DR9306-CS 931127 November 2?, 1993 {T_Qt.~~ ~
Mr. Ken Griffin, P.E. 17J~ /~. ~~
City Engineer
City of Coppell
P.O. Box 478
Coppell, Texas 75019
~f Channel Improvements for Stream G-6, Tributary to Grapevine Creek, Coppell, Texas
The following will serve as a draft scope of work for the refere:
~ a r~ch of cr~ ~pprox~m~t~ 2,300 f~t in [~h. ]
~ch ~ ~t ~ ~oint n~arl~ 1200 f~t up~tr~a~ of th~ c~
}ethel School Roa~ and en~s at the creek's confluence with Grape- --vzne
I. OVER~EW ~
~he "City-Wide Storm M~ud~" (~anagement Sgu~), date~
~tes tha~wo ~ouses lie within th~ 100 year flo~
under fully developed con~tions. The Study~o indicates~
creek ch~ subject to severe erosion ~n ~me areas, ~
~ ~~2~ ~~~or t e subject area c[si[s 4 severa;'
1 Increm ca' culvert under ~
6 x 10 box to existing structure.
~t a 12 wid kc ;ere pilot chan~00 loi
, ~
~ of Bethel ~ Road. Also co,trOt 4'%} retaining
)n both sides o: ~lot channe~an~pla~ rock rip-rap
a 50' ong .x ng emca waZ % !
a distance of~p~oxim~ely ~ uprt~~the end of the
roposed pilot c~nn~ debr~ and nd re-grass the
~ase the widt] to 20' f ~tance of 30'
of Road. ~e downstre~
's conf with Creek to pfc ide positive
igc.
o'brien engineering p.o. box 334 coppell, texas 75019 phone: (214} 241-0336 fax: (214) 241-0370
Mr. Ken Griffin, P.E.
November 27, 1993
Page 2
II. BASIC SERVICES
A. Data Gathering
1. Utilities - Contact utility companies with facilities in
the project area and request that all underground
utilities be probed and identified with flagging. Ob~'~ain
"as-built" drawings of drainage, water and sewer
facilities in the area.
2. Deed Research - Obtain copies of City records of
easements and rights-of-way in the study area. Research
county deed records as may be necessary if the City
records are lacking.
3. Studies - Obtain copies of soil surveys or boring logs
conducted for other facilities in the area.
4. Wetlands Jurisdictional Determination - Prepare a letter
to-the US Army Corps of Engineers (COE) requesting a
jurisdictional determination of the area based on the
proposed improvements. Accompany the COE on it's field
trip to assess the area.
B. Surveying - Conduct a topographic design survey of the area
sufficient to produce mapping at a scale of 1"=20' with a
contour interval of 1'. Obtain dimensions, locations and
elevations of culverts, manholes, utility flagging, drainage
structures, driveways, trees in excess of 3" in diameter,
fences, retaining walls, pools and other physical features
which potentially may affect, or be affected by, the proposed
improvements. Finished floor elevations of selected houses
will be surveyed to verify proximity to adjacent 100 yea=
water surface elevations.
C. Hydraulic Modeling Verification - USe data from the completed
topographic survey to verify the hydraulic model used in the
Management Study. Typical information to be compared will
include channel and culvert geometry, elevations, roughness
coefficients, house locations and elevations, and the like.
The model will be adjusted to correct minor inconsistencies.
The proposed facilities will be tested in the revised model to
assure that the projected results concur with those of the
Management Study.
D. Meet with the City to review topo and modeling results.
E. Soils Investigation - Coordinate with a soils testing
laboratory to obtain soil samples and conduct standard tests
for design purposes.
Mr. Ken Griffin, P.E.
November 27, 1993
Page 3
F. Preliminary Design - Based on surveyed information and
required drainage capacity, calculate the dimensions,
alignment and sizes of the channel and culvert. Prepare
preliminary plans to include plan/profile drawings of the
pilot channel and retaining walls, earthen channel, and
culvert (at a scale of 1"=Sty, 1"=20~h), details and utility
adjustments. Utility adjustments may include relocation of
water and adjusting ditch connections within the right-of-way
or easement. Gas, electrical, and TV cable line relocations,
if any, are to be performed by the appropriate utility
company.
