drainage area would
be transported to the proposed storm drain system via proposed curb inlet located at intervals within
the drainage area. This storm drain would ultimately confluence with drainage area 1 and flows would
be conveyed southerly through the storm drain system that follows the Otay Valley Regional Park trail
connection alignment to drain directly to the Otay River.
c. Post-Project Drainage Area 3
Post-project Drainage Area 3 is a 100-acre drainage area composed of 20.1 acres of off-site flow and
82.7 acres of on-site flow from the central and eastern areas of Village 8 West. This area includes the
Neighborhood Center and Neighborhood General Zones, a portion of Town Center, and the Community
Purpose Facility. Proposed improvements within this area include mass grading of pads and roadways
within Planning Areas M, O, Q, R, and S for future development. These planning areas are proposed for
single-family development, multi-family residences, an elementary school, mixed-use development, and
the CPF.
The basin receives off-site flow from Village 7. The quantity of off-site flow was previously determined in
Drainage Study for McMillin Village 7 Vista Verde prepared by Rick Engineering. Runoff from this
drainage area would be transported to the proposed storm drain system via proposed curb inlet located
at intervals within the proposed roadways. This storm drain would ultimately confluence with Drainage
Area 1 and flows would be conveyed southerly through the storm drain system. The southerly drainage
system extends off site along the Otay Valley Regional Park trail connection alignment to the Otay River
bottom to avoid potential finger canyon erosion on the slope between the southern edge of Village 8
West and Otay River. A USBR Type IV impact basin and 20-inch rip rap energy dissipater would be used
to decrease the velocity of flows from Drainage Areas 1, 2, and 3.
A southeast segment of Otay Valley Road discharges to the Village 8 East site. Flows from this area
would be accounted for in the design of the drainage system for Village 8 East. Until development of
Village 8 East, flows from this area of Village 8 West would flow directly to Otay River.
d. Post-Project Drainage Area 4 and Basin P
Post-project Drainage Area 4 is a 144-acre drainage area in the northeast corner of the site that consists
of the Town Center. This area is composed of 89.6 acres of off-site flow and 54.0 acres of on-site flow.
Proposed improvements within this drainage area would include mass grading of pads and portions of
La Media Road, Street A, and Main Street within Planning Areas B, C, D, E, and F, and portions of
5.11 Hydrology and Water Quality
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CV EIR 10-03; SCH No. 2010062093 Page 5.11-18
City of Chula Vista
November 2013
Planning Areas G and H. These planning areas are proposed for mixed-use development, multi-family
residences, the Town Square, and a middle school.
This basin receives off-site flow from Otay Ranch Village 7. The quantity of off-site flow was determined
in the Addendum Rough Grading Hydrology Study for Otay Ranch Village 7 prepared by Hunsaker
Engineering. Runoff for this drainage area would be transported to the proposed storm drain system via
proposed catch basins and curb inlets located at intervals within the proposed roadways. This storm
drain system would confluence with Drainage Area 5 and Basin P. Basin P encompasses Planning Area A,
which is proposed to be development as a community park and is not included in the overall drainage
design for the project. The Community Park would be self-treating because the large areas of
landscaping and open parkland would detain and treat the runoff from the limited impervious
development that would occur inside the park. Discharge from Drainage Areas 4 and 5 would outlet
through energy dissipaters, including an impact basin and rip rap, and flow westerly to a natural
drainage in Wolf Canyon. Basin P would also flow to Wolf Canyon.
e. Post-Project Drainage Area 5
Post-Project Drainage Area 5 is a 59-acre drainage area that encompasses the central and western
portions of Village 8 West including the Town Center and Neighborhood Center Zones. Proposed
improvements within this drainage area include mass grading of pads and portions of La Media Road,
Main Street, and other roadways within Planning Areas I, J, L, and N, and portions of Planning Areas G
and H. Future development proposed for these planning areas included the Town Square, mixed-use
development, detached single-family residences, and multi-family residences.
Runoff from this drainage area would be transported to the proposed storm drain system via proposed
catch basins and curb inlets located at intervals within the proposed roadways. This storm drain system
would confluence with Drainage Area 4 and ultimately outlet to an existing natural drainage channel
running westerly from Village 8 West to Wolf Canyon.
