Machado Lake Ecosystem Rehabilitation Project Wilmington Drain

Transcription

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City of Los Angeles • Department of Public Works • Bureau of Engineering
Machado Lake Ecosystem Rehabilitation Project
Wilmington Drain Multi-Use Project
Pre-Design Report • Executive Summary
July 2009
Funding Provided by:
City of Los Angeles Proposition O Clean Water Bond
California State Water Resources Control Board and
Department of Water Resources (Proposition 50, Chapter 8)
California Coastal Conservancy
and Wilmington Drain Multi-Use Project Pre-Design Report
Executive Summary
The purpose of this section is to summarize the Machado Lake Ecosystem Rehabilitation
and Wilmington Multi-Use Projects. The Pre-Design Report will serve as the basis for
detailed design of improvements to Machado Lake and Wilmington Drain. The report
is organized into 11 sections describing water quality, biological resources, stormwater
conveyance improvement, stormwater best management practices (BMPs), wetlands,
Machado Lake rehabilitation, park design, project alternatives and analysis, project
implementation, and final design.
Machado Lake Problem Statement: Eutrophication and other water quality
impairments in Machado Lake, including the accumulation of sediment, have degraded
habitat, damaged water quality, and prevented recreational fishing. Warning signs are
posted about the dangers of eating fish from the lake. This project seeks to rehabilitate
lake water quality and to improve ecosystem health.
Wilmington Drain Problem Statement: Trash, proliferation of invasive species, and
sediment accumulation have degraded water quality, habitat, and hydraulic capacity
of Wilmington Drain. Despite these conditions, endangered and sensitive species
inhabit the area. This project seeks to improve water quality, enhance habitat for the
endangered least Bell’s vireo and other sensitive species, and improve flood capacity,
while providing new recreational opportunities for the public.
Project Setting and Vicinity
The Machado Lake ecosystem, which includes Wilmington Drain, is one of the largest
remaining coastal wetland ecosystems in Southern California (CDM and Parsons 2008).
Ken Malloy Harbor Regional Park (KMHRP) and the Wilmington Drain are located in the
Wilmington and Harbor City communities of the City of Los Angeles, approximately
15 miles south of downtown Los Angeles and just west of the Harbor Freeway (I-110).
KMHRP is a 231-acre park that is owned, operated and maintained by Los Angeles
Department of Recreation and Parks (RAP). Harbor Park Municipal Golf Course borders
the northeast banks of Machado Lake and the Los Angeles Harbor College borders
the freshwater marsh situated south of the Lake. Pacific Coast Highway and residential
development borders KMHRP to the north, Vermont Avenue and a Kaiser Permanente
facility borders KMHRP to the west, and Anaheim Street and Conoco-Phillips Oil Refinery
are located to the south of the KMHRP.
North of KMHRP is the Wilmington Drain, a 150 foot wide and approximately one-half
mile long soft-bottom storm drain channel (from the end of the concrete channel to the
Pacific Coast Highway). Wilmington Drain collects stormwater runoff from a 14 square mile
watershed, consisting of residential and industrial development. Flow from Wilmington
Drain empties into KMHRP riparian woodland. The project area is located in the Machado
Lake subwatershed and is within the larger 100 square mile Dominguez watershed.
For project locations, please turn the page
JULY 2009
EXECUTIVE SUMMARY | 1
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Ken Malloy Harbor Regional Park (KMHRP) and the Wilmington Drain are located in the
Wilmington and Harbor City communities of the City of Los Angeles, approximately 15
miles south of downtown Los Angeles and just west of the Harbor Freeway.
Torrance
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Blv
Pasadena
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SD 510
W 255TH ST
DODGE AVE
PACIFIC COAST HWY
RIPARIAN
WOODLAND
P36466
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P6545
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MACHADO
LAKE
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Project 77
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LA Harbor
College Drain
ML Project 510 - Line C
FRESHWATER
MARSH
Project 643
Figueroa Drain
D7223
north
Legend
Direction of Flow
Existing Storm Drain
0’
250’
500’
P9481
P2533
Project 2747
Harbor Outlet
1,000’
2 | EXECUTIVE SUMMARY
JULY 2009
Wilmington Drain
Wilmington Drain is a Los Angeles County
Flood Control District facility managed by
the Los Angeles County Department of
Public Works. It is characterized by a 150foot wide soft bottom vegetated channel,
southern willow scrub plant communities,
non-native plants, urban litter, and rip-rapfilled gabions. From Pacific Coast Highway
to Lomita Boulevard, the Wilmington Drain
is bordered on both sides by residential
development. North of Lomita Boulevard,
the western bank provides habitat for the
endangered least Bell’s Vireo and other
native species, while north of I-110 the
channel is concrete lined.
Wilmington Drain looking upstream (north) from Pacific Coast Highway
Machado Lake
KMHRP is a 231-acre city park, which
is one of the largest in the City of Los
Angeles, and has one of the most diverse
habitats in the region, including a 40-acre
lake, a seasonal freshwater marsh, and
