HomeMy WebLinkAboutResponse to staff commentsAlan Gibbs, PE
City Engineer
City of College Station
P.O. Box 9960
College Station, Texas 77842
MITCHELL
MORGAN
Attn: Erika Bridges
RE: NO ADVERSE IMPACT STUDY for Entergy Site Development
Dear Erika,
Thank you for your review of the modeling.
511 UNIVERSITY DRIVE EAST, SUITE 204 • COLLEGE STATION, TX 77840 • T 979.260.6963 • F 979.260.3564
CIVIL ENGINEERING HYDRAULICS • HYDROLOGY • UTILITIES • STREETS • SITE PLANS SUBDIVISIONS
info @mitchellandmorgan.com • www.mitchellandmorgan.com
19ApI2010
Because of the comment #24, we have generated additional cut in the floodplain which further
improves the hydraulic efficiency and storage of the stream section. I have added the new
cut areas to the cross sections of the model and re- created Exhibit A, B, C, & D. Note that
this comment ripples though the computations. This requirement increases conveyance
which nominally increases flows which nominally increase the water surface at some of the
sections.
22. Please clarify why the post development Q is decreasing. The post development
Q is decreasing because of storage without conveyance within the model. Note that
comment 24 affects this result.
23. Please show us your assumptions of defining where the conveyance /storage
areas are located in accordance with Chapter 13 requirements. The
assumptions and approximations in the cross - sections should be shown in an
. average cross - section that extrapolated to the plan view of the site. The are no
assumptions here. The model does not utilize a storage area, only storage within the
cross sections.
24. The grading plan has been modified to accommodate this requirement. Please
see the grading plan for this information.
25. Why is the post - development conveyance capacity reduced at some points
upstream and downstream of the site.(ie at Sta 25- 45.035.) The calculations are
very sensitive to the water surface elevation: a small change (< 0.01) in the water
surface applied at a width of roughly 2000 feet computes to show a difference in
several of the computed variables.
26. Why is the post - development storage volume reduced at some points upstream
and downstream of the site? (ie at Sta 25- 45.035.) The calculations are very
sensitive to the water surface elevation: a small change (< 0.01) in the water surface
applied at a width of roughly 2000 feet computes to show a difference in several of the
computed variables.
The models and drawings are included on the CD provided with this letter. Please do not
hesitate to contact me to further discuss this analysis.
Sincerely,
Joe itchell, P.E.
P ner
*: .• •.* •
:
JOEL J. MITCHELL
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Attachments: Exhibit A: Entergy Floodplain Impact Study
Exhibit B: Adverse Impact Table
Exhibit C: Standard HEC -RAS Table 1
Exhibit D: CD with Model
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April 19, 2010
Matt Robinson, Staff Planner
Development Engineering
City of College Station
P 0 Box 9960
College Station, Texas 77842
RE: Entergy Switch Station Site Plan
Bleyl & Associates
Project Engineering & Management
Below is a listing of the comments received May 3, 2010 regarding the Site Plan for the referenced
project. These comments, along with our comments in italics, are below.
PLANNING
1. Remove previous boundary lines between the two properties. This will be one lot once
the plat is approved. These lines have been removed.
2. Remove owner and acreage information on the site drawing. This information should be
reflected in the title block. This is considered one 16.615 acre lot now. Noted and
corrected.
3. The title block should give the name of the project and then the legal description, which
should be Entergy Switch Station, Lot 1, Block 1, 16.615 acres. This has been
corrected.
4. Include the requested electrical easement /transformer location on the drawing. This is
now shown.
5. Remove the "to be dedicated to City of College Station" on the two easements shown on
the drawing. This are being dedicated via the plat, as such provide the name of the
easement and blanks for the volume and page number which can be filled in after the
plat is approved and filed. This change has been made.
6. Remove note #9. This note has been removed.
7. Provide a detail regarding the proposed lighting on site. This has been forwarded to you
under a separate cover on May 10th. Entergy will be required to meet the City's lighting
ordinance to obtain their certificate of occupancy.