G. Meet with the City to review proposed configuration and
facilities. A set of preliminary plans will be sent to each
utility company with facilities in the area for their
comments.
H. Final Design - Complete plans, incorporating final utility
company considerations and City comments.
I. Forward a copy of the final plans to utility companies. Obtain
possible further considerations and begin arrangements for any
necessary adjustments.
J. Engineer's Estimate - Based on completed plans, prepare an
engineer's estimate of the cost of construction. Meet with
the City to review plans, easement requirements and cost
estimate.
K. Specifications and Bid Documents - Prepare specifications'and
bid documents for the proposed .facilities.
L. Assist the City in presenting the proposed improvements by
attending a City Council meeting and homeowner meeting.
M. Construction Services
r~~ f 1. Assist th. City in th. bidding proc.ss by pr.paring an
advertisement for bids, preparing addendums which may be
~'~' / necessary, representing the City at a pre-bid meeting and
~_~, the bid opening, and checking contractors qualifications
and bonds. Prepare a bid tabulation and make a
recommendation for award of the contract.
2. Perform one-time construction staking of line and grade
for the following: 1) channel grading and grade to
drain; 2) pilot channel and retaining wall; and, 3)
culvert at Bethel School Road.
Mr. Ken Griffin, P.E.
November 27, 1993
Page 4
~~ / 3. Construction Administration - 1) visit the site during
v~--! conformance with plans and design intent, 2) convey
~~~ specific instructions or directions to the Contractor on
behalf of the City, 3) prepare routine change orders, 4)
review Contractor's pay requests and make appropriate
recommendation to the City, 5) coordinate with soils
testing laboratory for testing of the concrete in the
culverts, retaining walls, and pilot channel.
4. As-Builts - Construction inspection is to be performed by
the City. Perform final as-built survey, to include
measuring of critical dimensions and elevations. Using
the inspector's as-built mark-ups and survey information,
prepare as-built plans.
N. Request for Map Revision - Prepare a flood profile of the
creek in the study area depicting the existing conditions and
completed improvements 100 year flood. Compile the following,
together with the profile, for a submittal to FEMA to request
revision of the floodplain maps:
1. A letter from the City requesting map revision.
2. Printouts of the hydraulic output for existing conditions
and for the completed improvements for the 100 year
flood. Also include output under improved conditions for
the 10, 50 and 500 year floods.
3. A map showing the 100 and 500 year floodplains based on
completed improvements (the map produced for the
referenced management study will be used as a base in
addition to the appropriate FEMA panel number).
4. A letter/report indicating the hydraulic procedures used
for floodplain definition.
III. ADDITIONAL SERVICES
If additional services, beyond those described are required, these
services will be provided as requested by the City. Additional
services may include but not be limited to the following:
A. Representing Client at city council meetings or P & Z
meetings, and at staff meetings beyond those indicated in
basic services.
Mr. Ken Griffin, P.E.
November 27, 1993
Page 5
B. Preparing special surveys, studies and submissions (other than
those identified under basic services) required for approval
by any agency having authority over the project or immediate
area.
C. NOI - At this point it appears that an area significantly less
than 5 acres will be disturbed by the proposed improvements.
In the event that the disturbed area will exceed 5 acres, and
at the direction of the City, a Notice of Intent will be
submitted t'o EPA and a strom water pollution prevention plan
will be prepared.
D. Making revisions to the plans and/or hydraulic model as a
result of changes to the basic plan, configuration or
location, or as a result of errors in modeling by other
parties.
Services associated with preparation of easements required by
the proposed construction.
F. Construction staking beyond one-time staking.
G. Construction inspection.
H. Assistance to Client as an expert witness in any litigation
with third parties.
I. Additional copies of Plans and Specifications beyond 25 sets.
I appreciate the opportunity to provide this scope of work and look
forward to working with you on this project.
O'BRIEN ENGINEERING o~ ~0~'
/~, O'Brien, P.E.
rincipal