a riparian woodland. These areas have
been informally designated as a wildlife
sanctuary. Recreational uses of the lake
and park include picnic areas, fishing,
bird watching, and hiking. The KMHRP
provides habitat for a variety of plants and
animals and there are several endangered
and sensitive species that have been
observed within the vicinity of the park.
of the park, where it is discharged to the
West Channel of the Los Angeles Harbor.
This outfall structure has an outlet weir
for the purpose of retaining water in
the lower basin during the wet months.
Within KMHRP, a riparian woodland is
situated south of Pacific Coast Highway
and north of Machado Lake. High flows
from Wilmington Drain pass through
the riparian woodland before they enter
Machado Lake.
KMHRP open space park area
Machado Lake is comprised of upper
and lower basins separated by a low
earthen dam. The upper basin contains
the 40-acre recreational lake created by
impoundment of stormwater runoff;
the lower basin is a seasonal freshwater
marsh of roughly 63 acres. The dam was
designed to maintain the level of the
lake at a maximum of approximately 10
feet above mean sea level. During major
storms, water flows over the dam into
the lower basin and ultimately to the
Harbor Outfall at the southeastern corner
Stormwater flow to lower basin
JULY 2009
Machado Lake
Project History
Specific drivers for the Machado Lake
Ecosystem Rehabilitation and Wilmington
Drain Mulit-Use projects are to improve
water quality; meet adopted and future
Total Maximum Daily Loads (TMDLs);
enhance riparian, wetland, and upland
habitat; improve hydrologic and hydraulic
conditions; create new and restore
existing recreational amenities. Over the
last three decades, a number of individual
water quality improvement projects were
implemented at Machado Lake including
dredging, installation of bubble aerators,
and frequent removal of invasive aquatic
plants, both chemically and mechanically.
During the same period, a number of
studies on the lake were conducted.
Residents of Los Angeles approved
Proposition O, a $500-million bond
measure, in 2004 to improve water quality
for water bodies within the City. The City
of Los Angeles Bureau of Sanitation (BOS)
prepared Concept Reports for both the
Machado Lake and Wilmington Drain
projects in December 2006, identifying
the funding needed for design and
construction. Based on Citizens Oversight
Advisory Committee (COAC) and
Administrative Oversight Committee
(AOC) recommendation, City Council
authorized $117 million of Proposition O
funding for the two projects.
Proposition O funded projects must
fall within one or more of the following
categories:
River, lakes, beaches, bays, and ocean
water quality protection projects
Water conservation, drinking water,
and source protection projects
Flood water reduction, river and
neighborhood parks that prevent
polluted runoff and improve water
quality projects
Stormwater capture, clean-up, and
re-use projects
The Machado Lake and Wilmington Drain
projects fall within all of these categories.
Additionally, the Wilmington Drain MultiUse project has also been awarded $4.5
million for project construction through
Proposition 50, Chapter 8, of the State
of California’s Integrated Regional Water
Management Plan Implementation Grant
Program. The intent of Proposition 50 is to
encourage integrated, regional strategies
for water resources management, and to
provide funding through a competitive
process, for projects that:
Protect communities from drought;
Protect and improve water quality; and
Improve local water security by reducing
dependency on imported water.
JULY 2009
Regulatory Setting
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Jurisdictional Setting
The KMHRP is owned and operated by
RAP, and Wilmington Drain is owned by
the Los Angeles County Flood Control
District (LACFCD) and maintained by
the Los Angeles County Department
of Public Works (LACDPW). Therefore,
implementation of improvements
will require collaboration between
the City and the LACDPW. Three City
of Los Angeles departments/bureaus
are involved in this project: Bureau of
Engineering (BOE) and BOS, and RAP.
Additionally, the LACDPW maintains
Wilmington Drain as a flood control
channel. LACDPW annually maintains the
Wilmington Drain and will continue to
maintain the Wilmington Drain channel
during and after the completion of this
project. RAP will maintain the new park
and trail area along the western channel
bank. A formal MOU between the City
of Los Angeles and LACDPW will be
developed as the project progresses.
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Other regulatory requirements include
obtaining the permits from the California
Department of Fish and Game (CDFG) and
the U.S. Army Corps of Engineers (USACE),
and other agencies. Together, the lake, the
freshwater marsh, similar marshy areas
at the edge of the lake, and associated
riparian resources constitute about 112
acres, all of which would likely be deemed
waters of the United States. Generally,
this means that EPA and USACE have
jurisdiction under the Clean Water Act over
any activities affecting these resources.
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Both Machado Lake and Wilmington Drain
are listed on the Environmental Protection
Agency (EPA) 303(d) list of impaired water
bodies. Wilmington Drain is listed for
copper, lead, ammonia, and coliform
bacteria, and Machado Lake is listed for
algae, ammonia, Chem A (fish tissue),
