SS9301-SY 920301!
I Alternate Route Considerations
I
II Grapevine Creek Sanitary Sewer
Trunk Main - Branch I
I
I
for the
I
I City of Coppell, Texas
I
I
I
I March 1992
I
I GINN & CASE, INC. CONSULTING ENGINEERS
17103 PRESTON ROAD, SUITE 100, LB-Il8
i DALLAS, TEXAS 75248
(214) 248-4900
I
I
Alternate Route Considerations
Grapevine Creek Sanitary Sewer
Trunk Main - Branch I
for the
City of Coppell, Texas
March 1992
GINN & CASE, INC. CONSULTING ENGINEERS
17103 PRESTON ROAD, SUITE 100, LBoll8
DALLAS, TEXAS 75248
(214) 248-4900
EXECUTIVE SUMN~RY
~I~PEV~NE CREEK SANIT&RY SE~ERN~N - BI~2~CH ~
The selection of the route of the proposed 30" sewer main was
very difficult due to many complications. The ideal route, that
lends itself to easy construction, minor disturbance of the area,
the least inconvenience to all, and meeting all design criteria
does not exist. Many alternatives were considered.
1. Paralleling the existing 20' sewer easement was complicated
by the numerous improvements and encroachments of pools,
decks, storage sheds, etc.
2. Construction space requirements, depth of line, removal of
massive amounts of trees, and potential greater erosion
problems prevented selection of the top bank route.
3. The creek route alignment, eliminating the aerial crossings,
removing a majority of flows from the existing 12", doing
the least amount of damages to all creek lots, although not
a good route, appears to be the only route.
4. The railroad route creates extra deep excavations,
additional major creek crossings, does not eliminate the
flows of the existing 12" line, provides difficult ties for
future sewer lines, and requires consideration of boring or
microtunnelling operations which are undesirable.
5. The Belt Line Road route has the same implications as the
railroad route, plus the added 2000 foot length of sewer
line required.
6. The pump station/force main selection is complicated by the
size requirement of the station wet well, the size of the
pumps, the location of the station in a populated area,
noise and odor problems, high monthly maintenance and
operational costs, need for stand-by power, the fact that
the 12" remains surcharged, and that no new developments
could easily tie to the system.
After careful consideration of all the alternatives, the creek
route was selected to meet all the criteria.
With regards to the questions about erosion in the creek bottom
and banks, it should be noted that erosion is o~curring now as
evidenced by the Albert Halff study. The same ma? be said about
the damage to the trees. The Halff study depicts this as a part
of the natural channel erosion cycle.
After completion of the sewer line installation, the Halff study
drainage and erosion recommendations, when done, should provide
an aesthetically pleasing and functional solution to the creek
area.
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LINE RD. ,{ .7 " ROUTE 6-LIFT STATION/FM '
'" ' .... E. BETHEL RD. (NOT SHOWN) :"
i
TABLE OF CONTENTS
GENERAL CRITERIA FOR DESIGN .................................... 1
GENERAL PARAMETERS FOR DESIGN .................................. 2
SPECIFIC DESIGN CONSIDERATIONS ................................. 2
ROUTE 1 - EXISTING 20' SANITARY EASEMENT ....................... 3
ROUTE 2 - SOUTH OF EXISTING 20' EASEMENT ....................... 4
ROUTE 3 - CREEK BOTTOM ......................................... 5
ROUTE 4 - RAILROAD ROUTE (NORTH SIDE) .......................... 6
ROUTE 4 - RAILROAD ROUTE (SOUTH SIDE) .......................... 7
ROUTE 5 - BELT LINE ROAD ALIGNMENT ............................. 9
ROUTE 6 - PUMP STATION/FORCE MAIN .............................. 10
ROUTE 7 - MEADOWCREEK OR E. BETHEL ROAD ........................ i2
SUMMARY OF PROJECT COSTS ....................................... 14
BREAKDOWN OF PROJECT COSTS ..................................... 15
EXCERPTS FROM CITY-WIDE STORM WATER STUDY
QUESTIONS AND ANSWERS TO CITIZENS CONCERNS
GENERAL CRITERIA FOR DESIGN OF GRAPEVINE CREEK SEWER - BRANCH I
ALL SEWER LINES IN THE SOUTHERN AND WESTERN HALF OF THE CITY
(WHICH IS APPROXIMATELY 38% OF THE TOTAL AREA OF THE CITY) FLOW
INTO ONE CENTRAL COLLECTOR LINE. THIS LINE, KNOWN AS THE
GRAPEVINE CREEK SANITARY SEWER MAIN RUNS FROM NEAR THE TRINITY
RIVER, AT THE EASTERN EDGE OF COPPELL ALONG BELT LINE ROAD, AND
MEANDERS WITH THE GRAPEVINE CREEK , TO THE INDUSTRIAL AREA IN THE
WESTERN PART OF TOWN. THIS LINE WAS INSTALLED IN 1967. THE LINE
SIZE WAS 12" AND THE PIPE MATERIAL WAS CLAY TILE. IT HAS BECOME
APPARENT THAT THE EXISTING LINE IS UNDERSIZED AND IN NEED OF
REPAIR. LARGE AMOUNTS OF GROUNDWATER AND/OR CREEK WATER APPEAR
TO BE ENTERING THE WASTEWATER SYSTEM. POTENTIAL ENVIRONMENTAL
PROBLEMS ARE CREATED BY THE FULL SEWER LINE AND MANHOLES WITH THE
POSSIBILITY OF OVERFLOWING ON THE DOWNSTREAM PORTIONS OF THE
LINE.
THERE ARE SEVERAL MAJOR BENEFITS FROM THE NEW LINE. IT WILL BE
CONSIDERABLY LARGER AND DEEPER THAN THE EXISTING LINE, THUS IT
WILL BE ABLE TO ACCOMMODATE THE FULL EXPECTED FLOW WHEN THE CITY
IS "BUILT OUT". ALSO, THE UNSIGHTLY AERIAL CROSSINGS WHICH NOW
EXIST WILL BE REMOVED. THE MOST SIGNIFICANT BENEFIT IS THAT THE
MAJOR WASTEWATER FLOWS WILL BE ROUTED AWAY FROM EXISTING
STRUCTURES AND CAPACITY WILL BE AVAILABLE TO ALLOW THE TAX BASE
TO GROW.
THE INTENT WAS TO FIND THE MOST PRUDENT AND COST EFFECTIVE ROUTE
THAT WOULD CAUSE THE LEAST INCONVENIENCE TO EVERYONE, NOT ONLY
FOR CONSTRUCTION BUT FOR FUTURE MAINTENANCE PURPOSES.
GRAPEVINE CREEK SANITARY SEWER MAIN PAGE I
GENERAL PARAMETERS FOR DESIGN
'~/. REPLACE EXISTING UNDERSIZED LINE THAT IS IN POOR CONDITION.
'~. SIZE NEW LINE TO HANDLE FUTURE FLOWS FOR ENTIRE BASIN.
'~3~. CONNECT EXISTING LINES TO NEW LINE...REMOVE FROM EXIST 12".
~4~. REMOVE EXISTING AERIAL CROSSINGS ON CREEK.
5. MEET ALL CRITERIA SET FORTH IN MASTER WASTEWATER PLAN.
· f~.J DESIGN UPPER REACH OF BRANCH I TO ACCOMMODATE FUTURE
PROJECTS, SUCH AS BRANCHES II, III, AND IV.
7. MEET ALL CRITERIA OF TEXAS WATER COMMISSION'S "DESIGN
CRITERIA FOR SEWERAGE SYSTEMS".
8. STAY WITHIN EXISTING EASEMENTS, WHERE POSSIBLE, SINCE
EXISTING 20' EASEMENT IS ALREADY IN PLACE, TO AVOID
HAVING TO ACQUIRE NEW EASEMENTS.
~ DESIGN AND LOCATE IN AREA THAT IS BENEFICIAL TO THE MAJORITY
OF THE CITIZENS OF COPPELL.
10. STAY WITHIN THE ESTIMATED TOTAL PROJECT BUDGET: $1,800,000.
SPECIFIC DESIGN CONSIDERATIONS~
MUST MEET MANHOLE (MH) GRADE OF LOWER END: TRA LINE ELEV. 431.75
MUST MEET MANHOLE (MI{) GRADE OF UPPER END: SW BLVD. ELEV. 499.5
(LENGTH BETWEEN LOWER/UPPER MH'S...17,920 FT.)(3.4 MILES).
MH ELEV. AT MOCKINGBIRD SET DUE TO DALLAS'S 54" WATER LINE
AND TU ELECTRIC'S 42" (MAKE-UP WATER LINE) CROSSINGS LOCATED
BETWEEN MOCKINGBIRDANDMAC ARTHUR. TU'S 42" CAN BE LOWERED,
THE OTHER CAN'T.
MH ON WEST SIDE OF DENTON TAP NEEDS TO ACCOMMODATE FUTURE
ELEVATION FOR FLOWS FROM NORTH (PHASE III) AND CURRENT
PROPOSED FLOWS (PHASE II) FROM WEST...ALSO CONSIDERATION
MUST BE GIVEN TO FUTURE PHASE IV, OF THE MASTER PLAN.
GRAPEVINE CREEK SANITARY SEWER MAIN PAGE 2
DESCRIPTION OF ROUTE SELECTION FROM DENTON TAP RO&D EAST
TO MOORE ROAD AND BEYOND TO MOCKINGBIRD LANE FOR THE
GRAPEVINE CREEK SANITARY SEWER MAIN - BRANCH I
FIRST ROUTE SELECTED:
Utilizing the existing 20' easement that was established in the
1967 construction of the original 12" clay tile pipe sewer line.
This alignment runs through the middle of many of the
imporvements of all lots along Meadowcreek.
1. Approx. 30 lots along Meadowcreek affected.
2. North side of easement is extremely close to existing homes.
3. Heavy landscaping on all 30 lots, would hinder construction.
4. RR tie or timber or concrete retaining walls on 24 lots.
5. Large trees all 30 lots...very hard to replace, in kind.
6. Swimming pools encroaching easement on 10-12 lots.
7. Wood decks or similar construction encroaching 12 lots.
8. Garages, carports, wood sheds, etc. encroaching 12-15 lots.
9. Concrete paving, drives, patios encroaching 12-15 lots.
10. Heavy, thick wooded area all 30 lots, beyond 20' easement.
11. Depth of proposed sewer would require removal of a 30'-40'
wide path of trees for construction purposes.
GRAPEVINE CREEK SANITARY SEWER MAIN PAGE 3
SECOND ROUTE SELECTED=
Attempting to get away from the 20' easement and the problems
associated with the construction therein, a route further south,
towards the creek was tried. Utilizing the area between the
existing 20' sanitary easement and the top bank of the creek,
being located in the back yards of the homeowner's of Meadowcreek
Road.
1. Extremely tight construction area between easement and top
bank, for a great majority of lots.
2. Fences along back property line on 22 lots, hampering work
between top bank and back yard area.
3. Areas between back yard fence and top bank very small on
approximately 25 lots, thereby preventing adequate working
room for construction in those areas.
4. Steep slopes where construction could occur prevents safe
operating area for construction equipment.
5. Digging near top bank would create further erosion of bank.
6. Many trees would have to be removed to facilitate
construction. Due to depth of line, an area 40' wide may be
required for adequate construction area.
GRAPEVINE CREEK SANITARY SEWER M~IN PAGE 4
FOURTH ROUTE CONTINUED...ALONG SOUTH SIDE OF RAILROAD...
For the route along the South side of the railroad, in addition
to the above problems, the following needs to be Considered:
1. Existing ground is uphill from creek to railroad, while
sewer line would be going downhill, thereby creating extra
deep excavations, some in the neighborhood of 50' in depth.
2. The route along railroad would be very deep for quite a
ways, providing deep excavations, deep manholes and more
costly construction. Typically, 50' excavations are not
common, and are impractical. Trench safety would be a
considering factor in the construction procedures. More
expensive boring or microtunneling operations would have to
be considered as more desirable from a construction
standpoint.
3. Three railroad spur crossings required. No open cuts
allowed. High cost to bore and encase.
4. The bore under Denton Tap, parallel to the railroad would be
over 50' deep. This presents a difficult construction
situation with location and size of needed bore pits.
5. The existing railroad ROW is not readily accessible.
Outside of the ROW along the south side, there is a building
that would be affected by the open cut method of
construction, or even by the boring method.
6. One additional RR crossing would be required, at Mockingbird.
7. Deep excavation in vicinity of railroad not good practices.
8. Additional bore under Moore Road would be required.
9. Curved alignment in sewer lines, not acceptable, thereby
causing additional manholes to be constructed.
GRAPEVINE CREEK SANITARY SEWER MAIN PAGE 7
10. The proposed grade of the line in the creek crossing west of
Mockingbird is approx. 444.0, while the creek bottom in this
area is 442.0. This precludes any kind of acceptable
construction in this area. If we go lower than the creek
bottom, we can't get to the TRA manhole elevation. If we go
higher, or above the creek bottom, then we have an aerial
crossing, which we doubt will be an acceptable alternative.
11. This alignment has Approximately 10,000 LFJ of line (1000
ft. greater than the creek alignment) and 30 manholes...some
60 feet deep, thereby increasing construction costs.
12. Either alignment along the railroad route would not allow
any new subdivisions (Chateaugae, Big Cedar, or Country
Estates, for example) to be connected to the new line
without constructing another major interceptor sewer line in
order to relieve the existing 12" from these proposed flows.
~I~PEVINE CREEK B~I~'rT~RY SEWER ~'rN PA~E ~
FIFTH ROUTE SELECTED...BELT LINE RO&D ALIGNMENT...
