HomeMy WebLinkAboutFOSSIL CREEK ESTATES PUD PRELIMINARY - 50 92D - CORRESPONDENCE - RESPONSE TO STAFF REVIEW COMMENTS (2)October 27, 1993
Project No: 1318-01-92
Kate Malers
City of Ft. Collins Storm Water Utility
P.O. Box 580
Ft. Collins, Colorado 80522
Re: Fossil Creek Estates P.U.D.; Ft. Collins, Colorado
Dear Kate,
This letter is written in response to your review comments of September 8, 1993 and further
review comments noted on the . plans included. with the Preliminary Drainage and Erosion
Control Report which was initially submitted on September 7, 1993.
The following response is in the order of the September 8, 1993 Project Comment Sheet, a copy
of which is attached for reference.
* The subsurface investigation report for the entire Fossil Creek Estates property was
submitted to Kirsten Whetstone in Planning. I believe you have received a copy already. If
not, let me know.
A conceptual discussion of groundwater conveyance for the project, has been added to the
report as requested..
* An engineered dewatering system will be provided. . Homes will be constructed with
basements. The sub -drain will be installed with the sewer lines, then be directed away from
the sewer line trench and continue north to Fossil Creek. The outfall for the eastern portion
of the site will discharge via the storm sewer adjacent to Shields Street. The outfall for the
western portion of the site will discharge with the storm sewer systems. Grade differentials
allow this concept.
* Discussions are currently under way with the ditch lateral owners and users. We do not
know at this time if any of the laterals are going to be lined. We should have this question
answered at the time of final submittal. Generally, we are anticipating that the Scenic Knolls
ditch will be lined.
* Discussions regarding the irrigation laterals have been expanded in the Preliminary Drainage
and Erosion Control Report. Clarification is required concerning the comment to add more
detail to the plans regarding the ditch laterals.
* The Scenic Knolls Ditch currently crosses under Shields Street via a siphon. This crossing
must be improved with Shields Street widening construction. Siphon reconstruction detailing
will be presented with the Shields Street design with the Utility Plans at final. This item is
also being discussed with the owners and users of the Scenic Knolls ditch. We have labeled
the siphon on the plans.
* We are aware that the construction of Phase II of this development is dependent on the a
connection to Taft Hill Road to the west. If there are no plans for development on the
property to the west of Fossil Creek Estates at the time of Fossil Creek Estates Phase II final
planning, the connection would be the responsibility of the Fossil Creek Estates
development. This would include the the designing and construction of the ditch crossing.
4836 S. College, Suite 12 Fort Collins, CO 80525 (303)226-5334
PAGE 2
October 27, 1993
Project No: 1318-01-92
Re: Tossil Creek Estates P.U.D.; rot. Collins, Colorado
* We understand that ditch compa }%approval of the final utility plans is required prior to City
of Fort Collins approvals. is City of Fort Collins policy for all projects involving
ditches.
* Discussion concerning historic drainage conditions have been expanded in. - the Preliminary
Drainage and Erosion Control Report. All historic drainage conditions have been analyzed
with the utilization of the City's Quarter section topographical maps. You are correct
regarding the areas of the historic and developed basins. No change is anticipated. Historic
conditions calculations have been revised to include the southwestern offsite contributing
area. The Historic conditions plan has also been revised.
* Developed offsite flows have in fact been considered. We are providing you with copies of
the City's topographical maps which define the topography and drainage scenarios which we
are visualizing. Also attached is a copy of USGS map for this area. We are including the
USGS map as an exhibit to the report to supplement the Historic conditions plan.
* We understand that the drainage design for the most easterly portion of the site must be
coordinated with the South Shields Street widening plans. We are not sure if you had also
received a copy of the 3-sheet Preliminary Master Utility Plan. Sheet 3 clearly shows the
storm sewer adjacent to Shields, and its relativity to ultimate Shields Street improvements.
We utilized the Shields Street improvement plans which were prepared in conjunction with
the Clarendon Hills project by Intermill Land Surveying and Dennis Donavan.
Additional Right -of -Way for Shields Street will need to be dedicated for full width
improvements with the property to the north. Our preliminary plans have been revised to
reflect the future 50 foot 1/2 Right -of -Way for Shields Street adjacent to the property to the
north. We will not be requesting Right -of -Way dedication at this time. However, we will
request the dedication of a fifty foot (50D utility and drainage easement at this time, to
facilitate storm sewer and sanitary sewer construction adjacent to Shields Street.
The proposed sewer line will ultimately remain within the Right -of -Way once the additional
20' of Right -of -Way is dedicated. The storm sewer will ultimately remain within the
dedicated easement and will not be within the Right -of -Way.