chlordane, DDT, dieldrin, eutrophic, odor,
PCBs, and trash. To date, the Machado
Lake Trash TMDL (Resolution number
2007-006) has been adopted and the Basin
Plan has been amended to include this
resolution. The Regional Board adopted the
Machado Lake Eutrophic, Algae, Ammonia,
and Odors (Nutrient) TMDL as a Basin Plan
Amendment (Resolution number 2008006). The Nutrient TMDL is in effect as of
the EPA approval date of March 11, 2009.
TMDLs have not been developed for the
other 303(d) listings for Machado Lake or
Wilmington Drain.
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The Los Angeles Regional Water Quality
Control Board established beneficial uses
for Machado Lake, formerly known as
Bixby Slough and Harbor Lake, in the “Los
Angeles Region Basin Plan for the Coastal
Watersheds of Los Angeles and Ventura
Counties”, which include Water Contact
Recreation (REC-1), Non-Contact Water
Recreation (REC-2), Warm Freshwater
Habitat (WARM), Wildlife Habitat (WILD) ,
Biological Habitats of Special Significance
(BIOL), Rare, Threatened or Endangered
Species (RARE), Wetland Habitat (WET).
Beneficial uses were not established for
Wilmington Drain in the Basin Plan.
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Overall
Project Objectives
The broad goal of the Machado
Lake Ecosystem Rehabilitation and
Wilmington Drain Multi-Use projects
is to improve the water quality
conditions, visual aesthetics, and the
biological diversity of the ecosystem
to attain and sustain its desired uses
and characteristics (i.e. wildlife habitat,
environmental education, recreational
fishing in Machado Lake), and to
meet TMDL requirements and other
water quality targets. This effort will
be accomplished through integrated
ecological and engineering strategies
and solutions involving watershedbased management approaches,
in-lake rehabilitation and streambed
assessment techniques, riparian system
enhancements, and treatment BMPs at
strategic areas in the park. Long-term
success will require the promotion of a
lasting stewardship of the ecosystem
through community education programs
and collaborative public and private
partnerships.
least Bell’s Vireo sighting in Wilmington Drain (Photo by Kylie Fischer 2007, provided courtesy of ICF Jones & Stokes)
Overall Approach
The pre-design phases for both Machado
Lake and Wilmington Drain included a
series of common tasks and surveys.
Biological surveys were performed to
identify baseline conditions of sensitive
and invasive biological resources on the
project site, including habitat assessment
for special status species, vegetation, bird
and wildlife, and fish and aquatic species.
A preliminary geotechnical investigation
was conducted to identify baseline
conditions. The investigation included
geotechnical borings in Wilmington Drain
and in KMHRP, and sediment sampling in
Machado Lake, the Freshwater Marsh, and
Riparian Woodland.
A hydrologic and hydraulic model
of existing conditions for the overall
watershed discharging to the Harbor
Outfall was developed. The model was
run under several rain event scenarios to
simulate the proposed conditions after
construction of the project.
A wet and dry weather pollutant load
runoff model was developed to estimate
existing pollutant loads to Wilmington
Drain, Machado Lake, and the Harbor
Outfall and to quantify pollutant load
reductions attributable to structural
stormwater BMPs.
An in-lake water quality model was
developed to estimate existing nutrient
concentrations in Machado Lake and
to forecast future in-lake nutrient
concentrations with the recommended
project in place.
Best Management Practice (BMP) options
to help meet adopted and future TMDLs
were identified. BMPs are compatible
with, and support to the extent possible,
the other project goals including visual
aesthetics, recreation, habitat and public
education.
Wetlands enhancement and creation
opportunities were developed. Because
of their habitat value, potential for
contaminant removal and extensive
distribution throughout KMHRP, use of
wetlands is considered a sustainable
way to support the water quality
improvement, habitat enhancement, and
recreational opportunity goals.
A variety of in-lake rehabilitation water
quality and habitat improvements were
evaluated to reestablish important
missing or altered lake processes and
native aquatic species.
Landscape, habitat and recreational
amenities to create opportunities for
passive recreation within the enhanced
native environment were evaluated.
These options seek to control pedestrian
circulation and access in order to
minimize impacts to habitat.
A recycled water feasibility study was
conducted to provide conceptual level
information on the feasibility of using
recycled water for in-lake recharge of
Machado Lake, irrigation of surrounding
landscaping, and wetlands enhancement.
Alternative facilities and projects
development and evaluation were
conducted for both the Wilmington Drain
and Machado Lake improvements.
Eight public workshops were conducted
to engage stakeholders in the planning
process.
JULY 2009
Alternative Development and Analysis
For both the Wilmington Drain Multi-Use Project and Machado Lake Ecosystem Rehabilitation
Project a comprehensive alternative analysis process was required to evaluate the
alternatives. This process evaluated the costs and benefits, inherent risks, and trade-offs
for each combination of BMP, lake rehabilitation, wetlands enhancement, recreation and
