HomeMy WebLinkAboutStaff Report 3.C 01/07/2019Axl
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DATE: January 7, 2019
TO: Honorable Mayor and Members of the City Council through City Manager
F
FROM: Din S oiin, .A — irector, Public Works and Utilities
Jasot Beat; E. —Assistant Director of Public Works
SUBJECT: Resolution to Adopt a Mitigated Negative Declaration for the Denman Reach
Phase 4 Project and Approve the Project with the Incorporation of Mitigation
Measures
RECOMMENDATION
It is recommended that the City Council adopt the attached Resolution to Adopt a Mitigated
Negative Declaration for the Denman Reach Phase 4 Project and Approve the Project with the
Incorporation of Mitigation Measures.
BACKGROUND
Completing flood mitigation projects within the Petaluma Watershed in concert with the
development of a river and creek front trail system was envisioned in the 1996 River Access and
Enhancement Plan and was adopted as a policy in the General Plan 2025 in 2008. There were
three vacant parcels located on the west side of Industrial Avenue that were originally sought for
acquisition by the City to allow terracing along the Denman Reach of the Petaluma River to
lower flood waters and construct a river front access trail. Due to funding limitations the Denman
Reach Phase 3 project only acquired two of the three properties.
In the fall of 2016, the Sonoma County Water Agency (Agency) approached the City of
Petaluma with an opportunity for $1.9 million in California Department of Water Resource
(DWR) Proposition 1E grant funds for a flood prevention project. As a result, the proposed
"Phase 4" project was developed and includes acquiring the third vacant parcel on Industrial Ave
of 5.47 acres, creating a flood detention basin, and removing a sediment buildup in the Petaluma
River at the Corona Road bridge. The project would also protect river corridor open space, create
additional river access trails, increase riparian habitat in the Denman Reach area, and reduce the
risk of scour of the foundation of the Corona Road bridge. In May 2017, DWR approved an
amendment to an existing Prop 1E grant agreement to allow the Agency to complete the
Petaluma River Flood Management Denman Reach 4 project in lieu of a previously approved
project in Sonoma Valley. In February 2018, the City entered into a Funding Agreement with the
Agency to execute the project. Based on the project characteristics, it was determined that CEQA
could be satisfied by adopting a Mitigated Negative Declaration.
DISCUSSION
The proposed project will provide continued flood improvements along the Petaluma River by
providing offline detention basins at Denman Reach to capture peak flows during storm events,
and removal of sediment near the Corona Road bridge in order to return the channel to the
original cross section designed during bridge installation.
The detention basins at Denman Reach will be divided into two basins within the parcel that are
broken up by the existing sewer and water mains that split the parcels. Each basin will have a
spillway opening to allow the peak flows into the basin. The spillways will be installed in line
With the existing trail, which will maintain compliance with the guidelines set forth by the
Americans with Disabilities Act. This project will also provide additional access trails with an
additional 1,000 linear feet of a loop trail around the basins. The detention basins will provide
nearly 10 acre -ft of storage. Another aspect of this portion of the project will be to create
seasonal wetlands to mitigate the existing wetlands that are being removed as part of the basin
excavation.
Roughly 6,150 cubic yards of the sediment will be removed at the Corona Road bridge to restore
the originally designed channel for the bridge installation. To accomplish this task, vegetation
and trees within the channel will be removed and be mitigated within the new channel along
newly -graded slopes. Riprap will be installed against the bridge abutments to prevent scouring
during high flow conditions.
An Initial Study and Mitigated Negative Declaration (MND) was prepared, published, and
circulated for public comment in August 2018. Public Notice of the documents availability was
published in the Argus Courier on August 30, 2018 and distributed to all property owners within
a 500 -foot radius of the project site a week prior to the publishing date. Public Notice was also
distributed to the State Clearinghouse and all appropriate referral agencies. Comments received
to date are attached in Attachment 3. Written responses to comments are attached in Attachment
4. Recommended amendments and/or additions to the Initial Study are attached in Attachment 5.
None of the amendments or additions identify new avoidable significant impacts or show
proposed mitigation or project revisions are inadequate to mitigate identified impacts. Therefore,
recirculation of the MND is not required as the result of the amendments. Mitigation measures
for the Project are set forth in Exhibit A of the proposed Resolution, Attachment 1.
FINANCIAL IMPACTS
Project funding is provided by two State grants: with $1,754,322 from the DWR and $880,302
coming from the Agency Zone 2A Budget for a total project budget of $2,634,624. The City will
contribute $29,165 of in-kind services as a fund match by performing project management and
provide perpetual maintenance of the acquired property and the flood control measures.
The proposed action has no unanticipated financial impacts.
ATTACHMENTS
1. Resolution w/ Mitigation Monitoring Plan
2. Location Map
3. Comments Received on Initial Study
4. Responses to Comments received on Initial Study/Amendments to the Initial Study
reflecting comments received from agencies and the public
® Items listed below are large in volume and are not attached to this report but may be viewed in the
City Clerk's office.
5. Initial Study dated August 2018
6. Final Initial Study dated January 2019
3
Attachment 1
RESOLUTION ADOPTING A MITIGATED NEGATIVE DECLARATION FOR THE
DENMAN REACH PHASE 4 PROJECT, AND APPROVE THE PROJECT WITH THE
INCORPORATION OF MITIGATION MEASURES
WHEREAS, the City of Petaluma has adopted policies'calling for the development of
flood terraces and a riverfront trail system in the 1996 River Access and Enhancement Plan and
the 2008 General Plan 2025; and
WHEREAS, the Sonoma County Water Agency has been awarded an initial grant from
the State Department of Water Resources in the amount of $1,754,322 for land acquisition and
flood control management in the Denman Reach area of the Petaluma River; and
WHEREAS, the Sonoma County Water Agency (Agency) has approved $881,600 in
funding for the project; and
WHEREAS, the Agency entered into an agreement with the City to provide $2,635,000
in funding to execute a flood protection project to acquire a vacant 5.47 -acre parcel on Industrial
Avenue, create a flood detention basin, create additional river front trails, and remove sediment
buildup in the Petaluma River at the Corona Road Bridge; and
WHEREAS, the City prepared an Initial Study for the Project consistent with CEQA
Guidelines sections 15070 through 15074.1 and determined that a Mitigated Negative
Declaration (MND) was required to analyze the potential for new or additional significant
environmental impacts of the Project beyond those identified in the General Plan EIR; and
WHEREAS, on or before August 22, 2018, the City's Notice of Availability and Notice
of Intent to Adopt a MND based on the Initial Study, providing for a minimum of 30 -day public
comment period commencing August 23, 2018 and ending September 22, 2018 published and
mailed to all property owners within 500 feet of the Project as well as all persons having
requested special notice of said proceedings; and
WHEREAS, pursuant to the analysis in the Initial Study, the Project does not have the
potential to degrade the quality of the environment, substantially reduce the habitat of a fish or
wildlife species, cause a fish or wildlife population to drop below self-sustaining levels, threaten
to eliminate a plant or animal community, substantially reduce the number or restrict the range of
a rare or endangered plant or animal or eliminate important examples of the major periods of
California history or prehistory; and
WHEREAS, pursuant to further analysis in the Initial Study, the Project does not make
significant impacts that are individually limited, but cumulatively considerable, nor have
environmental effects which may cause substantial adverse effects on human beings, either
directly or indirectly; and
WHEREAS, on January 7, 2019, at a duly noticed public meeting, the Petaluma City
Council reviewed the MND, all supporting documents including but not limited to the Initial
rd
Study and proposed amendments and additions, staff reports and related materials, and all public
comments and evidence presented at or before the meeting; and
WHEREAS, the Initial Study and MND identify mitigation measures applicable to the
Project, as incorporated herein by reference; and
WHEREAS, the Project is not located on a site listed on any Hazardous Waste Site List
compiled by the State pursuant to Section 65962.5 of the California Government Code; and
WHEREAS, the MND reflects the City's independent judgment and analysis of the
potential for environmental impacts from the Project; and
WHEREAS, the MND, Revised Initial Study, and related project and environmental
documents, including the General Plan 2025 EIR and all documents incorporated herein by
reference, are available for review in the City Community Development Department at Petaluma
City Hall, during normal business hours. The custodian of the documents and other materials
which constitute the record of proceedings for the proposed project is the City of Petaluma
Public Works and Utilities, 2020 North McDowell Blvd, Petaluma, CA 94954, Attn: Tim
Moresco, Associate Civil Engineer.