8. An electrical transformer is proposed to be located on the northern side of the site at the
edge of the landscaping buffer. Plantings may need to be relocated /adjusted on site.
Bob Ruth has adjusted his plantings near the transformer. Please see revised
Landscaping Plan.
9. Please note that any changes made to the plans, that have not been requested by the
City of College Station, must be explained in your next transmittal letter and "bubbled" on
your plans. Any additional changes on these plans that the City has not been made
aware of will constitute a completely new review. Saul Nuccitelli, formerly of PBS &J has
1722 Broadmoor
Suite 210
Bryan, TX 77802
Bryan Austin Conroe
(979)- 268 -1125 (512)- 328 -7878 (936)- 441 -7833
(979)- 260 -3849 (512)- 328 -7884 Fax (936)- 760 -3833 Fax
left their firm. Jeffrey Kessel, P.E. and Duke Altman, P.E. have reviewed and sealed
these engineering documents. As part of their review, they asked that specific language
be added in places to distinguish which firm provided what information. Specific notes
have been bubbled where this language has changed. The entire General Notes section
on the site plan has been bubbled as well. Following is a list of these notations that
have been altered:
Changes to the GENERAL NOTES.
i. Note 1— UTILITIES WERE.... OBSERVATION BY FITTZ & SHIPMAN
ii. Note 2 — The following sentence was added. CONSTRUCTION
CONTRACTOR IS RESPONSIBLE FOR LOCATING AND AVOIDING
ALL UTILITIES.
Note 3 — The Last sentence was changed to read: "FITTZ & SHIPMAN,
INC. AND PBS &J DO NOT WARRANT NOR . "
iv. Note 4 — A second and third sentences added to read: "VERTICAL
DATUM IS BASE ON_(FILL IN DATUM SYSTEM USED)_. BENCH
MARKS ARE DESCRIBED HEREON. TOPOGRAPHIC CONTOURS
ARE PROVIDED BY FITTZ & SHIPMAN WHO ARE RESPONSIBLE FOR
THEIR MAPPED ACCURACY"
v. Note 5— Sentence changed to read: "THIS PROPERTY IS ZONED "A -O"
AS ESTABLISHED BY THE CITY OF COLLEGE STATION'S GIS
MAPPING SYSTEM.
vi. Note 6 — Sentence added at the end reading: "ACCESS ROAD DESIGN
DETAIL PROVIDED BY ENTERGY. GRADING AND DRAINAGE
CALCULATIONS AND DRAWINGS PROVIDED BY BLEYL &
ASSOCIATES.
vii. Note 7 — Added the following at the end of the sentence following.... TO
THIS PROPERTY "AS PART OF THIS SITE DEVELOPMENT."
viii. Note 8 — Add a sentence following the first one reading: "ALL DESIGN
AND ENGINEERING PROVIDED BY MODULAR CONNECTIONS."
ix. Added another note stating: "SCHEDULE B PROVIDED BY FITTZ &
SHIPMAN.
x. Added another note stating: "WATER AND SANITARY SEWER
INFORMATION PROVIDED BY ENTERGY.
There are other incidental items like the removal of a barbwire fence that is now shown
and bubbled.
ENGINEERING COMMENTS NO. 2
1. Please provide additional details for the removal and replacement of the water tank
including type of fill to be utilized and required compaction._ Note 9 now describes the fill
material, and how it shall be placed.
2. Would the activities on this site fall under Army Corps NWP 12? Yes the project falls under
NWP12.
3. The proposed drainage swales need to be in private drainage easements which may be
recorded by separate instrument. Please show and label the easements with recordation
information. These have been added.
4. Rip -rap or some other energy dissipation measure should be added at the ends of the
swales. This has been added.
5. Based on the survey data, it does not look like the floodplain is shown in the correct location.
Please revise. This has been revised.
6. Please add a note to the plans stating that stockpiles are temporary and will have all
necessary erosion control in the interim. A note has been added.
7. Please add a note stating that mitigation areas will need to be maintained by the owner to
ensure they continue to function properly. This note has been added as General Note #15.