2. Post-Project Drainage Flows
The Advanced Engineering Software Rational Method computer program based on the 2002 Chula Vista
Subdivision Manual, and the County of San Diego Hydrology Manual Methodology were used to
determined pre- and post-project flow rates. Refer to the drainage study in Appendix I2 for additional
information regarding the study methodology. Pre- and post-project flows to Wolf Canyon are shown in
Table 5.11-2 and pre- and post-project flows to Otay River are shown in Table 5.11-3.
Table 5.11-2 Pre- and Post-Project Drainage to Wolf Canyon
Storm Event
Pre-Project
(cubic feet per
second)
Post Project (cubic feet per second)
Flow Into Detention
Basin (Drainage
Areas 4 & 5)
Flow Out of Detention
Basin (Drainage
Areas 4 & 5) Basin P
Total Basin P and
Flow out of
Detention Basin
2-Year Storm 155.6 243.8 42.6 18.4 61
10-Year Storm 246.0 380.1 136.4 28.7 165.1
25-Year Storm 261.2 402.8 157.2 30.5 187.7
50-Year Storm 322.3 493.8 241.2 37.4 278.6
100-Year Storm 368.3 559.3 313.4 42.4 355.8
Source: Hale Engineering 2011b
5.11 Hydrology and Water Quality
Otay Ranch Village 8 West EIR
CV EIR 10-03; SCH No. 2010062093 Page 5.11-19
City of Chula Vista
November 2013
Table 5.11-3 Pre- and Post-Project Drainage to Otay River
Storm Event
Pre-Project
(cubic feet per second)
Post-Project Drainage Areas
1-3 and Otay Valley Road
(cubic feet per second)
Percent Increase from
Pre-Project Conditions
2-Year Storm 118.6 155.5 31%
10-Year Storm 191.2 243.9 28%
25-Year Storm 203.5 258.7 27%
50-Year Storm 253.4 319.9 26%
100-Year Storm 291.4 362.5 24%
Source: Hale Engineering 2011b
As shown in Table 5.11-2, the proposed on-site hydromodification detention basin within the storm
drain system would reduce post-construction flows discharging into Wolf Canyon to less than existing
flows. Refer to the hydromodification study in Appendix I3 for detail on the design of the detention
basin. Therefore, the project would not increase the rate of erosion or siltation off site. Refer to the
drainage study in Appendix I2 for additional information regarding the Advanced Geotechnical Solutions
Review. The project would result in less than significant impacts related to alteration of the existing
drainage pattern of Wolf Canyon.
As shown in Table 5.11-3, the post-project peak flow from the projects to Otay River is anticipated to
increase up to approximately 31 percent over existing flows from Village 8 West. However, an Otay River
Watershed Assessment Technical Report, prepared in August 2004 by Aspen Environmental Group,
determined that the Savage Dam at the Lower Otay Reservoir impounds runoff from over 60 percent of
the Otay River’s tributary watershed and, as such, the flow capacity for the Otay River downstream of
the dam is approximately 22,000 cubic feet per second for the 100-year storm event. The attenuation
provided by the Savage Dam on 60 percent of the overall watershed reduces flows in the river such that
even with the increase in flows from development downstream of the dam, including flows from Village
8 West, total flow would still be reduced compared to the flows prior to the dam construction.
Detention for any development below the dam would be ineffective as the peak flows fro m these
smaller watersheds would pass well before the reservoir would fill to the point that flows would overtop
the spillway (Hunsaker & Associates 2011). Village 8 West is located downstream of the Savage Dam.