habitat restoration options. This process began with the Concept Report issued in 2006, and
continued through the development of this Pre-Design Report to provide the guidance
required to make final decisions and chart the course for the final design and construction
of the best technical solutions. The alternative analysis utilized a series of goals, performance
measures, and weightings to evaluate and compare alternatives.
Goals: The objectives define the essential purposes of the Wilmington Drain Multi-Use
Project and Machado Lake Ecosystem Rehabilitation Project in broad, overarching terms.
The Goals can be seen as a set of objectives that answer the question:
Why do we want to implement a Wilmington Drain Multi-Use project
or Machado Lake Ecosystems Rehabilitation project?
To accurately reflect the relative importance of these Project Goals, the City and County
leadership staff weighted the goals in a facilitated group exercise on March 12, 2009.
The accompanying figure shows the results of the exercise; satisfaction of water quality
objectives was identified as the most important Project Goal.
Performance Measures: The quantifiable indicators or indices of how an alternative
performs relative to the goals. Performance measures answer the question:
How well does an alternative meet the desired Goals?
Performance measures were defined for each Goal for Wilmington Drain and Machado Lake.
14%
Project Goals
14%
13%
13%
32%
3%
11%
Provide flood
protection
Provide a
sustainable project
Achieve cost efficiency
Minimize short-term
construction impacts
Satisfy water quality
objectives
Enhance habitat
Enhance recreational
opportunities
Results of the goal weighting exercise are shown here. Satisfaction of water
quality objectives was identified as the most important project goal.
Alternatives: The means of accomplishing the stated Goals. The alternatives answer
the question:
How can we meet the desired goals?
A total of three alternatives were developed for Wilmington Drain and a total of seven
alternatives were developed for Machado Lake. The alternatives were evaluated using
Criterium® Decision Plus® (CDP), which provides a structured format to facilitate the
decision-making process. Using CDP, a rating scale was created for each performance
measure, with a value of 0.00 assigned to the worst performance and 1.0 to the best
performance; intermediate results were determined using CDP by linear interpolation
between the minimum and maximum performance measure results. Next, the results
were weighted using the results of the March 12, 2009 facilitated group exercise.
JULY 2009
Wilmington Drain
The most significant challenge in developing alternatives for Wilmington Drain was finding solutions capable of passing the 50-year
storm flow while maintaining habitat for the least Bell’s Vireo, a federally listed endangered species, observed in the project area. For
each of the three alternatives, a hydrologic and hydraulic model was developed to determine if the alternative was able to pass the
50-year storm event and meet the County of Los Angeles flood control requirements. The primary difference between the three
Wilmington Drain alternatives was the amount of excavation required in the channel.
Alternative 1 included excavation of
approximately 60,000 cubic yards and
re-grading of the channel to the conditions
present in 1977. Returning to the 1977
contours would involve major excavation
of the island in the southern portion of the
channel. Preliminary biological studies
determined that the island provides high
quality habitat due to the maturity of the
trees and structural complexity of the area.
During discussions with the California
Department of Fish and Game it was
learned that this alternative would not
be permitted.
Alternative 2 incorporated several
channel modifications to increase the
hydraulic capacity of the channel and
pass the 50-year storm event. However, to
maintain the hydraulic capacity throughout
the entire year, it was recommended that
vegetation in the channel be maintained
at a height of less than 2 to 3 feet, which
would require vegetation clearing several
times a year. Sediment storage capacity is
limited and the alternative would have only
a 1 to 5 year life before excavation would
again be required.
Alternative 3 combines aspects of
Alternative 2 with additional channel
modifications to improve hydraulic
and sediment capture capacity. This
alternative included removal of
approximately 15,500 cubic yards of
sediment and re-grading the soft-bottom
channel. This alternative would extend
the life of the channel by allowing a
longer period of sediment capture before
major excavation would be necessary,
while avoiding or minimizing impacts to
least Bell’s Vireo habitat, namely, southern
willow scrub.
Each of the Wilmington Drain alternatives was coupled with a series of common elements to address water quality, provide recreational
opportunities, and enhance habitat.
Wilmington Drain Recommended Alternative
Trash Net Structure
0
11
HA
RB
OR
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FW
Island
Naturally Created Low Flow Channel
LOMITA BLVD
Trash Net Structure
Invasive Plant Removal
Park, BMPs, Smart Irrigation
PACIFIC COAST HWY
Stabilize Existing Gabions, As Needed
Legend
LA County Flood Control District
Protect Southern Willow Scrub
Habitat, Clear Toe-to-Toe
north
0
350
700
1400’
Regrade
JULY 2009
TYPICAL WALKWAY WITH PERMEABLE PAVING THRU NATIVE
OPEN SPACE SETTING WITH OVERLOOKS, INTERPRETIVE
