HomeMy WebLinkAboutItem 4.14 Tassajara Road Culvert
STAFF REPORT
CITY COUNCIL
DATE:July 19, 2016
TO:
Honorable Mayor and City Councilmembers
FROM:
Christopher L. Foss, City Manager
SUBJECT:
Update and Background on the Tassajara Road Culvert Replacement
Project
Prepared by: Andrew Russell, City Engineer
EXECUTIVE SUMMARY:
The City Council will receive an update and additional background on the Tassajara
Road culvert replacement project that required the temporary closure of Tassajara Road
in both directions beginning May 2 until December 1, 2016.
STAFF RECOMMENDATION:
Staff recommends that the City Council receive the report.
FINANCIAL IMPACT:
N/A
DESCRIPTION:
Background on the Tassajara Culvert
The segment of Tassajara Road over the culvert has long been a concern for the City.
In 2010, the roadway failed and a large sinkhole appeared which required an unplanned
closure of the road and emergency repair. Though temporarily repaired, the roadway
and embankment continued to degrade. It was clear to the City’s Public Works staff
that the culvert and roadway needed to be rebuilt to prevent a catastrophic road failure
and to support the traffic coming from and going to Danville and San Ramon's
Dougherty Valley. The project to rebuild the culvert and roadway segment was placed
on list of conditions of approval for the Moller Ranch project, which was formally
approved in early 2013.
In late 2015, during the El Nino cycle, it was discovered that the roadway embankment
under the asphalt had been worn away, leaving a five-foot void between the asphalt and
its supporting structure. Upon learning of the situation, the City authorized an
emergency repair in advance of the scheduled work by Toll Brothers (Moller Ranch
project owner), in order to create a safe condition for the traveling public and to keep
the road open through the rainy season.
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The following is a status update on the Tassajara Road culvert replacement project
being constructed by Toll Brothers:
Latest Project Update
Excavation for the new culvert is approximately 60 percent complete. Excavation on
both the west and east side of the existing culvert is complete. The 20-inch DSRSD
water main temporary bypass and pipe bridge is installed and new culvert segments are
being lifted and placed in the excavation along the new creek alignment. The contractor
has removed the asphalt roadway and the remaining culvert excavation work (under the
old roadway) will occur once DSRSD has inspected and commissioned the bypass pipe
and the old waterline removed . Backfilling around the culvert will take place from both
sides of the excavation simultaneously so that the culvert will stayed aligned and have
proper support.
With respect to the City’s inspection and monitoring, the City is inspecting the entire
project daily. Additionally, the Public Works inspectors attend the weekly construction
meetings at the contractor’s job trailer. The City’s geotechnical consultant, Cal
Engineering and Geology, also is onsite monitoring and inspecting geotechnical work.
Overall Description and Construction Sequencing
The project will replace the existing 9-foot diameter, 140-foot long culvert with a new 18-
foot diameter, 400-foot long culvert and includes many discrete construction steps. The
project-to-date has completed several activities; however, there are several remaining
to complete, most of which must occur in succession.
As noted above, once the temporary DSRSD water line is online, the contractor will
complete excavation of the existing roadway in order to connect the west and east
excavations to allow the continued placement and assembly of the 400-foot long culvert.
The culvert will be placed in segments, with the bottom or “invert” section of culvert
placed first, then backfilled placed, then the remaining section of culvert will be bolted to
the bottom section to create the circular pipe cross-section. Backfilling around the
culvert must be coordinated such that both sides of the culvert are backfilled at the
same time. This prevents the culvert from being dislodged or deformed.
At the same time the culvert is being backfilled, the contractor will be constructing the
concrete headwalls at each end of the 400-foot long culvert. These walls are special
retaining walls that serve to support the slopes and roadway above, while also directing
creek flows into and out of the culvert.
Once the culvert is in place and backfilled to the “top-of-pipe”, the contractor will
continue backfilling another 40 vertical feet of soil to bring the surface up to the bottom
level of the new roadway (subgrade). The contractor will also backfill the interior of the
culvert to a depth of six feet with rock. This buried culvert design will allow wildlife to
travel through the culvert, which was a requirement of the permitting agencies. When
complete, the 18-foot diameter culvert will only have 12 feet of clear height in the interior
and will appear to be a 12-foot high arch when viewed from either the east or west end.