SOUTH ALONG WEST SIDE DENTON TAP...TO BELT LINE INTERSECTION
THEN ALONG BELT LINE ROAD TO MOCKINGBIRD LANE
1. Some of the very same reasons for this route selection as
for the railroad route...even deeper excavations...potential
conflict with recently installed cross-town water
line...12,000 LF. of line, (2000 ft. greater than creek
alignment, plus extra depths) 30 manholes, many 60' deep.
2. Intersection of Belt Line/Denton Tap/Southwestern is so
crowded, with existing utilities, even at 50-60'depths, the
boring would be impractical. Space requirements for bore
pits would be impractical. Microtunnelling would have to be
considered. Launch tunnels would require less space than
normal boring pits.
3. One additional major railroad crossing would be required.
This would be located at Mockingbird, to get back across to
the north side of the tracks. It would be almost 28' deep.
4. Cost to tie any existing line to this new line would be
prohibitive. Existing 12" line could not be connected.
5. Extra deep excavations, manholes etc. would require
different type of pipe material to be used. For example, for
up to 40' depths, the pipe materials specified would have
no problem, but increasing the depths to 60' '~;ould require a
stronger, thicker wall pipe, with different typ~ bedding
requirements, and the bores would have to be encased,
manholes will have to be structurally more sufficient to
sustain the greater depths, and the manholes would have to
be greater in diameter to accommodate the greater depths.
GRAPEVINE CREEK SANITARY SEWER MAIN PAGE 9
SIXTH ROUTE SELECTED... PUMP STATION AND FORCE MAIN.
Current flow of 2.5 MGD and projected flow of 7.5 MGD would have
to be considered in design of any pump station. Some detriments
to construction of pump station and force main ....
1. Size of PS would be too large to consider for the areas
where it would have to be located...storage would have to be
provided or pumps would have to be pumping continuously,
which is not good engineering design.
2. Location of PS...no area is conducive to locating PS.
Accessibility and potential nuisance aspects must be
considered. Station must be protected from 100-year flood,
and be accessible during a 25-year flood. Lift stations
should be located as remotely as .possible from populated
areas.
3. Noise problems with operation of pumps.
4. Potential odor problems.
5. Daily maintenance costs to City. (approx. $10,000/year)
6. High monthly operation/electrical costs. ($45,000/year)
7. Large size pumps needed...dual installation for best
operation. Separate dry well/wet well is recommended.
8. Larger pumps needed so as to be sized for peak capacity
discharge, even though lower flows will be utilized until
build out of proposed system is completed.
9. Need for standby power...requires possibly emergency
generator. In case of power outages, the wastewater
retention capacity, in the station's wet well, spill
retention facility, and incoming gravity lines, needs to be
sized so that no discharge of untreated wastewater will
GRAPEVINE CREEK SANITARY SEWER MAIN PAGE 10
occur. Even the minimum time required would necessitate a
very large wet well, which is impractical. An emergency
power supply or adequate detention facility must be
provided. Electrical service from two independent power
companies, from two independent feeder lines, or automatic
starting electrical/gas operated generators must be
provided.
10. Provision for by-pass required should problem with pumps
occur, which would mean dumping into the creek. Not good.
11. PS designed to incorporate surges in flows.
12. Current low flows may have to provide pretreatment,
(chlorination) prior to entering the sewer system.
13. The FM for the current flows would only be required to be
approximately a 12" or 14" line, but the projected flows
would require a 24" or 30". Installation of the larger line
now, with the lower flows associated with the current flow,
would not provide an acceptable velocity in the large line,
then special facilities must be provided for cleaning the
line at specified intervals, otherwise maintenance becomes a
problem.
14. No new development could easily tie on to the FM.
15. Existing 12" line still remains surcharged.
16. Pressure sewer systems not necessarily a substitute for
well designed gravity systems, i
GRAPEVINE CREEK SANIT~%RY SEWER MAIN PAGE 11
SEVENTH ROUTE SELECTED:
MEADOWCREEK ROAD OR E. BETHEL ROAD ROUTE...
Consideration was even given to placing the line in the right-of-
way of Meadowcreek Road or E. Bethel Road. This idea was quickly
dismissed as a viable option.
Disadvantages for either of these selected routes...
1. Crossing Grapevine Creek at Denton Tap Road would present
great depths at Denton Tap and Meadowcreek intersection.
2. Only have 50' RW for work area...with deep cuts, this is not
feasible.
3. Tie ins from existing 12", in back, to proposed 30", in
front, is not practical.
4. Access to homes along Meadowcreek/Bethel would be difficult,
probably impossible throughout duration of contract.
5. Existing utilities already in Meadowcreek/Bethel preventing
any construction being done in that area.
GRAPEVINE CREEK SANITARY SEWER MAIN PAGE 12
OPINIONS OF PROBABLE CONSTRUCTION COST ESTIMATES
The construction cost of the Project indicates the total cost to
the City of Coppell, for the actual construction only.
Since Ginn, Inc. has no control over the cost of labor,
materials, equipment or services furnished by others, or over the
Contractor(s) methods of determining prices, or over competitive
bidding or market conditions, our opinion of the probable
construction cost provided for herein is made on the basis of our
experience and qualifications and represent our best judgment as
an experienced and qualified professional consulting engineer,
familiar with the construction industry; but Ginn, Inc. cannot
and does not guarantee that proposals, bids or actual
construction costs will not vary from opinions of estimated
probable cost prepared by us.
Since the area between the TRA manhole and Mockingbird is not a
point of contention, that cost sould remain the same for all
alternatives (routes). Construction costs for the area between
Mockingbird and Denton Tap were computed for comparison purposes.
Estimates for some alternates, due to the vast number of unknowns
inherent in the proposed locations, and the infeasability of
construction were not prepared.
The cost of the portion between the TRA manhole ~nd Mockingbird
Lane area is $460,31S.00.
GRAPEVINE CREEK SANITARY SEWER MAIN PAGE 13
SUMMARY OF TOTAL PROJECT COSTS FOR SELECTED ROUTES
ROUTE 3 - CREEK BOTTOM ........................... $ 1,775,000.00
ROUTE 4 - RAILROAD ROUTE ......................... $ 4,970,000.00
ROUTE 5 - BELT LINE ROAD ......................... $ 8,400,000.00
ROUTE 6 - PUMP STATION/FORCE MAIN ................ $ 4,630,000.00
GRAPEVINE CREEK SANITARY SEWER MAIN PAGE 14
~;PL!C.AT~ON FSR PAYMENT 'SRAPEV~NE CREE~ SEWER TRUNK ~AIN - B~ANCH !
~[0 OATE: TRA ~ANHOLE T'2 ~CC~NGBIRD .AWE
iOTiCE TO PROCEED narc. SAME ~OR ~' .....
..... ~.~ ~LiSNMENTS - 25% OF DRn~PT LENGTH
OWNER: CITY OF ~2P~:). ,..., TEXAS APPLICATION ~OR
-~NG[NFER: G[NN AND r,¢~ , n
.q~. SCNSUIT~NG ENGINEERS oA'¢~ENT NO. n
NO. I 9T¥ jL!,IT,,.-rT gq[cc A~OL:NT '0~TE '* n-
20..- 60;FURNISHING AND PLACING trip<nE, 0 25 LS Sa,0n~ 00 $~ g00.00 $0 00 C.~ JZ
'-:..~-, ABANDON STING - $350.00 .~n
.X. MANHOLES r,-mar~
~C-2 IABAN00N ~X,S,[NG ~ q .,N~, IN-PLACE 0.25 i~S $§,000.00 $!,5~,00 $0 90
)":~-~ iREMOVE ~XIqTr~a S~N SEWER ~r~c 0 "c
.............2300 iJACKING OR BORING 2!0 I,~ $550.00 $l,c 50n ,n $0 ~ .... ~.g
2480 .AWN AN0 LANDSCAPE R=p(ar~ecuT 0.25 ,IS $5,000.00 $~ 250.00 $0.30 3 ~c
2§00-1 ISTANDARD 5' DIAN,,.~" (0-'n).u 4 lEA $2,250,00 $9,000.00 JO.gO .'
..... u. AM MH (.0 ~, 3 :EA $3,250.00 $9,750,00 .~ 3
Z~00-3 ISTANDARD 5' OIAMMH (!5-2~} ~ IEA .-~ ..... ~. ~.nn 50.00 ~, f0 .... ~n ~ $0..~.
)600-4 !STANDARD 6' n~ . 'S-20) 'iEA $5.37S.~0 ~'
~.AM MH { $5,375.00 $0m90i , 55,375.oo
2S00-5 STANDARD 6' OIAM MH (on-o~ oiEA . ' ~
...... : $6,3?5.00 $12.750.00 $0 O0 ,: .......
-?600-5 STANDARD 6' ~" MH (25-30) iCA · ' ~
~..M ' ' $7,375.00 $73375.00 $0 00 ~ , .
2600-7 STANOARO 6' 9[AM MN (30-35) 0 iEA $8,375.00 $0.00 $0,30 I 0
2500-8 5' D!AM DROP MH {!5-20) ! !EA $4,650.00 $4,650.00 $0.0g I 1 $g,550.SC
25C0-9 5' DIAN TYPE'S' MH (10-'5) 0 iEA $3,850.00 $0.00 $~.00 { ~ $0,2'2
'2500-!0 5' DIAN TYPE'S' MN (15-20) 0 IEA 54,850.00 $0.00 $0.00 {~ 0
2600-11 5' OIAM TYPE'S" MH (20-25) O lEA $5,850.00 $0.00 50.e~ , n
26oo-12 5' 9[AM TYPE'S" DROP MH (10-15) 9 IEA $4,250.00 $0.00 $0.00 J 0 $0.00
2500-!3 5' O!AM TYPE'S' 0ROP MH (20-25) 0 lEA 55,250.00 50.00 $0.00 I 0
2600-14 5' DIAN TYPE'S' SHALLOW MH (0-10) O JEA $!,825.00 $0.90 $0.00 I 0
2500-!5 6' OIAM OROP ME (25-30) 0 lEA $7,775.00 $0.00 $o.o0 i 0
..25~0-~ 30' PVC SEWER PIPE (0-!0) !462 JLF $66.00 596,492.00 $o.oo i !462 $95,492.32
25!0-2 30' PVC SEWER PIPE (10-15) 218 ILF $?2.00 $15,696.00 50.00 ) 2!8 $15,596.~S
25~0-3 30' PVC SEWER PIPE (!5-20) 950 ILF $SO.00 $7 ,000.00 $0.00 I 95O $76,000.0C
2610-4 30' PVC SEWER PIPE (20-25) 475 ):F 588.00 541,800.00 50.00 I 475
'2510-5 30' PVC SEWER PIPE (25-30) 80 ILF $96.00 $7,680.00 $0.00 { t0
2610-6 30' PVC CARRIER SEWER PIPE IN CASING P[PI 210 iLF 550.00 $10,500.00 $0.00 ~' ~'0 $'"
2610-7 24' PVC SEWER PIPE (15-20) 0 iLF $68.00 50.00 $0.00 ]l ~
-26!0-8 12' PVC SEWER PIPE (0-!0) 0 ILF 525.00 $0.00 $0.00 Ii 9 $0.0C
2510-9 8' PVC SEWER P~P~ (0-10) 0 ILF 52?.50 $0.00 $0.00 '~ ~
2810-10 JB' PVC SEWER PIPE (10-15) 0 ILS $25.00 50.00 $9.00 I) 0 $0.9C
~,~-:, 18" PVC SEWER PiPE (20-~) 0 iEA $30.00 $0.00 $0.00 .~ g
n , ILF
251~-,2 JCONNECTIONS TO EXISTING MANHOLES ! $500.00 $500.00 $0.00 JJ 1 5500.0g
2610-13 jCONNECTIONS TO EXIST SANITARY SEWER LINE O ILF $500.00 $0.00 $0.00 il O $0.Ot
26!0-14 JTRENCH SAFETY FOR SEWER LINES 0.25 ILS $~0,000.00 SS,000,00 $0.00 I 0.25 $s,ooo.cc
2610-15 JVENTS FOR MANHOLES, COMPLETE 5 ,,A ~ 5250.00 $1,500.00 $0.00 J 5
2221-! JCONCRETE ENCASEMENT - TY ! 80 ILF $10.00 5800.00 $0.00 I 8o 5800.e~
2221-2 {CONCRETE ENCASENENT - TY 2 n, ~,.'~P 5i5.00 $0.00 $0.00 { 0
26!7-1 148' DIAN STEEL ENCASENENT PIPE 0 ILF $120.00 $0.00 $0.00 I 0
~A'7-2 148' DIAN STEEL ENCASEMENT oipE 0 i,-
..... ,~ 5120.00 $0.00 $0.~0 I 0
2617-3 J48' DIAN STEEL ENCASEMENT PIPE 0 JLF $120.00 $0.00 $0.00 ) O $0,0~
2517-4 !48' DIAN STEEL ENCASEMENT PIPE ~°0 ILF $120 O0 514,400.00 $0.00 :~
26~8 ILOWER 42' WATER LINE 40 JLF $250.00 $!0,000100 $0.g0 .: 40
4~.~? ICONCRETE RIP-RAP REPLACEMENT 0 ILS 57,500.00 $0.00 50.q~.. jj'' 3 JO.CS
i $0.00 50.00 IJ O
! SUBTOTAL 5460,318.00 SD."""
.,~C~T~O., FOR ......... ~.R 'EUNK WA,N - 9R,N~H !
_810 wA.: ~ '": ROUTE 3 - "R~K~ .... BOTTOM
OTICE TO PROCEED DATE:
.ONTRACT AMOUNT: ENGINEER'S KA<'.~.. E~T~MATE ~CHmm
- n, , ~ ? K~ ~ ~A~MENT NO. 0
N~:NEER: G!NN ANO CASE iNC. CONSULTING ~NG,N..R ....
