St Andrews Est-CS040407T H E · C I T Y · O F
COFFELL
April 7, 2004
Pete Hcnncssey, P.E.
Hermcsscy Engineering, Inc.
1417 W Main St, Suite 100
Carrollton, TX 75006
RE: St Andrews Estates
Construction Plan Review Comments
Dear Mr. Hennessey:
The City of Coppell has reviewed the referenced plans and has the following comments to offer:
General Layout -
1. There are three plan & profile sheets that can be consolidated into two plan sheets of the
same type - Paving Plan & Profile and Storm Sewer Plan & Profile. If additional sheets are
needed, they should be for storm sewer profiles only.
Plat -
1. You show an 8' drainage and wall maintenance easement on the SW comer of the
development. This should be a privately maintained HOA easement.
2. The 100-year floodplain designation should be from the August 2001 map, not the July 1997
map.
3. Under Note I add the phrase, "and all HOA easements" as shown.
4. The existing 20' drainage and utility easement needs to be expanded to provide at least 10'
from the centerline of the new pipe to the edge of the easement.
Paving Plan & Profile -
1. Provide a 25' minimum radius on the curb return at the intersection of Deforest Road.
The
same radius is required for the intersection of St. Andrews and Stonewick Lane.
2. You show driveways on some lots, and not others. Provide an explanation of why you have
done so. In addition, the curb return of driveways shall not cross the property line.
3. Show the stationing of the Stonewick Lane construction on the plan sheet. If construction
will stop at the western property line, please indicate so on the plans.
4. Provide station and elevation information for all the curb inlets shown to be constructed on
this sheet.
5. Indicate high and low points in the plan view with drainage arrows indicating direction of
flow.
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6. This sheet indicates a 4' sidewalk, which will be required, however there is some question as
to whether it will be built with the street, or when the homes are built.
7. The typical pavement section calls out 3000 psi concrete, whereas your general notes call out
4000 psi concrete. Resolve the discrepancy and ensure that the contractor uses the City of
Coppell standard details for that construction.
8. Move the low point along the cul-de-sac to the property line to allow for proper driveway
access to all lots.
Water & Sanitary Sewer Plan -
1. Details are needed on the proposed connections and the crossing of Deforest Road. There are
significant grade differences there as well as a masonry wall, so more detail is needed.
2. Show the existing 6" waterline that feeds the existing fire hydrant. Show this to be removed
and plugged at the main.
3. There are some existing water meters shown that need to be removed and plugged at the
main.
4. Add the additional fire hydrants and relocate the proposed fire hydrants to meet spacing
requirements. The existing fire hydrant is to be removed and delivered to the City of Coppell
Service Center.
5. Water services should be to the center of the lot.
6. Ensure a minimum 10' separation between the water and sewer services to each lot.
7. Add a valve on the proposed 8" waterline in Stonewick Lane as indicated in the mark-ups.
8. Install a 2" blowoff at the end of the waterline in the Stonewick Lane right-of-way.
9. Sewer line "A" should end in a manhole.
10. The manhole for sewer line "B" should be in the street.
i 1. Can this line be tied into the 6" line installed with the St. Andrews Manor addition?
Storm Sewer Plan & Profile -
1. Put all storm sewer plan information on one plan sheet rather than two.
2.
3.
If you need
additional sheets for profiling, use profile only sheets.
What is being done to convey the Deforest Road drainage across St. Andrews Lane at that
intersection? Is it being picked up in your system?
Again, the 8' drainage and wall maintenance easement is inadequate for public infrastructure.
The best solution would be to make that line behind Lots 21 & 22 a privately owned &
maintained line.
4. Easements will need to be obtained where you show to stub drains on the adjacent private
property. Those can be private easements dedicated to the HOA for maintenance of those
stub-outs. Provide a copy of those documents to the City for our files.
5. Show all line sizes and necessary information such as stationing, elevations, etc. for the
construction of all the storm sewer facilities for this site.
6. There should a junction box rather than a wye connection where the 30" line in Stonewick
Lane connects to the 36" line in St. Andrews Lane.
7. Show on the drainage plan the proposed limits of the easement to serve Line A.
8. At station 7+00 the lateral for the east side of the street should tie into the inlet on the west
side of the street so you have only one connection to the main line.
9. Extend the headwall structure at station 1+98 outward beyond the proposed structures on
Lots 16 & 17, or provide sufficient reason, with exhibits, for not extending it. Provide
erosion protection for Lots 16 & 17.
10. Ensure that enough stabilization is in place on the 30" outfall to the creek to keep the bank
from eroding.
11. The detail for the inlet on this property and the inlet on the adjacent property is unacceptable
for publicly owned and maintained infrastructure. Make this a private system
12. At station 7+70 where the 36" RCP ends, construct a junction box or grate inlet that the pipes
for the private system can connect into.