A channel will convey the pipe discharge to Fossil Creek and Erosion control will be
,provided. We are anticipating riprap protection from the storm sewer outfall to Fossil Creek,
similar to that provided with the Shields Street box culvert at the Fossil Creek crossing.
* You are asking us to provide proposed contours at 2' intervals. I understand that this is a
requirement and that proposed contours or spot elevations is an item on the preliminary
drainage report checklist. We have not completed this exercise yet. Are there certain areas
of specific interest to you at this time? Can this wait till final?
Slope stability will be addressed in detail with final as requested.
Your comment concerning wetlands, plant species, etc. are currently being studied and
discussions are continuing with Natural Resources regarding their requirements, questions,
concerns. These will be addressed separately via the wetlands consultant retained for the
project.
PAGE 3
October 27, 1993
Project No: 1318-01-92
Re: Fossil Creek Estates P.U.D.; Ft. Collins, Colorado
The outfall at the end of Prairie Clover Court has been better defined to depict a channel
downstream, paralleling the north property line, north of the existing 20' easement located on
the property to the north. The channel will direct runoff easterly to the secondary outfall
channel to Fossil Creek. The preliminary plans have been revised. -Expanded discussion
concerning this item has been provided in the Preliminary Drainage and Erosion Control
Report.
* The Drainage and Erosion Control Plan has been revised to show lot numbers. Crosspans
have also been added to the plans.
* We note your comments concerning items: required at final. These items will be addressed
and provided at final.
There are additional items which we would like to address which were not a part of your
comment response sheet. Some responses may be to verbal discussions which we had at our
meeting on October 13, 1993.
* We have analyzed the existing channel downstream (secondary outfall to Fossil Creek)
where concentration point A„ is located. A cross-section of the channel has been added to the
plans which includes the potential water surface level for the anticipated peak flow for a non -
redefined channel. We are not anticipating improvements to this channel.
We are supplying you with a copy of the survey of the property to the north for your
reference and files. Note the REA power line along the south property line. We have noted
the power poles on our plans. You may also notice that where our proposed Fossil Creek
Drive intersects with Shields Street, the north portion of the drive lies on the property to the
north of Fossil Creek Estates P.U.D. We will be requesting a formal dedication of Right -of -
Way for the location of Fossil Creek Drive as shown. Final Right -of -Way descriptions will
be presented at final after verification of the exact locations of the existing power poles and
how they are affected by the vertical design of Fossil Creek Drive.
We understand that an easement will be required on the property to the north for the
increased flows due to development of Fossil Creek Estates P.U.D. We have represented an
easement on the drawings based on the anticipated water surface elevation for a 100-year
storm as represented by the channel section which we are providing (Section A -A). We
believe our approach is correct. We will provide an easement dedication request and detailed
easement description at final.
If you have questions concerning our response to your initial comments, please call at 226-5334.
We will provide complete revised storm drainage calculations at final, once all issues have been
identified and resolved.
PAGE 4
October 27, 1993
Project No: 1318-01-92
Re: Fossil Creek Estates P.U.D.; Ft. Collins, Colorado
Si
B.
Shear Engineering Corporation
BWS / jmb
attachments
cc: Kirsten Whetstone; City of Fort Collins Planning
Kerrie Ashbeck; City of Fort Collins Planning
Carter Ewing; Fossil Creek Partners
Jim Sell Design
SHEAR ENGINEERING CORPORATION
PAGE 10
DATE 09/07/93 PROJ. NO.1378-01-92
TIME 1257 HOURS BY MEO
FILE NAME FOSSIL
FLOW SUMMARY
BASIN I
HISTORIC
BASIN I
DEVELOPED
2 YEAR
10 YEAR
.100 YEAR
2 YEAR
10 YEAR
100 YEAR
CCF
0.25
0.25
0.31
CCF
0.41
0.41
0.51
Tc
28
28
26.5
Tc
19
19
18
I
1.50
2.70
4.45
I
1.90
3.35
4.85
A
17.32
17.32
17.32
A
16.23
16.23
16.23
Q
6.495
11.691
23.893
Q
12.64
22.29
40.14
BASIN
II HISTORIC
BASIN
II DEVELOPED
2 YEAR
10 YEAR
100 YEAR
2 YEAR
10 YEAR
100 YEAR
CCF
0.25
0.25
0.31
CCF
0.37
0.37
0.47
Tc
42
42
41
Tc
43
43
42
I
1.18
2.10
3.45
I
1.15
2.08
3.40
A
52.25
52.25
52.25
A
53.34
53.34
53.34
Q
15.41
27.43
55.88
Q
22.70
41.05
85.24
DEVELOPED BASIN SUMMARY
SUBBASIN
UPSTREAM
ONSITE DOWNSTREAM
TOTAL
ac
ac ac
ac
I
0.47
12.69 3.07
16.23
II
13.69
32.78 6.87
53.34
TOTALS
14.16
45.47 9.94
69.57
HISTORIC BASIN SUMMARY
SUBBASIN
UPSTREAM
ONSITE DOWNSTREAM
TOTAL
ac
ac ac
ac
I
0.47
13.50 3.35
17.32
II
13.69
31.69 6.87
52.25
TOTALS
14.16
45.19 10.22
69.57
pA C?-,- 17..