'ONTRACTOR:
iTEM ~=¢~P'~"A~ ........... ~[9 i' ' ~!0 °'9 TOTAL '~TY TO!, ~MOUNT = ,jT¥
NO. ~,YnY IUNITIUNIT PRICE ] AMOUNT ' i CA'E "~.~ C~TE .~_. --.r,,j:x_ :MOL'~'
:i
..~ ~L .......~ Ex]STiNG ......... ~ .... ~c ,"~ ...... $5 290.~0 ~ ?50.00 ,; S0.~O i 9. ~. $3,~.
:~'n-,nn,PREP~RE ~rn, Y .~c w,v 9~.93 [STA S150.00 $14,839.50 Il
O~O-'021CLE.ARING ~N9 3RUBBING 0.-=" .... !LS $,.,000.00 .~ SO.SD ,1' ....
20~O-1601FURNISN!NG. . ~NO PLAC{NG TOPSO{L 0.,. Y~ ;LS $8,000.nn~, $6,000.nn-~ ii $9.~.n~ il ~.n ~,. $5.000.~'i.
............ · ..,o. ,..~.. - !N-brACE 9 ..EA $350.00 !50. {{ .~ g ~,'59.
2~50-2 IABAN00N EXISTING 5.S ~.NE, IN-PLACE 0 75 'LS $6,000.00 $4,500.90 ,,
2050-3 :REMOVE EXISTING SAN SEWER LINE 295 ;LF $10.00 52,950.00 }{ 59.00 295
2300 {JACKING OR 8ORING 397 LF $550.00 5212,~50.00 ', $0.0° ~ $212,
~0~. $3,750.00 ~{
2~80 {LAWN AND LANDSCAPE REPLACEMENT 0.75 tS 55.n n 00 , $0.00 9.~ $~ 750.~'
2600-1 iSTANOARO ~' 9IAM MH (0-~n) 0 EA 52,250.00 50.00 ~,
2600-2 ISTANDARD 5' 0,~M MH (10-15) 9 EA 53,250.00 $o.0o {] 5o. o i o
~600-3 .c, 5' )5-20) i EA
,~,ANOARO OIAM MH ( $4,250.00 $8,500.00 $0.00 I 2
)600-4 {STANDARD 6' D!AM MH (15-20) I EA $5,3?5.00 55,3?5.00 50.00 I 1
2600-5.iSTANOARD 6' DIAM MH (20-25) 2 FA_ 56,3?5.00 5~,.,,.~0.00 50.00 I 2 $'2. ,=--.-~<n --
?500-5,)STANDARD 6' 91AM MH ,--~°"-~n~--~ ~ EA $7,375.00 $~4,750.00, $0.00 I .~ $!{,750.0C
2600-7 ISTANOARO 6' O[AM MH ~30-35) I . ~vc -
IEA $8,375.00 $8 ..... 00 $0.00 I l
2600-8 {5' 9!AM DROP MH (!5-20) 2 iEA 54,650.00 $9,300.00 50.30 I 2 $9,300.C2
2600-g '"'~ 01AM TYPE'S' MH (10-15) 5 lEA $3,850.00 $!9,250.00 $0.00 I ~ $~Q'-,---l-°~n rI
~¢nn_~n ,c, qrAM TYPE "~' MH C!5-20) i IEA $4,850.00 54,850.00 $0.00 I l
2600-11 6' OIAM TYPE 'e'~ MH ~.v-,,~n 9~ ! {¢~A 55,850.00 $5,850.00 $0.00 II ~
2600-12 5' DIAM TYPE "S' CROP MH (]0-15) 2 {EA $4,250.00 $8,500.00 $0.00 { 2 $8,500.2C
2500-13 6' OIAM TyP~ 'S' DROP MH (20-25) ~ '~
.. ~ ,.A $5,250.00 $15,750.00 50.00 iI ~ q .,' .~.
2500-!4 5' 0IAM TYPE'S' SHALLOW MH (0-!0) 33 lEA $1,925.00 $60,225.00 $0.00 ] 33 S60,225.2C
2600-15 6' 0IAM DROP ~M (25-30) ' JEA. $?,.,,~?".00 57,??5.00 50.00 Ii 1 S?,??E.0C
~-~ 30' DVC SEWER PIPE (0-~0) 3830 ILF 566.00 $252,780.00 $0.00 'I 3830
~10-2 30' PVC SEWER D'D¢ ('0-'c) 2680 JLF $72.00 $192,960.00 $0.90" 26~0 $192,95~.0C
,6,0-3 30' PVC SEWER PIPE (!5-20) 1078 IL¢ $80.00 $86,240.00 $0.00 JJ 10?8 $86,2~9.3~
2610-4 30' PVC SEWER P[PE (20-25) 1816 JLF $88.00 $!59,808.00 $0.00 i! 1816 5159,808.9C
"2610-5 30' PVC SENER PIPE ~-~n~ , $I
~ .... ~ 204 ILF $95.00 $10,584.00 S0.00 'I 204 9,584.2[
25!0-~ 30' PVC CARRIER SEWER PIPE IN CASING PIP 287 ILF $50.00 $14,350.00 $0.00 28? $14,350.0C
26!0-7 24' PVC SEWER PIPE (15-20) 60 ILF 568.00 $4,080.00 $0.00 50 $~,080.0<
2510-8 {2' PVC SEWER PlPE (0-10) 14 {LF $25.00 $250.00 $0.00 !4 5350.CC
25'0-g 8' PVC SEWER PIPE (0-10) 44 ILF $27.50 $1,210.00 $0.00 44 $],210.0C
2610-10 8" PVC SEWER.oTP~., ~ (10-15) ln~ ILS $25 . OD $25o.oo 5o.0o ,0: 5250
2610-~1 8' PVC SEWER PIPE (20-25) 48 lEA $30.00 $~,440.00 50.00 {8 $],{40.~C
2610-1~ CONNECTIONS TO EX[STING MANHOLES 6 i~F $500. ~ 000.00 ~0.00
2610-!0 CONNECTIONS TO EXIST SANITARY SEWER LINE 2 ILF $500.00 $1,000.00 $0.00 2 5~,~00.0E
2610-14 TRENCH SAFETY FOR SEWER LINES 0.75 ILS $20,000.00 $15,000.00 II $o.oo o.75 s~,ooo.0~
25!0-:~ 'VENTS FOR MANHOLES, COMPLETE 17 IEA 5250.00 $4,250.00 II $0.00 '? $¢,250.0[
222!-1 CONCRETE ENCASEMENT - TY 1 140 ILF $10.00 51,400.00 II 50.00 140
22~!-2 CONCRETE ENCASEMENT - TY 2 3920 ILF $15.00 $5~,800.00 II 50.00 ~g20
2617-1 48' 01AM STEEL ENCASEMENT PIPE 147 LF 5120.00 5!?,640.00 II $0.00 147
2517-~ 48' DIAN STEEL ENCASEMENT PIPE !40 LF $120.00 $16,800.00 II 50.00 ~0
2617-3 48' OIAM STEEL ENCASEMENT PIPE 90 LF 5120.00 $10,800.00 II 50.C0 90 5~0,S00.0<
2617-4 48' ClAM STEEL ENCASEMENT PIPE 0 LF $120.00 $0.00 {I 50.~0 0 S010'
2618 LOWER 42' WATER LINE 0 LF 5250.00 $0.00 ii $0.00 C SCl'
432 CONCRETE RIP-RAP ~EPLACEMENT 1 LS $7,500.00 $7,500.n0" $0.00 ~
SUBTOTAL $1,313,531.50 Il $0.00 $1,3!2,531.52
TRA MANHOLE TO MOCKINGBIRD PORTION $460,3!8.00
TOTAL $1,773,849.50
~PPL~CAT~ON COR PAYMENT GRAPEVINE CREEK SEWER TRUNK UA~N - BR~NCH I
B19 DATE: ROUTE 4 - RAILROAD ROUTE
v ,~E TO PROCEED DATE:
;ONTRACT AMOUNT: ENGINEER'S COST,~.ccT'~c,,., ~
r ~m TEXAS
OWNER: CITY OF ~OP...L, APPLICATION FOR
~NGINEER: S!NN ~ND CASE, !NC...NSUL,,NG ENGINEERS PAYmeNT NO..
.~,- OATE ? ~T&L
NO. , < ...... ,,
~010 'LOCATION OF EXISTING UTILITIES ' :LC i $5,000.00 $~,000.00 Ii $0.00
~010-1001PREPARE RIGHT-O:-WAY !00 ISTA i $150.00 $~5,00~.00 II $0.~0 '0{
~"'n '^~'CLEAR!NG AND ~RUBB,N~ 0.?5 iLS ,$15,000.00 $I~ 250.30 1
2010-1601FURNISH!NG AND PLACING TOPSOII n ~ I,¢ .~
..... ,.) .,ooo.oo s6,ooo.0o II .
~ .×,~,ING MANHOLES - g ~EA ~ .~ ......
--~050-1 iABANDON F tot IN-PLACE , ' $350.00 $3,'50.00 l{ $C ~" ~ $2,'ch "'
2050-2 IABANDON EXISTING S.S. LINE, IN-PLACE 0.25 ILS I $6,000.00 $4,500.00 $0.00 3.25
2050-3 IREMOVE EXISTING SAN SEWER '~NE~., .~9K~ ,.~ c ,' $i0.00 $2,950.00 $0..~n 2~5 $2,
._2300 'JACKING OR BORING 5500 I ,6oo.oo ,3.3oo.ooo.o0 ,C.C
2480 LAWN AND LANDSCAPE REPLACEMENT 0.-~ .c ~: '~ ~ $3,75C.20 SC n~ ~ -c
2600-i STANOARO 5' DIAM MN (0-I0) ~ EA $2,250.00 $2,250.00 $0.00 ' $~,25C.2S
~nn_o STANDARD 5' D{AM MH (!0-~53 3 EA $3,250.00 59,?50.00 $0 O0 ~ $9,250.
$4,~,0.~0 $!7,000.00 ~
?500-3 STANDARD 5' D!AM MH (15-203 4 EA ^cn
2600-4 STANDARD 5' 91AM MH k30-.5~ 6 SEA $8,375.00 $50,250.00 $0.~0 . $52,25C.~2
~nn_c STANDARD 6' OIAM MN (35-403 4 iEA $10,500.00 *~o nnn.o0 $0.00 {) 4 (ao nnn n.-
_2600-6 STANDARD S' O[AM MH ~{0-45) 5 {EA $11,750.00 558,750.00 SD.00 I[ 5 $58,~50.2C
2E00-7 STANDARD 6' OIAM M~ (45-50) ~ {EA $]3,000.00 $52,000.00 $0.00,~" ~ $52,000.0C
2500-8 SHORING OF OPEN PITS 21 lEA $20,000.00 $420,000.00 $0.00 21
2600-9 5' OIAM TYPE "S" MH (10-!5) 0 jEA $3,$50.00 $0.00 $0.00 n $0.3~
~500-,0 D!AM TYPE'S' MH (!5-20) 0 lEA 54,050.00. $0.00 $0.00 0
2600-1! 16' D[AM TYPE's" MH (20-25) 0 lEA $5,~50.00 50.00 $0.00 0 $0.0C
2500-~2 15, olAM TYPE'S' 0ROp MH (10-!5) 0 jEA $4,250.00 S0.00 , $0.00 o SO.CS
2600-13 {6' DIAM TYPE'S" DROP MH (20-25) 0 IEA $5,250.00 50.00 $0.00 0 $0.0~
2500-14 {5' DIAM TYPE "S' SHALLOW MH (0-103 0 IEA $1,825.00 $0.00 $0.00 0 $0.~?
2600-15 BORE PIT EXCAVATION I ILS $80,000.00 $80,000.00 $0.00 : $80,000.C~
...25!0-1 30' PVC SEWER PIPE (0-!0) 0 ILF $~6.00 $0.00 $0.00 0 $0.00
2510-2 30' PVC SEWER PIPE {10-15) 0 LF 5?2.00 $0.00 Il $0.00 0
2610-3 30' ~vc SEWER PIPE (15-20) 0 LF $80.00 $0.00 II $0.00 0 $0.0~
2610-4 30' Pvc SEWER PIPE (20-253 AVERAGE 4500 LF $88.00 $396,000.00 {i $0.00 ~500
2510-5 30' PVC SEWER PIPE (25-303 0 {LF 5DB.00 $0.00 l{ $0.00 0
25'0-6, ,-:0' PVC CARE!c~., ~c.c-;_,_. PIPE IN CASING PIP 0 ~'LF $50.00 $0.00 Il $0.00 ."
25!0-? 24' PVC SEWER PIPE (15-203 0 {LF $60.00 $0.00 Il $0.00 0 $0.0C
2610-8 12' PVC SEWER PIPE (0-10) 0 ILF $25.00 50.00 {I $0.00 0
2510-9 8' PVC SEWER PIPE (0-10) 0 ILF 527.50 $0.00 {I 50.00 0 S0.
