HomeMy WebLinkAboutResponse to staff comments�_„ Kimley -Horn
and Associates, Inc.
Memorandum
To:
From:
Michael Moore, P.E.
Subject: CSISD Greens Prairie Elementary (SP) — Site Plan
# 10- 00500065
Response to City Comments
Date: June 14, 2010
This memorandum is to address the City of College Station staffs comments on the above mentioned project as
received by Kimley -Horn and Associates, Inc. in the memo dated May 27, 2010 and received by KHA June 2,
2010. The following information has been included in this submittal for your review.
• Two sets of revised Civil Plans
• Four copies of revised Site Plan (Folded)
• One copy of Landscape Plans (Folded)
• Revised Fire Flow Report
• Revised Drainage Report
• PUE Dedication Application
• Grease Interceptor Work Sheet
• Engineer's Opinion of Probable Construction Cost
Please find the written responses to staffs comments on the following pages. The numbered responses in each
section correspond to the numbered comments in the staff comment memo received by Kimley -Horn and
Associates, Inc. in the memo dated May 27, 2010.
to•14;Ib
KHA Job No. 66077400
K: \CST Civil \66077400 -CSISD \Dots
Matt Robinson — Staff Planner
City of College Station
Page 1 of 6
CSISD Greens Prairie Elementary School
MMCNAEL J. AAOORE
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❑�ri Kimley -Horn
and Associates, Inc.
KHA Job No. 66077400
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CSISD Greens Prairie Elementary School
PLANNING
1. Please list the site area for Phase 1 and Phase 1A on the site plan.
The site area was previously shown on sheet C -02.0 "Overall Site Plan ". It has been added to
Sheets C -02.1 and C -02.2.
2. Include the note on the site plan regarding landscaping for Phase 1A being installed with Phase 2
construction.
This note has been added to C - 02.1 as Note #21.
3. See Transportation's comments regarding throat length. These do not appear to be correct.
The throat lengths have been revised per Transportation's comments.
4. Note #18, correct wording to say "curbs"
Corrected
5. Hackberry trees are not on the approved planting list and as such the one proposed to be barricaded
will not count towards meeting the landscaping point requirement.
Corrected — The tree has been removed from the table and the calculation updated.
6. FYI, it appears that the frontage along a right -of -way has increased from the previous submittal. As a
reminder, driveway openings can be removed from the total frontage calculation.
Noted
7. Landscape Requirement Box — Please fix the Landscape Points title for Phase 1A. It is currently shown
as Phase 1.
Corrected
8. A meeting has been setup for June 14th at 11am at City Hall to discuss site plan issues as well as
transportation related items.
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.
TRANSPORTATION
1. 300' minimum driveway spacing must met based on a minor arterial classification or variance must
be requested based on hardship or constraints such as topography or environmental issues.
The driveways along Royder Road have been updated to meet the minimum driveway spacing
for minor arterial classification.
2. Please check throat length it appears it is not being measured from future 4 lane minor arterial edge
of pavement.
The throat lengths on Royder Road were measured from the future minor arterial edge of
pavement. We have adjusted the measurement of the throat lengths on Greens Prairie Trail to
also be measured from the future edge of pavement.
3. All other transportation questions or comments will be discussed at the June 14th transportation
infrastructure needs meeting between the City and CSISD.
❑ �„ Kimley -Horn
and Associates, Inc.
CSISD Greens Prairie Elementary School
ENGINEERING COMMENTS NO. 1
1. Sh.2.1 — Please label the isolation valve and add the isolation valve note.
Per your previous comments, this was labeled on sheet C -09.1.
The isolation valve has been labeled and the note added as note #23 to C -2.1.