NOW, THEREFORE BE IT RESOLVED, that the City Council of the City of
Petaluma hereby:
Based on its review of the entire record herein, including the MND, the Initial
Study, all supporting, referenced and incorporated documents and all comments
received and responses and additions thereto, the City Council further finds that
there is no substantial evidence that the Project as mitigated and conditioned will
have a significant effect on the environment, that the Mitigated Negative
Declaration reflects the City's independent judgment and analysis, and that the
Mitigated Negative Declaration, Initial Study as amended, and supporting
documents provide an adequate description of the impacts of the Project and
comply with CEQA, the State CEQA Guidelines and the City of Petaluma
Environmental Guidelines.
2. The Initial Study and MND shall incorporate the text additions and amendments
contained in the attached Attachment 4.
The City Council adopts the Mitigation and Monitoring and Reporting Program
set forth in Exhibit A hereto and incorporated by reference. All mitigation
measures contained therein shall be conditions of approval of the Project.
4. The City Council hereby approves the Petaluma River Flood Management
Denman Reach Phase 4 Project.
5
EXHIBIT A
L U City of Petaluma, California
R Public Works and Utilities
z85s
Project Name: Denman Reach Phase 4
Address/Location: 1300 block Industrial Ave. (APN 007-412-033)
Petaluma River/Corona Bridge
REPORTINGIMONITORING RECORD — MITIGATION MEASURES
This document has been developed pursuant to the California Environmental Quality Act,
Public Resource Code Section 21.081.6 to ensure proper and adequate monitoring or reporting in
conjunction with project approval which relies upon a Mitigated Negative Declaration.
2
Review
Dept.
Due
Date
Date
Completed
Staff
Initials
Biological Resources
A. 13I0-1: Prior to filling of jurisdictional
PW&U,
RPI
waters, or construction activities within
CDFW,
Corps, RWQCB or CDFW jurisdiction,
RWQCB
necessary regulatory permits will be obtained
from the appropriate agencies. Regulatory
permits to be obtained include a Corps
Permit, Regional Water Quality Control
Board Section 401 Water Quality
Certification and/or Waste Discharge
Requirement. Prior to proposed filling of
jurisdictional waters, compliance with all
regulatory agency permit conditions shall be
demonstrated. Permanent impacts to
jurisdictional wetlands will be mitigated
1.5:1 ratio at a minimum, with the 1:1
relating to on-site restoration and 0.5 of
additional mitigation to compensate for
temporal losses, on a functions and values
basis by: (1) restoring wetlands in the Study
Area; (2) purchasing an appropriate amount
of mitigation credits by an approved
mitigation bank, or (3) another type of
mitigation as approved by the Corps,
2
RWQCB, and/or CDFW through the
permitting process. With the implementation
of these measures, the Project impact on
waters of the U.S. and State will be less than
significant.
B. 13I0-2: Prior to removing riparian vegetation
PW&U,
RPI
or construction activities within CDFW or
CDFW,
RWQCB jurisdiction, necessary regulatory
RWQCB
permits will be obtained from the appropriate
agencies. Regulatory permits to be obtained
include a CFGC Section 1602 Streambed
Alteration Agreement. The project shall
comply with all regulatory agency permit
conditions and compensatory mitigation
measures as determined and required by
regulatory agencies during permit
authorization but shall be no less than 1:1
replacement ratio. Mitigation options will
include the following: (1) planting
replacement riparian vegetation, (2) purchase
of mitigation bank credits from an approved
mitigation bank, and/or (3) paying an in -lieu
fee to a natural resource agency or habitat
resource organization. For habitat that is
preserved and/or established for mitigation, a
Habitat Mitigation and Monitoring Plan
(HMMP) shall be prepared. The HMMP will
include a detailed description of
restoration/enhancement/preservation actions;
restoration performance criteria for each
biological parameter (i.e., native/invasive
plants, wildlife use); and
monitoring/maintenance/reporting
requirements for each biological parameter to
evaluate restoration performance criteria.
With the implementation of these measures,
the Project impact on riparian vegetation will
be less than significant.
C. 13I0-3: A permit from the City of Petaluma
PW&U,
CoC
will be acquired for the removal of any
PD
protected tree within City, limits. Conditions
of approval may include tree replacement
plantings or the payment of in -lieu fees. With
the implementation of these measures, the
Project impact on protected trees will be less
than significant.
D. BIO-4: Six special-status plant species have
PW&U,
CA
potential to occur in the Study Area. To
CCNB
avoid impacts to special-status plants,
DFG
protocol-level surveys shall be conducted
during the documented bloom period of the
species. Two site visits, including one early-
season (May), and one late-season (July) will
be sufficient to cover the bloom periods of
the six species with potential to occur.
Survey timing may fluctuate based on
blooming periods of appropriate reference
site locations. If special-status plant surveys
result in negative findings, no impacts would
occur, and no mitigation would be required.
However, if special-status plants are
identified in the impact area, mitigation will
be required. Mitigation will include
avoidance, or if avoidance is not feasible,
seeds collection and re-establishment at a
minimum 1:1 ratio (number of plant
established: number of plants impacted) in
preserved, suitable habitat. Re-established
populations shall be monitored annually in
accordance with an approved HMMP for a
minimum of five years. Reports describing
performance results will be prepared and
submitted for years 1, 3, and 5 during the
monitoring period. With the implementation
of these measures, the Project impact on
special-status plants will be less than
significant.
E. 13I0-5: While trees are not typically used as
PW&U,
CA
hibernation roosts, mature oaks and other
SCWA,
large trees on the property could potentially
CDFW
be used as day or maternity roosting sites by
bats. All bat roosts, including those of non-
special-status bats are protected by CDFW.
To avoid impacts to roosting bats, any
project activities that would impact potential
bat roosts shall be initiated outside of the
maternity roosting season (March 1 — July
31). If project work such as the felling of
trees cannot occur outside of the maternity
season, then a bat roost survey shall be
conducted within 14 days prior to the start of
such activities. Any structures or trees that
are determined to support roosts shall have a
200 -foot no work buffer placed around them,
and the buffer shall not be lifted until the
maternity season has completed. In addition,
when any large trees are removed, they shall
be allowed to lie undisturbed on the ground
for one night to allow any roosting bats to
escape on their own before the trees are
processed. With the implementation of these
measures, the Project impact on bats will be
less than significant.
F. BIO -6: For the protection of special -status
PW&U,
CoC
birds, and native nesting birds protected by
PD
the MBTA and CFGC, future Project
activities shall occur outside of the nesting
season from September 1 —January 31, to the
extent feasible. If working outside of the
nesting season is not possible, and project
activities are initiated during the nesting
season (February 1 — August 31), a qualified
wildlife biologist shall conduct a nesting bird
survey no more than 14 days prior to the start
of Project activities. If no active nests are
identified during the surveys, no impacts will
occur to birds and work will progress without
restriction. If active nests are identified, a no -
disturbance buffer around the nest shall be
implemented to avoid impacts to nesting
birds. Buffers will be determined by a
qualified biologist, and typically range from
25 feet to 500 feet depending on the species
and protection status of that species. Once an
active nest is determined to no longer be
active, because of young fledging or
predation, the buffer around the nest shall be
removed and work shall progress without
restriction. With the implementation of these
measures, the Project impact on nesting
and/or protected birds will be less than
significant.
G. BIO -7: Aquatic habitat activities shall be
PW&U,
RPI,
completed during the dry season, between
CDFW,
CA
July 15 and October 1. Regulatory approval
RWQCB
shall be obtained for all work within
potentially jurisdictional areas from
respective agencies. Approvals from the
RWQCB, CDFW, and Corps are required
based on project designs (City of Petaluma
2016). The Petaluma River is also designated
critical habitat for California central coast
chinook and California central coast
steelhead and is considered EFH for coho
and chinook salmon. Therefore, it is likely
that the Corps will consult with the USFWS
and NMFS for impacts to the Petaluma
River. All work within these areas shall
conform to any conditions imposed by the
regulating agencies.