2610-10 8' PVC SEWER PIPE (10-153 0 {LC 525.00 $0.00 $0.00 0 $O.0C
2510-11 B' PVC SEWER PIPE (20-25) 0 JEA 530.00 $0.00 $0.00 0 SO.CC
2610-12 CONNECTIONS TO EXISTING MANHOLES 2 ILF $$00.00 51,000.00 50.00 2
2610-13 CONNECTIONS TO EXIST SANITARY SEWER LINE 0 ILF $500.00 $0.00 $0.D0 0
2610-34 TRENCH SAFETY FOR SEWER LINES 0.5 ILS 520,000.00 $I0,000.00 $0.00 0.5 $!0,000.CC
2§10-15 VENTS FOR MANHOLES, COMPLETE 15 lEA $250.00 $3,750.00 $0.D0 15 $3,250.0C
2221-1 CONCRETE ENCASEMENT - TY 1 0 ILF 510.00 $0.00 50.00 II o
222!-2 CONCRETE ENCASEMENT - TY 2 0 JLF 515.00 $0.00 $0.00 {I 0 $0.0C
2612-1 48' DIAM STEEL ENCASEMENT PIPE 100 ILF $120.00 $12,000.00 $0.00 II I00
2517-2 48' DIAM STEEL ENCASEMENT PIPE 0 ILF $120.00 $0.00 $0.00 Il 0
2517-3 48' DIAM STEEL ENCASEMENT PIPE 0 ILF $120.00 $0.00 $0.00 II 0 $0.0C
2617-4 48' DIAM STEEL ENCASEMENT PIPE 0 ]LF $120.00 $0.00 $0.00 )I 0
"2~18 LOWER 42' WATER LINE 0 {LF $250.00 $0.00 , SO.GO ii 0 SO.CZ
432 CONCRETE RIP-RAP REPLACEMENT 0 ILS $7,500.00 $0.00 $0.~0 II 0 $0.''~
SUBTOTAL I $4,506,350.00 50.00 {i .......
TEA TO MOCKINGBIR0 PORTION $460,318.00
TOTAL $4,g66,~68.00
pp,,ca"~ FOR PAVMENT '~'nF'TU~ '
............ j,,~r ..... CREEK SEWER 'RUNK cAiN - ~qANCH
--, .... N~ ROAO
TG
nr~nc TO PROCEED DA~:
SNTRACT AMOUNT: ENGINEER'S COST ESTZMATE v~C" ' 'q~
~1 I : ~- . . .
OWNER: CITY OF COPP .... rKvas APPLICA~'ON
=NG!NEER: GINN AND CASE, .NC. ,-n~¢n,,,~a ENG;NEERS ~AYMENT NO. J
i~NIT UNIT -~,~ &MOUNT '. '0 SATE
~0S0-1 ABANOON EXISTING MANHOLES - ,N-P~AC~ 0 iEA $350.00 $0.00 $0.00 l!
'":n-~ ABANDON K¥I¢YING ¢ ¢ LINE TN-PlACE 0.?~ I~S $6,000.00 $4,EDO On $~.~, I~
Z050-~ REMOVE EXISTING SAN SEWER LINE 2~5 iLF $?D.DO $2,~50.00 $0.90 ;~
2300 JACKING OR BORING ~1400 I~. $600.00 $6,~40,000.00 $0.00 ,,'~
'480 LAWN AND LANDSCAPE REPLACEMENT 0.?5 ;LS $5,000.00 $3,?50.00 $0.00 ~i ....
!600-! STANOARO 5' OIAM MH (0-10) ! EA $2,250.00 $2,250.00 $0.00 I! 1 $2,250.CC
2600-2 STANDARD 5' DIAN MM (10-15) 3 EA $3,250.00 $9,?50.00 $0.00 !1 3
"600-3 STANDARD K' 0IAM MH (15-20) 4 EA $4 250.00 $1?,000.OO $0.00 4
600-4. STANDARD 6' DIAN MH (30-35) l! $8,3?5.00 $92,125.00 $0.00 It $92,!25.~
2600-5 STANOARO 6' OIAM MH (35-40) 3 EA 1510,500.00 $31,500.00 $0.00 3 $3!,500.CC
J600-$ 'STANDARD 6' 01AM MH (40-45) 3 EA I$II,750,00 $35,250.00 ~ $0.20 3
1600-? STANOARO 6' DIAN MH (45-60) l0 EA 1513,000.00 $!30,000.00 $0.00 l0 $130,000.?0
J600-8 SHORING OF OPEN PITS 2? EA $20,000.00 $540,000.00 $0.00 2? $540,000.~?
250'0-9 5' D[AM TYPE'S' MH (10-15) 0 EA $3,850.00 $0.00 $0.00 0
-!500-10 9!AM TYPE'S' MH (!5-20) 0 lEA $4,850.00 $0.00 $0.00 0 I0.D0
)600-11 6' OIAM TYPE'S' MH (20-25) O lEA $5,850.00 $0.00 $0.00 ~ $0.00
2600-12 :' DIAN YvpE 'S' DROP MH (10-lO) 0 lEA S4,250.00 $0.00 $0.00 0
~600-13 6 0IAM TYPE'S' 0ROP MH (20-25) 0 ,~A 250.00 $0.00 $0.00 0 $0.00
2~00-!~ 5' DIAN TYPE'S' SHALLOW MH (0-!0) 0 lEA $1,825.00 $0.00 $0.00 0 $0.00
2500-15 8ORE PIT EXCAVATION ~ ,~S $80,000.00 $80,000.~0 $0.00 il
2610-1 130' PVC SEWER PIPE (0-!0) 0 iLF $66.00 $0.00 $0.00 II 0 $0.00
25!0-2 130' PVC SEWER PIPE (10-15) 0 iLF $?2.00 $0.00 $0.00 0
2610-3 i30' PVC SEWER PIPE (~$-20) 0 ILF $80.00 $0.00 $0.00 0 $0.~0
2~10-4 130' PVC SEWER PIPE (20-2S) AVERAGE SOO LF $88.00 $44,000.00 II $0.00 500 $4~,000.52
?~!0-5 '30' PVC SEWER PIPE ~25-30) 0 LF $06.00 $0.00 II $0.00 0
~10-6 30' PVC CARRIER SEWER PIPE IN CASING PIP 100 LF SS0.00 SS,000.00 ~ $0.00 100 $5 000
2610-? 24'.PVC SEWER plP~. ~ ~,:-~nl,~ --, 0 LF $68.00 $0.00 !l $0.00 0
25!0-8 !2' PVC SEWER PIPE (0-10) 0 LF $2S.00 $0.00 II $0.00 0
~5!0-g 8' PVC SEWER PIPE (0-10) 0 LF $2?.50 $0.00 il $0.00 0 $0.~0
2610-10 8' PVC SEWER PlPE (10-15) 0 ILS $25.00 $0.00 I $0.00 0
2§10-!! 8' PVC SEWER PlPE (20-2S) 0 lEA $30.00 $0.00 I $0.00 0 $0.90
-'-2610-12 CONNECTIONS TO EXISTING MANHOLES 2 ILF $S00.00 $1,000.00 I $0.00 2 $:,000.0~
2510-13 CONNECTIONS TO EXIST SANITARY SEWER LINE 0 ILF $500.00 $0.00 I $0.00 0 $0.00
2610-14 TRENCH SAFETY FOR SEWER LINES 0 ILS $20,000.00 $0.00 I $0.00 0 SO.OS
.2610-15 VENTS FOR MANHOLES, COMPLETE !5 lEA $250.00 $3,750.00 $0.00 15
222!-1 CONCRETE ENCASEMENT - TY I 0 ILF $10.00 $0.00 $0.00 0 $0.0~
2221-2 CONCRETE ENCASEMENT - TY 2 0 ILF $15.00 $0.00 $0.00 0 $0.00
2617-1 ~8' OIAM STEEL ENOASEMENT PIPE 100 ILF $120.00 $12,000.00 $0.00 Il 100 $12,000.00
2617-2 48' DIAN STEEL ENCASEMENT PIPE 0 i~F $120.00 $0.00 $0.00 II 0 SO.OS
261?-3 48' 0IAM STEEL ENCASEMENT PIPE 0 ILF $120.00 $0.00 $0.00 Il 0 $0.00
2617-~ ~8' n~ $0.00 n
~,AM STEEL ENCASEMENT PIPE 0 ILF $120.00 $0.00 ~ $0.~0
'2618 LOWER 42' WATER LINE 0 ILF $250.00 $0.00 $0.00
432 CONCRETE RIP-RAP REPLACEMENT ' 0 ILS $?,500.00 $0.00 $0.00 0 $0.
SUBTOTAL I $?, 802,0?S. 00 $0.00
TRA TO MOCKINGBIR0 PORTION $4§0,318.00
FOTAL $8,352,303.00
~PAL!CAT[ON FOR PAYMEN' m'~ P~ ~
:..A .V.NE :REEK SE~ER TRUNK MA~N - 5RANCH
BID DATE: ROUTE 5 - PUMP STATION AND FORCE MAIN
IOTICE TO PROCEED DATE:
OWNER: ~'~ OF
~,Y COPPELL, TEXAS ~pOIIP~'IAN FOR
ENGINEER: G!NN AN0~A~¢~, INC. CCNSULT;NG ENGINEERS P~Y~ENT NO. 3
;;N'DACTOR:
[TEV ' 0E!CR!PTION ' 8!0 ~ : :$ ~!O 'C'~L IQTY TO AMOUNT ii 9TM
NO. I ' QTY Jq:" ~N! PRICE *~OUNT :A~ T~ ....... '* ~T:. 'C-:
~'~-!00;PREPARE RIGHT-OF-WAY '~4 JSTA $!cn ^n ~on ~ ~n $0 nD., :~, ~ '~0 nn
, ~n.O0 ,
2g'0-~O2JCLEAQING AN0 gRUBBING ' '¢ $15,g00.00 $ 5,..~ $0.00
~^5n-1 )ABANDON ~v~-~un .~
............. ~NHOLES - iN-PLAC 2 !EA $350.00 $?00.90 $0 An . 2 $ .....
2050-2 IABANOON CV~Y~Nn ¢ ¢ '~ ¢ ~N-mar n ~ , ~ no
s.N_, .5 $5,v00 ~ ¢, ~n no
............ $0.00 ~ '~ ~ ¢'
....~n50-3 REMOVE EXISTING SAN SEWER LINE O ILF $~0 ~0 ~0130 ~Omm~O m ~ ii
"~ $550 00 $550 000 00 $0.00 ' 'nn" ' :~ '~ '~
2300 JACKING OR BORING 1000i~. , - , .... Si.b,..=...
2480 LAWN ANO .... ¢~oF qEPL~CEMENT ' ..~ $5,000.00 $0.30 i
...... ~.- ILS $5,~""~ "" , , ,
2600-i AIR RELIEF VALVES 4 ;EA $'0 nn0 .n $40 nnn 00 $0.00 j ' J
2600-2 STANDARD ~'~ ~M~" ~H C10-,~5) 0 ,~AI~ .... $o.oo o.oo II ,, $0.3o
2500-3 STANDARD ~' DIAM MH ~':-10) 0 'EA $4 ,5~ $0 00 $0.00 ,i q
2600-4 STANDARD S' 9)AM ~H ~'5-20) O lEA $5,375.00 SS.00 { S0.00.:i 0
, . ' " 0
2500-5 STANDARD 6' O[AM MH (20-25) 0 EA $6 3?5 00 $0 00 i $0.00 mm
2600-6 STANDARD 6' DIAM MH (25-30) 0 EA $7,375.09 $0.00 ,~ $0.00 I{ C
' $0 0~" $0.00
2~00-7 STANDARD 6' D!AM MH (30-35) 0 EA $8,3?5 00 $0.00 ~ . . ,I 0
2500-8 5' 0lAM DROP MH ~!5-20) 0 EA $4,650 00 $0.00 { $0.00 i{ n $0.22
_2600-9 5' DIAM TYPE 'c'~ MH (10-15) 0 EA $3,850.00 $0.nn~ ', $0.~°n i' 0
2600-10 ~' DIAM TYPE'S' MH ~,~-~n~ .... ~ 0 EA $4,850 00 $0.00 '~ $0.00 'i ~ .....
2500-!I 6' OlAM TYPE'S' MH (20-25) 0 EA $5,850.00 $0.00 I $o.oo I: o
2500-12 5' D!AM TYPE ,e, DROP MH ~ : EA . " 3
~ ,10-1~) O $4,250 00 $0 00 I $0.00 .~
2500-!3 6' D[AM TYPE IS' 0ROP MH (20-25) 0 EA $5,250.00 $0.001 ..oo :, o
2600-!4 c,, DIAM YYP¢,. . 'S' SHALLOW MH (0-10) 0 EA St,,..~§ 00 $0.00 I $0.00 'I~ O
2600-!5 6' DIAM 0ROP MH (25-30) 0 EA $?,??5.00 · $0.00 I $0.00 i: 0
~'0-1 PUC FORCE ~A!N {0-8) !1000 LF $75 00 $82S 000 00 ) $0.00 'I l'O0O
2610-230' PUC SEWER PIPE (I0-15) 0 $?2.00 $0.00 I S0.00 !) 0
· ii 0 (A qA
,, ! $0.00 ,~
2510-3 30' PVC SEWER ~PE (15-20) 0 LF $80 00 $0 00 ~
26!0-4 30' PUC SEWER PIPE (20-25) 0 LF $88.00 $0.00 I $0.00, o
25!0-5 30' PVC SEWER PIPE (25-30) 0 LF $96.00 $0.00 I $0.00 I 0 $0.00
2§10-6 30' PVC CARRIER SEWER PIPE IN CASIN 1000 LF $50.00 $50,000.00 I $0.00 I !000
2510-? 24' PVC SEWER PIPE {!5-20) 0 LF $68.00 $0.00 I $0.00 I 0
2510-8 12' PVC SEWER PIPE (0-10) 0 }LF $25.00 $0.00 i' $0.00 I 0
25!0-g 8' PUC SEWER PIPE (0-I0) 0 ILF $27.50 $o.oo I So.oo ) o
251O-lO 8. PVC SEWER PIPE (10-15) 0 )LS ;25.oo $0.00 $0.o0 I 0
.2$10-!! 8' PUC SEWER PIPE (20-25) 0 lEA SD0.00 $0,00 )) $0.00 ) 0
2610-12 CONNECTIONS TO EXISTING MANHOLES ~ ,~i,F" $500.90 $I,000o00 ~1" $0.00 i ,~
2§10-13 CONNECTIONS TO EXIST SANITARY SEWER) I ILF $500.00 $500.00 I) $0.00 l
2510-!4 TRENCH SAFETY FOR SEWER LINES I 1 ILS $20,000.00 $20,000.00 Ii $0.00 ! $20,000.00
2§10-15 VENTS FOR MANHOLES, COMPLETE ) 0 IEA $250.00 $0.00 )l $0.00 0 $0.00
2221-1 CONCRETE ENCASEMENT - TY ! ) 0 ILF $10.00 $0.00 I) $0.00 0
2221-2 CONCRETE ENCASEMENT - TY 2 ) 0 )LF $15.00 $0.00 )I $0.00 0 $0.00
25!?-! 48' DIAM STEEL ENCASEMENT PIPE ~ 1000 )LF $120.00 $120,000.00 Il $0.00 ) 1000
2617-2 48" D!AM STEEL ENCASEMENT PIPE 0 ILF $120.00 $0.00 I) $0.00 II o
2617-3 48' DIAM STEEL ENCASEMENT PIPE 0 iLF $120.00 $0.00 IJ $0.00 ~.