No Adverse Impacts
8. I have reviewed the recently submitted flood study with Alan Gibbs and Carol Cotter, and we
feel that it is not demonstrating several points of the ordinance. Please contact us to
schedule a meeting at your convenience. This meeting was held on May 14 th . Mitchell &
Morgan will be submitting their revised report and a brief summary of findings under a
separate cover.
ELECTRICAL COMMENTS NO. 2 REQUIRING IMMEDIATE ATTENTION
1. Developer provides descriptive easements for electric infrastructure as designed by CSU for
electric lines. Noted.
2. Developer may be responsible for locating easements on site to insure that electrical
infrastructure is installed within easement boundaries. Noted.
3. If applicable, the following easements will be required:
CSU will require a 15' P.U.E. for the entire route of the single -phase conduit, including
and encompassing the transformer pad location. Noted.
GENERAL ELECTRICAL COMMENTS NO. 2
1. Conduit from existing CSU pole to proposed single -phase transformer location for
Station House will be installed by Developer or their contractor. Noted.
2. CSU will require 2 -2" pvc conduits at no less than a 4' depth installed according to CSU
design and specs. CSU will provide design drawings as project develops. Noted.
3. Developer will intercept existing conduit at designated transformers or other existing
devices and extend as required. Noted.
4. If conduit does not exist at designated transformer or other existing devices, developer
will furnish and install conduit as shown on CSU electrical layout. Noted.
5. Developer /Contractor will provide 30' of rigid or IMC conduit for each riser. Riser
installed by CSU. Noted.
6. Transformer pad will be provided by CSU and installed byDeveloper /Contractor.. Noted..
7. Meter to be mounted on meter pedestal at proposed transformer location. Meter
pedestal to be provided and installed by Developer /Contractor. Noted.
8. Primary Conductor from existing CSU pole to proposed transformer will be provided and
installed by CSU. Noted.
9. Service Conductor from transformer to meter will be provided and installed by CSU.
10. Conduit and Conductor from meter location into service location (Station House) to be
sized, provided, and installed by Developer /Contractor. Noted.
11. Developer provides digital AutoCAD 2000 or later version of site plan, SP1 February
2010 or latest version showing location of Station House. Send to gmartinez(a cstx.gov.
This has been sent.
12. Developer will provide CSU with the load requirements for the Station House as soon as
it becomes available so that a transformer can be sized appropriately and allocated to
this project. Lead time to order transformers not currently in CSU stock can be up to 40
weeks. Send to gmartinez(a�cstx.gov. This has been sent.
13. Final site plan must show all proposed electrical facilities necessary to provide electrical
service, i.e. transformer(s), pull box(es), switchgear(s), meter location and conduit
routing as designed by CSU. Noted.
14. To discuss any of the above electrical comments please contact Gilbert Martinez at
979.764.6255. Noted.
Please do not hesitate to call if you have any questions about this submittal.
Sincere , Litvti\.7,...,,
am ernon, P.E.
Bleyl & Associates
June 16, 2010
Erika Bridges, EIT
Graduate Civil Engineer
Department of Public Works
1101 Texas Ave.
College Station, TX 77842
RE: Entergy Switch Station Site
Bleyl & Associates
Project Engineering & Management
Below is a listing of the comments received June 4, 2010 regarding the Site Plan for the
referenced project. These comments, along with our comments in italics, are below.
1. Please remove the private drainage easement from the site plan. Removed the private
drainage easement from the site plan.
2. Please make sure that the legend and hatched /shaded areas are legible. The
lineweights have been adjusted and the hatched /shaded areas are now legible.
3. Please add FEMA note to site plan. No action on this item per your email on June 10,
2010.
4. We have met with Joel and asked him to revise his report to better meet all the NAI
criteria. No action taken on this item. This has been approved by email from Alan on
June 9, 2010.
5. For the cut/fill calculations, please verify that the volume reflects only the areas on your
site outside the conveyance area (i.e. floodway + 100 -ft or 18" depth). No action taken
on this item. This has been approved by email from Alan on June 9, 2010.
Please do not hesitate to call if you have any questions about this submittal.
cerely,
Sam J \1-rnon P.E.