Prior to construction, the contractor shall be
required to prepare an Accidental Spill
Prevention and Cleanup Plan. This plan shall
include required spill control absorbent
material, for use beneath stationary
equipment, to - be present on-site and
available at all times.
All refueling and maintenance of equipment,
other than stationary equipment, shall occur
at least 100 feet from the creek's top -of -
bank. Refueling or maintenance of stationary
equipment within the channel (top of bank to
top of bank) shall only occur when secondary
containment sufficient to eliminate escape of
all potential fluids is in place. Any hazardous
chemical spills shall be cleaned immediately.
All stockpiling of construction materials,
equipment, and supplies, including storage of
chemicals, refueling and maintenance, with
the exception of stationary equipment, shall
occur outside the creek channel. No
equipment shall be washed where runoff
could enter the creek.
No motorized equipment shall be left within
the channel (top of bank to top of bank)
overnight.
10
Work shall be conducted in isolation from
flowing water. Prior to the start of
construction activities, the work area shall be
isolated using temporary water diversion
materials such as sand bags or other similar
methods, and flowing water shall be
temporarily diverted around the isolated area.
A 3 to 5 -foot buffer zone will be created,
offset from the sandbags, to further reduce
the chances of sediment depositing into the
river during construction.
If de -watering is necessary, pumps with 0.2 -
inch mesh shall be used to remove standing
water from the work area within the
cofferdams to a filtration basin to prevent
direct discharge into the creek. If a filtration
basin is not available, filter bags will be
placed surrounding the hose -release and the
hose -release end shall be placed on a level
area outside of the wetted creek channel to
allow water to settle prior to returning to the
creek.
No pumped water shall be directly
discharged into the creek. Allowing the
pumped water to settle in a filtration basin or
release through filter bags will prevent
increase in turbidity or sediment loads during
the de -watering process. If de -watering is
necessary, a de -watering plan shall be
submitted for agency approval.
By implementing these measures, the
Project's impacts to special -status fish,
including salmonids, shall be reduced to less
than significant.
H. BIO -8: Although the lack of upland habitat,
PW&U
CA
lack of connectivity to suitable breeding
habitat, intense flooding, sedimentation and
introduced predators/competitors reduce the
11
potential for CRLF to occur within the Study
Area, measures to avoid CRLF impacts shall
be implemented. The following measures
shall be implemented to avoid CRLF and are
in agreement with the measures described in
the NLAA that was issued for this project
(Corps 2016).
An environmental awareness training for all
crews working on the site shall include
education on sensitive resources such as
protected wildlife with the potential to occur
within the area (identification, regulatory
status, natural history), water quality and
environmental protection measures.
Within 48 hours prior to any construction
activities, a biologist approved by USFWS
(Approved Biologist) shall conduct surveys
for CRLF in and adjacent to the Action Area,
100 feet upstream and 100 feet downstream
of the Study Area.
The Approved Biologist shall have stop work
authority to protect natural resources or
ensure personal safety or the safety of
workers.
If CRLF are detected during surveys, work
shall cease until consultation with the
appropriate agencies can be completed.
If no CRLF are found during the
preconstruction surveys, the Study Area shall
be surveyed each day prior to
commencement of work by the Approved
Biologist or a qualified biologist under the
direction of the Approved Biologist to ensure
that no CRLF are present in the Study Area
until vegetation removal and exclusion fence
installation are complete. After vegetation
12
clearance and exclusion fence installation,
activities may continue inside fenced areas
without the presence of a biologist unless
work is halted for more than 10 days, then a
pre -construction survey for CRLF shall be
conducted prior to re-initiation of work.
All workers shall ensure that food scraps,
paper wrappers, food containers, cans,
bottles, and other trash from the work area
are deposited in covered or closed trash
containers. Trash in the containers shall be
removed and disposed of off-site daily.
Prior to the commencement of operation of
wheeled or equipment with tracks in
undisturbed areas, vegetation that could
conceal CRLF shall be removed by hand
under the supervision of a qualified biologist
after the Approved Biologist has surveyed
the area and determined it to be free of
CRLF. If vegetation is too dense to be
adequately surveyed (tall grasses, blackberry
etc.), the Approved Biologist, at his or her
discretion, may request that vegetation is cut
to a height of 6-12 inches (and cut vegetation
removed) prior to conducting a survey. If no
CRLF are found, the vegetation shall be cut
to ground level, and this shall ensure that no
CRLF are harmed by cutting tools.
Exclusion fence shall be installed around
staging areas and Study Areas after
vegetation removal is complete. A qualified
biologist under direction of the Approved
Biologist will oversee the installation of the
fence. Once the fence is installed, the
periodic inspections by the qualified
biologist and construction contractor shall
ensure that the fence is maintained
13
effectively for the duration of the project. If
exit/entries to the enclosed areas are required,
they shall be closed at the pnd of work each
day to ensure exclusion of CRLF overnight.
Erosion control structures shall not include
plastic or be of types that may entrap wildlife
and shall be constructed of tightly woven
natural fibers.
All construction activities shall cease one
half hour before sunset and shall not begin
prior to one half hour before sunrise.
Additionally, construction activities shall not
occur during rain events or within 24 hours
of events projected to deliver >0.2 inches of
rain or within 24 hours after rain events
exceeding 0.2 inches in measurable
precipitation, as CRLF are most likely to
disperse during periods of precipitation. No
work shall occur after 0.5 inches of rain has
occurred after November 1 in the year work
is occurring.
Any open holes or trenches shall be covered
or have escape ramps no steeper than 45
degrees installed at the end of each working
day to prevent CRLF from becoming
entrapped. With the implementation of these
measures and those described for special -
status fish (13I0-7), any impacts to CRLF
shall be avoided.
I. BIO -9: Prior to the initiation of Project work
PW&U
CoC
in the reservoir or banks of the reservoir, a
qualified biologist shall conduct a
preconstruction survey for pond turtles. If a
pond turtle is found during surveys, the
qualified biologist will relocate it outside of
the Study Area, out of harm's way or it shall
be allowed to move out of the area under its
own power. With the implementation of
these measures and those previously
14
described for CRLF (13I0-7) and aquatic
habitats (13I0-1 and BIO -2) (exclusion fence,
work windows etc.), the impacts to Pacific
and turtle will be less than significant.
Geology and Soils
J. GEO-1: All provisions of the City of Petaluma
PW&U,
CA
Grading Ordinance, the project plans, and the
PD
project geotechnical report prepared for Phases
1 and 2 will be followed. Finished grades will
not be steeper than 2H:1 V.
K. GEO-2: Earthwork, including grading and fill
PW&U,
COC,
placement will only occur between the period
PD
CA
of June 1 and October 15. All disturbed areas
will be stabilized upon final grading and
protected using a combination of permanent
vegetative treatment, mulching, geotextiles, as
shown in the project Erosion Control Plan
(ECP) to be included in the grading plans. In
addition, the selected construction Contractor
will be required to develop a SWPPP (subject
to City approval) and implement the Plan. The
City's Project Manager will monitor (and
document) to ensure that the ECP and SWPPP
and other provisions of the approved
improvement plans are being followed.
L. GEO-3: Site grubbing and earthmoving
PW&U,
COC,
activities will be completed prior to October 15
DFG
CA
of the construction year. Work beyond October
15 (except for revegetation until November 15)
shall be specifically authorized in advance by
the appropriate regulatory agencies. All erosion
control shall meet specifications of the City of
Petaluma Erosion Control Ordinance. Erosion
control and sediment detention devices shall be
incorporated into the project design and
implemented at the time of construction. These
devices shall be in place prior to October 15
and the onset of rains for the purposes of
minimizing fine sediment and sediment/water
slurry input to flowing water, and of detaining
water to retain sediment on-site. These devices
will be placed at all locations where the
likelihood of sediment input exists. Sediment
collected in these devices shall be disposed of
away from the collection site and outside
riparian areas and flood hazard areas.
iG
M. GEO-4: Any soil or rock fill to be installed
PW&U,
COC,
within Water Board jurisdiction will include an
RWQCB
CA
evaluation of biotechnical methods and habitat
enhancement features to be incorporated in
order to avoid and minimize impacts of
hardened structures. All rock must be
demonstrated to be necessary and appropriately
sized through a hydraulic analysis performed
by a qualified professional. If biotechnical
methods and habitat enhancement features are
demonstrated to be infeasible, mitigation will
be required at a 1.5:1 ratio at a minimum.