The Otay River Watershed Assessment Technical Report also notes that the existing Otay River
downstream of the dam is starved for sediment and peak flows, stating that an increase in peak flow
would tend to counteract the degradation trends by replacing water impounded by the reservoir. The
peak flows of the river are due mainly to outputs into the river from upstream of Village 8 West, such as
the Otay Reservoir. The post project peak flow for the 100-year storm event would be 362.5 cubic feet
per second, with a peak flow time of 21 minutes. For a 100-year storm event the Otay River has a peak
discharge of 20,161 cubic feet per second and a time of peak flow of 21 hours 5 minutes at the Village 8
outlet point. Therefore, the post-project peak flow would be a minor portion of the total flow within the
Otay River at the project’s discharge point. Additionally, due to differences in peak flow timing, the peak
flows with the river and those from the discharge point would not coincide during the 100-year storm
event. The impact of the increased flow at the project’s discharge point is negligible at peak river flow.
The project is not required to reduce post-project flows to pre-project conditions because Otay River is
exempt from hydromodification requirements. A hydromodification management plan was approved by
the County of San Diego in July 2010. Characteristics of the Otay River, including low gradients,
significant natural peak flow attenuation, and wide floodplain areas result in this system having a low
5.11 Hydrology and Water Quality
Otay Ranch Village 8 West EIR
CV EIR 10-03; SCH No. 2010062093 Page 5.11-20
City of Chula Vista
November 2013
potential for channel erosion. Consequently, the Otay River system is exempt from hydromodification
requirements (see Appendix I1). Therefore, the portion of the project directly tributary to the Otay River
is exempt from the hydromodification requirements and the project is not required to reduce post-
project flows to pre-project conditions. The increase in flows from the project would not result in
substantial erosion or siltation. Additionally, the proposed outlet point from the project site to the Otay
River would include a USBR Type IV Energy Dissipater and additional erosion control provided by a
section of rip rap. The proposed energy dissipater would reduce flow velocity from Village 8 West and
minimize the potential for erosion. The drainage study concluded that the alteration to the existing Otay
River drainage pattern associated with project implementation would result in a less than significant
impact with respect to increases in erosion and siltation.
In conclusion, drainages serving the southern basin would be susceptible to increased erosion resulting
from increased peak flow rates, increased runoff volumes, and duration, which would result in a
potentially significant impact. Implementation of the proposed drainage facilities at construction would
minimize these impacts to a less than significant level. However, mitigation would be required to ensure
that the facilities are implemented and monitored throughout buildout of the project.
D. Threshold 4: Substantially alter the existing drainage pattern of the site or
area, including through the alteration of the course of a stream or river, or
substantially increase the rate or amount of surface runoff in a manner which
would result in flooding on or off the site.
Village 8 West currently consists almost entirely of permeable surfaces. The project, which would
involve the replacement of the permeable surfaces and exposed soils with urban development, would
substantially change the amount of impervious surface area within the project. As discussed under
Threshold 3, site-generated surface water runoff would be directed from Village 8 West to off-site
drainage facilities. The post-project drainage conditions were designed to adequately convey post-
project flows off site during a 100-year storm event. Therefore, the project would not result in flooding
on site. As shown in Table 5.11-2, post-project flows to Wolf Canyon would be less than existing flows.
Therefore, the project would not result in flooding off the project site in Wolf Canyon.
The project would result in an increase in flows to Otay River (see Table 5.11-3). However, as discussed
under Threshold 3, the project’s contribution to peak river flow is negligible. The Otay River has a 100-
year design flow of 20,000 cubic feet per second. The project would result in an increase in runoff during
the 100-year storm of only 71 cubic feet per second. The Savage Dam attenuates regional impacts
downstream of the dam so that the increase in the amount of runoff from Village 8 West would not
result in flooding along the Otay River. The small increase in flows from development of Village 8 West
would not increase the total flow to above pre-dam construction flows. Additionally, due to differences
in peak flow timing, the peak flows with the river and those from the Village 8 West discharge point
would not coincide during the 100-year storm event. Therefore, the project would not substantially
increase the rate or amount of surface runoff that would result in an increase in flooding along Otay
River.
In conclusion, drainages serving the southern basin would be susceptible to increased peak flow rates
and increased runoff volumes, which would result in a potentially significant flooding impact.
Implementation of the proposed drainage facilities at construction would minimize these impacts.
However, mitigation would be required to ensure that the facilities are implemented and monitored
throughout buildout of the project.