SIGNAGE, & SELECTIVELY PLACED TRASH RECEPTACLES,
DOG WASTE DISPENSERS & ENFORCEMENT/EDUCATIONAL
SIGNAGE
PARKING BAYS WITH 25 PARKING SPACES WITH
PERMEABLE PAVING & CONNECTION TO PARK
WALKWAYS
TYPICAL 17' WIDE WALKWAY/UTILITY
ACCESS ROAD WITH PAVING, SELECTIVELY
PLACED BENCHES, TRASH RECEPTACLES,
DOG WASTE DISPENSERS & RELATED
SIGNAGE
TYPICAL TREE
PLANTING TO
SCREEN ADJOINING
COMMERCIAL LAND
USES, TYPICAL
EXISTING ROAD & ALLEY FROM LOMITA BLVD .
EXISTING SALVATION ARMY FACILITY
McCOY ST
ENTRY SPECIMEN PLANTING
PUBLIC & MAINTENANCE VEHICLE
ACCESS GATES WITH FACILITY
SIGNAGE-REFER TO NOTES BELOW
EXISTING
APTS.
EXISTING CONCRETE WALL
WITH NEW DECORATIVE
GUARD-RAIL
TYPICAL NATIVE PLANTING ALONG
WALKWAY IRRIGATED VIA A
SMART/HIGH-EFFICIENT SYSTEM
PLAZA WITH
OVERLOOK KIOSK,
BENCH SEATING, &
SOLAR POWERED
SECURITY LIGHTING
COLORED
CONCRETE BULKHEAD TYPICALLY
AT
WALK-WAY/PLAZA
WITH GUARDRAIL
TYPICAL TREE, SHRUB &
GROUNDCOVER PLANTING
McCOY STREET
PARK ACCESS
EXISTING APTS.
SPECIMEN TREE
PLANTING
PUBLIC & UTILITY
ACCESS GATES
FROM PACIFIC
COAST HWY.-REFER
TO NOTES BELOW
EXISTING
FACILITY SERVICE
BUILDING
EXISTING OIL RIG
LEAST BELL'S VIREO &
MULTI-SPECIES ENHANCEMENT
(SEE NOTE 3)
EXISTING PLANT MATERIAL SHALL
REMAIN & BE PROTECTED FOR
LEAST BELL'S VIREO &
MULTI-SPECIES ENHANCEMENT
EXISTING APTS.
APPROXIMATE
LOCATION OF
NEW TRASH
CAPTURE DEVICE
EXISTING DRIVEWAY TO MAINTENANCE
ROAD WITH NEW MAINTENANCE
GATES-REFER TO NOTES BELOW
EXISTING ASPHALTIC MAINTENANCE ROAD
SHALL REMAIN, BE PROTECTED, & SHALL BE
OFF LIMITS FROM DIRECT ACCESS
NOTES:
1.
5' WIDE PEDESTRIAN GATES SHALL BE LOCKED
DUSK TO DAWN. VEHICULAR MAINTENANCE GATES
SHALL BE LOCKED AT ALL TIMES EXCEPT WHEN IN
USE BY COUNTY, CITY, FIRE, POLICE, & VECTOR
CONTROL VEHICLES. ENTRY ACCESS SHALL
RECEIVE PARK SIGNAGE, INFORMATIONAL &
DIRECTIONAL KIOSKS.
2.
SOLAR POWERED SECURITY LIGHTING SHALL BE
INSTALLED AT STRATEGIC LOCATIONS & SHALL BE
15' HIGH WITH A CITY APPROVED MODEL TYPE.
3.
LEAST BELL'S VIREO ENHANCEMENT INCLUDES
NON-NATIVE/INVASIVE VEGETATION REMOVAL ON
THE ISLAND & THROUGHOUT THE WILMINGTON
DRAIN CORRIDOR.
EXISTING DRAINAGE CHANNEL
Recommended Park Plan
Wilmington Drain Multi-use Project
APPROXIMATE
LOCATION OF
TRASH CAPTURE
SYSTEM
Recommended Wilmington Drain Alternative
The results of the CDP analysis indicated
that Alternative 3 received the best score
and is therefore the recommended
Wilmington Drain project. The goals
and performance measures for the
recommended plan are shown in the
table on the following page. As shown in
the figure, recommended plan includes
the following project elements:
Habitat and Park Design
An invasive species removal program
will be developed for Wilmington Drain
to remove invasive plant species from
the channel banks and in-channel island.
A natural park featuring walking trails
and educational opportunities will be
constructed on the west bank of the
channel and south of Lomita Boulevard
in an area that is currently undeveloped.
Interpretive signage will be installed at the
major park access nodes located in the
JULY 2009
new parking lot south of Lomita Boulevard,
and at the trail heads on Lomita Boulevard
and Pacific Coast Highway.
Channel Improvements
and Bank Stabilization
Wilmington Drain will be excavated and
re-graded to provide increased hydraulic
capacity. A total of approximately 15,500
cubic yards of sediment will be removed.
The box culverts under Lomita Boulevard
and Pacific Coast Highway will be cleaned
and the transition zone in channel above
and below box culverts will be graded. The
sediment plug on the northeast side of the
island will be removed to open up the low
flow channel on the east side of the island.
Streambank stabilization measures will
be incorporated into the channel design
to diminish adverse effects of high flow
velocities. Existing gabions on the west
channel bank, near Pacific Coast Highway,
will be stabilized, as needed.
BMPs
Two trash netting systems will be installed,
one north of Lomita Boulevard at the
outlet of the concrete lined portion of
the Wilmington Drain and the other in
the Project 510 storm drain entering
Wilmington Drain from the east. Porous
paving will be utilized in the new parking
lot immediately south of Lomita Boulevard.
Pedestrian trails will be developed in the
new passive recreation park, and along the
west side of the channel. Litter receptacles
will be provided at the major park access
nodes located in the new parking lot south
of Lomita Boulevard, and at the trail heads
on Lomita Boulevard and Pacific Coast
Highway. Smart Irrigation Controllers will be
utilized for the irrigation system installed in
the newly created nature park.
The combination of in channel/end of pipe BMPs, source control/site design BMPs and the excavation associated with the
recommended alternative will have a positive effect on water quality in Wilmington Drain and Machado Lake. The combination of
these BMPs will reduce trash, sediment and metals loading from wet weather flows to Machado Lake. They may also provide slight
reductions in bacteria concentrations in Wilmington Drain. However, the ability to achieve additional improvement in the water quality
of Wilmington Drain is directly dependent on the implementation of stormwater BMPs, to the extent practicable, throughout the
contributing watershed of Wilmington Drain.
Wilmington Drain Recommended Plan Performance Measure Results
Project Goal
Performance Measure
Result1
Satisfy water quality objectives