2517-4 48' DIAM STEEL ENCASEMENT PIPE 9 'LF $120.00 $o.oo )) $o.oo :1:
2618 LOWER 42' WATER LINE 0 iLF $250.00 $0.00 Il $0.o0 II n
PUMP STATION, COMPLETE-IN-PLACE LS $2,5OO.00O.0O $2.~00,000.00 Il $o.oo I;
SUBTOTAL I $4,16!,500.00 II $o.oo Il
TRA TO MOCKINGBIRD PORTION $460,318.00
TOTAL
EXCERPTS FROM CITY-WIDE STORM WATER MANAGEMENT STUDY
PREPARED BY
~LBERT H. HALFF ASSOCIATES, INC.
JANUARY 1991
GI~APEVINE CREEK SANITARY SEWER MAIN PAGE 15
I 'I'A IlI,E !
SUMMARY O1,' 5'I'REAM I:LIX}IilNG AND EROSION SITE RECOMMENI)ATIONS
I S'I~.F.A~t I RliCOM M I:.N 1) F.13 A LTIiI~N A'I'[V Ii I F.5'I'I MA'I'I;.13 COST' I
e~ Grapevine Cn:ck - 1½clt Linc Rd. Bridge & Upslream Channcliza, lon $ 560.000
· I:.ro~ion F~nton Tap Road to Moon: Road
a) I)rcliminary [)c:,ign $ 45.000
b) Rciainint~ W,~lls
· Erosion o. Unmuncd 'l'ribula~] at ,Maywood Citclc $ 90,000
· F. rosion near l.BJ Frccw,,y $ 400.000
Stream Gl · Ile~hcl School Road $ 555,000
· Coppel] Road $ 488.000
· Erosion Downslream of CoppeLI Road (Mitchell Street) $ 22,000
· Loch Lane $ 31,0(X}
· Unnamed 'Fributary-NCl[ Tract
· l}.-the! Road $ 426.000
· Fr~pon ISarkway/llcthel Road Inu:rsection $ 69,000
· U.,I.-rsized Storm Sewer Upstream of
Stream G2 Grouted riprap erosion prou:ction $ 26,000
Slream (]3 Meadowcn:e.k Road $ 29.000
Stn:am (34 Mcadowcreek Road $ 53,000
Stream G5 · Christi l.ane $ 4,000
· Can-'r Drive $ 3.000
Stream G6 · Bethel School Road culvert and channel $ 170,000
· Moon: Road erosion pmu:ction $ 230.000
· Ma~hy Areas ~c~og C'luumel-French Drain System No cost to City
· Tributary Over l.ue Dr&inage-Retaining wall $ 15,000
Elm Fork · i~ood lnsurance/l:lood Proofing No cost to City
· l~'.equeYt Inclusion in C.O.E. Feasibility Phase Study No cost to City
Denton Creek · [:lood lnsurano:/[.lood I)roo~-mg No cost to Ci~
· Andrew Brown P'ask Spillway $ 35,000
Stream DI · Coppell Road culverts/channels $ 118,000
· Cuqx~rau: Pank Boulevaud
Cottonwood Branch * A.dn:w llrown Padc berm $ 35,000
· State Road (Fmure Fn:epon Ruulcvard) $ '/$0,000
· Winding lldlow Lane
Stream CI S',.'," Road culvert $ 60,000
TOTAL S'IR .F_.AM FLOODING AND EROSION SFFE RECOMMENDATIONS $ 5,564,000
~ Costs shown an: toed estimated co~ls. Poesible city. dev¢lot~er or private pamcipation nc~ de,,'rmined.
~ Development rec0mmendatien included in report. Cost not estimated.
The local drainage an~dy~s addressed 46 dr;tinage problems previously itemized by the
Natural Drainage Subcommittee. City files were also reviewed and complaints from citizens
were logged during the study to compile a list totaling over I'/9 individual drainage complaints.
The majority of these complaints were addressed specifically either as stream flooding, erosion
or local dr, tinage sites. Table 2 contains a summary of the local drainage problem sites. Some
of the drainage complaints were addn:ssed by the recommendations shown in Table 1.
Additional information on each of these sites can be found in Chapter VTI.
XX
TABLE 3
SUMMARY OF BASIN-WIDE AND GENERAL WATERSHED RECOMMENDATIONS
RF. COMMENDAIION
Va]icy Storage Preservation --
Parallel Parkways S 2.700.000
Greenbelt Prcser3,ation/Opefl Space AcquisitWn (286 acres) --
Trail System Extension $ 880,000
General Watershed Recommendations
· Passive F]o~l W&ming Systems $ 26.000
Monumentation
· Construction Site I'-'ro~ion Control --
· Review of Drainage Construction Plans ---
· Creek Inspection --
· Urban Storm Wmer Permits --
a. Drtinagc Data Base Nm Estimar~l
b. Base Maps - Topography Not Estimated
c. Sampling/Gaging - Interim $ 4,000
· Finished FJoo~ Certification ---
Flood Plain Ordinance Revisions ---
· Initiate Regular i)h~h Maintenance Program --
· Initiate Regular St~ct Ma/ntenance Pm~ram ---
t Estintatcd Co, ts are tolal construction costs. City. developer o~ private paflicipm/on no~ estimated.
~ Provided to City Staff separately.
The final recommended Cir.-Wide Storm Water Management Plan is the culmination of
all these efforts. This plan was approved by the Coppell City Council in January of 1991 and
is estimated to cost $11,965,250, including structural flood control and drainage system
improvements as well as basin-wide and general watershed recommendations. The citizens of
Coppell approved $800,000 in drainage improvements in a 1990 bond package.
The individual recommendations were evaluated based on the severity of the problem,
public safety, property damage, danger to existing structures and height, velocity and duration
of flooding. This evaluation in conjunction with the approved bond funds was used to develop
a six phase suggested implementation plan which is included in Chapter VIII of this report.
Phases 1 and 2 correlate approximately to funds available in the existing bond program.
Additional funding will be required to complete subsequent phases of the proposed
improvements. Several of the flood control projects could also be funded through joint efforts
with individual property owners, developers or other entities. Other funding sources such as
municipal drainage utility districts and public improvement districts are also discussed in Chapter
VIII.
Implementation of this City-Wide Storm Water Management Plan will help to control
existing flooding and erosion problems and reduce the threat of increased flooding due to man's
activities. The flood plains of Coppell, a valuable natural resource, will also be preserved for
future generations.
o.o
XXlll
1. INTRODUCTION
The Coppcll area was first settled in 1832 and has known the names of Grapevine Springs and Gibbs.
The current name of Coppell was established around 1890. The City now occupies a unique and enviable
position. It is bordered by Interstate Highway 635 on thc southwest, State Highway 121 on thc north, and the
Dallas-Fort Worth International Airport Oil the west. This strategic location within the Dallas-Fort Worth
metroplcx places the City of Cx)ppell in an active development zone. In fact, the city is already experiencing
rapid development. In 1980, tile recorded population was only 3,826 persons? This number increased to
more than 10,$00 by 1986{z) and according to the recently released 1990 census data is currently 16,881.O)
Thc City of Coppeli contains three major waterways which ultimately drain into the Elm Fork of thc
Trinity River along the eastern corporate limits. Formed by centuries of flood water erosion, Grapevine
Creek, Cottonwood Branch, Denton Creek, and the Elm Fork flood plains contain a wealth of scenic and
environmental assets. The adjacent land areas have become highly prized and desirable locations for all types
of development. However, the same flood waters that created the rich variety of vegetation and wildlife
habitat, threaten both existing and future developments. Continued development along the flood plain and
in thc city increases storm water runoff, causing larger and more frequent floods, which are thc most fatal of
all natural hazards in the United States. Flooding accounts for 163 deaths across the U.S. in a normal year,
while tornadoes and lightning strikes arc responsible for 98 and 97 deaths, respectively.°} In the Spring of
1989, fl~x~ling caused approximately 25 deaths and in excess of 12 million dollars in damages throughout
North Texas.°) Developments in and along the flood plains of Coppell also experienced flooding and drainage
problems as a result of the 1989 floods. Realizing these problems, the City of coppell commissioned this City-
Wide Storm Water Management Study to address drainage problems that might be caused by both historic and
future floods.
A. Objectives of thc Study
Thc main objective of this study is to develop a comprehensive City-Wide Storm Water Management
Plan which will address existing drainage, flooding, and erosion problems and provide a master plan to control
future flooding problems within the city. The study consists of investigations into the designated 100-year
flood plain along Grapevine Creek, cottonwood Branch, Denton Creek, the Elm Fork of the Trinity River
and selected tributaries, as listed in Table I-1 and shown on Figure I-1. Investigations will also be made into
local drainage problems as identified by the citizens and staff of thc City of Coppell. Flooding sites will be
inventoried and alternative solutions to these problems will be presented. A comprehensive storm water
management plan will be devcioped which includes flooding and erosion mitigation measures, open space,
parkway and recreation plans and general watershed recommendations. The objectives of the _Co._p[~l! Cio/-
14ftde Storm Water Management Plan are:
1. To prevent loss of life;
2. To minimize property damage;
3. To minimize erosion and deposition;
4. To preserve open space;
5. To preserve animal and plant life;
6. To use the flood plain for water conveyance, transportation routes, and utility rights-of-way;
7. To provide recreational areas;
8. To put flood plain land to its best and highcst~priority usc;
9. To relate nearby areas to thc flood plain by providing scenic attractions in, and vistas of, the
flood plain;
I-1
10. To stabilize neighborhoods by enlisting residents to participate in cooperative efforts to
improve the basin, which will be a source of community pride and will impart a sense of
achievement; and
11. To minimize municipal capital and operating expense, and increase municipal income.
The City-Wide Storm Water Management Plan will provide the City of Coppell with the necessary tools
for orderly flood plain development and identify plans for mitigating flood damages.
B. Scope of thc Study
This study encompasses the flood plains of Grapevine Creek, Cottonwood Branch, Denton Creek, the
Elm Fork of the Trinity River and nine selected tributaries of these streams, as shown on Figure l-l. Flood
plain information is compiled utilizing existing hydrologic and hydraulic models for the major creeks and the
tributaries identified as Stream G1 and Stream G6. New hydrologic and hydraulic computer models are
developed for the remaining seven tributaries. All hydrologic and hydraulic models are based on fully
developed land use in thc watersheds and updated to reflect existing channel, bridge, and flex)d plain
conditions. Approved flood plain reclamation projects have also been incorporated into the hydraulic models.
Flooding and erosion sites along these streams are inventoried and allernative solutions are proposed.
Local drainage analyses of specific problem areas are also included in the scope of this City-Wale
Storm Water Management Study. Specified sites, as previously identified by the citizens and staff of Coppell
are listed in Table 1-2 and also shown on Figure I-1. In addition to these sites, other problem areas are
identified through staff and citizen input. A compilation of these drainage complaints is included in Appendix
C of this report. All complaints are investigated, solutions proposed and a recommended alternative with
associated cost estimates is formulated.
The final storm water management plan for the City of Coppell will include recommended solutions
to all of the known flooding problem areas, as well aa city-wide recommendations to reduce damages from
future flooding. Existing drainage and flood plain design criteria will be reviewed and a coordinated master
plan proposed. A glossary of the technical terms used in this report can be found in Chapter IX.
I~2
9. Erosion and Deposition
a) Watershed Erosion
Thc hydraulic transport of soil is common It) all stream.s, but thc amount of soil often
depends upon mans' activities. This transport of soil can cause three types of damage: 1) erosion at the site
from which Ihe soil originales; 2) pollulion of the waler which transports the soil; and 3) damage to the site
where the soil is deposited. Most of the soil carried in a watercourse originates from the watershed rather
than from the channel. The impact of rainfall dislodges soil particles, allowing them to be carried away by the
runofL Loose bare soil is most vulnerable. Grass cover reduces erosion by dissipating the energy of the
rainfall and by reducing the velocity of flowing water. Trees and shrubs intercept the rainfall and further
dissipate its energy. Such vegetation usually prevents unacceptable rates of erosion.
Numerous human activities affect the ertxlibility of soils. Developed areas usually
have a low erosive potential. The erosion protection provided by grassed areas is equal to or better than the
nalural vegetation. Houses, buildings, streets, parking lots, and olher impervious areas virtually eliminale
watershed erosion. However, developing areas usually have a high erosion polenlial. Erosion from
construction sites is oflen the greatest source of sediment in urbanizing watersheds. Contractors who are
unchecked by regulations often clear a sile of ground cover, preparatory to construction, with lillle regard for
the erosive consequences. The'bare soil is easily dislo~lged and carried by the runoff to storm sewer systems
and streams. The developer perceives little immediate damage to his land as a result of erosion, therefore,
he is generally unwilling to invest time and money in erosion control. The soil is also loosened and denuded
by certain types of cultivation, making it highly susceptible to erosion. This erosion of topsoil is economically
ruinous to the farmer. Unlike Ihe developer, it is in the farmer's best interest to practice proper conservation
techniques, such as contour plowing and maintenance of vegetative cover.