When road subgrade is complete, the contractor will install the sanitary sewer, storm
drain, water, recycled water, and joint trench (dry utilities). This requires trenching into
the street subgrade, installing the utility, and then backfilling the trench. Aggregate
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base will be placed before asphalt paving can begin. Finally, the road will be striped
and signs will be installed. A new traffic signal at the entry road to both the Moller
Ranch project and Tassajara Highlands project, will also be installed, but may not be
activated before Tassajara Road is reopened.
Construction Hours
The City has permitted the project with the following construction hours:
Monday through Friday: 7:30 AM - 5:30 PM
Saturday: 8:30 AM - 5:00 PM
The contractor can request exceptions to the above work hours and Public Works will
evaluate the request on a case-by-case basis. Construction hours are also regulated by
California Department of Fish and Wildlife (CDFW) for this project. CDFW limits
construction activity to the time between ½-hour after sunrise to ½-hour before sunset.
Project Background and Related Permitting
The Tassajara Road culvert replacement project is being constructed by Toll Brothers
as a condition of their residential subdivision project known as Moller Ranch. Tassajara
Road, at the project location, is currently a two-lane arterial that links I-580 to Contra
Costa County, where the arterial is named “Camino Tassajara.” The General Plan and
adopted Precise Plan for Tassajara Road is for a six-lane arterial, however a capacity
study was completed showing a need for only four lanes. With a recent City Council
approval, Staff is working in partnership with Contra Costa County staff on a revised
precise alignment for the change to a four-lane arterial. Contra Costa County staff is
preparing to take a general plan amendment to their Board of Supervisors for
consideration and City staff will need to do the same. The City Council will review this
on a future agenda.
The following table lists approvals related to the Moller Ranch project and the
construction of the culvert replacement:
Date Item Approval
11/27/2012 Planning PC Resolution 12-Vesting Tentative Tract Map 8102:
Commission 45 (subject to City Council approval of a
General Plan Amendment, Specific Plan
Amendment, Planned Development
Rezoning, and Stage 1 and State 2
Development Plan)
12/4/2012 City Council Resolution 203-12 Eastern Dublin Specific Plan
Amendment - Eliminating Requirement
for Development Agreements
12/18/2012 City Council Resolution 209-12 CEQA - Certification of environmental
document
12/18/2012 City Council Resolution 210-12 General Plan Amendment and Eastern
Dublin Specific Plan Amendment
01/15/2013 City Council Ordinance 1-13 Planned Development Rezone and
State 1 and Stage 2 Development Plan
01/15/2013 City Council Ordinance 2-13 Development Agreement* (see
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12/4/2012)
04/26/2013 Building Dept Demolition Permit Demolish 2 dwellings and 1 garage
09/03/2015 Public Works Encroachment PG&E Pole Relocation
Permit
09/04/2015 Public Works Grading Permit On-site bulk grading, corrective grading,
and erosion control.
09/04/2015 Public Works Sitework Permit On-site PG&E Pole Relocation
10/07/2015 Public Works Encroachment Temporary Recycled Water for
Permit construction water
10/26/2015 Public Works Grading Permit Rough Grading, storm drain
improvements, and erosion control
04/26/2016 Public Works Encroachment Road Closure and Culvert Replacement
Permit
04/26/2016 Public Works Sitework Permit Temporary 20” water line bypass and
pipe-bridge
Regulatory & Other Agency Permits
Date Item Approval
10/09/2014 California Streambed Streambed Alteration Agreement (No.
Department of Alteration 1600-2013-0049-03)
Fish and Agreement
Wildlife
12/12/2014 California Incidental Take Tassajara Road Culvert Replacement
Department of Permit (ITP) Project Incidental Take Permit (ITP No.
