HomeMy WebLinkAbout20140334.tiff RESOLUTION
RE: APPROVE WORK ORDER FORM (FLOOD REPAIRS - WEL-BR17/50A) PURSUANT
TO AGREEMENT FOR DESIGN SERVICES AND AUTHORIZE CHAIR TO SIGN -
AYRES ASSOCIATES, INC.
WHEREAS, the Board of County Commissioners of Weld County, Colorado, pursuant to
Colorado statute and the Weld County Home Rule Charter, is vested with the authority of
administering the affairs of Weld County, Colorado, and
WHEREAS, the Board has been presented with a Work Order Form (Flood Repairs -
WEL-BR17/50A) Pursuant to Agreement for Design Services between the County of Weld, State
of Colorado, by and through the Board of County Commissioners of Weld County, on behalf of the
Department of Public Works, and Ayres Associates, Inc., commencing January 13, 2014, with
further terms and conditions being as stated in said work order form, and
WHEREAS, after review, the Board deems it advisable to approve said work order form, a
copy of which is attached hereto and incorporated herein by reference.
NOW, THEREFORE, BE IT RESOLVED by the Board of County Commissioners of Weld
County, Colorado, that the Work Order Form (Flood Repairs - WEL-BR17/50A) Pursuant to
Agreement for Design Services between the County of Weld, State of Colorado, by and through
the Board of County Commissioners of Weld County, on behalf of the Department of Public
Works, and Ayres Associates, Inc., be, and hereby is, approved.
BE IT FURTHER RESOLVED by the Board that the Chair be, and hereby is, authorized to
sign said work order form.
The above and foregoing Resolution was, on motion duly made and seconded, adopted
by the following vote on the 3rd day of February, A.D., 2014, nunc pro tuns January 13, 2014.
BOARD OF COUNTY COMMISSIONERS
�� c� 4uher7T
ELD COUNTY, COLORADO
ATTEST: � �K �'
Weld County Clerk to the Bo-; 0. •
h`
1361 I� tile? Az(C41),
. '�:�::�` •=i •ara Kirkme er, Pro-Te
BY: Th �.
Dep A y Clerk to the Bo- Fv
4 Sean P. Conway
APPR FORM: 'n
Mike FreO-
y Attorney�����
William F. Garcia
Date of signature
0!'51`t
CC ' PLJ' DE/Y7 2014-0334
a- -/Y EG0070
BC0045
WORK ORDER FORM(FLOOD REPAIRS)
PURSUANT TO AN AGREEMENT BETWEEN
WELD COUNTY
AND
AYRES ASSOCIATES INC.
DATED: January 31,2014
Work Order Number: Ayres-2
Project Title: WEIR BR 17/50A Design Services(Immediate Needs Prior to Spring Runoff)
Commencement Date: January 13,2014
Completion Date: April 30,2014
Limitations on compensation: Not to exceed$25.900.00
Professional agrees to perform the services The attached forms are hereby accepted and
identified above and on the attached forms in incorporated herein: Exhibit A — Scope of
accordance with the terms and conditions Work, Exhibit B — Cost/Fee Breakdown,
contained herein and in the Professional Exhibit C—Proposed Schedule.
