HomeMy WebLinkAboutTHE LODGE AT MIRAMONT PUD - FINAL - 54-87AQ - CORRESPONDENCE - RESPONSE TO STAFF REVIEW COMMENTS (2)�
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January 30, 2001
Ted Shepard
City Planner
City of Fort Collins
281 North College Avenue
Ft. Collins, CO 80522-0580
Re: The Lodge at Miramont
Project No. 618-102
Dear Mr. Shepard:
We have received comments for the Lodge at Miramont final plans. We have made the
necessary changes to plans, as per your request. The purpose of this letter is to address
each comment and describe all changes made by our office.
Stormwater
1. There are still revisions needing to be made to the storm sewer p/an and profile
sheets. Please be sure that all sewer parameters (inverts, rim elevations, size,
length, etc.) on the plan and profile drawings match the calculations. P/ease
show FES and riprap on the profi/es and call out the WSEL of the pond at sewer
out/ets. Finally, p/ease use manholes at all bends and encase the storm sewer
over and within 18 inches below water lines.
Acknowledged.
2. Please request a variance for any grading steeper fhan 4:1, up to the maximum
allowable limit of 3:1. It appears that much of the pond and some of the swales
are graded at 3:1.
Acknowledged. A request for variance is inctuded in the cover letter for the
drainage report.
3. Please provide retaining walls for any slopes steeper than 3:1. For these
retaining walls, please call out top- and bottom-of-wall elevations.
Acknowledged. These have been included in the Grading Plan.
4. Please include calcu/ations for Swa/es C-C and D-D. Also, it appears that there
are some errors in the swa/e sizing tables. Please revise these tables and
include the bed s/opes.
Calculations have been provided in Appendix E. HEC-RAS analysis has been
done on section C-C to account for detention pond effects.
TST� �NC■ 748 Whalers Way - Buildink D
Fort Collins, CO 80�2�
Consulting Engineers (9711) 226-1►557
Metro (303) 595-9103
Fax (970) 226-0204
Email inFo@tstinc.com
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TST, INC.
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5. P/ease show the existing release rate of the pond with the pond summary on the
drainage p/an.
Release rate has been included on the drainage plan for the existing pond.
6. Please add details of manholes and concrete encasement, and provide a note or
detail for buried riprap to be buried with 6 inches of topsoil.
Acknowledged. Please see Detail Sheet 12 for manhole and concrete
encasement details.
7. Please define the headwall for ST-2 more clear/y. Call out top-and bottom-of-
wall e/evations and list the type and show a detail of the inlet configuration.
Final/y, since this is a/arge box cu/vert, p/ease provide grates on both ends of it
fo prevent debris and children from entering it.
Elevations have been called out on the Grading Plan. More detail is provided on
the Grading and Storm Sewer Plan & Profile sheets pertaining to ST-2. Per a
January 23 2001 meeting with Stormwater Staff, grates will not be necessary due
to a revised configuration of the culvert.
8. Please obtain an easement for the grading shown in the Miramont Entry
Subdivision in the southeast comer of the site. Also, p/ease submit a copy of the
agreement with Miramont Nerghborhood Park for the grading shown fhere.
Grading has been revised to eliminate need for an easement for the Miramont
entry. A draft agreement with the Park has been included in the submittal
package. A copy of the easement obtained for construction on the park site will
be forwarded when the paperwork is complete.
9. Please call out a minimum opening elevation for all buildings adjacent to the
pond.
The buildings will be slab on grade, so the finished floor elevations are the low
point elevations for the buildings.
10. It is unclear where the attenuated 2-year runoff of 54.8 cfs at DP1 was obtained.
Calcu/ations during review yielded a slightly different number. Please check this
calculation and revise if necessary.
Calculations have been so revised.
11. Please nofe that because of the increased permanent water surface area in the
pond, a groundwater augmentation plan may need to be filed with the State of
Colorado. Please address.
Permanent water surFace area has been decreased until it matched the existing
condition. No groundwater augmentation will be necessary.
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TST, INC.
Master Planning Comments:
1. P/ease provide the comp/ete output for the existing condition SWMM and
proposed condition SWMM. Also, provide e/ectronic copies of the models.
SWMM models have been revised to provide input "echo" and summary output
as discussed in a meeting with Staff on 1/23/01. This output has been included
in the Drainage Report. A CD-ROM has also been included containing electronic
copies of SWMM models.
2. Please provide, as documentation, a copy of the basin map and schematic for
the portion of the McClellands Basin in the vicinity of the projecf.
A basin map and schematic has been included in the Drainage Report.
3. The ana/ysis of ST-2 shows a 0.4 ft rise in water surface upstream of the project.
The proposed box culvert can not cause a rise (less than 0.1 ft) in water surface
e/evation on an off-site property. P/ease revise the design of ST-2 to not impact
off-site properties.
As discussed in the 1/23/01 meeting, proposed water surFace elevations
upstream of the proposed development will not inundate land outside the existing
stormwater drainage easement. HY-8 analysis has shown that tailwater
elevation has little or no effect on the split of water crossing under Boardwalk or
overtopping the road.
4. P/ease provide the output and cross-section plots for the HEC-RAS model for the
channel on the south boundary of the site. Also, provide an electronic copy of
the model.
These have been included in the Drainage Report.
5. The flows that overtop Boardwa/k were not accounted for in the ana/ysis of the
box culvert. Although some of this flow will continue to the east on Boardwa/k,
flows in excess of the curb height historically spilled into the road-side channel.
Please account for fhis flow when designing the culvert and entrance to the site.
By a consenrative assumption, the entire flow (178 cfs) has been used to design
the culvert and site entrance, as discussed in the 1/23/01 meeting.
Erosion/Sediment Control comments:
One or more of the previous comments have not been addressed. Please do so.