Hydrology and Water Quality
N. HYD-1: A detailed Storm Water Pollution
PW&U
COC,
Prevention Plan (SWPPP) shall be prepared
CA
and implemented by the Contractor, subject to
review and approval of the City of Petaluma,
as a line item in the construction agreement.
Construction plans should specify all erosion
and sediment control measures that will be
used, including (where applicable):
1. Limiting access routes to the creek channel
and stabilizing access points;
2. Stabilizing graded areas as soon as possible
with seeding, mulching, erosion control
materials or other effective methods;
3. Delineating clearing limits, easements,
setbacks, sensitive areas, vegetation, and
drainage courses by marking them in the
field;
4. Stabilizing and preventing erosion from
temporary conveyance channels and
outlets;
5. If rainfall occurs, using sediment controls
and filtration to remove sediment from
water collected on-site during construction
O. HYD-2: Implement established Best
PW&U,
COC,
Management Practices (BMPs) to control
RWQCB
CA
short-term construction water quality impacts.
1. Construction BMPs would reduce erosion
of disturbed soils during construction
activities and are used to minimize wind
and water erosion and transport of
sediments during construction. BMPs shall
include as a minimum the following
measures:
16
2. Temporary measures, such as flow
diversion, temporary ditches, and silt
fencing.
3. Surface disturbance of soil and vegetation
would be kept to a minimum.
4. Any stockpiled soil, awaiting removal from
the site, would be placed, and sloped so
that it would not be subject to accelerated
erosion.
P. HYD -3: Conformance with the State Water
RWQCB,
RPI,
Resources Control Board Construction
SCWA,
COC,
General Permit, including implementation of a
PW&U
CA
Storm Water Pollution Prevention Plan
(SWPPP) and the Sonoma County Water
Agency (SCWA) Stream Maintenance
Program Guidelines, which include Best
Management Practices. The BMPs cover
selective vegetation management, including
use of herbicides and other chemicals.
Q. HYD -4: Incorporate potentially hazardous
CDFW,
RPI,
materials storage and handling plan into the
PW&U
COC
overall Streambed Alteration Agreement.
CA
Provisions will include, but not be limited to
the following:
1. Refueling outside the riparian corridor with
measures for containing accidental fuel
spills.
2. All construction equipment and machinery
shall be checked for leaks prior to entry
into the stream channel (note: this BMP
would not apply to this project as no rolling
equipment is expected to be placed within
the stream channel).
3. Any construction equipment shall not be
stored or stockpiled in the creek channel.
4. No herbicide application in or near flowing
water, and all herbicides shall be applied
under the direction of a licensed Pest
Control Applicator, and in accordance with
appropriate re ulations.
Noise
R. NOISE -1: Temporary noise impacts will be
PW&U
COC,
limited by restricting construction activities
CA
to daylight hours: weekdays from 7:00 am to
7:00 pm, and Saturdays 9:00 am to 5:00 pm,
with no work on Sundays. This shall exceed
17
standards of the City of Petaluma Noise
Requested By or Due Date
PW&U Public Works & Utilities
GP
Ordinance which specifically prohibits
PD Planning Division
SPAR
Site Plan and Architectural Review
RA Regulatory/Referral Agency
construction activity between the hours of
Commencement of Construction
SCWA: Sonoma County Water Agency
10:00 p.m. and 7:00 a.m. Monday through
Control Board
Friday, and between 10:00 p.m. and 9:00
CDFW: Dept. of Fish & Wildlife
a.m. on Saturdays, Sundays, and State,
Construction Activity
RPI
Regulatory or Referral Permit
Federal, or local holidays.
Issuance (see RA list)
PCM
S. NOISE -2: Require hearing protection for
PW&U
CA
workers operating, and in close proximity to,
heavy machinery, including chainsaws, brush
mowers, and weed trimmers in accordance
with CFR 29, Part 1910.95, and OSHA
standards.
Department/ALYency
Requested By or Due Date
PW&U Public Works & Utilities
GP
Grading Permit
PD Planning Division
SPAR
Site Plan and Architectural Review
RA Regulatory/Referral Agency
CoC
Commencement of Construction
SCWA: Sonoma County Water Agency
RWQCB: Regional Water Quality
Control Board
CDFW: Dept. of Fish & Wildlife
CA
Construction Activity
RPI
Regulatory or Referral Permit
Issuance (see RA list)
PCM
Post -Construction Monitoring
18
Attachment 2
PETALUMA RIVER FLOOD MANAGEMENT
DEV
016301722
LOCATION MAP
Q-
PR T
v,
o\
Date : January 7, 2019
PROJECT SITE N City of Petaluma a�L
`° E Public Works and Utilities
PROJECT SITE S Department
xs5a
19
Attachment 3
'r STATE OF CAL[FORNIA
ria 1 " GOVERNOR'S OFFICE of PUNNING AND RESEARCH
� s
EDMUND G. BROWN .JR.
KE i ALEx
GOVERNOR
D[REGTOR .
October 15, 2018
Tim Moresco
City of Petaluma
202 N McDowell Blvd
Petaluma, CA 94954
Subject: Denman Reach Phase 4 - Petaluma River Flood Management Project
S CH#: 2018092029
Dear Tim Moresco:
The State Clearinghouse submitted the above named Mitigated Negative Declaration to selected state
agencies for review. On the enclosed Document Details Report please note that the Clearinghouse has
listed the state agencies that reviewed your document, The review period closed on October 12, 2018, and
the comments from the responding agency (ies) is (are) enclosed, If this comment package is not in order,
please notify the State Clearinghouse immediately. Please refer to the project's ten -digit State
Clearinghouse number in future correspondence so that we may respond promptly.
Please note that Section 21104(c) of the California Public Resources Code states that:
"A responsible or other public agency shall only make substantive comments regarding those
activities involved in a project which are within an area of expertise of the agency or which are
required to be carried out or approved by the agency. Those comments shall be supported by
specific documentation."
These comments are forwarded for use in preparing your final environmental document, Should you need
more information or clarification of the enclosed comments, -we recommend that you contact'the
commenting agency directly.
This letter acknowledges that you have complied with the State Clearinghouse review requirements for
draft environmental documents, pursuant to the California Environmental Quality Act. Please contact the
State Clearinghouse at (916) 445-0613 if you have any questions regarding the environmental review
process.
Sincerely,
.rcott Morgan
Director, State Clearinghouse
Enclosures
cc: Resources Agency
1400 10th Street RO, Box 3044 Sacramento, California 95812-3044
1-916-322-2318 FAX I-916.558-3184 www,opr,ca.gov
20
Document Details Report
State Clearinghouse Data Base
SCH# 2018092029
Project Title Denman Reach Phase 4 - Petaluma River Flood Management Project
Lead Agency Petaluma, City of
Type MND Mitigated Negative Declaration
Description The proposed project will provide continued flood improvements along the Petaluma River with the
fourth phase of the Denman Reach project by providing offline basins at Denman Reach, in order to
capture peak flows during storm events, and sediment removal near the Corona Road bridge and in
order to return the channel to its original section.