13. On Profile lB it appears that you are proposing to fill some area of the floodplain. If so, that
proposal will need to be evaluated with your LOMR.
14. Clarify your capacity calculations and what causes the change in capacity from one segment
to the other. It seems there would be a change in the Q, but I see no indication there would
be a change in the capacity of the pipe.
15. Install a concrete cradle for the crossing of the proposed sanitary sewer with the storm sewer
line.
16. The concrete collar detail does not appear to match the connection in the profile for different
size pipes.
17. Show how drainage will be handled across the typical retaining wall section.
18. Remove the wye connection at station 2+05.40 in the profile in accordance with the previous
comment.
19. The 48" RCP may need to be bell & spigot pipe with a rubber gasket for watertight
connections.
20. Add a bank / trench seal at outfalls.
21. The hydraulic grade line indicates that the water will back up onto the adjacent property. This
is not acceptable.
Grading Plan -
1. Again, extend the proposed headwall structure on the storm drain past the proposed buildings
shown on Lots 16 & 17.
2. Remove all the miscellaneous text on this sheet for legibility.
3. I have some concern on the private drainage system where low points are being constructed
with a small inlet adjacent to the homes. My concern is standing water adjacent to the
foundations that could cause issues in the future if those lines were to become clogged.
4. I have questions on the FFE of the garage being 4' lower than the FFE of the house on the
properties adjacent to Deforest Road. This should be evaluated further.
5. The parkway adjacent to the cul-de-sac between Lots 14 & 15 should have a 2% slope in the
parkway through the sidewalk, and a 3:1 slope to the property line. It appears there is a steep
grade adjacent to the cul-de-sac that could be a concem.
6. Who will construct the sidewalk through the cul-de-sac? Is it part of Lot 15 & Lot 14, or is it
a separate lot? If it is a separate lot, the construction of that sidewalk should be done with the
street construction.
Paving & Storm Sewer Plan -
1. All this plan information should be on one sheet, with profile information on additional
sheets as necessary.
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2. Again, Line D should be a privately owned and maintained line.
3. Construct a junction box or grate inlet at station 7+70 on Line D.
4. Provide a dimension between the limit of the existing 20' easement line, the center of the 36"
pipe, the center of the existing 10" sanitary sewer and the opposite easement line. We need
additional easement to provide for future maintenance. There should be 10' from the center
of the pipe to the easement line.
5. Construct a junction box and manhole at the intersection of Line A with Line C.
6. Is the section of Stonewick Lane shown on the adjacent private property to be constructed
with this development? If so, Line C should be extended and drainage will need to be
evaluated there.
7. Provide a concrete cradle at the crossing of the sanitary sewer line with Line H.
Erosion Control Plan -
1. The drainage area map & calculations shown on this sheet should be on a separate sheet. The
scale of the map should be increased.
2. Add a column to this hydraulic calculation showing the discharge point of the drainage area.
3. Include inlet and storm sewer calculations.
The City of Coppell will continue to work through the review process with you, however, no
permit will be issued for the construction of this infrastructure until the floodplain/floodway
issues have been resolved.
Please make the necessary changes and submit these marked-up plans and two sets of revised
plans to the City for review. If you have any questions, please contact this office at your
convenience.
Sincerely,
Keith R. Marvin, P.E.
Civil Engineer
Office Phone: (972) 304-7044
Fax: (972) 304-3570
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4. Provide a dimension between the limit of the existing 20' easement line, the center of the 36"
pipe, the center of the existing 10" sanitary sewer and the opposite easement line. We need
additional easement to provide for future maintenance. There should be 10' from the center
of the pipe to the easement line.
5. Construct a junction box and manhole at the intersection of Line A with Line C.
6. Is the section of Stonewick Lane shown on the adjacent private property to be constructed
with this development? If so, Line C should be extended and drainage will need to be
evaluated there.
7. Provide a concrete cradle at the crossing of the sanitary sewer line with Line H.
Erosion Control Plan -
1. The drainage area map & calculations shown on this sheet should be on a separate sheet. The
scale of the map should be increased.
2. Add a column to this hydraulic calculation showing the discharge point of the drainage area.
3. Include inlet and storm sewer calculations.
The City of Coppell will continue to work through the review process with you, however, no
permit will be issued for the construction of this infrastructure until the floodplain/floodway
issues have been resolved.
Please make the necessary changes and submit these marked-up plans and two sets of revised
plans to the City for review. If you have any questions, please contact this office at your
convenience.
Sincerely,
Keith R. Marvin, P.E.
Civil Engineer
Office Phone: (972) 304-7044
Fax: (972) 304-3570