Services Agreement between the parties, dated
January 13, 2014. In the event of a conflict ,
between or ambiguity in the terms of the Weld Co - ublic W Fks Dc _ enti
Professional Services Agreement and this work
order (including the attached forms) the By: - I/
Professional Services Agreement shall control. Projec nager f
Date: r -c>„1/�
By:
Ayres Associates Inc. % Director of Pu lic Works
�f Date: FEB 0 3 2014
By:
Title: 014,1 a g e 'SMr/�Oyv-CC✓
Date: l4/ QGl1 BY: ti Cbf Wier Ad.,
Douglas Ridemacher, OCC Chair
ATTEST: ` fa,La1/42
�`
Weld County Clerk to the Board tl6t'
By: ' (,U la A
Deputy Clerk to the Board
2014-0334
f3COok-t5
ooh
AyRES
Ayres Associates Inc ASSOCIATES
EXHIBIT A- SCOPE OF WORK
Weld County 2013 Flood Recovery
WEL017.0-50.0A County Road 17 over Big Thompson River
Structure Description:
This two-span bridge is 148 feet long with two nearly equal-length spans. The bridge has
double-tee concrete girders and vertical concrete abutments with wingwalls. The piers and
abutments are founded on steel H piles according to the 2010 bridge inspection report. The
concrete pier is a continuous wall under the full width of the bridge deck. The 2010 bridge
inspection report gave a Sufficiency Rating of 94.7 and an Item 113 (scour critical) code of 8,
which means the structure was expected to be stable under anticipated scour conditions. A pre-
flood aerial image of the crossing site is shown on the left below. The photo on the right below is
a field photo taken after the flood.
. t a i rte- j •
Flood Damages and Ongoing Issues:
The embankment behind the north abutment and the riprap protecting that abutment were
washed out during the flood. The roadway embankment south of the bridge is substantially
lower than the bridge deck profile and was overtopped during the flood, causing erosion of the
east shoulder and embankment slope. There is a long railroad embankment and railroad bridge
about 1,600 feet upstream that was also washed out and severely damaged during the flood.
The site is located in a slightly sinuous reach, but there are a number of old cutoffs (oxbows)
upstream and downstream indicating that the river has historically been a fairly sinuous
meandering channel in this location. Remnants of an old concrete bridge just upstream of the
WCR17.0 bridge have been flanked to the north, indicating that the channel in this location may
still be active laterally and vertically, especially given the presence of a large cutoff meander
loop in the immediate vicinity. A post-flood aerial image of the crossing site is shown below.
AYRES
' Ayres Associates Inc ASSOCIATES
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Although the roadway to the south was overtopped, it is likely that the bridge experienced both
significant pressure flow and contraction scour as indicated by the "blow-out" of the left (north)
bank and the deposition of sediment (seen as sediment splays) on both overbanks downstream
of the bridge. The left bank immediately downstream of the bridge retreated to the northeast as
much as 65 feet during the flood. In addition, riprap was scoured out from around the north
abutment and was transported and deposited on the left overbank and in the channel as much
as 100 feet downstream. The washout of the road behind the north abutment may have been
caused or aggravated by scour below the abutment wall allowing fill to escape under the wall.
There was no apparent overtopping of the road north of the bridge. The left bank upstream of
the bridge also eroded during the flood, but the amount of retreat was less than 10 feet. The
point bar area along the right (south) bank in the meander bend upstream of the bridge was
significantly reworked by the flood, but was partially protected by the old bridge remnants and its
remaining south approach embankment.
The County carried out emergency repairs of a temporary nature to allow the bridge to be
reopened to traffic. The washed out area behind the north abutment was filled in and repaved.
New riprap was placed along the toe of the repaired area beyond the abutment wing walls on
both the west and east sides of the road.
AYRES
Ayres Associates Inc ASSOCIATES
Work Recommended Prior to Spring Runoff(Phase 1):
• Check the streambed level vs pile cap on north abutment
• If the abutment walls and/or wing walls were undermined below the pile cap, restore
streambed level to an elevation above the pile cap
• Place temporary riprap around the base of both abutments and along wingwalls
• Place temporary riprap on the lower embankment side slopes for the first 25 feet beyond
the wing walls
• Survey the ROW limits and the roadway and embankment within the ROW for a distance
of about 700 feet south of the south abutment and about 200 feet north of the north
abutment
• Perform bathymetry survey obtaining cross sections at the upstream and downstream
face of the bridge as well as one section underneath the north span of the bridge
Work Anticipated for Phase 2:
• Remove concrete rubble from around upstream side of south abutment, wingwall and
right bank
• Extend rock protection on the left bank from the abutment to 200 feet upstream
• Rebuild and protect the abutment slopes through the bridge waterway
• Place permanent riprap along north and south abutments and wingwalls
• Repair and protect (with TRM and rock, see sketch below) the downstream side slopes
of the south roadway embankment (700ft)
• Extend abutment riprap at least 25 feet along the embankment slopes north and south of
the abutments
• Add a guidebank upstream on the north abutment
• Remove and replace ER embankment fill behind the north abutment and wingwalls
• If the abutment and/or wingwall footings were undermined, may need to backfill under
the footing with riprap and flowfill
• Riprap left (outer) bank of upstream meander bend as well (-250 ft)
Roadway
Riprap
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Potential Phase 3 work for Betterments and/or Resiliency:
• Add a span to the bridge on the south end to increase capacity
A S
ti Ayres Associates Inc ASSOCIATES
Detailed Scope of Work for Phase 1:
1. Kickoff Meeting. Ayres project manager/engineer and geomorphologist will meet with
County project manager at County Public Works office.