Discussion was held with Staff (1/23/01) to determine which comments had not
been addressed and in what manner.
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TST, INC.
Previous Erosion/Sediment Control comments:
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1. P/ease remove the "Once grading operations have been completed" language
from the erosion contro/ report.
Addressed with previous submittal.
2. Please provide ca/culations to support the BMP's, and an E.C. cost estimate.
Addressed with previous submittal.
3. Why is silt fencing being p/aced around the pond?
Silt fencing is proposed for placement around the pond due to relatively steep
(3:1) sideslopes surrounding the detention pond. It seemed that this measure
would be appropriate for preventing sediment from leaving the bank while
vegetation is established in that sub-basin. A previous submittal showed the silt
fence in the wrong location. It was moved to the correct location with the
December submittal.
4. The pond is enlarged, how are sediments going to be prevented from leaving the
site through the existing pond outlet?
A permanent water feature currently exists on-site and is intended to remain in
the proposed development (see stormwater comment no. 11). This existing pond
will act as a sediment trap, preventing sediments from leaving the site. Required
volume and proposed grading for the sediment trap are included on the Drainage
and Erosion Control Plan.
5. What happens in a storm to straw bales sitting on concrete trickle pans? Please
provide an alternative BMP.
City of Fort Collins criteria provide calculations for determining required erosion
control measures. These calculations indicate that straw bales are not
necessary to provide adequate protection in swales on the site. Therefore, the
straw bales have been removed. Calculations are provided in Appendix G of the
Drainage Report. Per City of Fort Collins Erosion Control Reference Manual,
Section 6.3.2, Drop Inlets, "Drop inlets in unpaved areas shall be filtered with
straw bales anchored with wooden stakes...". Straw bale filters have been used
in accordance with this requirement at drop inlets. A gravel pack will be placed in
the pan upstream of the straw bales to address the concern in this comment.
Redline comments from Stormwater:
1. P/ease provide a 20' easement for the existing storm line that parallels Lemay.
We were asked to provide 7.5' of additional Right-of-Way along Lemay by the
city. The existing 20' easement will become a 12.5' easement because of this
request. If we created a 20' easement for the storm sewer line, the existing line
would lie offset in the easement.
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TST, INC.
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Water and Wastewater
1. It appears that litt/e or no quality control was performed on this plan set before it
was submitted. Prior to resubmitting, provide an interna/ quality control review.
Acknowledged.
2. All fire hydrants must connect to the proposed water mains with a swivel tee.
Acknowledged.
3. As previous/y indicated, show and label all existing wafer/sewer mains and
services which extend into this property. C/ear/y identify whether the main or
service is to be used or abandoned. If it is to be abandoned, then provide
complete details of abandonment.
Acknowledged.
4. As previously indicated, provide complete details of all water main /owerings.
Include elevations, thrust blocks, gravity blocks (size), lengths or pipe, fittings,
etc. Use fifting to accomplish lowerings over 6 feet of bury depth.
Acknowledged. Please see utility sheets for lowering details.
5. As previously indicated, concrete encase aU sewer lines which cross above or
within 18-inches vertically of water mains.
Acknowledged.
6. As previously indicated, label existing streets, wafer, sewer, storm lines and other
pertinent items (i. e. sizes of existing mains and services, depths of mains if
warranted).
Acknowledged.
7. As previously indicated, provide insulation over all sanitary sewer lines (including
sanitary sewer services), which have less fhan 4 feet of cover. Provide all
information necessary for insu/ation (i.e. Manufacture, model, etc.). Provide a
copy of the calcu/ation for insu/ation for our review.
Acknowledged. A copy of the calculations for the sewer line insulation were
senUfaxed to Jeff Hill on 1/29/01.
8. As previously indicated, will an irrigation tap be needed for this development?
Show and label this if so.
At this time, the irrigation layout has not been designed.
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TST, INC.
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9. Clearly show and /abel all water, sanitary sewer and storm sewer crossings in
profile views.
Acknowledged.
10. Clearly label al/ fire lines as D.I.P.
Acknowledged.
11. Provide a copy of offsite construction easement document for our review.
Acknowledged. We are in the process of obtaining the easement for construction
on the park property. We will not be grading on the Miramont Entry Feature
property, and so will not require an easement. The 6" water line to the north of
our property lies within a drainage, utility and access easement as shown on the
plat off Oakridge West P.U.D., First Filing recorded at reception number
87054588 on 09/18/87 at the Larimer County Clerk and Recorders Office. We will
not need an easement to tie into that line as well.
12. Include the standard detail for a%"1 " meter pit with fhe next submittal.
Acknowledged.
13. See site /andscape and overall utility plans for other comments.
EnQineerinq
1. Show more detail for pipe connection to open swale adjacent to boardwalk.
Acknowledged. See note 7 on page 2 of these comments.
2. C/ean up numbers on grading p/an so they are readab/e.
Acknowledged.
Technical Services
1. P/at and Legal c/ose.
2. The 2%" cap at the E'/. corner has been in place and accepted since 1994, prior
to that it was a rebar in a box, per monument records this was at the same
location. Why is it now 0.81' off? This will need to be discussed before plat is
accepted.
Please see note 8 on the plat.
3. Plat wil/ need to be of a reproducible quality.
4. Note referring to the PSCo easement along the north side of Boardwalk is
unclear, Note 7 does apply to this area.
Acknowledged and changed to note 6.
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TST, INC.
5. How was Boardwalk dedicated?
Please see plat.
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We believe that the issues raised during this review have been addressed adequately to
allow this project to move ahead in the approval process. If you should have any
questions or concerns, we would be happy to discuss them at your convenience.
Sincerely,
TST, INC., CONSULTING ENGINEERS
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Fraser Walsh
FW/cros