Lead Agency Contact
Name Tim Moresco
Agency City of Petaluma
Phone 707-778-4355 Fax
email
Address 202 N McDowell Blvd
City Petaluma State CA Zip 94954
Project Location
County Sonoma
City Petaluma
Region
Lat/Long 38° 15'41.1 " N / 122° 39'37.9" W
Cross Streets Indu'strial Ave/Corona Rd
Parcel No. 007-412-033
Township Range
Proximity to:
Highways
Airports
Railways
Waterways
Schools
Land Use
101
SMART
Petaluma River
Corona Creek ES
OS
Section
Base
Project Issues Biological Resources; Flood Plain/Flooding; Water Quality; Water Supply; Wetland/Riparian
Reviewing Resources Agency; Department of Fish and Wildlife, Region 3; Department of Parks and Recreation;
Agencles Department of Water Resources; California Highway Patrol; Caltrans, District 4; Air Resources Board,
Transportation Projects; State Water Resources Control Board, Divison of Financial Assistance; State
Water Resources Control Board, Division of Water Quality; State Water Resources Control Board,
Division of Water Rights; Regional Water Quality Control Board, Region 1; Native American Heritage
Commission; Public Utilities Commission
Date Received 09/13/2018 Start of Review 09/13/2018 End of Review 10/12/2018
21
Note: Blanks in data fields result from insufficient information provided by lead agency.
Sl?\'I'ti OI' ('ALIFORNIA--CAI_IFO[tNIA STATE TRANSPORl'ArION AGFNC'Y MNII)ND G BROWN Jr Govemnr
DEPARTMENT OF TRANSPORTATION (Ii( wY 10 1 Z C `�
DISTRICT 4
P.O. BOX 23660 _
OAKLAND, CA 94623-0660
PHONE (510) 256-5523
FAX (510) 2S6-5559, Age
TTY 711 voveov's office of ply MIN & R arch
www.di)t.ea.gov dlakirig cotrsrtration
OCT 10 2018 aCalljarniaWapof'Lifi.
STATE CLEARINGIOUSE
October 9, 2018
SCH# 2018092029
Mr. Tim Moresco, Associate Civil Engineer 04 -SON -2018-00328
City of Petaluma GTS ID 12654
Public Works and Utility
202 North McDowell Boulevard
Petaluma, CA 94954
Denman Reach Phase 4 — Petaluma River Flood Management Project— Mitigated Negative
Declaration (DiIND)
Dear Mr, Moresco:
Thank you for including the California Department of Transportation (Caltrans) in the
environmental review process for the above -referenced project, In tandem with the Metropolitan
Transportation Commission's (MTC) Sustainable Communities Strategy (SCS), Caltrans mission
signals a. modernization of our approach to evaluate and mitigate impacts to the State
Transportation Network (STN). Caltrans' Strategic 1Llanagernent Plain 2015-2020 aims to reduce
Vehicle Miles Travelled (VMT) by tripling bicycle and doubling both pedestrian and transit travel
by 2020. Our comments are based on the MND,
Project Understanding
The proposed project will provide continued flood improvements along the Petaluma River with
the fourth phase of the Denman Reach project by providing offline detention basins at Demean
Reach to capture peak flows during storm events, and sediment removal near the Corona Road
bridge and in order to return the chazmel to the cross section designed during bridge installation,
The detention basins at Denman Reach will be divided up into two basins within the parcel that
are broken up by the existing sewer and water mains that split the parcel. Each basin will have a
weir opening to allow the peals flows into the basin. The weirs will be installed in line with the
existing trail, which will maintain compliance with the guidelines set forth by the American
Disabilities Act. An additional 1,000 linear feet of a loop trail around the basins will be
constructed. The detention basins will provide nearly 10 acre-feet of storage,
Seasonal wetlands will be constricted to mitigate the existing wetlands that are being removed as
part of the basin excavation. Roughly 6,150 cubic yards of sediment will be reconstructed at the
Corona Road bridge to restore the channel to the section designed during the bridge installation,
To accomplish this task, vegetation, as well as several trees within the current channel will be
"Provide a safe, sustainable, haegraled and e%ficlenl transportation
Svsteai 10 wrliance California's VV0110MY and livability"
22
Mr, Tim Moresco, Associate Civil Engineer
City of Petaluma
October 9, 2018
Page 2
removed, The two basins are located approximately 0,4 miles and 1.2 miles southeast of the US
101/Pataluma Boulevard North intersection, respectively,
Hydraulics
In the Hydrology and Water Quality section of the MND checklist, there are four items checked
as less than significant with mitigation; sections c -f, However, there is no discussion of sections d
(alter drainage pattern or increase runoff) and e (create or contribute runoff which would exceed
the capacity of drainage systems). Please address sections d and e,
Lead Agency
As the Lead Agency, the City of Petaluma is responsible for all project mitigation, including any
needed improvements to the STN. The project's financing, scheduling, implementation
responsibilities and monitoring should be fully discussed for all proposed mitigation measures.
Mitigation that includes the requirements of other agencies such as Caltrans are fully enforceable
through pen -nit conditions, agreements, or other legally -binding instruments tinder the control of
the City.
Should you have any questions regarding this letter, please contact Stephen Conteh at 510-286-
5534 or stephen,contelh@dot,ca.gov,
Sincerely,
�GC-1
PATRICIA MAURICE
District Branch Chief
Local Development - Intergovernmental Review
c; State Clearinghouse
"Provide a safe, sustainable, integrated and eJJieieal uransfWrtation
suelem to enhance Callfornia s economy and lirabitily"
'.23
OA LII OA MIA
Water Boards
San Francisco Bay Regional Water Quality Control Board
Sent via electronic mail: no hard copy to follow
Mr. Jason Beatty
City of Petaluma, Public Works and Utilities
202 N McDowell Blvd
Petaluma, CA 94954
Email: ibeattyl'bci.petaluma.ca.us
EDMUND G. BRDveI JR.
MA/THEW IiDDRIDUEZ
9ECfl¢TARY PON
ERYIRDIILIEIITAL PROTE6T01f
GCS IUW \ a� lc�
September 26, 2018
VOvemcr's Office of Planning & Ro arch
SEP 2 6 2018
STATE CLEARINGHOUSE
Subject: Comments on Initial Study. (IS) for Petaluma River Flood Management
Denman Reach Phase 4. Project, Sonoma County
Dear Mr. Beatty:
San Francisco Regional Water Quality Control Board (Water Board) staff appreciates
the opportunity to provide comments on the Initial Study (IS) for the Petaluma River
Flood Management Denman Reach Phase 4 Project (Project) by the City of Petaluma
Department of Public Work and Utilities (the City) pursuant to the California
Environmental Quality Act (CEQA). The City posted the IS for public review on August
23, 2018. Based on our review, we support the determination that a Mitigated Negative
Declaration (MND) will be prepared: Accordingly, as a Responsible Agency under
CEQA, we offer the following comments to guide the City in preparing the Project's
MND,
1. Project Description and Technical Basis. The Project as described in the IS does
not provide a level of clarity needed to appropriately analyze the impacts versus
benefits. Please address the following:
a. The benefits to flooding are unclear based on the 100 -year flood boundary
figures provided in the memo provided by WEST Consultants, Inc. (Technical
Memo), How much infrastructure and buildings would be protected in the 100 -
year storm due to the implementation of this Project? Please provide a figure
depicting the increase in flooding that will result from the Project during the 25 -
year storm.
b. The technical basis for the sediment excavation parameters and cross-sections
proposed for the mainstem of the Petaluma River is unclear. Please provide a
basis for the assertion that the Project will be restoring the channel to previously
DR, TFRR/ F. YOUNG. CHAIR I BRUCE H, WOLFE, EXECUTIVE OFFICER
... _... _....... ............ .... ....................................... _...___..._.......__.._...._...._..._-......--._.._-__--_........ -................ --._....... ..._......__........... ... _......... ...... .._....__..._............_..
1515 Clay St., Suite 1400, Oakland, CA 84612 1 www.waterbcar(1s.ca.gov/sanrranciscobay
6) RECYDLED PAPER 24
Mr. Jason Beatty - 2 - September 26, 2018
Denman Reach Phase 4 Initial Study
existing conditions, such as historical cross sections or bathymetry data. In many
cases, excavating a wider and more uniform channel promotes increase
sediment deposition until the channel has equilibrated. We recommend analyzing
geomorphic dredging methods that include excavating a low flow channel,
leaving low floodplain benches, and mimic natural conditions of channel
equilibrium to the maximum extent possible for a more sustainable Project.