2. Site Assessment. Ayres project manager/engineer and geomorphologist meet at the site
with County project manager to observe current field conditions, assess geomorphology
and discuss what emergency repairs were done.
3. Survey. Perform boundary survey of the right of way and topographic survey of the
pavement and road embankment for a distance of 700 feet south of the south abutment
and 200 feet north of the north abutment. Perform bathymetry survey obtaining cross
sections at the upstream and downstream face of the bridge as well as one section
underneath the north span of the bridge. Boundary survey should have adequate
coverage to accommodate possible activities identified under Phase 2.
4. Prepare brief environmental documentation for permitting the work at this site.
5. Progress Meeting. Conduct one progress meeting with County project manager and
county floodplain administrator at County Public Works office.
6. Design. Develop design of Phase 1 grading and temporary riprap.
7. Plans and Deliverables. Prepare abbreviated Phase 1 construction documents following
the CDOT "writeup plans" format. Estimate quantities and prepare engineer's estimate of
probable cost for Phase 1 activities. Also prepare a ROW Plan for CDOT's review to
cover anticipated work through Phase 2.
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Exhibit C: Schedule of Weld County Flood Repairs on the Big and Little Thompson
Priority Task Completion
Site Task Task Start Date Date
Scoping Meetings January 13, 2014 January 28, 2014
Site Assessment January 16, 2014 January 31, 2014
Survey February 5, 2014 February 12, 2014
1 WEL027.5-048.0A Design & Plans February 13, 2014 February 28, 2014
Review& Revisions* February 28, 2014 March 7, 2014
Bidding* March 10, 2014 March 24, 2014
Construction* March 31, 2014 April 28, 2014
Scoping Meetings January 13, 2014 January 28, 2014
Site Assessment January 16, 2014 January 31, 2014
Survey February 8, 2014 February 15, 2014
2 WEL017.0-050.0A Design &Plans February 17, 2014 March 1, 2014
Review& Revisions* March 1, 2014 March 7, 2014
Bidding* March 10, 2014 March 24, 2014
Construction* March 31, 2014 April 28, 2014
Scoping Meetings January 13, 2014 January 28, 2014
Site Assessment January 16, 2014 January 31, 2014
Survey February 11, 2014 February 18, 2014
3 WEL013.0-044.0B Design & Plans February 19, 2014 March 5, 2014
Review& Revisions* March 5, 2014 March 12, 2014
Bidding* March 13, 2014 March 27, 2014
Construction* March 31, 2014 April 28, 2014
Scoping Meetings January 13, 2014 January 28, 2014
Site Assessment January 16, 2014 January 31, 2014
Survey February 11, 2014 February 18, 2014
4 WEL054.0-013.0A Design & Plans February 19, 2014 March 5, 2014
Review& Revisions* March 5, 2014 March 12, 2014
Bidding* March 13, 2014 March 27, 2014
Construction* March 31, 2014 April 28, 2014
*Schedule dependent upon other parties not Ayres Associates such as Weld County
or the eventual contractor.
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