5.11 Hydrology and Water Quality
Otay Ranch Village 8 West EIR
CV EIR 10-03; SCH No. 2010062093 Page 5.11-21
City of Chula Vista
November 2013
E. Threshold 5: Create or contribute runoff water, which would exceed the
capacity of existing or planned storm water drainage systems or provide
substantial additional sources of polluted runoff.
As discussed under Threshold 3, a drainage system has been designed for the project with the capacity
to convey post-project flows during the 100-year storm event and includes energy dissipaters to
minimize the potential for erosion. The project would reduce flows to Wolf Canyon and would not result
in an increase in siltation or erosion as a result of increased flows to Otay River. The project would not
result in runoff water that would exceed the capacity of drainage systems. Even though the project
includes features to reduce the amount and rate of runoff to a less than significant level, these features
are also prescribed as mitigation measures to assure implementation and facilitate monitoring through
buildout of the project.
F. Threshold 6: Otherwise substantially degrade water quality.
As discussed under Threshold 1, the project is required to comply with the Chula Vista Development
Storm Water Manual and the General Construction Permit. Implementation of a project-specific SWPPP
during construction in accordance with these regulations would ensure that significant impacts to water
quality would not occur as a result of runoff from Village 8 West. Management, inspections, and
maintenance are required for construction impacts to ensure that BMPs are operating efficiently.
Additionally, as discussed under Threshold 3, a drainage system has been designed for the project with
the capacity to convey post-project flows during the 100-year storm event and includes energy
dissipaters to minimize the potential for erosion. The project would reduce flows to Wolf Canyon and
would not result in an increase in siltation or erosion as a result of increased flows to Otay River. The
BMPs proposed in the water quality report would ensure that runoff associated with development of
infrastructure and mass grading of the site would not result in a substantial source of polluted runoff
that would degrade water quality. The proposed drainage system would not result in an increase in
erosion or siltation off site. However, supplemental water quality studies are required to indentify which
site-specific BMPs identified in the water quality technical report would be necessary for individual
development projects to comply with the manual. Therefore, impacts related to water quality would be
potentially significant.
G. Threshold 7: Place housing within a 100-year flood hazard area as mapped
on a federal Flood Hazard Boundary or Flood Insurance Rate Map or other
flood hazard delineation map, and
Threshold 8: Place structures within a 100-year flood hazard area which would
impede or redirect flood flows.
The 100-year flood hazards boundary of the Otay River, as designated by the Federal Emergency
Management Agency (FEMA), is shown on the proposed drainage plan provided in the Drainage Report
(Appendix I2). Village 8 West is not within a 100-year or 500-year floodplain as mapped by FEMA (DWR
2011), as the flood hazard boundary is located 0.3 mile south of the project site. The southern end
(approximately 100 feet) of the proposed off-site trail and access road would be within the 100-year
flood hazard area; however, the trail does not include any structures or other components for which
flooding would be a hazard. Therefore, the project would not place housing or other structures within a
100-year flood hazard area. No impact would occur.
5.11 Hydrology and Water Quality
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November 2013
H. Threshold 9: Be inconsistent with General Plan, GDP, or other objectives and
policies regarding water quality thereby resulting in a significant physical
impact.
Table 5.11-4 evaluates the consistency of the project with the applicable General Plan objectives and
policies and Table 5.11-5 evaluates the consistency of the project with the applicable GDP goals and
objectives. As shown in Table 5.11-4 and Table 5.11-5, the project would be consistent with the General
Plan and GDP policies that pertain to hydrology and water quality.
Table 5.11-4 Project Consistency with Applicable General Plan Drainage and Water Quality Policies
Applicable Policies Evaluation of Consistency
Objective PFS 2: Increase efficiencies in water use, wastewater
generation and its re-use, and handling of storm water runoff
throughout the city through use of alternative technologies.
Policy PFS 2.2: As part of project construction and design,
assure that drainage facilities in new development incorporate
storm water runoff and sediment control, including state-of-
the-art technologies, where appropriate.
Policy PFS 2.3: In designing water, wastewater, and drainage
facilities, limit the disruption of natural landforms and water
bodies. Encourage the use of natural channels that simulate
natural drainage ways while protecting property.