Bleyl & Associates
ID 40
tip • ID
Pvc
1722 Broadmoor
Suite 210
Bryan, TX 77802
Bryan Austin Conroe
(979)- 268 -1125 (512)- 328 -7878 (936)- 441 -7833
(979)- 260 -3849 (512)- 328 -7884 Fax (936)- 760 -3833 Fax
April 19, 2010
Erika Bridges, EIT
Development Engineering
City of College Station
P 0 Box 9960
College Station, Texas 77842
RE: Entergy Switch Station Site
Bleyl & Associates
Project Engineering & Management
lo. �I
ID
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Below is a listing of the comments received April 8, 2010 regarding the Site Plan for the referenced
project. These comments, along with our comments in italics, are below.
1. Please verify that removal of the water tank area does not require a Corps Permit.
Pond 1 is a stock tank constructed on a hillside within upland vegetation communities.
Because the pond is not associated with a tributary stream channel, and is not located
immediately adjacent to a relatively permanent waterway, there is no significant nexus
to jurisdictional waters of the U.S. (USACE, 2007) As such, Pond 1 would not be
regulated under Section 404 of the CWA or Section 10 of the Rivers and Harbors Act.
ref - U.S. Army Corps of Engineers (USACE). 2007. U.S. Army Corps of Engineers
Jurisdictional Determination Form Instructional Guidebook.
2. Please provide details for the removal and replacement of the water tank. The contours
have been revised and note #10 has been added on SP1 sheet.
3. Please include finished floor elevations for the control house and electrical
infrastructure. These have been added to sheet GD1.
4. Please provide a detail for the access road. The access road needs to meet our
minimum standards: 1.5" asphalt pavement on top of a 6 -inch limestone base or 5 -inch
concrete reinforced with #4s at 18 -inch on center. An access road section detail has
been added to SP1, but it is shown as compacted crushed stone as previously accepted
by CoCS Fire.
5. Is there a sheet "GD2" as referenced on the GD1 sheet? If so, we did not receive it.
GD2 is part of the set (and last set as well) and has been included again in this
submittal. Please contact Sam Vernon @ 268 -1125 if it is not received as part of this
packet.
6. Please provide additional grading information for the remainder of the property which will
be regraded (including the mitigation area and the access road). Grading is shown
across the whole property including the access road and mitigation area.
7. Please provide a detail for the proposed swales along the top of the pad including its
longitudinal slope. This is now shown on sheet GP1.
8. How will the swales transition back to proposed grade? For example, on the western side
of the pad the invert elevation of 249.95 seems to be tying into the 253 contour. Please
clarify. This has been revised and clarified.
9. What is the purpose of the 18" CMP? The 18" CMP is a driveway culvert for the access
road.
1722 Broadmoor
Suite 210
Bryan, TX 77802
Bryan Austin Conroe
(979)- 268 -1125 (512)- 328 -7878 (936)- 441 -7833
(979)- 260 -3849 (512)- 328 -7884 Fax (936)- 760 -3833 Fax
10. Please show the floodplain and floodway on the drainage plan. These are both shown
and re- labeled on GDI.
11. Please add a note indicating where you derived the location of floodplain /floodway.
Please sheet SPI, note #3.
12. Additional silt fencing should be added downstream of the mitigation area. This has been
added to the Erosion Control Sheet.
13. Please provide applicable City Standard Details. These have been added to the Erosion
Control Sheet.
14. Please provide a Letter of Acknowledgment. This is included with our submittal package.
15. Please show the referenced stockpile location and indicate what erosion control
measures will be provided. This has been revised.
16. Please indicate how offsite drainage (which currently drains through the area which will
be filled for the pad) will be rerouted. The proposed swale shown on the last submittal
will reroute this drainage. A detail and drainage calculations have been added to this
submittal.