2. Sh.2.1 - Please add a note indicating the required materials for the water and sanitary sewer lines.
This is labeled on sheet C -09.1 " Utility Plan"
An additional note has been added to C -02.1 as Note #22
3. Sh.2.1 - Note the required fire flow per fire hydrant.
This was previously provided on Sheet C -09.1
The note has been added to C -02.1
4. Sh.4.1/4.2 - Please identify the limits of disturbance.
The limits of disturbance were previously provided on sheet C -10.1 / C -10.2
The limits have been added to sheet C -04.1 / C -04.2
5. Sh.7.0 - Label the large drainage area south and east of the proposed building.
As indicated on the plan, this sheet is intended to provide rational method drainage
calculations for the on -site storm sewer system. This area is not captured by the on -site
system and as such is included on the overall drainage area map Sheet C -06.0. However, per
your request, we have added this area to the on -site storm sewer system drainage area map.
6. Sh.8.1 — FYI...We recommend a 0.1 -ft drop be provided across manhole inverts, matching soffits of
the storm pipes, and using RCP instead of HDPE in areas subject to vehicular loadings.
Noted. RCP is provided in public right - of - ways.
7. Please include City Standard Details in plans.
We have included a full set of the City's details in the plans for your review.
City Standard Details were previously included in the plans by reference. See General note #1
on C -01.0 which states, "All construction to be in accordance with these plans and the City of
College Station department of public works "Standard specifications and construction
details ", latest edition"
FYI...I noticed that TxDOT standard details were provided in the plans, but City details should be
utilized instead, if possible, since the property is being annexed.
TxDOT details are provided for storm sewer items which the City does not have details for.
These items are Box culvert construction, Box culvert wing walls, and safety end treatments
for sloped headwalls.
8. Sh.9.1 — Tapping sleeves and valves may only be used on a 12" main if the tap diameter is less than
or equal to half the main line diameter. Please specify tees and cut -in valves instead.
Wellborn Water Supply has specifically requested that we do not cut in tees for each
connection. Their direction has been to cut in one tee and add two gate valves at that tee to
their 12 inch line. The other connections are to be tapping sleeves.
9. Sh.9.1 - Please provide 2 gate valves at each tee.
2 gate valves are provided at each tee.
10. Sh.9.2 - Please provide a minimum 4 - ft cover.
Comment Addressed.
11. Sh.9.2 — Please label the vertical bend at Sta.2 +00 of Waterline "C."
Comment Addressed.
12. Sh.9.2 — It appears that Waterline "C" is being reduced at Sta.0 +05 and Sta.6 +30.
Line C is an 8" line from its connection to the fire hydrant. A separate call has been added for
the 8 "x6" reducer at the hydrant.
KHA Job No. 66077400
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Kimley -Horn
❑ 1M,1 and Associates, Inc.
13. Sh.9.2 — Please add note regarding TCEQ requirements for water /sanitary sewer crossings and
verify that those requirements are being met.
This note was previously provided on Sheet C -01.0.
Per your request, it has been added to sheets C -09.2 and C -09.3
14. Sh.9.3 — All manholes should be precast rather than constructed on -site as the plans suggest.
The plans do not specify cast -in -place manholes and all construction is to be per BCS
standard details. An additional note has been added to C -09.2 General Note #9 stating that all
manholes shall be precast.
15. Sh.9.3 — The drop manhole should include an inside drop.
The drop manhole has been eliminated.
16. Sh.9.3 — Please match soffits at Sta.0 +00 and 4 +97.76.
Comment addressed
17. Sh.9.2/9.3 — Please label the drawing scale.
Scale is labeled in the title block
18. Please submit the PUE dedication application.
The dedication application is included.
19. Please revise the Engineer's Cost Estimate to include only the sanitary sewer which will be
maintained by the City.
The water line items have been removed from the cost estimate.
20. Water Report — It appears that the initial pressure assumptions were based on a fire flow requirement
of 2500 gpm rather than 3125 gpm. Please revise if necessary.
An updated water report is included with this submittal.
21. Water Report — The report needs to state the required fire flow and minimum number of fire hydrants
based on the International Fire Code.
An updated water report is included with this submittal.
22. Drainage Report — It appears that the flow to the adjacent property to the south is being reduced.
Since this property owner depends on the offsite drainage to maintain his pond, it seems that
proposed drainage should be amended to closely match existing conditions.