Consistent. The project would be consistent with these
policies regarding drainage. As discussed under Threshold 2,
the drainage study for Village 8 West outlines the drainage
infrastructure required for detention of storm runoff and
sediment control, including incorporation of energy dissipaters
to minimize potential erosion. The project would reduce flows
to Wolf Canyon and would contribute a negligible amount of
new flow to Otay River. Additionally, as discussed under
Threshold 1, the water quality report outlines the proposed
water quality BMPs including low impact development to
encourage the use of natural channels that simulate natural
drainage ways. Implementation of the project would not
disrupt any natural water bodies.
Objective E 2: Protect and improve water quality within surface
water bodies and groundwater resources within and
downstream of Chula Vista.
Policy E 2.4: Ensure compliance with current federal and state
water quality regulations, including the implementation of
applicable NPDES requirements and the Chula Vista Pollution
Prevention Policy.
Policy E 2.5: Encourage and facilitate construction and land
development techniques that minimize water quality impacts
from urban development.
Consistent. The project would be consistent with these
applicable water quality policies. As discussed under Threshold
1, prior to construction a site-specific SWPPP would be
prepared in accordance with the NPDES General Construction
Permit. The Chula Vista Development Storm Water Manual
requires the project to meet site-specific performance
standards, site management requirements, seasonal
requirements, limitation of grading, and potential advanced
treatment for any identified sedimentation. Section 3 of the
manual has been followed in order to identify pollutants of
concern for the project, and to determine BMP requirements.
Low impact development BMPs have been proposed to meet
treatment requirements.
Objective E 15: Minimize the risk of injury and property damage
associated with flood hazards.
Policy E 15.1: Prohibit proposals to subdivide, grade, or develop
lands that are subject to potential flood hazards, unless
adequate evidence is provided that demonstrates that such
proposals would not be adversely affected by potential flood
hazards and that such proposals would not adversely affect
surrounding properties. Require site-specific hydrological
investigations for proposals within areas subject to potential
flood hazards; and implement all measures deemed necessary
by the City Engineer to avoid or adequately mitigate potential
flood hazards.
Consistent. Village 8 West is not located in a floodplain or dam
inundation hazard area. Implementation of Village 8 West
would include a drainage system that adequately conveys
flows from the project area.
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Otay Ranch Village 8 West EIR
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Table 5.11-5 Project Consistency with Applicable GDP Drainage and Water Quality Policies
Applicable Policies Evaluation of Consistency
Part II, Chapter 5 – Capital Facilities, Section C –Public Facility Plans
Goal: Provide protection to the Otay Ranch project area and
surrounding communities from fire, flooding and geologic
hazards.
Objective: Individual projects will provide necessary
improvements consistent with the National Flood Insurance
Program, drainage master plan(s) and engineering standards.
Policy: Storm drain runoff should be managed to minimize
water degradation, to reduce the waste of fresh water, to
protect wildlife and to reduce erosion.
Consistent. As discussed under Threshold 3, the grading and
drainage plans for Village 8 West meet these goals and
objectives by sizing drainage facilities appropriately to convey
the generated flows and detain run-off as required. The
development limits would avoid encroachment into
floodways. The plans provide for protection of adjacent
sensitive habitats by directing flows away from habitat to drain
directly into Otay River.
Objective: Storm water flows shall be controlled and conveyed
based on statistical models and engineering experience, as
specified in the city engineering standards consistent with
NPDES BMPs.
Consistent. As discussed under Threshold 1, development
would comply with NPDES and other regulatory requirements,
including implementation of BMPs.
Objective: Reduction ion the need for construction of flood
control structures
Objective: Preservation of the floodplain environment from
adverse impacts due to development.
Consistent. As discussed under Thresholds 7, 8, 10, and 11,
Village 8 West is not located in a flood hazard area. The
proposed drainage system would prevent flooding on site.
Objective: Require on-site detention of storm water flows such
that existing downstream structures will not be overloaded.
Policy: Require measures to decrease the adverse impacts
created by increased quantity and degradation in the quality of
runoff from urban areas.
