HomeMy WebLinkAbout2013-06-24 Ordinance 5202Ordinance No. 5202
Ordinance of the Council of the City of Palo Alto Approving and Adopting
a Plan for Improvements to EI Palo Alto Park
The Council ofthe City of Palo Alto does ORDAIN as follows:
SECTION 1. Findings. The City Council finds and declares that:
(a) Article VIII of the Charter of the City of Palo Alto and Section 22.08.005
ofthe Palo Alto Municipal Code require that, before any substantial building,
construction, reconstruction or development is commenced or approved, upon or with
respect to any land held by the City for park purposes, the Council shall first cause to be
prepared and by ordinance approve and adopt a plan therefor.
(b) EI Palo Alto Park is dedicated to park, playground and recreational space.
(c) The City intends to authorize the construction of certain park
improvements within EI Palo Alto Park, as shown on the Bonde Fish Weir Passage Design
Report (the "Design Report"), attached as Exhibit "A/' including:
(1) Removal of a bank-to:..bank concrete sill, known as the Bonde
Weir, that acts as a barrier to fish passage under current conditions, and the
replacement of the Bonde Weir with a re-graded and IIroughenedll channel;
(2) Installation of scour protection and native plant erosion control
measures along the edges of the work area and access route; and
(3) Installation and construction of additional irrigation facilities to
rapidly establish the new vegetation (the "Project").
(d) The improvements at EI Palo Alto Park will include an area of the Park
located in Palo Alto that spans the length of the San Francisquito Creek portion of the
Park.
(e) The Project will be constructed in a manner as to avoid protected trees
and other sensitive natural resources, if any. In addition, the existing park uses will be
restored following the completion of construction of the Project.
(f) The Project is consistent with park and conservation purposes.
(g) The Council desires to approve the Project, described above and as more
specifically described in the Plan, attached hereto as Exhibit IIA."
SECTION 2. The Council hereby approves the Design Report for the
construction of the improvements at EI Palo Alto Park, and it hereby adopts the Design
130S16'dm 00710210A
Report, attached hereto as Exhibit "A/' as part of the official plan for the construction of
the park improvements at EI Palo Alto Park.
SECTION 3. The Council finds that the San Mateo Resource Conservation
District has determined the Project (to construct the facilities at EI Palo Alto Park) is
categorically exempt under the California Environmental QualityAct.
SECTION 4.· This ordinance shall be effective on the thirty-first day after the
date of its adoption.
INTRODUCED: June 10, 2013
PASSED: June 24, 2013
AYES: BERMAN, BURT, KLEIN, KNISS, PRICE, SCHMID, SHEPHERD
NOES:
ABSENT: HOLMAN, SCHARFF
ABSTENTIONS:
~9-~ City Clerk
11'0------------
Mayor
APPROVED AS TO FORM: APPROVED:
.~~
Senior Asst. City Attorney
130516 dm 00710210A
San Mateo County·
RESOURCE
/
Exhibit "A"
650.712.7765 IPHONE
650.726.0494 I FAX
625 Miramontes Street, Suite 103, Half Moon Bay. CA 94019
www.sanmateorcd.org
Bonde Weir Fish Passage and Channel Stabilization Project
Project Description
San Francisquito Creek
Palo Alto & Menlo Park, CA
February 2013
. Summary: The Bonde Weir Fish Passage and Channel Stabilization Project (or project) is
located in San Francisquito Creek in the cities of Palo Alto and Menlo Park. The project site
occupies a portion of the border between Menlo Park and Palo Alto about 1.7 miles southwest of
V.S. Highway 101 near EI Camino Real Bridge (Appendix. A). The project proposes to remove a
bank-to-bank concrete sill, known as the Bonde Weir, that acts as a barrier to fish passage under
current conditions and replace it with a re-graded and "roughened"channel. This channel type
uses engineered s1reambed materials to maintain and improve stability over a wide range of
streamflows while providing vastly improved conditions for fish migration and movement. In
particular, the project is intended to benefit steelhead trout (Oncorhynchus mykiss), as the San
Francisquito Creek watershed provides habitat for this species. The watershed is part of the
Central California Coast steelhead Evolutionarily Significant Unit in which steelhead are
considered "threatened" under the federal Endangered Species Act. The project also will improve
channel stability over existing conditions.