The drainage shown is in accordance with our discussions during our meeting on March 23
with Allan Gibbs and yourself. In design of the storm system, we have matched the flow rate
of the lower events as closely as possible to ensure the downstream owner is not negatively
impacted and flows from "every day" events are maintained. The flow rate of the higher
events has been slightly reduced. Adjustment of the system to more closely match the higher
events will result in significant increases in the more common lower year events which we
believe will negatively impact this owner.
East Side Pre and Post Development Discharge Comparison
23. Drainage Report — On the "Drainage Area Maps," what is the difference between "Max. Proposed
Release Rate to West Creek" and the "Max. Proposed Pond Release Rate ?"
There is a portion of the site located between the pond and the creek that drains directly into
the creek (See DA — 5 on Sheet C- 06.0). Due to the fact that the runoff from this area does not
KHA Job No. 66077400
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CSISD Greens Prairie Elementary School
Existing Flow Rate
Proposed Flow Rate
Change in Rate
2 -year
42.3 cfs
41.6 cfs
-0.7 cfs
10 -year
84.8 cfs
72.7 cfs
-12.1 cfs
25 -year
101.3 cfs
84.9 cfs
-16.4 cfs
50 -year
116.1 cfs
95.6 cfs
-20.5 cfs
100 -year
130.0 cfs
105.7 cfs
-24.3 cfs
Kimley -Horn
❑ 1M,1 and Associates, Inc.
13. Sh.9.2 — Please add note regarding TCEQ requirements for water /sanitary sewer crossings and
verify that those requirements are being met.
This note was previously provided on Sheet C -01.0.
Per your request, it has been added to sheets C -09.2 and C -09.3
14. Sh.9.3 — All manholes should be precast rather than constructed on -site as the plans suggest.
The plans do not specify cast -in -place manholes and all construction is to be per BCS
standard details. An additional note has been added to C -09.2 General Note #9 stating that all
manholes shall be precast.
15. Sh.9.3 — The drop manhole should include an inside drop.
The drop manhole has been eliminated.
16. Sh.9.3 — Please match soffits at Sta.0 +00 and 4 +97.76.
Comment addressed
17. Sh.9.2/9.3 — Please label the drawing scale.
Scale is labeled in the title block
18. Please submit the PUE dedication application.
The dedication application is included.
19. Please revise the Engineer's Cost Estimate to include only the sanitary sewer which will be
maintained by the City.
The water line items have been removed from the cost estimate.
20. Water Report — It appears that the initial pressure assumptions were based on a fire flow requirement
of 2500 gpm rather than 3125 gpm. Please revise if necessary.
An updated water report is included with this submittal.
21. Water Report — The report needs to state the required fire flow and minimum number of fire hydrants
based on the International Fire Code.
An updated water report is included with this submittal.
22. Drainage Report — It appears that the flow to the adjacent property to the south is being reduced.
Since this property owner depends on the offsite drainage to maintain his pond, it seems that
proposed drainage should be amended to closely match existing conditions.
The drainage shown is in accordance with our discussions during our meeting on March 23
with Allan Gibbs and yourself. In design of the storm system, we have matched the flow rate
of the lower events as closely as possible to ensure the downstream owner is not negatively
impacted and flows from "every day" events are maintained. The flow rate of the higher
events has been slightly reduced. Adjustment of the system to more closely match the higher
events will result in significant increases in the more common lower year events which we
believe will negatively impact this owner.
East Side Pre and Post Development Discharge Comparison
23. Drainage Report — On the "Drainage Area Maps," what is the difference between "Max. Proposed
Release Rate to West Creek" and the "Max. Proposed Pond Release Rate ?"
There is a portion of the site located between the pond and the creek that drains directly into
the creek (See DA — 5 on Sheet C- 06.0). Due to the fact that the runoff from this area does not
KHA Job No. 66077400
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CSISD Greens Prairie Elementary School
In let ID
Inlet Size
Q100Yr
Depth
17 +37.61 Line B
15'
15.42 cfs
5.88 in
17 +06.77 Line B
15'
15.42 cfs
5.88 in
1 +85.80 LAT A2
15'
11.88 cfs
4.94 in
5+17.05 Line A
10'
8.04 cfs
4.99 in
2 +29.93 LAT B1
5'
2.54 cfs
4.58 in
❑� Kimley -Horn
and Associates, Inc.