17. Please verify that the runoff coefficients utilized are consistent with Appendix C, Table C-
3 of the Stormwater Design Guidelines. As per the conversation with Mark Savarino
from Bleyl & Associates, the runoff coefficients utilized within the drainage
calculations are based on Appendix C, Table C -3 for all surface conditions other
than for the proposed surface of the Entergy switch station. Because this surface is
made of 1"-2" rock with little to no fines, no runoff coefficients with Table C -3
represented this surface appropriately. Because of this, a different runoff coefficient
was chosen due to the similarities between the switch station surface and a railroad
yard (railroad yard ballasts are made of 1"-2" rock). The runoff coefficient of 0.4
established by the USGS for a railroad yard was used. This USGS table was
reprinted within the design manual "Stormwater Collection Systems Design
Handbook" written by Larry W. Mays, PhD, PE, PH.
18. Please provide tables showing how the given pre - development and post - development
flows were obtained. The pre - developed and post- developed flow calculations are
attached.
19. Please provide a Drainage Certification letter in accordance with Section II.C.3.b. of the
Stormwater Design Guidelines. A letter providing the drainage certification is
attached.
20. Please provide all required drainage information in accordance with Section 111.0.3 of
the Stormwater Design Guidelines. To Mr. Savarino's knowledge, all additional
information needed has been provided. This includes the addition of the current
FEMA floodplain map, a preliminary FEMA floodplain map based on the B /CS
FEMA digital file, a general location map, drainage area maps, and flow and
infrastructure drainage calculations. The report is provided through the use of the
Technical Design Summary — Appendix D and is supplemented by the use of the
executive summary.
21. It appears that you are encroaching the floodway with the mitigation area. Encroachments
in the floodway are not permitted. Work within the floodway is confined to creating a
narrow channel to tie in the compensatory storage area into the standing water pond.
There is no fill or structures planned that would obstruct the floodway. The floodway as
defined by the ordinance is the area that must be reserved to ensure the discharge of the
base flood without increasing the water surface elevation. A No Adverse Impact Study
has been performed which shows that the water surface will not be increased further
illustrating this work is not an encroachment.
No Adverse Impacts
22. Please clarify why the post - development Q is decreasing. Mitchell & Morgan will be
providing separate responses for these items.
23. Please show us your assumptions of defining where the conveyance /storage areas are
located in accordance with Chapter 13 requirements. The assumptions and
approximations in the cross - sections should be shown in an average cross - section and
extrapolated to the plan view of the site. Mitchell & Morgan will be providing separate
responses for these items.
24. For the storage area, please demonstrate that storage volumes are not changing by
providing cut/fill quantities. A spreadsheet showing these quantities is included in this
submittal.
25. Why is the post - development conveyance capacity reduced at some points upstream and
downstream of the site (i.e. at Sta.25 +45.035)? Mitchell & Morgan will be providing
separate responses for these items.
26. Why is the post - development storage volume reduced at some points upstream and
downstream of the site (i.e. at Sta.25 +45.035)? Mitchell & Morgan will be providing
separate responses for these items.
Please do not hesitate to call if you have any questions about this submittal.
incerely,
Sam J. Vernon, P.E.
Bleyl & Associates
An employee -owned company
April 19, 2010
Ms. Erika Bridges
City of College Station
1101 Texas Avenue
College Station, TX 77842
Re: Letter Acknowledging City Standards for Proposed Entergy Switchyard, College Station, TX
Dear Ms. Bridges:
The purpose of this letter is to acknowledge that the construction plans for the water, sanitary sewer, streets
and drainage for the above referenced project, to the best of my knowledge, do not deviate from the B /CS
Design Guideline Manual. Any alternate design or construction methodology that was used is listed
below:
1) Compacted crushed stone instead of asphalt for the access road leading to the Entergy switch
station as discussed and agreed upon with the City of College Station Fire Department.
I also acknowledge, to the best of my knowledge, that the details provided in the construction plans are in
accordance with the Bryan /College Station Standard Details.
Sincerely,
Saul A. Nuccitelli II, PE, CFM
Water Resources Program Manager
PBS &J Job. No. 100001539
6504 Bridge Point Parkway, Suite 200 • Austin, Texas 78730 • Telephone: 512.327.6840 • Fax: 512.327.2453 • www.pbsj.com