Page 1 of 12
San Mateo Count\.'
RESOURCE
CONSER'R~ro~ DISTRICT
650.712.7765 I PHONE
650.726.0494 I FAX
625 Miramontes Street, Suite 103, Half Moon Bay, CA 94019
www.sanmateorcd.org
Need for the project: The Bonde Weir has been recognized by local biologists and state and
federal resource agencies as an impediment to steelhead passage for at least ten years. The
deteriorating condition of the weir may also pose a risk to channel stability. Under low flow
conditions, stream flow pools upstream from the weir resulting in a lack of flow over the weir or
in sheet flow unfavorable to migrating fish due to inadequate water depth. Under higher flow
conditions, water velocity may further limit migration opportunities. The majority of the
watershed's spawning and rearing habitat occurs in San Francisquito Creek and its tributaries
upstream from the weir, suggesting that limits to in-migrating steelhead have substantial effects
on the steelhead population. Further, under low flow conditions, fish may be prevented or
delayed from moving downstream to favorable habitats or to out-migrate, possibly resulting in
mortality. The project will greatly improve passage conditions and opportunities to successfully
complete the steelhead life history.
The remainder of this project description includes sections that characterize existing conditions
at the project site, elements of the project, sequence and schedule of proposed activities, staging
areas and access, related permits and measures to avoid impacts. The description has been
prepared by the San Mateo County Resource Conservation District (RCD) on behalf of the
several organizations partnering to implement the project to provide information to reviewing
agencies and the interested public. Questions or comments on any aspect of the project are
welcomed and may be addressed to the RCD staff listed at the end of this document.
Existing site conditions: The Bonde Weir is located in San Francisquito Creek where the creek
passes through EI Palo Alto Park. The weir is about 15 feet downstream from the pedestrian
bridge crossing and approximately 80 feet downstream from the bridge over which the Caltrain
tracks cross the creek. It consists of an 11 foot long and 45 foot wide concrete sill.
The weir is located near the midpoint of a right trending bend (looking downstream) in the creek.
The creek upstream of the weir has trapezoidal shape with a bed width of about 20 feet, a right
bank (looking downstream) side slope of about 0.6 feet horizontal to 1 foot vertical (0.6: 1), and a
left bank side slope of 0.8:1. The creek bed is about 20 to 25 feet below the adjacent top of banks.
A concrete wall along the right bank (looking downstream) extends from 3 feet downstream of
the weir to about 150 feet upstream. The left bank is composed of native material. Sheet C2 from
the design plans (Appendix B) shows the-site topography and planimetric features. A view of the
creek looking upstream of the pedestrian bridge is shown in Figure [1].
Page 2 of 12
San ]\IIateo COlmtv
RESOURCE
CO.SER'AT!O~ DISTRICT
650.712.7765 IPHONE
650.726.0494 I FAX
625 Miramontes Street, Suite 103, Half Moon Bay, CA 94019
www.sanmateorcd.org
Figure 1: Looking Upstream from Bonde Weir.
The sill slopes downstream at 4.8 feet horizontal to 1 foot vertical (4.8: 1, or about 20 percent).
The low point along the weir crest is at elevation 46.6 feet (all elevations are relative to
USC&GS BM H7) and the downstream end of the weir is at elevation 44.5 feet. Figlll'eS [2], [3],
and [4] show frontal, side, and top views of the weir, respectively.
