HomeMy WebLinkAboutGLENMOOR P.U.D, 2ND & 3RD FILING - PRELIMINARY / FINAL - 8-95C - CORRESPONDENCE - STAFF'S PROJECT COMMENTS (3)4 REVISION v� 866`O
y COMMENT SHEET
DATE: January 26, 1999 TO: Transportation Ping.
PROJECT: #8-95C Glemnoor P.U.D., 2n1 & 3rd Filing —
PDP/Final - Type 1 (LUC)
All comments must be received by Bob Blanchard no later than the staff
review meeting:
Wednesday, February 17, 1999
No Comment
b--- Problems or Concerns (see below or attached)
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Date: U /� Signature:
CI ECK HERE IF YOU TO RECEIVE COPIES OF REVISIONS
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11. Please verify the channel and overbank lengths of cross-section 1415, 1668, and 1709.
These lengths in the model do not appear to match the floodplain map.
RESPONSE:
12. Please provide a copy of all HEC-2 and SVRVM1 models on disk.
RESPONSE:
13. Please plot the proposed condition 100-year floodplain and show the 100-year water
surface elevations on sheet 8. The proposed condition floodplain should be shown to
tie-in with the upstream and downstream effective floodplain.
RESPONSE:
14. If the design of the Plum Street Channel will include cattails in the bottom (see
Drainage Comment #3), then the hydraulic analysis should account for a higher
roughness reflective of a cattail bottom.
RESPONSE:
15. Please provide actual cross -sections for each of the HEC-2 cross -sections used in the
analysis.
RESPONSE:
16. It was noted that the Plum Street Channel is designed to carry 133% of the `existing
condition' discharge. Please document that the channel can handled the `fully
developed condition' discharge as well. The City has this information available.
RESPONSE:
Please refer to the redline plans and report for additional review comments.
glenmoor2&3-2.doc
5. On the floodplain map, please begin and end each cross-section at the same location
as used in the model.
RESPONSE:
6. The model shows an elevation of 27' for station 221 of cross-section 1383. It appears
this elevation should be 57'. Please correct the model to match the proposed
topography.
RESPONSE:
7. The model shows an elevation of 28' for stations 222 and 229 of cross-section 1383.
It appears this elevation should be 58'. Please correct the model to match the
proposed topography.
RESPONSE:
8. The hydraulic analysis shows high velocities with supercritical flow likely for the
flow exiting the culverts of Taft Hill Road. High velocities are a concern because of
erosion of the channel and the high possibility of the flow not following the ninety -
degree bend of the channel. Please provide additional erosion protection and energy
dissipation downstream of Taft Hill to transition the flow back to a low velocity
subcritical regime.
RESPONSE:
9. A floodplain use permit was received with the submittal. However, a final version of
the floodplain use permit version, with all applicable signatures, will be needed when
the project is finalized. Also, the $300 floodplain use permit fee will be needed at
that time.
RESPONSE:
10. Please provide a summary table in the text of the report showing proposed and
existing cross -sections numbers, water surface elevations, discharges, and velocities
for the areas impacted by the proposed construction.
RESPONSE:
glemnoorM3-2.doc
Floodplain Administration Comments
1. More information is needed for the floodplain analysis such as: more discussion in the
text regarding the analysis, a duplicate effective model for the site and upstream of
Taft Hill, comparison of existing and proposed condition floodplains, etc. This
information is needed to fully document the site's impact on the floodplain. The City
can provide guidelines that will help in preparing a floodplain report. Please contact
the floodplain administrator (Marsha Hilmes at 224-6036) to set up a meeting to
discuss this project.
RESPONSE:
2. Please provide more information on the existing/effective condition floodplain
through the site and upstream of Taft Hill Road. This baseline condition is needed to
verify the project is not impacting off -site properties. The existing condition model
should be run with the updated flows from the Canal Importation Hydrology Update.
Please map this existing condition floodplain through the site and show cross -
sections.
RESPONSE:
3. There is a concern the modifications to the Plum Street Channel and the culverts
under Taft Hill Road may increase the water surface elevation upstream of Taft Hill
Road. Please provide more detail for the existing and proposed condition analysis of
the Taft Hill Road culverts. Please show the cross -sections and floodplain mapping
for no less than one cross-section upstream of Taft Hill as part of the floodplain
mapping for the entire site. Please add cross -sections at the upstream and .
downstream faces of the culverts and provide encroachments to reflect expansion and
contraction of flow through the culverts needed for SC analysis. The BT card for the
overflow of Taft Hill should also be verified with the actual conditions of Taft Hill.
