HomeMy WebLinkAboutOLD TOWN NORTH - FDP - 28-99C - SUBMITTAL DOCUMENTS - ROUND 1 - CITY STAFF (3)Page 4
January 7, 2002
Project No: 1646-01-98
Re: Old Town North — Project Development Plan
Response to Stormwater Comments, dated May 18, 2001
General Comment
1. "Floodplain comments to follow. "
R Acknowledged. Floodplain comments have been responded under separate letter.
We trust that this response has addressed all of your specific comments and concerns. If you
have any questions or further comments during your next detailed project review, please call at
(970) 226-5334.
Sincere ,
-----------
Michael Rohlfs
Shear Engineering Corporation
cc: Monica Sweere; Palladian Construction Co.
Troy Jones; City of Ft Collins, Planning
Russell Lee; BHA
Page 3
January 7, 2002
Project No: 1646-01-98
Re: Old Town North — Project Development Plan
Response to Stormwater Comments, dated May 18, 2001
R Acknowledge. Poudre River, Dry Creek floodplains and the Product 6 Corridor boundary
are now more clearly presented on a separate sheet title "Floodplain Plan."
2. "Please provide documentation for the 500 year water surface elevations used on sheet 55.
How were the elevations developed? "
R Two tables are included in Section III.A of the report summarizing the Dry Creek 100-year
and 500-year flood elevations. References to the source of the data are discussed in the
section. Additionally, the Floodplain administrator (Ms. Marsha Hilmes-Robinson) was
contacted and provided assistance in providing accurate elevations.
3. "In the Northern Engineering modeling report dated 5-17-2001, random calculations
performed by the Cityfor the discharge using the orifice equation and input values does not
agree with the calculations for the orifice rating curve in the report appendix. .41so, the
values in the SWMM rating curve do not exactly agree with the rating curve calculations.
Please explain. "
R Acknowledged. Changes have been made. Please refer to Appendix I — Detention Pond in
your review.
4. "Please show the peak water surface elevation, storage, and release rate for the pond on the
drainage plan. Currently, there is a rating curve for 61 and 62 but not 61.45 WESL. Please
note this information should come from the combined pond model. "
R Acknowledged. The rating curve for the pond is shown on the drainage plan. The top of
berm elevation is at elevation 61.50 feet.
5. "Please include additional storage -discharge points on the pond -rating curve to reflect the
spillway discharge in the report and on the plans. "
R The top -of -berm elevation is at 61.50 feet and is included on the rating curve.
6. "The analysis of the culvert connecting the two ponds assumed a 0.5 foot head difference.
Please explain this assumption. "
R Ackknowledged. This assumption has been reconsidered.
Page 2
January 7, 2002
Project No: 1646-01-98
Re: Old Town North — Project Development Plan
Response to Stormwater Comments, dated May 18, 2001
columns are partially complete. This design information is still in process. The 100-year
WSEL is included for the completing the elevation certificates for the CO. This table may
also be found under Appendix VI of the report.
R Again, once grading is completed, this table will be formalized and will be provided
immediately for your review.
4. "Please provide cross sections of all swales oil the plans and label swales with slope on
grading plans. "
R Acknowledged. A swale table will be provided summarizing various configurations with
call -outs locating the specific location each is applicable to. This table will be included on
the grading or drainage sheets. Once completed, this information will be provided
immediately for review.
5. "Please provide street capacity calculation per SDDC Manual. Maximum water elevation is
not always the same as the curb elevation for the 2-year storm. Also, please add the
additional street capacity calculations when completed. "
R Street capacity calculations are included in Appendix I of the report for your review. The
discussion may be found in Section V.G. of the report.
6. "Please revise the pond rating curve to reflect the new WSEL and spillway elevation and
make sure the report is consistent with Northern Engineering's report. "
R The revised detention pond -rating curve may be found under Appendix I — Detention Pond
for review. Northern Engineering Services' report may be found under Appendix VII of the
report. A discussion of the detention pond regarding detention and water quality may be
found in the report under Sections V.D and V.E. respectively.
SWAM Comments
1. "Please ensure the Poudre River and Dry Creek floodplains (inchiding the product 6
corridor for the Poudre River) are more legible; it is very difficult to discern the floodplains
on sheet 54. Please note the SWMM analysis will need to be revised to reflect the final
grading and layout of the site. "
January 7, 2002
Project No: 1646-01-98
City of Fort Collins
P.O. Box 580
700 Wood Street
Ft. Collins, CO 80522-0580
Attn: Wes Lamarque
Re: Old Town North — Project Development Plan
Response to Stormwater Comments, dated May 18, 2001
Dear Mr. Lamarque:
This is a response to your project comments regarding Old Town North — Project Development
Plan — Type II (LUC) dated May 18, 2001. Original comments and responses to each are
provided:
I. "Water quality is not currently included in the design for this site. Please provide a water
quality outlet structure in the detention pond and calculations in the report. "
R Water quality calculations are now included in the Final Drainage and Erosion Control
Report (report) for the project. Please refer to Section V.E. of the report for the discussion of
the subject. Calculations are provided in Appendix I of the report.
2. "Please provide detailed calculations for storm sewers using either UDSewer or StormCad.
Explain any assumptions or expected condition concerning the outfall into Lake Canal. "
R A discussion, including assumptions and expected conditions, relating to the outfall into Lake
Canal is included in Section V of the report. Calculations are provided in Appendix I of the
report.
3. "Please show detailed grading including side -lot swales and high points for all lots. "
R Acknowledged. Detailed grading of the lots and side -lot swales are in process.
R The 100-year and 500-year WSEL have been calculated and are presented on the Drainage
and Erosion Control Notes sheet. A copy of which is included in the Appendix VIII of the
report. Information on this sheet also includes the Regulatory Flood Protection Elevation
(500 yr WSEL + 1.5 feet). Columns presenting the Actual Finished Grade, Lowest Floor
Elevation and the Lowest Floor — 500 yr Elevation are also included. These last three
4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 Fax (970) 282-0311 wwwshearengineering.com