Watershed erosion causes water pollution when the sediment becomes suspended.
The polluted water flows downhill to the slreams and rivers, contaminating their waters. The effects of the
sediment loading are numerous and varied. Certain fish suffocate because they are unable to respirate the
silted water. Diminished light penetration reduces photosynthesis, thus interfering with the normal aqualic
biological processes. Sedimenl also transports other pollutants such as applied maintenance chemicals
(fertilizers and insecticides) and serves as a medium for transporting various hydrocarbons and mineral
pollutants.
Damage is also caused by the deposition of the sediment. Sediment loads remain
suspended in the water only as long as velocities and turbulence are sufficiently high. The heavier particles
settle out first as the water slows and becomes more tranquil. Lighter particles are deposited next. Eventually
all suspended particles fall to the bottom. This may result in silt-filled lakes, clogged storm drains, and choked
channels. Rescrx'oir storage can lac reduced and shipping channels in coastal cities may have to be dredged
due to the deposition of silt.
b. Channel Erosion
Natural channels arc formed by thc concentration of storm water runoff. The fiowing
water has thc energy to scour thc earth, which continues throughout thc life of the stream. Sediment is
deposited in thc channel bottom at thc same time that thc channel is eroding. Thc channel bottoms and banks
will gradually erode, naturally forming a larger channel. Initially thc volume of erosion from a particular reach
will bc far greater than thc volume of deposition. Aa the stream matures, the rate of deposition approaches
the rate of erosion. When thc stream becomes stable, thc rate of disposition equals thc rate of erosion. This
stable condition cominues as long as there is not an alteration of thc flow pattern. If thc activities of man
or nature alter the watershed or channel, thc balance is broken and a period of restabilization follows.
Urbanization of a watershed is a common activity which disturbs this balafi'~. Developing watersheds wHh
III-25
expanding impervious areas, reduced infiltration rates, increased runoff, increased flood peaks and increased
flood frequencies oflen suffer severe erosion problems. The higher discharges and velocities increase channel
erosion, thus creating a larger channel. Structures near the channel are often imperiled and, in some cases,
damaged by the eroding banks. This process is shown graphically in Figure 111-3.
c. Erosion and Deposition in the City of Cx)ppell
All of tile above factors are active in Ihe erosive rorccs prevalent in the Cily of
Coppcll. Deep, swift moving channels have been crc?_t.ed.by..de?a.des__o!'_n.al.u, ral_~gWs' !h_ro?gh _¥2!ls._o_f_v._a.r¥in, g
resis!a~.n, ce.~_ C(!n_.tinued urbanizatio_~n i .nc_r_casc_s._t.h_e._m__agn_it_u(!e_and fr_equency of erosive flooding. Thc boundary
shear forces exerted by the water on the soil are being m(xlificd by recent flood plain fill cases and storm water
diversions as urbanization of the adjacent areas expands toward the flood plains.
Erosion sites were identified during the walking inventories of the streams in Coppell,
as well as, from the log of drainage complaints. These sites are listed in Table 111-10 and also included on
Figure 111-4. Tile sties listed under Stream Silos are discussed in Chaplet VI. Those listed under tx)cai Sites
arc discussed in Chapter VII. In general, thc most severe erosion sties are along Grapevine Creek and its
tributaries, which is als() the most heavily developed area. Urbanivation and flood plain encroachment has
increased flows and velocities thr.o_u~h these areas causing the loss of trees, fences and storage buildings. So
far, no permanent residential structures arc-threatened, q'he~w lOCal eroston stt~s inventoried are on man-
made channels or ditches.
Ail of these erosion sites are the results of human a_cti._.vit~ies__..whi___ch hav?altered_the~~
channel, flood plain and watershed. The re-grading and re-direclion of channels along with increased
impe__rvjgu.~ areas~'.and und~.rg~'o.u..n_.d' s._to___r.m~..e?sr__s)?tcms t"h-rou~.'h~ui i'he cit](has a. ftere~l'llov~ [~at(erfi,?ci'eat~ng
unstable stream channel.s. In most cases, the erosion and any related deposition should be monitored and
corrected only as it threatens existing structures or causes increased flooding. The stream channels should be
allowed to stabilize naturally, if possible. Corrections for the specific severe erosion problems which may
eventually threaten structures are discussed in Chapter VI and VII. Effective erosion control measures for
construction sites should be strongly enforced.
TABLE 11140
EROSION SITES - COPPELL, TI'LXAS
Stream Lo~ation Deserlplion
Grapevine Creek Dowl~,lr~'dm of 1.14. 635 Severe channel crc~ion
Downstream of Demon Tap Rd. Severe bank erosion; failure of retaining walls
Unnamed Trib al Maywood Circle and Mcadowcreck Rd. Channel erosion; retaining wall failures
Stream G1 Parallel to I.och Lane Channel erosion
Stream G2 Parallel to Plantation Dr. Channel & bank erosion
SIrcam G5 Carter Dr. Erosion upstream through private properly
Christi La. Erosion downslream face of culvert
Stream G6 U.S. Bethel School Rd. Channel erosion upstream of culvert
D.S. Moore Rd. Channel & bank ereaion
Stream Cl State Rd. Erosion Upslream of culvert
Demon Creek .Andrew Brown Park Spillway Erosion al spillway
Parkwood Cl~anncl Downstream of Parkway Boulevard Channel erosion
Woodridgc Channel Llpalream of MacAflhur Boulevard Channel erosion; slope failure
III-26
CHANNEL EROSION CYCL1
aisting Channel/Overbank Configuration
. ....
I ~ .... - ' --~
The ~jcle begins with a bank-~ll discharge that sc
the sides of the channel, especially at meanders.
When the water subsides, lite steep saturated shit
slough into the channel.
Subsequent flows remove the sloughed materi
leaving an ugly, denuded channel.
FIGURE III
following a wet period, when the ground is already saturated. Saturated clay soils perform similar to an
impervious surface with practically 100 percent runoff.
Thc residents of Coppcll voluntarily use many of thes~.'watcrshed management methods which
help reduce peak flows of small floods. Thc mitigation of large floods through watershed management
requires more restrictive land usc policies or onsitc storm water detention. These techniques, their
effectiveness, and their costs are discnssed in detail in the Fivemile Creek Flood Plain Management Plan.°)
8. Debris Removal
The accumulation of trees, brush, and other debris at bridges and culverts can have dangerous
cnn.~..qucnces for strcam~ in Coppell. Thc obstruction of flow causc~ higher flood stages Upstream °fa bridge
which can overtop the bridge and even cause structural failure of thc bridge or road embankment. In Coppeli,
thc Public Works Department is responsible for creek debris removal. Thc policy relating to floodways and
drainagcway casements where no structural improvements have been installed is to monitor with budgeted
funds, thc area to insure compliance to thc high grass and weed regulations, address health issues and insure
that no vertical structures arc constructed which would impact or restrict positive drainage. The City docs not
take responsibility for debris removal on private property which includes many of the streams in Coppell.
The removal of debris that is deposited in a stream or its flood plain is an essential
component of any city's flood plain management program. In addition, greeks must be i~pected_peri .odjcailv
to remove dead trees, or trees whose root systems have bccn debilitated by erosion. An inspection program
of this type should be aimed at prevention rather than reaction. Erosion protection measures should be
instituted i_n areas where significant trees would be in danger of being uprooted by flood waters. Thc program
should also identify and corrcct areas where siltation could signifi~ntly decrease the flood ca _rDdng capacity
of thc stream channel and the bridge's waterway.
9. Inspection of Engineering Works
The periodic inspection of bridges, culverts, levees, and dams determines if the structures are
still functional, thus detecting a flaw in the structure before it fails. Inspections should especially be performed
in areas suspected of having potentially unstable soil?~ In addition to thc many bridges and culverts
throughout Coppcll, there arc dams of significant height on the Elm Fork and Stream G4. These dams should
be inspected annually.
E. Structural Damage Prevention Measures
Flood losses can be reduced by the construction of engineering works. Such structural measures
reduce flood stages or confine the storm water to a floodway or channel.
x
1. New Channel Construction or Old Channel Improvements
Channclization is a proc__~_s of excavating a watercourse by widening, deepening, or
straightening the stream. These alternatives may be used singularly or collectively to obtain an increase in
storm water conveyance. Channel side slopes may be grass lined when the slope is relatively fiat and velocities
arc low, or concrete lined when thc slopes arc steep or velocities are high. Typically, such alterations of
natural channels require significant maintenance. Deposits of sediment. ._may ! .ead...l.O.voRo~ti¥~ Rf~, wtti~
causes a reduction in flow if not periodically removed. Channclization ia unn~ry wherever an adequate
natural drainageway cannot be acquired for flood conveyance. Excavated channels are not uncommon in
IV-5
J. Erosion Control
Eroding creek banks that present an immediate danger to structures will be stabilized, wherever such
measures are economically justified. Slopes steeper Ihan 1.5-to-I will re ut~J.~.~_reinforced concrete retaining~_
walls or other_su!table stabiliTation. Less steep slopes may be secured with channel or bank armor such as
reinforced concrete slope protection. Bank erosion that doc~ not pose an immediate danger lo struclures may
be controlled by a small retaining wall or by low, dense-growing plants Ihat protect and retain the soil. The
~atural processes of erosion and deposition in the channel .sho. uld be allowed to con.tinue~i.n...r, each_~_whcre
there is no develop__m_e_.nt..near the creek_
K. Appearance
The City of Coppell, its tributaries, and their flood plains, should be aesthetically pleasing to residents
and visitors. These centrally located creek environments should be inviting and attractive. Their shapes,
proportions, water surfaces, and surroundings should be scenic and restful !o the eye. The walcr should
possess the magnetic quality of a gently, yet ever-changing feature of the landscape. The creeks should also
compliment and enhance their surroundings, including park areas, bridges, and adjacent houses and
businesses. Their flood plains should provide a pleasant setting for both active and passive recreation.
V-6
VI. .~I'RF..~ MANAGEMENT ALTERNATIVES AND RECOMMENDATIONS
A. Introduction
Generally speaking, stream corridor and flood plain management efforts in the City of Coppeli have
been successful in keeping houses out of the 100-year flood plain. This report shows only 15 occupied
residential structures inundated by thc 100-year fl~md along thc 25 miles of streams studied. All but five of
these residences are in older areas of town which may be expected to re-develop. Twenty-four streets on
clcvcn streams are aLso overtopped by floodwaters. A complete list of these stream flooding sites is found in
Chapter 11I, Table !,11-8. An inventory of all existing structures crossing the streams is contained in Appendix
D. Eleven erosion problem sites along streams in Coppell were also identified in Chapter 111, Table II1-10.
These sites are prevalent in the rapidly developing areas of the city. Alternatives such as bridge, culvert and
channel improvements are investigated to solve these stream flooding and erosion problems indicated on
Figure 1[[-4. Other local drainage problem sites, not directly related to a natural stream channel are discussed
in Chapter VII.
Currently, the majority of the flood plains in Coppell are restricted to private open space with the
largest single use being Riverchase Golf Course along the Elm Fork of the Trinity River. A limited number
of parks and athletic fields are found. However, a significant amount of the flood plain remains undeveloped.
The re. al challenge of this study is one of pre. serving and protecting these remaining undeveloped scenic and
environmentally significant reaches of the stream. The natural'channels and wooded open spaces can be
significant contributors to the quality of life in the neighborhoods that soon will develop in Coppell. To
accomplish this task, alternatives such as parkways, hike and bike trails, and open space preserves are
investigated. Criteria for the preservation of the natural valley storage within the stream system arc also
'presented, and ail key elements in preventing increases in downstream flooding due to future dc~,elopment.
Construction cost estimates for all alternatives are included. These estimates of probable construction
cost are based on April 1990 unit prices compiled by the City of Dallas Public Works Department, unless
otherwise noted. The total estimated costs include construction, engineering design, surveying, geotechnical
testing and easement documentation. Easement acquisition costs are not estimated. Evaluation of the
alternatives and final recommendations are included. Implementation of the re. commended City-14~ute Storm
Water Management Plan will be discus,seal in Chapter Vlll. Delineation of the 100-year flood plain for a fully
developed watershed is shown on the Plates in Appendix F.
B. SIM~:iflc Stream Fiooatn~. Sites
- 1. Grapevine Creek
Grapevine Creek is a tributary of the Elm Fork of the Trinity River. The creek enters the
City of Coppeil at the southeastern CoppeWIrving corporate boundary under IH-635 and flows in an easterly
direction for six miles along portions of the southern border of the city to its confluence with the Elm Fork.
Under existing channel conditions, the 100-year discharge (fully developed watershed) will flood three
residences in the vicinity of Bethel School Road and Hawk lane. In addition, Belt Line Road, the St. Louis
and Southwestern Railroad, the Bethel Road approach, and Bethel School Road are inundated by the 100-year
flood. Severe bank erosion is also occurring downstream of IH-635 and in the reach from Denton Tap Road
to Moore Road.
Grapevine Creek is the most developed of the three major streams which traverse the city.
Two major reclamation projects; the Irving Flood Control District Section 111, near the confluence with the
Elm Fork, and the channelization downstream of IH-635, have been completed in the last ten years.
VI-!
Numerous residential developments also exist in the reach from Belt Line Road to Denton Tap Road,
including several phases of tho Northlake Woodlands Additions and the recently constructed Creekview
Addition. Minor amounts of fill along the l]oodway fringe were constructed as a part of Ihese developments.