Furthermore, the purpose and benefits of the sediment removal portion of the
Project are unclear. Does the sediment aggregation at this site cause increased
flooding impacts, and if yes, what is the root cause of sediment aggregation and
does the proposed Project address it? If not, will sediment removal maintenance
be required in the future to sustain the Project's flood benefits? The Technical
Memo states thatJhe channel excavation will result in lower water surface
elevation's upstream, but an increase downstream. What is the comparison of
flooding impacts to infrastructure and buildings upstream versus downstream for
both the 25 -year and 100 -year storm? Is the purpose of sediment removal to
relieve flooding pressure on the more urbanized upstream watershed?
2. Impacts to Federal and State Jurisdictional Wetlands and Other Waters. The IS
acknowledges that a CWA Section 401 water quality certification (401 Certification)
and a CWA Section 404 Permit from the U.S. Army Corps of Engineers will be
necessary as the Project impacts waters of the U.S. To ensure the impacts to waters
of the US and waters of the State have be correctly identified and analyzed, the
appropriate agencies (RWQCB and Corps) should verify the wetland and other
jurisdictional water features at the study area.
The impacts analyzed generally relate to one-time construction impacts but do not
address potential operational impacts of the detention basins, such as sediment
removal after large storm events and erosion impacts at the basin outlets. Impacts
related to erosion control and site grading include placement of riprap as a proper
mitigation effort. The installation of rock within jurisdictional features is considered a
fill impact that has not been analyzed. The impacts associated with sediment
removal are also unclear. Based on the memo provided by WEST Consultants, Inc.
(Technical Memo), it appears that large portions of the existing banks and riparian
habitat will be excavated out for a wider more uniform channel cross section. This
appears to be a permanent loss of riparian habitat and could also result in more
frequent sediment removal maintenance impacts to the reach as widened channels
generally promote increased sediment fall out and aggregation. However, this
potential impact was not included in the IS analysis.
The Water Board requires impacts to be avoided and minimized to the maximum
extent practicable before accepting compensatory mitigation, such as the options
described in Mitigation Measure 13I0-1 and BI0-2. We recommend including an
analysis of long-term basin operation impacts and main channel sediment removal
impacts, to provide a basis for the development of project alternatives (see #3
25
Mr. Jason Beatty - 3 - September 26, 2018
Denman Reach Phase 4 Initial Study
Alternatives) and/or additional mitigation measures that will address these impacts
(see #4 Mitigation Measures).
3. Alternatives. For the Water Board to permit the proposed Project pursuant to CWA,
Section 401, we require a project proponent to conduct an alternatives analysis
consistent with the U.S. Environmental Protection Agency's 404(b)(1) Guidelines.
The Water Quality Control Plan for the Basin Plan incorporates the 404(b)(1)
Guidelines by -reference to determine the circumstances under which filling of
wetlands, streams or other waters of the U.S, and/or the State may be permitted. In
accordance with the Basin Plan, filling, dredging, excavating and discharging into a
wetland or water of the state is prohibited unless the project meets the least
environmentally damaging practicable alternative (LEDPA) standard as determined
through the 404(b)(1) alternatives analysis. Although the LEDPA analysis is not
required by CEQA, a project proponent may tailor the IS to fulfill both the CEQA and
404(b)(1) requirements to help expedite the Water Board's issuance of a 401
Certification and/or waste discharge requirements under Porter -Cologne.
Accordingly, we recommend the City prepare and analyze alternatives in the IS that
would meet the LEDPA standard to help expedite future Water Board actions, and
avoid the potential need for a IS supplement or amendment.
The Guidelines sequence the order in which proposals should be approached: 1)
Avoid - avoid impacts to waters; 2) Minimize - modify project to minimize impacts to
waters; and, 3) Compensate — once impacts have been fully minimized, compensate
for unavoidable impacts to waters. When it is not possible to avoid impacts to water
bodies, disturbance, should be minimized. Compensatory mitigation for lost water
body acreage and functions through enhancement, restoration, and/or creation
should only be considered after disturbance has been minimized. Where impacts
cannot be avoided, the enhancement, restoration, and/or creation of adequate
mitigation habitat to compensate for the loss of water body acreage, functions and
values must be provided pursuant to the California Wetland Conservation Policy
(also known as the "no net loss" policy; Executive Order W-59-93).
The following are some of the items that the Water Board may require analyzed.
within the Alternatives Analysis:
A. No Action Alternative: The Project as proposed does not show a very clear and
significant benefit to flooding in the area. An analysis of the flooding benefits
compared to the overall project impacts to waters of the State is required to
determine if the Project is practicable.
B. Floodplain Bench Widening Alternative: The IS states that a widened floodplain
bench alternative, instead of the two disconnected detention basins, was
analyzed and then abandoned due to the resulted increase in flood elevation
downstream shown through the modeling. To compare the impacts vs magnitude
of benefits of this alternative and the chosen alternative, a review of the model
26
Mr. Jason Beatty - 4 - September 26, 2018
Denman Reach Phase 4 Initial Study
and comparison of the output results for the 25- and 100 -year flood elevations
would be required.
C. Bridge Replacement Alternative: The Technical Memo states that the majority of
the water surface reduction would result from the Corona Road sediment
removal portion of the Project. Based on the preliminary review of provided
photos and material, it appears that the bridge piers. across the channel could be
resulting in a variety of impacts that cause sediment accumulation along this
reach. Replacement with a full spanning bridge and removal of the instream piers
may result in the same or better flood benefits while also providing a net benefit
to habitat in the Petaluma River. Therefore, this alternative should be included in
the analysis for the LEDPA
D. Wetland Detention Basin Alternative: To minimize and/or potentially eliminated
compensatory mitigation, a wetland forming detention basin design should be
analyzed for the Project. The soil, groundwater, and hydrologic characteristics of
the site should be evaluated to determine if the site could sustainably provide
wetland habitat. The detention basin should be evaluated to determine a design
that will result in the least amount of maintenance requirements, such as
sediment excavation after large storm events. With wetland vegetation'plantings
and a monitoring plan to verify wetland establishment success, this could be
counted as mitigation for impacts existing seasonal wetlands.
E. Alternative Detdntion Locations: To ensure the Project provides the maximum
amount of flood risk reduction and habitat benefits within the watershed, an
analysis of alternate locations where detention or floodplain bench widening
could occur should be performed. If there are other locations that would result in
amore significant flood reduction than the current basin location (individually or
in some combination), they should be included in the analysis for the. LEDPA. For
example, to the west of the western study area where 30 percent plans propose
wetland restoration for compensatory mitigation, an evaluation of widening the
floodplain. bench at that location to detain higher frequency storm event flows and
mitigate the increases in flood elevation at the 25 -year storm should be
considered.
F. Fill Impacts: The Water Board shall require an analysis of the areas of permanent
impacts associated with soil and/or rock installation, and riparian tree removal,
for opportunities of avoidance and minimization of impact to waters of the State.
We will require more habitat friendly biotechnical solutions to be evaluated where
appropriate with the integration of native riparian plants and trees.
4. Mitigation Measures. This letter outlined additional impacts that the Water Board
believes should be analyzed in the IS in comment 2. We recommend evaluating the
following mitigation measures to be included in the Mitigated Negative Declaration to
avoid and minimize impacts to less than significant levels.
27
Mr. Jason Beatty - 5 -
Denman Reach Phase 4 Initial Study
September 26, 2018
a. Mitigation for Operational Impacts: The development of the detention basin
design will include an evaluation of alternative layouts and design components to
determine the most sustainable design that results in the least amount of
maintenance post -project after design storm events. Please note that a wetland
detention basin design could minimize maintenance requirements.
b. Mitigation for Fill Impacts: Any soil and rock fill proposed to be installed within
Water Board jurisdiction will include an evaluation of biotechnical methods and
habitat enhancement features to be incorporated in order to avoid and minimize
impacts of hardened structures. All rock must be demonstrated to be necessary
and appropriately sized through a hydraulic analysis performed by a qualified
professional. If biotechnical methods and habitat enhancement features are
demonstrated to be infeasible, mitigation will be required at a 1.5:1 ratio at a
minimum.
c. Mitigation for Sediment Removal: Impacts on the Petaluma River sediment
transport processes and hydraulics resulting from sediment removal along this
reach will be avoided and minimized to the maximum extend through the use of
geomorphic dredging methods to mimic natural conditions of channel equilibrium
to the maximum extent possible for a more sustainable Project and minimize
future sediment removal maintenance.
d. Mitigation for Temporary Disturbance Impacts: Temporary impacts on the
Petaluma River and seasonal wetlands within the Study Area will be avoided and
minimized to the maximum extent practicable. Any areas with unavoidable
temporary impacts will be mitigated at a 1.5:1 -ratio at a minimum, with the 1:1
relating to on-site restoration and 0.5 of additional mitigation to compensate for
temporal losses.