Fish and 2081-2012-041-03)
Wildlife
06/26/2015 Army Corps of Section 404 Permit Section 404 Clean Water Act
Engineers Certification (No. 2013-00056S) issued
by the Army Corps of Engineers
09/30/2015 California Streambed Streambed Alteration Agreement,
Department of Alteration Notification No. 1600-2013-0048-R3
Fish and Agreement
Wildlife
10/23/2015 California Streambed Amendment 1 of Streambed Alteration
Department of Alteration Agreement, Notification No. 1600-2013-
Fish and Agreement 0048-R3
Wildlife
10/23/2015 Regional Water Water Quality Amended Water Quality Certification for
Quality Control Certification the Moller Ranch Residential Project
Board
11/25/2015 Regional Water Water Quality Amended Water Quality Certification for
Quality Control Certification the Tassajara Road Culvert
Board Replacement Project (Site No. 02-01-
C1157)
03/03/2016 City of Danville Encroachment Encroachment Permit (Permit No.
Permit EE161467)
03/23/2016 Contra Costa Encroachment Encroachment Permit (Permit No.
County Permit 33057)
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03/29/2016 City of San Encroachment Encroachment Permit (Permit No. 061-
Ramon Permit 16)
Road Closure Preparation and Outreach
Staff conducted extensive outreach prior to closure of Tassajara Road. Close
coordination with the public works staff from Contra Costa County, Danville, and San
Ramon was needed because of the traffic coming from and going to the Dougherty
Valley and Tassajara Valley. Also, encroachment permits were needed from each of
those jurisdictions for construction detour signs, fencing, and barricades. City staff also
communicated with many other entities, both public and private, in the months leading
up to the closure. Public notices, with a map of alternate routes, were mailed, email
notifications were sent, and letters were delivered to community leaders, community
partners, and nearby residents. The City issued a media advisory and pushed out
information via Twitter and the City's website.
In addition to the meetings, mailings, and email notifications, Staff presented the project
and proposed closure at the April 5, 2016, City Council meeting in an item about
summer road construction. Finally, the project information, public notice, alternate
routes map, and frequently asked questions were integrated with the City’s website on
the Road Work page:
www.dublin.ca.gov/Roadwork <http://www.dublin.ca.gov/Roadwork> and
www.dublin.ca.gov/1807/Tassajara-Road <http://www.dublin.ca.gov/1807/Tassajara-
Road>.
NOTICING REQUIREMENTS/PUBLIC OUTREACH:
The outreach is noted above.
ATTACHMENTS:
1. Photographs of Construction Progress
2. Excerpt of Moller Ranch Conditions of Approval Related to the Culvert Project
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ATTACHMENT 1 – PHOTOGRAPHS - CONSTRUCTION PROGRESS
Culvert Outlet (West) - May 4, 2016 Looking West - May 23, 2016
West Side, Looking North - June 3, 2016 Looking West – June 16, 2016
Looking East - June 30, 2016 Looking West – June 30, 2016
4.14 attch 1.docx Page 1 of 2
Looking West – July 1, 2016
Looking East – July 8, 2016
Looking West – July 8, 2016 Looking West – July 11, 2016
Looking West – July 12, 2016 Culvert Assembly – July 12, 2016
4.14 attch 1.docx Page 2 of 2
ATTACHMENT 2 – CULVERT SPECIFIC CONDITIONS OF APPROVAL
The following conditions of approval are from the Vesting Tentative Tract Map 8102, Planning
Commission Resolution 12-24, approved on November 11, 2012. The conditions were
approved contingent upon City Council approvals of a General Plan Amendment, Eastern
Dublin Specific Plan Amendment, Planned Development Rezoning, and Stage 1 and Stage 2
Development Plan, which occurred with City Council adoption of Resolutions 209-12 and 210-
12 on December 18, 2012, and Ordinance 1-13 on January 15, 2013.
No. Condition of Approval When
Required,
Prior to:
30 Public Streets: Developer shall construct street improvements and First Final Map
offer for dedication to the City of Dublin the rights of way for Tassajara
Road, and interior streets as shown on the Tentative Map, to the
satisfaction of the City Engineer. The right-of-way for Tassajara Road
shall be dedicated along the entire length of the project with the first
final map to be filed. The right-of-way dedication shall be in general
conformance with the alignment shown on Exhibit “B” to the Vesting
Tentative Map, and as may be modified by the City prior to the map
recordation.