Reduce sediment load to Machado Lake

1 million pounds per year
and downstream receiving waters

217 pounds per year
Reduce wet weather metals load to Machado Lake (Cu + Pb)

Enhance recreational opportunities

Provide walking trails and educational opportunities

Yes
Provide flood protection

Provide capacity equal to or better than 1977 condition

Yes
Provide a sustainable project

Years before major excavation required

8-15 years

Routine clearing of vegetation required

1 time per year
Enhance habitat

Net loss of protected habitat

0 acres

Estimated capital cost

$14,276,000

Estimated operational cost

$442,000 per year

Dredged material removal requirement

15,500 cubic yards
Minimize short-term construction impacts
1
See Pre-Design Report, Section 9 for a detailed discussion
JULY 2009
Machado Lake
The Machado Lake alternatives primarily vary with respect to the number of features included to provide water quality benefits.
Dredging the lake is the most important element in meeting water quality objectives. All of the other treatment options offer
additional probability of meeting water quality objectives in the lake or downstream.
Three groups of alternatives were developed for Machado Lake, each successively built on the previous alternative. Within each group
there was an option to use potable water for supplemental water requirements, or recycled water from the Terminal Island water
Reclamation Plant (TIWRP), for a total of six alternatives.
Alternative 1A improvements for
Machado Lake incorporate various
common elements, most notably:
the dredging of Machado Lake by
approximately three feet, removal of
invasive plants, re-vegetation in both
the riparian woodland and the lower
freshwater marsh, and provision of BMPs
at major storm drain outfalls, specifically
a continuous deflection separation
(CDS) device at the Project 77, D24010,
D2773, and Figueroa Drain outfalls. This
alternative does not involve re-contouring
to significantly change the flow regime
of runoff in the wetland areas or
construction of new wetlands. Advanced
treated water from the TIWRP would be
used to maintain the appropriate lake
water level.
Alternative 1B improvements for
Machado Lake are identical to Alternative
1A, with exception that potable water
would be used for lake augmentation.
Alternative 2A improvements include
all the Alternative 1A improvements and
several others, including: construction of
a 4.3-acre offline recirculation wetland on
the southeast side of the lake; creation
of new freshwater marsh wetlands in
the area downstream of Machado Lake
Dam; creation of an enhanced vegetative
swale at the Project 77 storm drain
outfall; and installation of stormwater
BMPs, specifically a gross solids removal
device (GSRD) at the Harbor College and
P6545 storm drain outfalls to provide
supplemental collection of trash from
these smaller watersheds.
The offline recirculation wetland in
Alternative 2A provides an increased
probability of meeting TMDLs over
Alternatives 1A and 1B. The enhanced
vegetative swale at the outlet of the 77
outfall will provide a park amenity as well
as provide treatment of dry weather flow
and polishing of recycled water before it
enters the lake.
An additional 6 acres of wetlands would
be created in the lower freshwater
marsh to treat storm drain runoff prior
to discharge to the Harbor Outfall. The
wetlands in the lower freshwater marsh
and the GSRD at the Harbor College
outfall would be part of the basin-wide
strategy to meet future TMDLs at the Los
Angeles Harbor.
Alternative 3A improvements include
all the Alternative 2A improvements and
several others, including: creation of a
riparian woodlands runoff capture area at
the upper margin of Machado Lake and
provision of a lake aeration system, with
the capability of alum addition, as needed.
Alternative 3A offers the full suite of lake
rehabilitation options, offering greater
probability than Alternatives 1 and 2 in
meeting TMDLs. In addition, Alternative
3A would re-contour a portion of the
riparian woodland to capture storm runoff
to the lake and decrease the sediment
load upstream from Machado Lake.
An alternative analysis was performed as a tool to help decision makers develop the final, recommended Machado Lake project. A
series of technical workshops were held with the City of Los Angeles (BOE, BOS, RAP) in May and June 2009. Based on these workshops,
various components of the three alternatives emerged as preferable for the recommended Machado Lake Ecosystem Rehabilitation
project. All project components were discussed during the workshops , with each component receiving a “yes” or “no” decision. The
“yes” components were combined into a single recommended alternative that will be carried forward into the design phase. This
recommended project is considered to be the alternative best able to meet project objectives while minimizing environmental impacts.
JULY 2009
Recommended
Machado Lake Plan
Habitat and Park Design
An intensive program of invasive removal
will take place throughout KMHRP.
Invasive species like Ludwigia will be
removed, while the Southern Tarplant
and the Coastal Sage Scrub will be
enhanced to satisfy habitat enhancement