We welcome the opportunity to provide additional comments on a draft MND when it is
available for review. If you have any questions about our comments please contact
Nicole Fairley of my staff at nicole.fairley(a)waterboards.ca.gov or (510) 622-2424.
Sincerely,
Digitally signed
by Nicole Fairley
Date: 2018.09.26
16:41:42 -07'00'
Nicole Fairley
Water Resource Control Eng.
Cc: CDFW:
James Hasen, James, Hansen(a),wildlife. ca.gov
Corps, SF Regulatory Branch,
28
Mr. Jason Beatty - 6 - September 26, 2018
Denman Reach Phase 4 Initial Study
Holly Costa, Holly. a.Costa(a-),usace.army.miI
NMFS, Gary Stern, Gary. Stern(a,)noaa.gov
U.S. EPA, Jennifer Siu, Siu.Jennifer(a)-epa.gov
City of Petaluma, Tim Moresco, TMORESCO(a)-ci.petaluma.ca.us
State Clearinghouse, State.Clearinghouse(),opr.ca.gov
29
Moresco, Tim
From: Samuel Baumgardner <Samuel.Baumgardner@sonoma-county.org>
Sent: Monday, September 24, 2018 4:42 PM
To: Moresco, Tim
Cc: Beatty. Jason; Janice Thompson; Johannes Hoevertsz
Subject: RE: Denman Reach Phase 4 Initial Study
---Warning: Use caution before clicking any attachments. THIS EMAIL IS FROM OUTSIDE OUR EMAIL SYSTEM.—
Tim,
Thanks again for reaching out to me. I've taken a look at the information provided. I've had to skim quite a bit, and It
appears that that majority of the information is pertaining to the environmental impacts of the project. It appears the
section that addresses the bridge and channel is near the end, starting on PDF page 129, with the memo issued by,West
Consulting. The changes underneath the bridge are described by Figure 4 of the memo. Please let me know if I've
missed any pertinent details or if my understanding is incorrect.
It does appear to me that this project could impact the structural integrity of the Corona Ave Bridge over Petaluma River
(Bridge No. 200O299). Whether the impact would be negative or positive is not obvious. The primary concern is
whether or not that changes would increase the scour potential at the piers and abutments of the bridge. Your
hydraulic engineer should be able to comment on whether the scour potential would be negatively impacted. I would
like to see the response from your hydraulic engineer.
Additionally, the bridge has already experienced some has been scour beneath one of the abutments. Establishing the
channel section effectively underneath the bridge could be difficult, as It won't be possible to compact the soil
underneath the abutment where it has scoured. In this case a concrete backfill mix is generally employed (similar to
what is done for large underground pipes).
I think the City might be required to seek a permit from Permit Sonoma, but I am not certain. I will discuss it up the
chain and get back to you.
Please let me know if you have any questions.
Thanks,
Samuel Baumgardner, PE
Senior Engineer
County of Sonoma Department of Transportation & Public Works
From: Moresco, Tim[mailto:TMORESCO@ci.petaluma.ca.us]
Sent: Monday, September 17, 2018 3:11 PM
To: Samuel Baumgardner <Samuel.Baumgardner@sonoma-county.org>
Cc: Beatty. Jason <jbeatty@ci.petaluma.ca.us>
Subject: RE: Denman Reach Phase 4 Initial Study
Hi Samuel,
I was hoping to have comments back by September 26, if possible. Do you think that would be adequate?
Thanks,
ITE
Attachment 4
RESPONSE TO COMMENTS ON
DENMAN REACH PHASE 4 PUBLIC DRAFT IS/MND
This document provides a response to comments received on the Public Draft Initial
Study/Mitigated Negative Declaration (IS/MND) that was prepared for the Denman Reach Phase
4 Project. In accordance with the California Environmental Quality Act (CEQA) of 1970 (as
amended) (California Public Resources Code 21000 et. seq.), the Public Draft IS/MND was
circulated for a 30 -day public review and comment period from August 27, 2018 to September 26,
2018.
Notice of availability and notice of intent to adopt the IS/MND was mailed to property owners
within 500 feet of the project site, published in the Argus Courier, posted to the City of Petaluma's
(City) Website, and submitted to the State Clearinghouse for distribution to State Agencies.
COMMENTS RECEIVED
A number of written comments were received during the public review and comment period for
the IS/MND. Comments were also received orally from one resident, who neighbors the project
area.
Agencies, organizations, and individuals that submitted written or oral comments on the IS/MND
are listed below; comment letters received on the IS/MND are included in Appendix 1:
Agencies
1. California State Clearinghouse
2. California Department of Transportation
3. San Francisco Regional Water Quality Control Board
4. Sonoma County Department of Public Works and Transportation
Local Individuals
1. John Aguiar (orally via phone call)
SUMMARY OF COMMENTS AND RESPONSES
California State Clearinghouse
The letter acknowledges that the City of Petaluma complied with the State Clearinghouse review
requirements for review of draft environmental documents. The State Clearinghouse also
Attachment IV - 1
Response to Comments On
Denman Reach Phase 4 Public Draft IS/MND
31
forwarded a copy of the comment letter from the California Department of Transportation and San
Francisco Regional Water Quality Control Board. No response is necessary.
California Department of Transportation (Caltrans)
The letter acknowledged project understanding and requested that within the Hydrology and Water
Quality section of the MND Checklist, sections d (alter drainage pattern or increase runoff) and e
(create or contribute runoff which would exceed the capacity of drainage systems) be addressed in
more detail. These sections have been addressed with the following addition to the Discussion
section of the Hydrology and Water Quality section:
"The removal of the understory vegetation and grading efforts to be done within the river channel around
Corona Bridge could cause a temporary increase in runoffpotential during construction, and an increase
inflow levels downstream during a 25 year storm event.
During construction, there will be an increase in runoffpotential along the river banks due to the
removal of the understory vegetation, however, this will only be temporary until the new vegetation gets
established which the City will install as part of the project. During a 100 year event the model shows
the project will result in a reduction in water surface elevation upstream and downstream of the bridge.
For the 25 year event the model shows a slight increase in water surface elevation downstream of
Corona Road at the Corona Creek confluence gradually increasing to a maximum increase of 0. 09feet
near the constriction weir, and then decreasing again from that point down zero increase near Adobe
Creek. There are no structures in the 100 year flood plain near the constriction weir and, thus, no
structures would be affected by this 0. 09feet rise in a 25 year event in this area.
Other features that will either not impact drainage patterns or will have minimal effect are features such
as the detention basins spillways, due to the location at being near the top of the bank, along with the
loop trail around the basins. The riprap to be installed along the abutments of the Corona Road Bridge
will have minimal impact to the drainage patterns and should not increase runoff, especially considering
the bridge will provide cover to prevent runofffrom occurring.
The goal of this project is to decrease the water su7face elevation and flood plain area for the 100 year
event by detaining waterpeakflows within the detention basins, reducingflow constraints, and scour of
abutments at the Corona Road bridge. "
San Francisco Regional Water Quality Control Board (Water Board)
The letter listed how the project described in the Initial Study does not provide a level of clarity
needed to appropriately analyze the impacts versus benefits. To provide clarity, the Water Board
asked the City to describe, in more detail, the benefits this project will provide to the 100 -year
flood map, in terms of infrastructure and buildings. By referring to sheet 1 of 3 in WEST
Consultant Inc.'s memo, the green hatch represents the areas of 100 -year flooding that will be
removed due to this project. From this diagram, several nearby parcels will see a significant
Attachment IV - 2
Response to Comments On
Denman Reach Phase 4 Public Draft IS/MND
101
amount of flood plain reduction, although none are completely taken out of the 100 -year flood
zone. The note also asks the City to provide a figure depicting the increase in flooding that will
result from the project during a 25 -year storm. Based on the model results shown in Table 2 of
the Memo provided by WEST Consultants, Inc., the largest downstream increase from this project
during a 25 -year storm is 0.09 feet, which equates to 1.08 inches near the constriction weir. A
graphic depiction of this minor impact wouldn't be relevant as it is within the margin of error
introduced in the mapping process. Additionally, there are no structures in the 100 -year flood
plain in this area, thus there would be no affected structures by a slight increase in the 25 -year
event.