31 Tassajara Road Grading / Slope Easements: The developer shall First Final Map
dedicate grading and slope easements along Tassajara Road as
determined necessary by the City Engineer to allow road grading and
construction.
32 Moller Creek Culvert: The Tassajara Road culvert crossing of Moller Prior to Culvert
Creek shall be replaced and improved in general conformance with the plans
preliminary culvert design shown in Exhibit “A” to the vesting tentative approved,
map. The developer shall be responsible for obtaining all resource bonded, and
agency permits required for the work. The developer shall be permits issued
responsible for acquiring right-of-way needed for the culvert and by Resource
associated creek stabilization work from the property on the west side Agencies prior
of Tassajara Road, unless the property has been previously dedicated to final map.
by the property owner or otherwise acquired by the City. Acquisition of Culvert to be
offsite right-of-way covered by this condition shall be subject to Section under
66462.5 of the Subdivision Map Act. The developer shall be eligible for construction
Eastern Dublin Traffic Impact Fee (EDTIF) credits for the cost of the prior to
improvements, design, permitting, and land, in an amount not to construction of
exceed the cost for the culvert shown in the 2010 EDTIF Update. first unit.
Culvert to be
completed prior
to occupancy
of 61st unit.
4.14 attch 2.doc Page 1 of 3
No. Condition of Approval When
Required,
Prior to:
33 Tassajara Road Improvements, Fallon Road to Street “A”: Prior to Culvert
Tassajara Road shall be improved from Fallon Road to Street “A” in plans
general conformance with the design shown on Sheet 9, Offsite approved,
Tassajara Road Improvements. The final layout and striping plan shall bonded, and
be subject to approval of the City Engineer and City Traffic Engineer. permits issued
by Resource
Agencies prior
to final map.
Culvert to be
under
construction
prior to
construction of
first unit.
Culvert to be
completed prior
to occupancy
of 61st unit.
34 Tassajara Road Improvements, Street “A” to Contra Costa County Prior to Culvert
Line:
The developer is obligated for the grading and construction of
plans
the frontage improvements on Tassajara Road (grading, curb and approved,
gutter, sidewalk, and 20’ of pavement) along the Tassajara Road bonded, and
frontage from Street “A” north to the Contra Costa County line, permits issued
consistent with the City adopted 2004 alignment for Tassajara Road. by Resource
These improvements may be deferred, pending completion of a final Agencies prior
plan line for this portion the road by the City of Dublin and the County to final map.
of Contra Costa. The developer may elect to be absolved of the Culvert to be
responsibility for installing the frontage improvements by deducting the under
cost of the frontage improvements from the EDTIF fee credits due to construction
the developer for the reconstruction of the Moller Creek culvert and prior to
associated work on Tassajara Road.construction of
first unit.
Culvert to be
completed prior
to occupancy
of 61st unit.
35 Traffic Signal, Tassajara Road/ Street “A”: A traffic signal shall be Occupancy of
installed at the intersection of Tassajara Road and Street “A”. The 25th House
developer shall be responsible for the initial cost of the 3-way signal,
and Developer may enter into a reimbursement agreement for any cost
.
over 50% of the total signal cost
36 Tassajara Road Overhead Utility Line: The developer shall be Prior to the
responsible for undergrounding the existing overhead utility line on Final Map
Tassajara Road from Fallon Road to the northerly side of the Street creating the
“A” intersection. 60th unit
4.14 attch 2.doc Page 2 of 3
No. Condition of Approval When
Required,
Prior to:
50 Resource Agency Permits: Prior to the start of any grading of the Issuance of
site as necessary, permits shall be obtained from the US Army Corps Grading Permit
of Engineers, The San Francisco Bay Regional Water Quality Control
Board, the State of California Department of Fish and Game and the
US Fish and Wildlife Servic for grading or alteration of wetlands areas
within the site. The project shall be modified as needed to respond to
the conditions of the permits
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