Bqtwcen Bolt Line Road and Moore Road, homes arc constructed immediately adjacent to thc channel bank
ana have le,~,; than ese foot of frccboo_rd_..b__clW~;~.th¢..fln3t floor and thc 100-year flood elevation (fuLly-
~Ie¥1:Io[}~ wat. grshed'}..These homes were built under previous City of Coppell criteria with minimum finished
floor elevations set based on the 1984 Flood Insurance Study (FIS). In this particular reach of Grapevine
Creek, this study's 100-year flo{×l elevalions (fully developed watershed) are almost 3.5 foot higher than the.
100-year flood elevations published in tho 1984 FIS. Furlher upstream between Moore Road and Denton Tap
Road, the homes also crowd ihe. creek but are well above the I00-year flood elevation. Erosion is prevalent
a!9..ng .t_he_m.e.ande.~ old.the _st.ream in this _r.each especially- i_n .!he vic!nity of Denton Tap Road. Alternatives
to alleviate the. flooding and erosion problems along Grapevine Creek are discussed in the following sections.
a. Flooding at Bethel School Road and Hawk Lane
Grapevine Creek runs parallel to Bethel School Road in this area and the 100-year
design fltx.M (fully developed land use) inundates throe residences in the vicinity of the intersection of Bethel
School Road and Hawk Lane. Some of these homes were not built to the minimum Iinished floor elevations
shown on the c{_~nstruction p!~ns..~,.w._.hi~le~.!h__e.r.L_w.~re constructed With minimum freeboard, not ~lccounting~,for
ingf~a~e,,~ in wal¢~' ,s.u_Lfac~e!?a_._ti~p_n_s_d_u.e ?_L.u_pstre. am .and downstream development. Depths of inundations
would be les~ Ihan one foot during occurrence of Ihe 100-year design flood. Two allernatives, bridge
improvements and channelization, were considered to alleviate this flooding.
i. Belt Line Road Improvements
This alternative involves constructing a new bridge at Belt Line Road over
Grapevine Creek plus channelization between Belt Line and the St. Louis and Southwestern Railroad and
upstream of the railroad for a distance of 70 feet. No channelizalion is included under the railroad bridge
itself. 'The proposed channel is earthen with a 60 foot bottom width and 3:1 side slopes and will cost an
estimated $15,000. The proposed Belt Line Road bridge opening has a 66 foot bottom width with 2:1 concrete
lined side slopes and will cost an estimated $545,000. The improvement of Belt Line Road is anticipated as
the existing improvements east of MacArthur Boulevard are extended to the west. This solution removes each
of the three inundated residences along Bethel School Road from Ihe 100-year flood plain and provides
approximately one foot of freeboard for the residences. Total cost of the project is estimated to be $560,000.
ii. Belt Line Road with Downstream Channelization
A second alternative was considered which provides for an additional 1 to
2 foot of freeboard for the homes along Bethel School Road..This involves, in addition to the new bridge,
the construction of an earthen channel for approximately 4000 feet downstream of Belt Line Road to connect
with the existing Irving Flood Control District Section III channel near MacArthur Boulevard. Improvements
are also made to the channel under the railroad bridge. This alternative allows for the reclamation of valuable
commercial real estate in the vicinity of Belt Line Road as well as alleviating the above mentioned flooding
problems. However, 130 acre-feet of additional storage ou~ide of tho proposed channel is required to meet
the criteria discussed in Section C.2. A drop structure may also b¢ required to control erosive velocities
upstream of Belt Line Road..This type of structure could also be used in the proposed channel to raise Ihe
waler surfac~ elevations providing addilional valley storage within lbo channel..The eslimated cost of these
improvements is $1,665,000, which could be borne by the developer of tho commercial silo. A bridge adequate
for future Belt Line Road is included in the hydraulic model but not in this cost estimate. If the Belt Line
Road bridge is included, the total cost for this alternative is estimated to be $2,210,000.
VI-2
A proposed realignment of Belt Line Road and Grapevine Creek dated July, 1988
was supplied by Ginn, Inc. This alignment was not utilized for the alternatives evaluated in this study due to
Ibc presence of 2 - 90 degree bends in the proposed Grapevine Creek chann¢lization. The proposed bridge
in the two alternatives above assumes that Belt Line Road will remain in its current location.
The Belt Line Road improvements (Alternative i.) are the recommended design
solution to remove the homes on Bethel School Road from the flood plain. The minor amount of upstream
channcliz~tion is required to control erosive velocities. These improvements are estimated to cost $560,000.
Development pressures in lhe commercially zonc~l area downstream of Belt Line Road may result in further
consideration of thc channclizalion alternative but it ia not included in thc flood plain management plan
shown on Plate 3-2. Any channclization proposed in the future should be required to compensate for valley
storage loss to ensure that thc existing Irving Flood Control District levees are not overtopped.
b. E, rosion Downstream of Denton Tap Road/Meadowcreek Road
~ Severe erosion has degraded the channel downstream of Denton Tap Road.
Numerous complaints have been received along tfii?s'6t~h' ~l'~'~f M~i~i0~;~i'~i~-R~d from prol~Yi3?o"~'~'~
with lots backing up to Grapevine ereek. In some areas existing retainin$?._afl_l_s_ have failed and portions of
fences and back yards have been lost. The creek meanders through this reach and narrows significantly at each
bend. Velocities for the 10(}-year flood are highly erosive ranging from 8_to 13..f_eet p~_r second. The channel
banks are l0 to _15 feet h!gh and_ !~_ea.r.ly v_cr_t.i.ca_l. In several areas along the south side of the creek new homes
have b_een constructed wit.h no set back_ from the top of bank. Gabions have been utilized with some success
in a few of the meanders, but_th~_r9_~ e.~vi_d~e.n..ce of u?.,~.dermi.n, in_g_beginning along, the downstream edges of
several of these structures.
In spite of thc construction along thc banks of thc channel, thc area remains very
scenic and environmentally significant. Blue gill, large mouth black bass and a variety of birds including red-
winged black birds, belted king fishers and blue jays were spotted during thc field reconnaissance of this reach
of Grapevine Creek. To aid in the preservation of this area, the reeommcnded design solution to the erosion
problems includes the identification of critical areas along thc bends of the creeks. Straighter reaches and
areas where erosion is not threatcning private property should be left natural. These critical areas are shown
on Figure VI-l. Structural stabilization is required along thc full length of these bends extending 100 feet
downstream, in areas such aa thc 100 block of Meadowcreek Ro_ad and under the east aerial sewer c_rossine.
the existing retaining walls arc failing. These should be torn down and replacexl extending thc full length of
thc bends. V/here gabion structures currently c_xist, the edges sho_u.!d be monitor.._ed for failures and repaired
or extended immedi~ tcly, if nex. essary.
,Due to the high velocities an.el st._.~.p..nec, a of the ex_~_' ting creek banks co_ ncrete _retainine
,,walls are recommended. These should be structural retaining walls with adequate foundations such as drilled
piers. Large rock ri ;} rap or gabions can be placed along the toe of the walls to control creek bed erosion.
Decorative facings cx~uld also be added to there: walls to enhance the beauty of the channel. Figure VI-2 show
scvcral conceptual t~'eatment plans for the crcekside embankments which could be incorporated into final
designs.
The estimated probable cost of these improvements, not including decorative facings,
is $600 per linear fooc This correlates to approximately $60,000 for an average size creek lot. ']j~e estimated
probable cost for the 0.roposed erosion protection in the critical areas shown on Figure VI-I is $1,350,000.
Final design of this ::rosion control should include detailed surveyed cross sections where severe erosion is
occurring since these areas may have altered significantly since the topography used in this study was prepared
in 1985.
VI-3
To aid in coordination and ensure that the methods utilized for erosion control reflect
sound engineering analyses, it is recommended that thc City of Coppcll prepare the preliminary engineering
design of these crosion ta}ntrol improvements. This would include dclailcd design surveys and recommended
or 'approved' types of erosion control for the critical area,c. Additional surveying in the areas of slope failures
and field ties to existing property lines would also be included. A map detailing the specific reaches of
Grapevine Creek requiring erosion control and preliminary consiruction plans would be developed. These
plans could be used b~..~.}.~...'ro 'rty ..... owners, builders or thc city to produce Iinal construction documents fi)r each
individual erosion site along the creek. They may al~) include widening the channel is some areas, thereby
reducing the length or height of the retaining wall required. In this way, the City of CA)ppell would have a
coordinated, city approved plan of erosion rcmediation which could be utilized by individual_, r~,~2ro erty owners,
as they seek to control erosion adjacent to their lots. The plans would include repair or replacement of the
existing retaining wall at the city owned aerial sewer crossing. Detailed specifications of approved erosion
control methods would be provided which could be used by city inspectors lo monitor important construction
details such as the installation of filter cloth, weep holes and toe walls of sufficient depth. The estimated cost
of this preliminary design effort is $45,000 includ_!ng..s.'~..rv.ey~in$,..~.e_o.!ec.'hnical studies and ,prelimina~_
conslruclion plans. Although the Ci.~t[~?..C}.~l}.|!~cil..d. 0.c.'s' n~.u~`u.a-l~.y.~.a~.s~u-.t`n-~.the~`r`~p-~-.n~ib`~i~!~:-y~.f~r'~m~?tena~ce
in a flo(~tw'_ay_.c'_a_s..e~me.~n.L.s,.u,.c.h_.as.t~his,.~it--~_r~!n.~fl~d that some t.,~e of city participamm be considered.
City participation along with the proposed design study would help to insure a coordinaled effort for erosion
control along the individual reaches of the stream.
It is als{) reta)mmended that Ihe city investigate the creation of some type of
maintenance entity such as a Homeowner's Association along this reach of Grapevine Creek. Most types of
erosion control require regular inspection and maintenance to ensure longevity. Edges and toe walls should
be inspected periodically for undermining and repaired immediately. Gabion structures should be inspe, cted
for ve$~!ati3)n, g. row_.t_h a..n.d?a .m_.a. ge_.to, th.e.w.i, re..l).askc!s which.could_cause_.a. It)ss of slr_uc.'tt~al inte~rit¥.~ia
Which could damae¢ structures define fl~ .~Od evggtts sho~$ld _be fg~t..}v_ed from the ch_a_n, nel immediately. Regular
maintenance such as this is vital to the success of any erosion control system.
City slaff has also indicaled that several building permit reqdesls for fences, pools,
lennis courts, etc. have been received in this reach of Grapevine Creek. There has already bean.some loss of
fences and portions of b_ac_lo2ards due to slope failures. Therefore, requirements are developed for permitting
improvements within or adjacent to the flood plain. The recommended req~uire_ments are:
· Show compliance with city flood plain management ordinance.
· No fill in the flood plain.
· Provide slope stability and foundation analysis by a qualified geolechnical
cnginccr if proposed construction is within 30 fcct of the creek bank.
Provide surveyed cross sections and/or prcconstruction surveys certified by
Registered Public Surveyor.
· Provide as-built surveys certified by Registered Public Surveyor.
· Provide grading and/or construction plans sealed by a registered professional
engineer.
· Show compliance with City-Wide Storm Water Management Plan including
details on proposed crosion control, if required.
· Show 2- and 100-year water surface elcvations and velocities for fully
developed land u.~ condition.~.
· Provide structural analysis and dclails for walls or piers in the. flood plain.
· Provide 'Hold Harmless" statements to thc City on construction plans.
VI-4
~~ ~ ' , .... . ~ ,. . ~..~ :~,. . .~..~ : -.
.? ~'.- ~ _ ~ ._.. - ~_.
.-~ . .. ~ · , ~ . -'-...~ ~. .. .
-. . -. ~ ~ ~ .' ~.. ~~ .
, _- .. .:-~ ~ ,' .. ..... ~ ~.~ · . . ..- .. ·
- -" .I ~ ~ ,/ ~ -~'~ ~ ~'~' ' ·
, . / .
- ~ ...... i' ?':1 * - , I ' GRAPEVINE CREEK EROSION
' - - ;'- ~" ~ ' CONTROL CRITICAL AREAS
FIGURE VI-2
GRAPEVINE CREEK
CHANNEL STABILIZATION ALTERNATIVES
® Storm Water Detention
· Erosion/Sedimentation Control
· Buffer Zones (Parallel Parkways)
· Open Space Preservation
All of the alternatives considered are coordinated with the City of Coppeil's Comprehensive Plan
published in February 1987.~s~
1. No Action
'['he first basin-wide management alternative considered is no action. A comprehensive
basin-wide management plan would not bc in~plcmcnted. Land<~wncrs who wish to reclaim llood plain land
will apply to the city for a fill permit tin an individual site-by-site basis. The flood plain would continue lo
be delined based on frilly developed land use discharges and reclamation projects would still have to meet all
City of Coppell and Federal Emergency Management Agency criteria. I-towever, downstream flooding could
be increased due to valley storage depletion caused by fill in the fl¢~d plain. Development would continue
on a piecemeal basis wilh no (x)nsistency or continuity. Public acce~ to th_e. streams would be limited or
virt.ually elitn!n'_at_e.d in some arc~. Environmentally sensitive reaches of manet streams could be lost I'~)rever.
Thc project_cos_'t of this alternative' is zero. T~c I.o.f.~g.ran~,e_c?st..i.s continued_and p_oss.i_b_l~ increasing flood
damages within thf_ c!t_.y.a_~.d, ih~.~_..l.~e.?t!a.l.a, ni .m..os!.t.y' .o.f._.c. it_i.z, en½_t_owa, rd '_their local government.