The Water Board also requested that the City provide a technical basis for the sediment excavation
and new cross sections, as well as, describe, in further detail, the purpose and benefits of the
sediment removal. The basis for this work is to reduce flow restriction and scour of the abutments
at the Corona Road Bridge. The City has designed the new channel cross section to mimic the
original cross section that was created at the bridge's installation, which can be seen in Attachment
V. Based on review of project plans and documents of the original Corona Road Bridge design,
the river alignment upstream of the bridge was a wide, straight channel. In the existing conditions,
the river channel is aligned in such a way that high flows are directed to the northern abutment of
Corona Road Bridge. This which has most likely been caused by bank, erosion over time that was
a catalyst of the buildup of sediment and vegetation. This project proposes to create a straighter,
wider, and more uniform channel for higher flows and a narrower low flow channel at the Corona
Road Bridge returning river channel to its original cross section design so that it is less likely for
sediment and vegetation debris to accumulate and cause a reduction in the flood conveyance
capacity. To prevent future bank erosion, proper bank stabilization will be installed as part of the
project in the form of proper compaction and revegetation. Certain geomorphic dredging methods,
such as excavating a low flow channel with low floodplain benches, have also been considered
into the design of the channel cross section to address the warmer months when the river flows are
considerably less. With this future sediment removal activities are expected to be avoided.
Based on the model, the Project will decrease flood levels up to 0.71 feet (8.5 inches) for the 25 -
year storm and 0.9 feet (-11 inches) for the 100 -year storm around the Corona Road Bridge and
Industrial Avenue Business Park, with only minimal negative downstream impacts (-1.08 inches)
during the 25 -year storm event and no negative downstream effects during a 100 -year storm event.
The Water Board stated that the impacts, such as installation of rock within jurisdictional features,
are considered fill impacts and were not analyzed in the Initial Study, as well as, the permanent
loss of riparian habitat from the removal of large portions of the existing banks. The mitigation
measure "GE04" has been added to the Geology and Soils section of the CEQA Checklist to
address the impacts from the installation of rocks or soils within jurisdictional features. Mitigation
Attachment IV - 3
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Measure, 13I0-1: Impacts to waters of the United States, and Waters of the State, also addresses
filling of any jurisdictional feature. The impacts to the riparian vegetation were addressed in the
Mitigation Measure, BI0-2: Impacts to Riparian Vegetation. Due to the Water Board stating that
they require impacts to be avoided and minimized to the maximum extent practicable before
accepting compensatory mitigation, an Alternatives Analysis was added to the CEQA
Environmental Checklist after the Project Description to demonstrate that the City has taken the
proper steps to avoid and minimize the impacts to the biological habitat.
The Water Board listed several alternatives that they may require to be analyzed within the
Alternative Analysis. As mentioned above, the Alternatives Analysis has been added to the CEQA
Environmental Checklist after the Project Description.
The Water Board recommended to the City to evaluate the following mitigation measures to be
included into the Mitigated Negative Declaration.
Mitigation for Operational Impacts in reference to the post -project maintenance of the
detention basins. Prior to deciding on the current design layout of the detention basins, the
City analyzed different project options and potential alternate locations to determine the
most sustainable design. These alternate options have been inserted into the Alternative
Analysis section (page 3 of the IS/MND). Typical maintenance of the basins will include
semi-annual site mowing to maintain the proper functionality of the basins, and possibly
sediment removal after large flood events. Due to limited amount of funding for Parks
Maintenance, the City feels that it will be difficult to maintain the wetland detention basin
design, as it would require extra care to monitor that both the wetland and detention basin
are both functioning as they should.
Mitigation for Fill Impacts has been addressed by adding Mitigation Measure GE04 to
the Geology and Soils section of the CEQA Environmental Checklist (page 15 of the
IS/MND), and it reads as follows:
GEO-4: Any soil or rock fill to be installed within Water Board jurisdiction will include an
evaluation of biotechnical methods and habitat enhancement features to be incorporated in order
to avoid and minimize impacts of hardened structures. All rock must be demonstrated to be
necessary and appropriately sized through a hydraulic analysis performed by a qualified
professional. If biotechnical methods and habitat enhancement features are demonstrated to be
infeasible, mitigation will be required at a 1.5:1 ratio at a minimum.
Mitigation for Sediment Removal have been identified in the Geology and Soils section
of the CEQA Environmental Checklist. The City has designed the channel section so that
it returns the channel to its original design capacity when the Corona Road Bridge was
Attachment IV - 4
Response to Comments On
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constructed with 'some geomorphic dredging methods, such as excavating a low flow
channel and leaving low floodplain benches, being implemented into the design in order to
minimize future sediment buildup. As the Geology and Soils section discusses, the channel
banks will be installed in a stable condition and will not exceed 2 to 1 slopes. This project
will create a straighter, wider, and more uniform channel for high flows and a low flow
channel so that it will be less likely for the sediment and vegetation debris to accumulate.
Mitigation for Temporary Disturbance Impacts have been discussed in Mitigation
Measures 13I0-1, "Impacts to Waters of the United States, and Waters of the State" and BI0-2,
"Impacts to Riparian Vegetation."
Sonoma County Department of Public Works and Transportation
The email details some concerns over the impacts that the project will have on the structural
integrity of the Corona Road Bridge over Petaluma River (Bridge No. 200O299) and whether or
not the changes would increase the scour potential at the piers and abutments of the bridge. WEST
Consultant Inc. performed scour calculations and described them in their revised analysis. The
analysis found that under current conditions, pier scour is calculated to be 7.1 feet and under the
proposed conditions, the pier scour would be reduced to 6.0 feet.
The email also expresses concern regarding the preexisting scour at the abutments. To reduce the
risk of future scouring from occurring, riprap is planned to be installed along and around the bridge
abutments and will follow the mitigation measure GEO-4 of the Geology and Soils Section.
Mr. John Aguiar (Phone Call)
Mr. Aguiar inquired about the location of the detention basins, in which the City detailed the
location of APN 007-412-033. He also asked what the City plans to do with the soil removed. As
the IS mentions, the soil will be off -hauled to an acceptable site.
Mr. Aguiar also expressed concern that the sediment removal under the bridge will increase the
flood levels in the Downtown/Payran Area. The City has modeled the proposed project with the
sediment removed and has found that the water surface elevations are reduced through the
Downtown/Payran Area during the 100 -year event. Modeling showed for the 25 -year event slight
increase in water surface elevation downstream of Corona Road at the Corona Creek confluence
gradually increasing to a maximum increase of 0.09 feet near the constriction weir, and then
decreasing again from that point down zero increase near Adobe Creek.
Any new additions to the IS/MND, as they have been discussed above, will be indicated in
underline in the Initial Study Document.
Attachment IV - 5
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CONCLUSION AND STAFF RECOMMENDATION
After carefully reviewing the comments on the Initial Study and proposed Mitigated Negative
Declaration, the City of Petaluma believes that the environmental document has sufficiently
addressed the potential environmental impacts of the proposed Project and does not meet any of
the conditions under CEQA Section 15073.5. Therefore, the recirculation of a revised IS/MND or
the preparation of an Environmental Impact Report (EIR) is not required. Consistent with the
CEQA Guidelines, the added information clarifies the information and analyses in the IS/MND.
The City of Petaluma will consider the updates to the Manual and IS/MND, together with this
Response to Comments document, prior to adopting the IS/MND.
Attaclunent IV - 6
Response to Comments On
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