RESPONSE:
4. The discharge downstream of Glenmoor PDP and the starting water surface elevation
were not changed in the HEC-2 analysis to reflect the updated hydrology of the basin.
This downstream hydrology may effect the backwater analysis through the site.
Please revise the existing and proposed condition models to reflect the updated
hydrology.
RESPONSE:
glenmoor2&3-2.doc
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10. Please include calculations in the report for all the swales denoted in the plans. The
swale cross -sections should include 100-year WSEL's and side slopes.
RESPONSE:
11. Please do not include the entire Plum Street Basin Master Drainage Plan report with
this report, but instead include only the portions relative to this site.
RESPONSE:
12. If any of the proposed retaining walls have a drop of greater than three feet than safety
railing will be required. Please consider this and use where necessary.
RESPONSE:
13. There appears to be some off -site drainage from the south. Please include the runoff
from this area in the hydrology calculations (it can be added to an existing basin).
RESPONSE:
14. Please provide an off -site construction easement for the south retaining wall.
RESPONSE:
15. The pan that flows off of the eastern retaining wall is a concern. Please riprap the
entire aiea of the swale around the pan outlet (including the other side of the swale
bank) to prevent erosion from the flow jetting off the retaining wall..
RESPONSE:
16. Please redirect the storm sewer in the northeast comer of the site to go around lot 14.
RESPONSE:
Erosion Control Comments
1. All comments have been discussed with the design engineer (Dick Rutherford) and
have been addressed. Erosion control plan is OK.
glenmoor2&3-2.doc
3. There appears to be wetlands in the existing Plum Street channel that will be
disturbed. Please address how the lose of these wetlands will be mitigated. Also, the
cobbles in the bottom of the channel may conflict with replacement of the wetlands.
Please contact the City's Natural Resources Department for further guidance.
RESPONSE:
4. Please provide riprap calculations for the various riprap pads throughout the site,
including the outlet of the culverts under Taft Hill Road. Please call out the
dimensions of each individual riprap pad in the plans.
RESPONSE:
5. The grading in the northeast corner of the site does not appear to tie-in. Please make
sure all proposed grading ties -in with existing grading.
RESPONSE:
6. Sub -basins 9 and 10 appear to be in the same basin. Please clarify.
RESPONSE:
7. Please show a more definitive overflow swale for the 4' curb inlet on Kirra Court.
Also, please include a cross-section of the swale with calculations that show the swale
has adequate capacity for the 100-year flows.
RESPONSE:
8. Please include calculations for the storm sewers and inlets at the site.
RESPONSE:
9. Please show the existing drainage easement along the east border of the site on the
plat and drainage plan.
RESPONSE:
glewnoor2&3-2.doc
n
REVISION
COMMENT SHEET
DATE: January 26, 1999 TO:V'Stormwater-
PROJECT: #8-95C Glenmoor P.U.D., 2n1 & 3rd Filing —
PDP/Final - Type 1 (LUC)
All comments must be received by Bob Blanchard no later than the staff
review meeting:
Wednesday, February 17, 1999
No Comment
MProblems or Concerns (see below or attached)
Drainage Comments
1. The main stormwater concern with this project is the realignment of the Plum Street _
Channel. The channel should be aligned in a more direct flow path from the Taft Hill
Rd. culverts to the Glenmoor Dr. culverts. This means aligning the channel with
more gradual bends, rather than the ninety -degree bends shown on the plans. Please
redesign the site to accommodate the channel design.
RESPONSE:
2. Please provide a profile of the 15' RCP extensions under Taft Hill Road.
RESPONSE:
Date:
CHECK HERE IF YOU WISH TO RECEIVE COPIES OF REVISIONS
Plat site _ Drainage Report _ Other
_ Utility _ Redline Utility _ Landscape
— 11✓in. Q��'�rvr�1
Citv of Fort Collins
Lori
City of Fort Collins
Commun;'v Planning and Environmental S-rvices
Current Pining
ADDITIONAL STAFF REVIEW COMMENTS
Richard A. Rutherford
Stewart & Associates
P.O. Box 429
Fort Collins, CO 80522
March 3,1999
The Stormwater Department and the Transportation Planning Department have reviewed
your plans and offer the following comments:
1. Stormwater Utility Department:
a. See the attached comment sheet, 2 copies of the drainage report, and redlined
plans.
2. Transportation Planning:
a. See the attached comment sheet, and redlined plans.
Be sure and return all your redlined plans when you resubmit. If you have any.questions
about these or any other issues related to this project please feel free to call be at 221-
6750.
Tours truly,
Troy Jones
City Planner-
281 North College avenue • P.O. Box 580 • Fort Collins, CO 80522-0580 • (970) 221-6750 • FAX (970) 416-2020