Consistent. As discussed under Threshold 3, the proposed
drainage system would include a hydromodification detention
basin and other facilities to detain storm water to prevent
overloading downstream facilities.
Goal: Ensure that water quality within the Otay Ranch project
area is not compromised.
Objective: Ensure that water quality within the Otay Ranch
project area is not compromised, consistent with NPDES BMPs,
and the RWQCB Basin Plans.
Policy: Discretionary land development applications dependent
on imported water will only be approved if the service provider
reasonably expects that water facilities will be available
concurrent with need, and that all appropriate requirements
will be met through conditions placed on project approval.
Consistent. As discussed under Threshold 1 and Threshold 3, a
drainage plan has been prepared for Village 8 West that would
adequately provide for management and containment of
urban runoff, and development would comply with all
applicable city and regional water quality protection
standards.
Part II, Chapter 8 – Safety
Goal: Promote public safety and provide public protection from
fire, flooding, seismic disturbances, geologic phenomena and
manmade hazards in order to preserve life, health and
property; continue government functions and public order;
maintain municipal services; and rapidly resolve emergencies
and return the community normalcy and public tranquility.
Consistent. As discussed under Thresholds 7, 8, 10, and 11,
Village 8 West is not located in a flood hazard area. As
discussed under Threshold 3, The proposed drainage system
would prevent flooding on site. Hazards and fire are addressed
in Section 5.13, Hazards and Hazardous Materials and seismic
disturbances and geologic phenomena are addressed in
Section 5.8, Geology and Soils.
Objective: Prevent property damage and loss of life due to
seiches, dam failure and heavy rains.
Objective: Preservation of the floodplain environment from
adverse impacts due to development.
Consistent. As discussed under Thresholds 7, 8, 10, and 11,
Village 8 West is not located in a floodplain or flood hazard
area. As discussed under Threshold 3, The proposed drainage
system would prevent flooding on site, including during heavy
rain events.
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Table 5.11-5 Project Consistency with Applicable GDP Drainage and Water Quality Policies (continued)
Applicable Policies Evaluation of Consistency
Part II, Chapter 10 – Resource Protection, Conservation and Management
Goal: Preserve floodways and undisturbed flood plain fringe
areas.
Objective: Restore and enhance highly disturbed floodways and
flood plains to regain former wildlife habitats and retain/restore
the ability to pass 100-year flood flows.
Objective: Preserve floodways and undisturbed flood plain
fringe areas in their natural state where downstream
development will not be adversely affected.
Consistent. The development limits in the SPA Plan would
avoid encroachment into floodplain areas. The proposed
drainage system would detain storm water on site and direct
project storm water flows directly to Otay River. The project
would not significantly impact a floodplain area. As discussed
under Threshold 3, Otay River Valley in the proximity of the
project is starved for sediment and peak flows, and an
increase in peak flow from the project would tend to
counteract the degradation trends by replacing water
impounded by the reservoir.
I. Threshold 10: Expose people or structures to a significant risk of loss, injury or
death involving flooding, including flooding as a result of the failure of a
levee or dam.
As discussed under Threshold 8, Village 8 West, including off-site area, is not located within a 500-year
floodplain. Additionally, according to the EIR prepared for the Chula Vista General Plan and the
inundation map for the Savage Dam, Village 8 West is not located within a potential dam inundation
area (City of Chula Vista 2005b, City of San Diego 1974). Therefore, the project would not expose people
or structures to a significant risk of loss, injury or death involving flooding, including flooding as a result
of the failure of a levee or dam. No impact would occur.
J. Threshold 11: Result in a substantial increase in risk of exposure to inundation
by seiche, tsunami, or mudflow.