Page 3 of 12
San Mateo County
RESOURCE
CONSERVATION DISTRICT
Page 4 of 12
650.712.7765 IPHONE
650.726.0494 I FAX
625 Miramontes Street, Suite 103, Half Moon Bay, CA 94019
www.sanmateorcd.org
San Mateo County
RESOURCE
CON1>EJ!VAll,Ofl orSTUCT
Page 5 of 12
650.712.7765 IPHONE
650.726.0494 I FAX
625 Miramontes Street, Suite 103, Half Moon Bay, CA 94019
www.sanmateorcd.org
San Mateo Countv
RESOURCE
C.OllS·El!V!I 11.0 if 0 IS n 1.CT
650.712.7765 I PHONE
650.726.0494 I FAX
625 Miramontes Street, Suite 103, Half Moon BaYJ CA 94019
www.sanmateorcd.org
Figure 3: Bonde Weir looking from the right bank above.
Figure 4: Bonde Weir looking from upstream to downstream from the pedestrian bridge above.
Apool forms upstream of the weir during low flows. The pool characteristics are inflUenced by
several factors, including the hydraulic characteristics of stream bends, which typically induce
scour along the outside toe of the bend. At the weir, local scom,also occurs in the lee of a
sackcrete storm drain outlet apron and at the backwater resulting from the weir. Using the weir
crest to define the pool swiace, the pool extends more than 160 feet upstream of the weir. The
deepest part of the pool is along the downstream end of the drainage outlet, where the substrate is
about 4 feet below the lowest point of the weir crest. Figure [5] shows the storm drain outlet.
Page 6 of 12
San Mateo County
& .. ~I'
RESOURCE
650.712.7765 IPHONE
650.726.0494 I FAX
625 Miramontes Street,Suite 103, Half Moon Bay, CA 94019
www.sanmateorcd.org
Figure 5: StOIDJ. dl'8in outfall on the left bank just upstream from Bonde Weir.
Downstream of the weir, the channel width increases to about 25 feet. The adjacent banks range
in slope :from 5:1 to 2:1. Toward the tep of the adjacent banks, slope ranges from 2:1 to 1:1.
Figure [6] shows a view of the creek downstream of the pedestrian bridge.
Page 7 of 12
San Mateo Countv
RES'QURCE
QolisnV"·'! 1011 DUTlilcl
650.712.7765 I PHONE
650.726.0494 IFAX
625 Miramontes Street, Suite 103, Half Moon Bay, CA 94019
www.sanmateorcd.org
Figure 6: San Fransquito Creek Channel looking downstteam from. .uuJLI ......
Concrete rubble and large rock are found in the bed immediately downstream of the weir. The
mbble does not appear to be a significant portion of the bed and will have to be removed from
thesite. The exact volume of rubble to be removed will likely be less than 50 tons. 1bis mbble
will be disposed of at an approved waste facility. The large rock will be evaluated by the field
engineer to ensme it meets hardness criteria and will likely be included in the proposed channel
design.
Page 8 of 12
/
San Mateo Countv
RESOURCE
!;~IiSE~Vnl0. DISTuer
650.712.7765 IPHONE
650.726.0494 I FAX
625 Miramontes Street, Suite 103, Half Moon Bay, CA 94019
www.sanmateorcd.org
Project elements and activities: The project will remove the existing weir, add scour protection
to the retaining wall at the Caltrain bridge, re-profile the channel using engineered streambed
materials, and stabilize and re-vegetate adjacent stream banks. The following describes each of
these activities in greater detail. Sheets C2 and C3 in Appendix B provide plan and profile views
of each of the project elements.
Remove existing weir: In this part of the project, heavy equipment will be used to demolish the
existing weir and remove the associated debris. As-built design drawings of the weir were
unattainable and the exact dimensions of the weir are unknown. However, the weir is not
believed to be attached to the concrete wall protecting the foot of the pedestrian and Caltrain
bridges. Concrete mbble and limited amounts of poor quality rock will be removed from the site
during this phase and disposed of at an approved waste facility. It is expected about 400 cubic
yards of material will be removed from the site.