KHA Job No. 66077400
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Detention Pond Outfall Velocities
'x3' Concrete Box Outfall Velocities (East Side
Page 5 of 6
CSISD Greens Prairie Elementary School
route through the detention pond, the peak release allowed from the pond ( "Max. Proposed
Pond Release Rate ") must be reduced to account for this bypass. The "Max. Proposed
Release Rate to West Creek," includes both flows from DA -5 and the detention pond, and was
designed to be less than the predevelopment runoff values to Peach Creek. The comparison
point for detention is the Peach Creek Outfall point, which is noted on both the existing and
proposed drainage area maps.
24. Drainage Report - Please verify that the max. ponding within the parking lot will not exceed 6 inches.
The inlets on Line B have been increased to ensure that ponding will not exceed 6 inches in
the parking area. Depth of ponding was computed assuming weir flow with a discharge
coefficient of 3.0 (See table below).
Inlet Pondin i Depths
25. Drainage Report - Please provide a table with the outfall velocities verifying that the energy
dissipation measures are adequate.
The outflow velocity for the 100 year event are included in the Drainage Report as required.
That information is supplemented here with the outflow velocities for the 2, 10, 25, and 50 year
events for your review in the table below. All evaluated storm events' discharge velocities are
less than the 10 ft/s maximum design velocity allowed by BCS Unified Stormwater Design
Guidelines Table C - 11. As noted in the plans and drainage report, 12" to 18" diameter rock rip
rap underlain with filter fabric will be used to dissipate energy from detention pond
discharges and 6" to 10" diameter rock rip rap will be used at the 3'x3' box outfall.
Additionally, both outfalls have been designed back from the property line to allow time for
the dissipation of the energy before the flow leaves the property.
Discharge Rate
Velocity
2 -year
8.3 cfs
3.87 ft/s
10 -year
15.7 cfs
4.67 ft/s
25 -year
18.5 cfs
4.89 ft/s
50 -year
21.0 cfs
5.05 ft/s
100 -year
23.4 cfs
5.20 ft/s
❑� Kimley -Horn
and Associates, Inc.
KHA Job No. 66077400
K:\CST_Civil\66077400-CSISD\Docs
Detention Pond Outfall Velocities
'x3' Concrete Box Outfall Velocities (East Side
Page 5 of 6
CSISD Greens Prairie Elementary School
route through the detention pond, the peak release allowed from the pond ( "Max. Proposed
Pond Release Rate ") must be reduced to account for this bypass. The "Max. Proposed
Release Rate to West Creek," includes both flows from DA -5 and the detention pond, and was
designed to be less than the predevelopment runoff values to Peach Creek. The comparison
point for detention is the Peach Creek Outfall point, which is noted on both the existing and
proposed drainage area maps.
24. Drainage Report - Please verify that the max. ponding within the parking lot will not exceed 6 inches.
The inlets on Line B have been increased to ensure that ponding will not exceed 6 inches in
the parking area. Depth of ponding was computed assuming weir flow with a discharge
coefficient of 3.0 (See table below).
Inlet Pondin i Depths
25. Drainage Report - Please provide a table with the outfall velocities verifying that the energy
dissipation measures are adequate.
The outflow velocity for the 100 year event are included in the Drainage Report as required.
That information is supplemented here with the outflow velocities for the 2, 10, 25, and 50 year
events for your review in the table below. All evaluated storm events' discharge velocities are
less than the 10 ft/s maximum design velocity allowed by BCS Unified Stormwater Design
Guidelines Table C - 11. As noted in the plans and drainage report, 12" to 18" diameter rock rip
rap underlain with filter fabric will be used to dissipate energy from detention pond
discharges and 6" to 10" diameter rock rip rap will be used at the 3'x3' box outfall.