2. Valley Storage Preservation
As a part of the rccemly completed [Vldte Rock Creek Flood Plain Management Study, Ihe
effects of flood plain tilling on the valley storage characteristics of natural streams were examined. Flood plain
encroachment reduces the stream's natural ability [o store lion,water often causing increases in downstream
flooding. The main stem and its tributaries were tested for various levels of valley storage reduction. In
general, loss of valley storage on the main channel caused increased flooding downstream. The smaller
tributaries were less sensitive to valley storage reduction. The adverse effects of valley storage depletion have
also been recognized in other watersheds.
In 1985 the Corps of Engineers, sponsored by the North Central Texas Council of
Governments (NCTCOG), began preparation of a Regional Envir~)nmental Impact Study of the Trinity River
and its tributaries in the Dallas-Fort Worth, Texas area. The April, 1988 Record of Decision establishes a
zero percent reduction in valley storage capacity for the Elm Fork, West Fork and main channel of the Trinity
River. For minor tributaries with drainage areas less than 10 square miles, a maximum of 15 percent reduction
in storage will be allowed for the 10(Nye. ar flood. Furthermore, the Corps now reviews the cumulative impact,
upstream of, adjacent to, and downstream of reclamation projects,t~) Cumulative impacts are important
because done project ia permitted, other projects should be considered to have the same chance of being built.
Analysis of these results indicat~ that the effects of valley storage depletion are cumulative
and can be responsible for greater increases in downstream fltmding Ihan any other urbanization change. In
order to prevent increased downstream flooding, this parameter should be taken into consideration in the
evaluation of all reclamation and channelization projects. Cx)mplete details of this analysis as well as
descriptions of other relevant studies are found in the White Rock Creek Flood Plain Management Study.®
Additional information on valley storage can also be found in this report, Chapter II, Section B.2.b.
VI-31
As a result of these studies of valley storage sensitivity, the following criteria for valley storage
reduction is proposed as a part of the Coppell City-Wide Storm Water A4,~nagernent Plan:
Elm Fork, Denton Creek, No reduction in valley storage for the 100-year
Cottonwood Branch and flood (fully developed watershed)
Grapevine Creek
All Other Tributaries - 15 percent maximum reduction evaluated on a site-by-site
basis for the 100-year flood
Cottonwood Branch ha,: a total drainage area of less than 10 square miles however, duc to
the existing and potential flooding problems discussed in Section BAl., it is included in the zero reduction
category.
It is also recommended that flood plain encroachment be strongly discouraged since
encroachment increases downstream flooding and destroy~ a valuable natural resource. Existing cumulative
valley storage data for the streams in Coppell is included in Appendix E, Summary of Hydraulic Data.
3. Flood Plain Encroachment Limits
This alternative evaluates thc establishment of flood plain encroachment limits for
streams in CoppelL These limits would represent the maximum encroachment allowed for developers wishing
to reclaim flood plain acreage. Extensive flood plain reclamation has already taken place along the Elm Fork,
Gralaevine Creek, and Denton Creek. Review of the existing property ownership, as well as coordination with
the other flood plain management alternatives, indicates very limited opportunities for further encroachment.
Therefore, thi~ rer~ort recommen~ds_' n_o f.u.r3_h.e.r.e?c~ro.~c~h.m_ .e.n.t.i.n. to_ t..h.e._l.00, ye~. ~r.fl. _o~..d~.p].aj.n_{~lly developed
watershed~ for new residential developments.
However, development pressures may require consideration of some flood plain
reclamation in the light industrial and commercially zoned western areas of the city. This type of reclamation
could be allowed as long as the valley storage and 'no rise' criteria discussed previously is met for all projects.
These criteria are recommended to minimize increases in downstream flooding due to development. The
upstream reaches of Cottonwood Branch, west of proposed Freeport Parkway are all zoned light industrial.
Portions of the creek near Royal Lane have already been channelized and some additional reclamation may
be possible. The City of Coppell is already receiving complaints of high water from downstream homeowners
along this slream. Although the finished floors of Ihese homes are set approximately one foot above the
year flood elevation, the back-yards have only 0.20 feet or less 'of freeboard. Upstream encroachment without
compensating excavation could cause increases in flooding in this existing residential neighborhood in excess
of that shown in this report.
The same is true for SIreams CI, C2, and D1, tributaries of Cottonwood Branch and
Denton Creek, respectively. 'In general, no further flood plain encroachment is recommended, however
reclamation on these tributaries could be allowed aa long as the valley storage preservation criteria is met.
Typical methods of preserving valley storage with channelir-',tion schemes are: 1) large channel-~ with drop
structures to maintain the existing waler surface elevations, 2) swales paralleling the channel for storage
compensation, and 3) detention ponds. Reclamation plans for any of them areas should include detailed
hydrologic and hydraulic computations which clearly define the exisling characteristi~ of the channel and flood
plain and the prolx)sed conditions including valley storage mitigation. Swales or detention structures should
be placed in a drainage easement or right-of-way to ensure these areas remain dedicated to valley slorage
compensation.
VI-32
$. Erosion/Sedimentation Control
Thc purpose of the storm water management alternatives investigated in this study is to
mitigate the flooding of structures within thc tOO-year flood plain and to develop alternatives to prevent future
flooding problems while preserving the natural channel. The velocity of the water is held below erosive levels,
wherever channel modification is ne. ce.~ary. Flow velocities are, and remain, erosive in many areas of the
natural stream__s....The. _chann__el pOt. toms and banks will gradually erode, naturally forming a larger channel.
Channel modification to curb erosion in natural reaches would be expensive and disruptive.
Except for a few problem areas discuss-cd below, the natural erosi-ve p/'ocesses shoul~owed to ci~ntmue.
Thc stream will ultimately stabilize and rejuvenate the flora on and along its banks. Roads and structures
should be built a safe distance from the stream to accommodate the anticipated enlargement of the stream
channel due to erosion.
a. No Action
Erosion sites were identified in Chapter III. This alternative assumes that erosion
control and./or_ m. aintenanc, q.,.vil! b._c_l_m_.nd.l_ed by._t_l? pr. opcrty owner. Some of thc e.rosign, alonR the channels
is natural and should be ai_lo.we.d_.to cominue. Erosion and deposition sites should be monit_o__red and corrected
only as existing structures are threatened or increased flooding is caused.
b. Grapevine Creek Downstream of Denton Tap Road/Meadowcreek Road
Stabilization in the critical areas along this reach of Grapevine Creek is discussed in
Section B.l.b in this chapter. Additional recommendations for streams in Coppcll typified by meandering,
narrow channels with steep banks are thc establishment of a no flood plain fill or encroachment criteria and
a mi.,._n_imum build, lng set-back from the top of bank This would prevent new construction along existing
problem areas. These recommendations are also discussed in other sections of this chapter.
c. Grapevine Creek Between Freeport Parkway and LBJ Freeway (See Chapter V1.B.1.)
d. Stream G6 (See Chapter VI.B.7.)
e. Denton Cre~k (Se,~ Chapter VI.B.9.)
f. Parkwood Channel (sec Chapter VII.L,)
g. Woodridge Channel (See Chapter VII.O.)
6. Buffer Zones
a. Parallel Parkways
This alternative proposes a system of roadways parallel/ng the flood plains in Coppell.
The.se parkways would provide access to the flood plain as well as create a buffer zone which clearly transitions
between natural areas, subject to flooding and areas of other land uses. In this manner, the parkway prevents
future encroachment into thc flood plain. The flood plain within the buffer zone would either bc placed in
an easement or dedicated to the city.
Figure ¥I-9, thc Composite Open Space Plan, show~ the proposed parkway system
in relation to existing streets and the City of CoppeH comprehensive thoroughfare plan. These parkways arc
designed as local or collector streets providing scenic routes as a part of the transportation network. In
lhen transferred into usable Slate Plane Coordinales. Vertical data was also established using N.G.S. conlrol.
Differential leveis were run between each station using invar rods and an automatic level with a parallel plat
micrometer. This network of 71 monuments is being used as horizontal and vertical control for all future
development in the City of Piano.
A similar monumentation system is recommended for Coppell. A Syslem of 20 monuments
could provide effective horizontal and vertical control for all of the city. The estimated cost of such a system
is $25,000 to $3(),11(X) depending on the t)ptions chosen by the city. For example, this cost could be reduced
if city forces are used to install the monuments. Additional monumentation system details have been provided
to city staff separately.
3. Construction Site Erosion Control
Construction site erosion control regulations should be formally adopted and enforced by the
City of Coppell. To minimize sediment loading and siltation in the streams, the City should consider
requiring large construction projects to be phased to limit the land area that is bare at any one time, and
vegetation should be left undisturbed wherever possible. Graded areas should be replanted as soon as possible,
and mulches should be used during perioda that are not suitable for planting.
4. Construction Plan Review
One of the problems that hindered the analysis of local drainage problems was the lack of
drainage design information on existing drainage plans. Drainage plans submitted for approval to the city
should contain at a minimum the following:
· Drainage area map showing all subareas confirmed by field reconnaissance and
surveys, if necessary.
· All hydrologic computations.
· Hydraulic grade line computation for proposed and affected existing drainage
systems.
· Direction of flow arrows. '-
· lO0-year flood plain area.
· Existing and proposed contours on at least a 2 foot interval.
Detailed drainage criteria and check lists can be found in the City of Dallas' Drainage Design
Manual.
5. Creek Inspection
Creeks should be inspected periodically to find and remove fallen trees, or trees whose root
systems have been weakened by erosion. An inspection program of this type should be aimed at the prevention
of stream obstructions before they occur. Periodic inspections should identify City controlled floodway areas
in which siltation has decreased the. flood-c.9, rrying cap.a..c!ty_of, the stream channel. _A regular inspection
Program would ensure that prob_l.e_m_s._s_u.c_h_ ~. t~he siltat_i_on on Grapevine Creek downstream of Denton Tap
Road would be minimized.
6. Creek Vegetation Preservation
Natural vegetation should be preserved as a buffer zone in the channel and 20 feet beyond
the top of the banks within the flood plain, at a minimum.
V1-43
QUESTIONS AND ANSWERS TO CITIZENS CONCERNED WITH THE PROJECT:
Q. WHAT ABOUT ENVIRONMENTAL IMPACT ON ENVIRONMENT?
A. The creek will be impacted, somewhat, during construction in
the creek bottom, but should be returned to conditions that
existed prior to the construction, as much as possible. The
Corps of Engineers were contacted in September, 1991,
requesting a "jurisdictional determination" to see if a
permit were needed. As of this point in time, we have heard
nothing in the negative of the proposed creek alignment.
It is our opinion that a 404 permit (concerning
wetlands/mitigations) is not required. We checked with a
number of resources and determined that an EIS
(environmental impact statement) would not be required,
since we were not "filling" in the creek bottom.
Additionally, EPA (Environmental Protection Agency) is
usually concerned with wastewater discharges into the waters
of the U.S. or the water and wastewater treatment plants.
Q. WHAT ABOUT EROSION OF CREEK BOTTOM AND CREEK BANKS?
A. The creek bottom and creek banks will erode, even without
the construction of the sewer line. Halff's study has
indicated this several times. The ~ong term recommendations
in the study will alleviate some of the erosion problems.
The City is currently working on a draina~g~e district to
address these problems. Surrounding metroplex cities have
traditionally placed sewer lines in the creek bottoms for
a number of years.
We are awaiting our final soils analysis and recommendations
from our soils labs to try to come up with a solution to the
trench in the creek bottom "problem". We will provide the
best solution that we can to alleviate any future problems
with erosion, regarding the trench. It is our understanding
that when the "shale" remains open to the air, for a long
period of time, it begins to disintegrate. In our
specifications, the contractor is allowed to excavate only
as much trench, in a day, that he can install the sewer
line, concrete encasement and backfill in that same day.
We feel that this will not allow the shale to disintegrate,
and the concrete encasement will strengthen the surrounding
area of the trench. The top 6"-12" of the trench may have
to be cement stabilized or some other recommended solution
by the lab.
Q. WHAT ABOUT ASSURANCE THAT MY RETAINING WALL WILL NOT FALL
DOWN DUE TO THE INSTALLATION OF THE SEWER LINE?
A. We cannot assure that the retaining wall would not fall
down, even if the sewer line were not constructed. Halff's
study indicates that some erosion is occurring in some of
the gabion walls constructed already. If the walls fail, due
to the construction of the sewer line, then the City would
GRAPEVINE CREEK SANITARY SEWER MAIN PAGE 16
be obligated to have it corrected. The contractor will make
every effort to not damage the walls with his equipment or
operations. If he does damage the wall, he is responsible
for returning it to it's condition prior to the beginning of
construction. If, in later years, the wall fails, and it is
found to be caused directly by the sewer line construction,
then the city has an obligation to remedy the situation.
Q. WHAT ABOUT DAMAGES TO TREES?
A. The trees in the creek bottom will have to be removed if
they are an obstruction to installation of the sewer line.
The trees on the banks should not be destroyed, since the
contractor will be limited to the creek bottom for his
construction. Natural erosion will continue, after the
sewer line is constructed, and some trees may be lost at
that time. The Halff study indicates this happening as a
result of the natural channel erosion cycle.
Q. WHAT ABOUT THE ENVIRONMENTAL IMPACT OF THE SEWER LINE
LEAKING INTO THE CREEK?
A. With the type of pipe material we have specified and the
joints to be used, along with the concrete encasement, we do
not anticipate any potential problems with leaks. The
manholes will be constructed of poured-in-place concrete,
with sealed lids. Infiltration/exfiltration will be non-
existent.
Q. WHAT ABOUT MEANS AND METHODS OF CONSTRUCTION IN CREEK
BOTTOM?
A. We cannot say for sure what type equipment the successful
contractor would use in the creek bottom construction, but
the plans and specs will limit his area for construction,
therefore we feel that the least amount of equipment and
the ones that does the least damages would be utilized.
GRAPEVINE CREEK SANTTARY SE~R N~TN PAGE :1.7