opportunities. Construction of park
improvements including smart irrigation,
new trails, and site amenities, such as
fishing piers, are also recommended. Lake
edge treatments, or planted bioinfiltration
areas, will be constructed. These buffers
will be designed and constructed to
encourage pedestrians to utilize the park
trails and designated access points to
walk to the lake shoreline and to intercept
irrigation runoff before it enters the lake.
Schematics of the lake edge treatment
concepts are shown at right.
BMPs
BMPs were evaluated for each of the
major storm drain outfalls to remove
trash and sediment from runoff before
discharging to Machado Lake or the
Freshwater Marsh. BMPs include
Continuous Deflection Separation
(CDS®) units at storm drain D24010
and at the Figueroa Drain; a Gross Solid
Removal Device (GSRD) at Project 77;
a bioengineered vegetative swale for dry
weather treatment at Project 77; and a
bioengineered vegetative swale at Project
510 Line C. The golf course maintenance
yard will contain site BMPs.
Lake Options
The full suite of lake rehabilitation options
will be implemented in the recommended
alternative. This includes lake dredging
and lake augmentation with supplemental
water. Recycled water from the Terminal
Island Water Reclamation Plant will
be used for lake augmentation, while
potable water will be used as a backup
supply. Both these measures are needed
to achieve and maintain a lake depth of
Turf open space
with trees
Public viewing area
with interpretive
signage
Machado Lake
with protective edge buffer
Native planting area with trees and shrubs
for foot traffic control
Walkway
Turf
open space
Native planting area
with trees and shrubs
for foot traffic control
Turf open space Native planting area
with trees
with trees and shrubs
Turf
open space
Native planting
area with trees
and shrubs
Access
walkway
Fishing access
zone
Machado Lake
Fishing pier and
lake edge treatment
Machado Lake
Conceptual Illustrative Sections of Machado Lake Rehabilitation
JULY 2009
Machado Lake Recommended Alternative
Wilmington
Drain
Secondary
High Flow
Channel
P65
PACIFIC COAST HWY
45
P36
NORMANDIE AVE
Riparian
Woodland
40
10
TA
VE
366
D2
VE
RM
ON
Machado
Lake
Bioengineered
Vegetated
Drainage Swale
Golf Course
Maintenance Yard
Site BMPs
“L” ST
FW Y
T
72
23
north
P9
500
48
1
Pr oj ec t 27 47
et
Ha rb or Ou tl
D2
250
Drainage
Channel
Freshwater
Marsh
Drainage
Channel
P2 53 3
Potential MF/RO
AN
Recycled Water
AH
Pipeline AlignmentEIM S
Fig Pro
ue jec
ro t 6
a D 43
ra
in
r
bo in
ar Dra
H
LA lege
l
Co
Bioengineered
Vegetated
Drainage Swale
0
11 0 HA RB OR
“L” ST
Project 77
ML Project
510 - Line C
1000’
Legend
Notes:
CDS® System
In-Lake Sediment Traps
Land-Based Compressor
Non-Native Grasslands Replaced
with Southern Tarplant in Select Areas
(approximate boundary)
Supplemental Water
Drainage Channel
Containment Berm
Coastal Sage Scrub Upland
Enhancement
Vegetated Swale
Off-Line Treatment Wetland
(approximate boundary
Alum Injection System
Freshwater Marsh Wetlands
Aeration System
Runoff Capture Area
Existing Storm Drain
1. Includes park design improvements and smart
irrigation.
2. Includes lake dredging
3. Includes supplemental water
(recycled or potable).
4. Includes dam improvements.
5. Includes invasive plant removal in the riparian
woodland and freshwater marsh.
6. Includes in-lake Ludwigia removal.
7. Includes aquatic plant management and
littoral zone enhancements.
8. Includes constructed islands
(aquatic or terrestrial).
Proposed Lake Bathymetry
GSRD Unit
2’ MSL
4’ MSL
Pump House
3’ MSL
7’ MSL
Energy Dissipator
3.5’ MSL
10’ MSL
9. Includes alum treatment, as necessary.
10. Includes shoreline stabilization.
Vegetated Berm
JULY 2009
approximately 8 feet, which is important
in order to minimize internal nutrient
loading. Dredging the lake will also
remove sediment that is currently overenriched with nutrients and contributes
to the internal nutrient loading problem.
An offline-treatment wetland, an aeration
system, and alum injection (as necessary)
will also help satisfy the water quality
objectives by removing nutrients from the
water and increasing dissolved oxygen.
In-lake sediment basins will be constructed
in the northern portion of the lake just
south of the riparian forest and near the
Project 77 storm drain outfall to promote
localized sediment deposition. The dam
at the southern end of the lake will also
be modified so that the lake level can be
adjusted as desired. A final decision with
regard to floating versus terrestrial islands
will be made during the design phase.
Wetlands
In addition to the offline treatment
wetland adjacent to the lake, wetlands
improvements will be made in both the
riparian woodland and lower freshwater
marsh. Riparian woodland improvements
include a runoff capture area and
secondary flow channel. In the lower
freshwater marsh, various methods will be
used to increase flow dispersal, including
a series of swales and berms at Storm
Drain D7223. In addition, three acres of
new emergent wetlands will be created.
Machado Lake Recommended Plan Performance Measure Results
Project Goal
Performance Measure
Result1
Satisfy water quality objectives