Excavate project site: After the weir has been removed, the channel will be excavated down to 3
feet below the finished grade along the 100 lineal feet of channel where the roughened channel
will be located. Excavation will occur between streambanks and will maintain a slope of
1.5H: 1 V or flatter between excavated surfaces and existing surfaces to be undisturbed. The
excavated material will be sorted and stockpiled on-site. This material will be used in creating
the engineered streambed material in later construction stages.
Add Caltrain bridge scour protection: Approximately 65 lineal feet of rock riprap will be placed
along the left bank of the channel. The rock will be placed along the toe of the concrete wanto
protect the wall from erosion, and will extend downstream of the wall about 25 feet. The rock
will be placed at a 3 foot thickness and result in about 0.5-1 CY of rock per lineal foot of
protection.
Re-projile USing engineered materials and rock buttresses: The creek channel will be re-profiled
between a location about 20 feet upstream of the existing weirts upper extent and a location
about 80 feet downstream of the existing weir's lower extent. The roughened channel will be
about 100 feet long and will have a slope of about 1 percent.
The roughened channel construction includes 'importing various sizes of quarried rock, cobble
and gravel and mixing these Engineered Streambed Materials (ESM) with fines found on site.
The heterogeneous mix of ESM forms a tight structure that mjnimjzes loss of streamflow into the
bed and potential for scour during high flow events. Hydraulic modeling completed by
Northwest Hydraulic Consultants (2012) indicates that water depths and velocities in the
roughened channel will be. comparable to those found in proximate riffle sections of the creek.
The model results show that flow upstream from the project site will be unaffected by the
channel reconfiguration.
Page 9 of 12,
San Mateo COlll1tv
RESOURCE
elllisE~lIVIlTION DISHICT
650.712.7765 I PHONE
650.726.0494 I FAX
625 Miramontes Street, Suite 103, Half Moon Bay, CA 94019
www.sanmateorcd.org
After placement of the ESM, the contractor will install buttress/framework material, boulder
clusters, and engineered streambed materials per the design, and as directed by the engineer. The
field engineer will be onsite to verify the grade of the rock buttress material and the gradation of
the ESM to ensure it is placed properly. The contractor will likely set the rock buttresses at the
proper grade and fill the ramp between buttresses with 1 foot compacted lifts ofESM. Boulder
clusters will be placed as appropriate.
Stabilize and re-vegetate banks: Disturbed areas will be replanted with native plants sourced as
much as possible from the San Francisquito Creek watershed. An estimated 2,000 square foot
area will be temporarily disturbed and will need to be revegetated. Plantings will be watered and
maintained after the construction period to assure their survival. Temporary erosion control
measures will be used to maintain soil stability until plantings are established. .
Please see the Basis of Design Report (Appendix. C) by Northwest Hydraulics for additional
detail into the engineers rational for proposed project designs.
Sequence and schedule: Construction is expected to last approximately eight weeks, beginning
as early as June 2013 and completed by October 15,2013. Major tasks are listed below:
Establish staging and access areas
Mobilize equipment
Survey layout
Install temporary erosion control measures
Install traffic control and signage
Establish staging and equipment access areas
Removal and ofihaul weir
Excavate channel, and salvage and stockpile bed material
Imported ESM
Construct roughened channel
Restore and revegetate temporarily disturbed areas
Staging areas and access: Equipment will access the site as shown in sheet 02 of Appendix B
Equipment access will occur via a path between Palo Alto Avenue and the south side of the
creek. The access route will follow the route of an existing. 8 foot wide bike path and will
terminate at the least steep portion of the stream bank. The access route will be no wider than 11
feet, with unlimited overhead clearance.