Seismically induced hazards such as tsunamis and seiches are not considered significant hazards because
Village 8 West is located more than ten miles inland, is outside of the 500-year floodplain, and is not
within the potential dam inundation of the Otay Lakes. If at full capacity, it is possible that during a
strong seismic event with a long duration of shaking, minor localized overtopping of the City of San
Diego reservoir could occur. However, according to the Geotechnical Investigation prepared by
Advanced Geotechnical Solutions, Inc. for the project (Appendix G), an adequate margin of safety to
protect against overtopping exists for nearly the entire reservoir, except at the low point where the
paved access road meets the reservoir. At this location, any overtopping would be directed onto the
proposed paved access road and down to the proposed storm drain improvements. Given the likelihood,
volume of the reservoir, and area of potential overtopping, flooding from the reservoir is not considered
a substantial risk. Additionally, the Geotechnical Investigation determined that seismically induced
landslides, which include mudflows, are not a significant concern for Village 8 West. Therefore, the
project would not result in a substantial increase in risk of exposure to inundation by seiche, tsunami, or
mudflow. No impact would occur.
5.11.3 Level of Significance Prior to Mitigation
A. Water Quality Standards
Even though the project includes features and would implement BMPs to reduce the amount and rate of
runoff to a less than significant level, these features are also prescribed as mitigation measures to assure
implementation and facilitate monitoring through buildout of the project.
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B. Groundwater Supplies and Recharge
No significant impacts related to groundwater supplies and recharge have been identified with
implementation of Village 8 West.
C. Erosion or Siltation
Even though the project includes features and would implement BMPs to reduce the amount and rate of
runoff to a less than significant level, these features are also prescribed as mitigation measures to assure
implementation and facilitate monitoring through buildout of the project.
D. Surface Runoff
Even though the project includes features and would implement BMPs to reduce the amount and rate of
runoff to a less than significant level, these features are also prescribed as mitigation measures to assure
implementation and facilitate monitoring through buildout of the project.
E. Exceed Drainage Capacity
Even though the project includes features and would implement BMPs to reduce the amount and rate of
runoff to a less than significant level, these features are also prescribed as mitigation measures to assure
implementation and facilitate monitoring through buildout of the project.
F. Degradation of Water Quality
Even though the project includes features and would implement BMPs to reduce the amount and rate of
runoff to a less than significant level, these features are also prescribed as mitigation measures to assure
implementation and facilitate monitoring through buildout of the project.
G. 100-Year Flood Hazards
No significant impacts related to 100-year flood hazards, have been identified with implementation of
Village 8 West.
H. Consistency with Water Quality Policies
No significant impacts related to consistency with water quality policies have been identified with
implementation of Village 8 West.
I. Flooding
No significant impacts related to flooding have been identified with implementation of Village 8 West.
J. Inundation
No significant impacts related to inundation have been identified with implementation of Village 8 West.
5.11.4 Mitigation Measures
A. Water Quality Standards
5.11-1 Storm Water Pollution Prevention Plan. Prior to issuance of each grading permit for the Village
8 West SPA Plan area or any land development permit, including clearing and grading, the
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Otay Ranch Village 8 West EIR
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project applicant shall submit a notice of intent and obtain coverage under the National
Pollutant Discharge Elimination System permit for construction activity from the State Water
Resources Control Board. Adherence to all conditions of the General Permit for Construction
Activity is required. The applicant shall be required under the State Water Resources Control
Board General Construction Permit to develop a Storm Water Pollution Prevention Plan and
monitoring plan that shall be submitted to the City Engineer and the Director of Public Works.
The Storm Water Pollution Prevention Plan shall be incorporated into the grading and drainage
plans and shall specify both construction and post-construction structural and non-structural
best management practices on site to reduce the amount of sediments and pollutants in
construction and post-construction surface runoff before it is discharged into off-site storm
water facilities. Section 7 of the City’s Storm Water Manual outlines construction site best
management practices requirements. The Storm Water Pollution Prevention Plan shall also
address operation and maintenance of post-construction pollution prevention measures,
including short-term and long-term funding sources and the party or parties that will be
responsible for said measures. The Storm Water Pollution Prevention Plan shall incorporate
construction and post-construction best management practices as outlined in the Village 8 West
Edge Plan. The grading plans shall note the condition requiring a Storm Water Pollution
Prevention Plan and monitoring plans.