Reduce sediment load to Machado Lake

510 tons removed per year

Reduce wet weather metals load

222 pounds removed per year
to Los Angeles Harbor from stormwater BMPs
Enhance recreational opportunities
Provide a sustainable project
Enhance habitat
Reduce mean summer phosphorus

63% reduction from baseline

Reduce mean summer nitrogen

Reduce mean summer chlorophyll-a

Provision of amenities

Medium

Length of new trails

2,370 feet

Probability of meeting TMDL

5 (rated from low [1] to high [5])

Supplemental water requirement

115 acre feet per year

Recycled water use

100%

Reuse of dredged material

10% of total excavation

New wetland habitat
7 acres

New upland habitat

5.4 acres

Invasive plant removal - primrose

5.9 acres removed

Invasive plant removal - Cal-IPC non-natives

11.5 acres removed
and other non-native threats
Minimize short-term construction impacts
1

Estimated capital cost

$70.2 million

Estimated annual operation and maintenance cost

$400,000

Dredged material removal requirement

11,250 bins of dredged material
See Pre-Design Report, Section 9 for a detailed discussion
JULY 2009
Project Implementation
During the pre-design process, Machado Lake and Wilmington Drain have largely been considered one project because they are
hydrologically connected and many of the field investigations were jointly conducted. However, the detailed design and construction
phases will be conducted under separate contracts to expedite implementation. Overall responsibility and long-term maintenance
involves multiple jurisdictions. The schedule for the joint projects is shown in a combined format here to illustrate the relationship
between them and their common permitting tasks.
Implementation Schedule
2009
Task
2010
2011
2012
2013
J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F
Combined Pre-Design Report
Wilmington Drain
50%
90%
100%
Design
Bidding and Award
Construction
Machado Lake
50%
90%
100%
Design
Bidding and Award
Construction
Common Tasks
Combined EIR
Permitting
CCC Grant Work
JULY 2009
Wilmington Drain
The overall proposed design, permitting,
bidding, and construction schedule for
Wilmington Drain assumes one construction
package will be prepared for Wilmington
Drain. The schedule assumes that the
detailed design is started in July 2009 and
completed in June 2010 with CEQA. A
construction bidding and award period of
6 months is shown on the schedule. The
construction contract is estimated to be
awarded in December 2010. A detailed
project schedule is included in Section 10 of
the Pre-Design Report.
The construction capital cost estimate is
shown on the table at right.
The total project cost estimate is:
Description
Estimate
Pre-Design, Design,
Bid & Award
$2,201,000
Construction (including
construction contingency)
$14,276,000
Construction Management,
Post Construction
$1,358,000
Total Project Cost $17,835,000
This is within the approved Prop O
funding for this project of $17,943,000. In
addition, the portion of the project cost
attributed to modifying the channel so
that it has the capacity to convey the flow
from a 50 year storm event will be borne
by the LACDPW. The amount will be
established by mutual agreement during
the design phase.
Construction Capital Cost Estimate
Description
Estimate
Flood Control Improvements
$2,487,000
Stormwater BMPs
$7,187,000
Park Components/
Landscaping
$4,057,000
Invasives Removal
$545,000
Total $14,276,000
Machado Lake
The overall proposed detailed design,
permitting, bidding, and construction
schedule for Machado Lake and KMHRP
assumes one construction package
will be prepared and ready for bids in
November 2010. The schedule assumes
that the detailed design for the Machado
Lake project will start in August 2009.
CEQA and permitting timeframes shown
on the schedule are the same as for the
Wilmington Drain, because they will be
jointly prepared for both projects. The
permitting timeframes control when the
design packages can be completed and
ready for bidding. The schedule assumes
a standard 6 month City bidding and
contract award period. Construction
is expected to begin in May 2011 and
would be completed in September 2012.
A detailed project schedule is included in
Section 10 of the Pre-Design Report.
The Pre-Design Phase opinion of probable
construction cost for the Machado Lake
project was prepared according to LABOE
guidelines for a Class C estimate and is
consistent with Proposition O estimating
procedures as detailed in Section 10 of
the report.
Construction Capital Cost Estimate
The total project cost estimate is:
Park Components
$3,460,000
Invasives Removal
$679,000
Description
Estimate
Pre-Design, Design,
Bid & Award
$12,990,000
Construction
$70,214,000
Construction Management,
Post Construction
$10,124,000
Description
Estimate
Stormwater BMPs
$2,898,000
Wetlands
$4,073,000
Lake Rehabilitation
$1,126,000
Dredging Cost
$57,978,000
Total
$70,214,000
Total Project Cost $93,328,000
This is within the approved total budget
of $99,524,000.
JULY 2009
O S A NG
OF L
EL
CI
ES
TY
E
OF
AN
TM
DP
A RK S
DE P A R
NT
R EC R EA TI O
N
City of Los Angeles • Department of Public Works • Bureau of Engineering
Wilmington Drain Multi-Use Project
Pre-Design Report • Executive Summary
July 2009
Funding Provided by:
City of Los Angeles Proposition O Clean Water Bond
California State Water Resources Control Board and
Department of Water Resources (Proposition 50, Chapter 8)
California Coastal Conservancy