Staging and materials access will be provided on the north side of the creek in an area east of the
Caltrain right of way in EI Palo Alto Park. The Parle is managed by the City ofMenIo Parle. This
Page 10 of 12
San Mateo Count'i'
RESOURCE
CO~SERVAT!ON DISTRICT
650.712.7765 I PHONE
650.726.0494 I FAX
625 Miramontes Street, Suite 103, Half Moon Bay, CA 94019
www.sanmateorcd.org
staging area will encompass approximately 8,000 square feet. All ESM will be delivered via a
route marked by the City of Menlo Park.
Avoidance of impacts: The project has been designed to minimize impacts to the site and to fish
and wildlife potentially utilizing the project area. The following specific actions will be
incorporated into the project description to reduce construction-related effects on vegetation and
landscape, water quality, and public access.
Vegetation and landscape: The portion of the equipment access route outside of the existing
bicycle path will be covered with 10 inches of mulch and overlaid with plywood or matting to
protect tree .roots. At locations where the access route requires excavation, an air spade or hydro
excavation will be used to expose roots along the edge of the proposed route. The roots will be
cleanly cut using a chainsaw or handsaw to prevent excavation of the access route from ripping
roots out of the ground. The access route will be established with 10 feet of clearance from trees
where possible. All trees within 6 feet of the access route will be protected (e.g., with snow
fencing and plywood when deemed necessary).
No trees will be removed on the Palo Alto side of the park; however, trees limbs will be removed
by the urban forester for the City to allow for equipment access, as necessary. Several small
shrubs that are in the access route will either be transplanted or replanted, and numerous small
trees (i.e., less than 2-inches diameter at breast height [dBH]) on the Menlo Park side will be
removed. Areas where vegetation will be removed to facilitate construction will be re-vegetated
as part of the project in accordance with Palo Alto's and Menlo Park's park improvement
ordinances.
Construction will occur in the dry season, minimizing the potential for erosion. Additionally,
erosion control measures, such as fiber rolls, jute mats and mulch will be installed to further
reduce the risk of sedimentation resulting from project activities. The project site, including the
equipment access road and staging area, will be re-vegetated and the plantings will be
maintained to ensure their survival after the construction phase.
Acterra, a local environmental non-profit in Silicon Valley, is currently active in native plant
revegetation efforts and will be hired to provide their services in conjunction with this project's
need for revegetation and erosion control in disturbed areas. Their volunteer network will
participate in implementing the project, and will assist in monitoring and maintaining the project
area in the park after the construction activities are complete.
Water Quality: During the proposed construction period, the creek is typically dry. Therefore,
stream dewatering and fish relocation/exclusion is not expected to be necessary. If the creek
Page 11 of 12
San Mateo Coulltv
&
'{"
RESOURCE
650.712.n65 IPHONE
650.726.0494 I FAX
625 Miramontes Street, Suite 103, Half Moon Bay. CA 94019
www.sanmateorcd.org
experiences flow dming the construction period, a qualified biologist will be retained to avoid
impacts to aquatic species.
Public Access~' All equipment will access the site on designated access routes and will be staged
in the designated staging area. Signage and traffic control will be accomplished in accordance
with Palo Alto and Menlo Park standards along the bike path and surface streets. Construction
will be limited to normal daylight hours.
Permits: The project will require the following permits:
• Clean Water Act, Section 404 Permit, U.S. Army Corps of Engineers
• Clean Water Act, Section 401 Water Quality Certification, San Francisco Regional Water
Quality Control Board
• Lake or Streambed Alteration i\.greement, California Department ofFish and Wildlife
• Biological Opinion, National Marine Fisheries Service
• Letter of Concurrence, U.S. Fish and Wildlife Service (possible)
• Park Improvement Ordinance, Tree Permit, and Encroachment Permit, City of Palo Alto
• Encroachment Permit, City of Menlo Park
Contact Information:
Kellyx Nelson, Executive Director
Resource Conservation District
KellYX@samnateorcd.org
650.712.7765 xl02
Joe IsseI, Conservation Assistant
Resource Conservation District
Joe@sanmateorcd.org
650.712.7765 xl06
Page 12 of 12