5.11-2 Supplemental Water Quality Report. Prior to issuance of each grading permit, the applicant
shall submit a supplemental report to the Preliminary Water Quality Technical Report for Village
8 West prepared by Hale Engineering dated December 8, 2011 that identifies which on-site
storm water management measures from the Water Quality Technical Report have been
incorporated into the project, to the satisfaction of the City Engineer. If a storm water
management option is chosen by the parcel owner that is not shown in the water quality
technical report, a project-specific water quality technical report shall be prepared for the
planning area, referencing the Preliminary Water Quality Technical Report for Village 8 West for
information relevant to regional design concepts (e.g., downstream conditions of concern) to
the satisfaction of the City Engineer.
5.11-3 Post-Construction/Permanent Best Management Practices. Prior to issuance of each grading
permit, the City Engineer shall verify that parcel owners have incorporated and will implement
post-construction best management practices in accordance with current regulations. In
particular, applicants are required to comply with the requirements of Section 2c of the Chula
Vista Standard Urban Storm Water Management Plan, the Chula Vista Development Storm
Water Manual, and the Preliminary Water Quality Technical Report for Village 8 West or any
supplements thereto to the satisfaction of the City Engineer. Specifically, the applicant shall
implement low impact development best management practices in the preparation of all site
plans and, the applicant shall incorporate structural on-site design features into the project
design to address site design and treatment control best management practices as well as
requirements of the hydromodification management plan. The applicant shall monitor and
mitigate any erosion in downstream locations that may occur because of on-site development.
5.11-4 Limitation of Grading. The project applicant shall comply with the Chula Vista Development
Storm Water Manual limitation of grading requirements, which limit disturbed soil area to 100
acres, unless expansion of a disturbed area is specifically approved by the Director of Public
Works. With any phasing resulting from this limitation, if required, the project applicant shall
provide, to the satisfaction of the City Engineer, erosion and sediment control best management
practices in areas that may not be completed, before grading of additional area begins.
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5.11-5 Hydromodification Criteria. The project applicant shall comply, to the satisfaction of the City
Engineer, with city hydromodification criteria or the hydrograph modification management plan,
as applicable, addressed regionally at the SPA Plan level concurrent with grading and
improvement plans for the project.
B. Groundwater Supplies and Recharge
No mitigation measures are required.
C. Erosion or Siltation
Mitigation measures 5.11-1 through 5.11-5 would reduce impacts related to erosion or siltation.
D. Surface Runoff
Mitigation measures 5.11-1 through 5.11-5 would reduce impacts related to surface runoff.
E. Exceed Drainage Capacity
Mitigation measures 5.11-1 through 5.11-5 would reduce impacts related to drainage capacity.
F. Degradation of Water Quality
Mitigation measures 5.11-1 through 5.11-5 would reduce impacts related to degradation of water
quality.
G. 100-Year Flood Hazards
No mitigation measures are required.
H. Consistency with Water Quality Policies
No mitigation measures are required.
I. Flooding
No mitigation measures are required.
J. Inundation
No mitigation measures are required.
5.11.5 Level of Significance After Mitigation
A. Water Quality Standards
With implementation of mitigation measures 5.11-1 through 5.11-5 identified above, impacts related to
water quality would be reduced to below a level of significance.
B. Groundwater Supplies and Recharge
Impacts would be less than significant without mitigation.
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C. Erosion or Siltation
With implementation of mitigation measures 5.11-1 through 5.11-5 identified above, impacts related to
erosion would be reduced to below a level of significance.
D. Surface Runoff
With implementation of mitigation measures 5.11-1 through 5.11-5 identified above, impacts related to
runoff related to implementation of the project would be reduced to below a level of significance.
E. Exceed Drainage Capacity
With implementation of mitigation measures 5.11-1 through 5.11-5 identified above, impacts related to
runoff related to implementation of the project would be reduced to below a level of significance.
F. Degradation of Water Quality
With implementation of mitigation measures 5.11-1 through 5.11-5 identified above, impacts related to
water quality would be reduced to below a level of significance.
G. 100-Year Flood Hazards
Impacts would be less than significant without mitigation.
H. Consistency with Water Quality Policies
Impacts would be less than significant without mitigation.
I. Flooding
Impacts would be less than significant without mitigation.
J. Inundation
Impacts would be less than significant without mitigation.