Additionally, both outfalls have been designed back from the property line to allow time for
the dissipation of the energy before the flow leaves the property.
Discharge Rate
Velocity
2 -year
31.3 cfs
5.18 ft/s
10 -year
57.9 cfs
5.07 ft/s
25 -year
71.5 cfs
5.26 ft/s
50 -year
83.0 cfs
5.43 ft/s
100 -year
94.4 cfs
5.61 ft/s
❑� Kimley -Horn
and Associates, Inc.
KHA Job No. 66077400
K:\CST_Civil\66077400-CSISD\Docs
Detention Pond Outfall Velocities
'x3' Concrete Box Outfall Velocities (East Side
Page 5 of 6
CSISD Greens Prairie Elementary School
route through the detention pond, the peak release allowed from the pond ( "Max. Proposed
Pond Release Rate ") must be reduced to account for this bypass. The "Max. Proposed
Release Rate to West Creek," includes both flows from DA -5 and the detention pond, and was
designed to be less than the predevelopment runoff values to Peach Creek. The comparison
point for detention is the Peach Creek Outfall point, which is noted on both the existing and
proposed drainage area maps.
24. Drainage Report - Please verify that the max. ponding within the parking lot will not exceed 6 inches.
The inlets on Line B have been increased to ensure that ponding will not exceed 6 inches in
the parking area. Depth of ponding was computed assuming weir flow with a discharge
coefficient of 3.0 (See table below).
Inlet Pondin i Depths
25. Drainage Report - Please provide a table with the outfall velocities verifying that the energy
dissipation measures are adequate.
The outflow velocity for the 100 year event are included in the Drainage Report as required.
That information is supplemented here with the outflow velocities for the 2, 10, 25, and 50 year
events for your review in the table below. All evaluated storm events' discharge velocities are
less than the 10 ft/s maximum design velocity allowed by BCS Unified Stormwater Design
Guidelines Table C - 11. As noted in the plans and drainage report, 12" to 18" diameter rock rip
rap underlain with filter fabric will be used to dissipate energy from detention pond
discharges and 6" to 10" diameter rock rip rap will be used at the 3'x3' box outfall.
Additionally, both outfalls have been designed back from the property line to allow time for
the dissipation of the energy before the flow leaves the property.
•
r7_� Kimley -Horn
and Associates, Inc.
CSISD Greens Prairie Elementary School
WATER/WASTEWATER COMMENTS
1. Please include COOS standard water /sewer details within the plan set.
City details have been added to the set.
2. Please depict the direction of sanitary sewer flow within the plan view of all plan and profile sheets.
Flow arrows have been added to the plan and profiles.
3. Please depict station labeling along the horizontal alignment of the proposed sanitary sewer line.
Stationing has been added to the sanitary line.
4. Sheet C -09.1: Please add a note within the plan set that describes how 24 -hour access will have to
be maintained to the existing Creek Meadows Lift Station during the proposed sewer line connection
into the existing upstream manhole.
A note has been added requiring 24 hour access to the lift station. Ref Sanitary Sewer Note #2
on C -09.1
5. Sheet C -09.1: Please add a note to this sheet that directs the contractor to the standard manhole tie -
in detail S1 -03.
Ref. Sanitary Sewer Note #3 on C -09.1
6. Sheet C -09.1: Please label the size of the proposed grease and food interceptors. How were they
sized? Please indicate on plans or submit MEP report.
The grease and food interceptor was sized by the MEP. Please see the attached "Grease
Interceptor Sizing Worksheet" provided by the MEP. The size has been added to the inset on
sheet C -09.1.
7. Sheet C -10.2: Please label the proposed sanitary sewer pipe material as SDR -26 (ASTM D- 3034).
The ASTM D -3034 has been added to the pipe previously labeled as SDR -26
8. Sheet C -10.2: Please depict all water /sewer line crossings with separation distances called out
within the profile view.
Separation distances have been added.
9. Sheet C -10.2: Please depict all water /sewer line crossings with separation distances called out
within the profile view.
Separation distances have been added.
KHA Job No. 66077400
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