SHEAR ENGINEERING CORPORATION
EXHIBIT A
PROJECT NAME: FOSSIL CREEK DATE: 12/06/93
PROJECT NO. 1318-01-92 TIME: 836 HOURS
BY : MEO
SWALE DESCRIPTION: SECTION A -A OF SWALE DOWNSTREAM OF PROPERTY
FILE NAME: FOSSIL
CAPACITY OF TRIANGULAR OR TRAPEZOIDAL CHANNEL
CHANNEL CONFIGURATION: TRAPEZOIDAL
CHANNEL LINING: GRASS
Da
Db
Dc
Sc n
W
I
(ft)
(ft)
(ft)
(X)
(ft)
(ft)
30.00
45.00
4.00
2.15 0.060
10.00
0.25
0.13 = LEFT BANK SLOPE
0.09 = RIGHT BANK SLOPE
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 0 V
(S.f.) (ft) (s.f.) (ft) (A/P) (cfs) (ft/sec)
4.00
85.00
190.00
85:44
1.70
0.15
1175.54
6.19
3.75
80.31
169.34
80.73
1.64
0.15
1007.70
5.95
3.50
75.63
149.84
76.01
1.57
0.15
85M3
5.71
3.25
70.94
131.52
71.30
1.50
0.15
718.43
5.46
3.00
66.25
114.38
66.58
1.43
0.15
595.76
5.21
2.75
61.56
98.40
61.87
1.36
0.15
486.89
4.95
2.50
56.88
83.59
57.15
1.29
0.15
391.17
4.68
2.25
52.19
69.96
52.44
1.21
0.15
307.91
4.40
2.00
47.50
57.50
47.72
1.13
0.15
236.44
4.11
1.75
42.81
46.21
43.01
1.05
0.15
176.05
3.81
1.50
38.13,
36.09
38.29
0.96
0.15
126.01
3.49
1.25
33.44
27.15
33.58
0.87
0.15
85.57
1.00
28.75
19.38
28.86
0.77
0.15
53.94
2.78
0.75
24.06
12.77
24.15
0.65
0.15
30.34
2.38
0.50
19.38
7.34
19.43
0.52
0.15
13.94
1.90
0.25
14.69
3.09
14.72
0.35
0.15
3.96
1.28
0.00
10.00
0.00
10.00
0.00
0.15
0.00
0.00
**fc*antt�,tt***,tyrAA-kicict#*:t-kic�kkk**,tA-lcicicichhtic�k:tick*�Airk,ttinhtirkkicAint#*ic
0,o6 fog f)ow At 7..0�
3S.z C1:eb p'«1,.�. l�s)
.i01Z= l'tJc.10lota� F)Ow 6)w JU1Zi' I,25
3, ZcvV, 0� Sec�,ety = o ti Solz+ I.0
`� I��s%o�,c FG �+ tj"
Cocvc\,jd�_ . Cj4fA"`iEL is A0dQVArG
_ 9AGE: iz R
EX .. .3 If W Cca v
CHECK FOR'FLOW DEPTH AND VELOCITY
FOR 0 = 85.24 cfs
STARTING DEPTH = 1.250 INCREMENT (ft) 0.001
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V
(s.f.) (ft) (s.f.) (ft) (A/P) (cfs) (ft/sec)
1.250 33.44 27.15 33.58 0.87 0.15 85.57 3.152
1.249 - 33.42 27.12 33.56 0.87 0.15 85.42 3.150
1.248 33.40 27.08 33.54 0.87 0.15 85.28 3.149
1.247 33.38 27.05 33.52 0.87 0.15 85.14 3.148
CHECK FOR FLOW DEPTH AND VELOCITY
FOR Q = 113.27 cfs ,
STARTING DEPTH - 1.430 INCREMENT (ft) - 0.001
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 0 V
(s.f.) (ft) (s.f.) (ft) (A/P) (cfs) (ft/see)
1.430 36.81 33.47 36.97 . 0.94. 0.15 113.75 3.399
1.429 36.79 33.43 36.95 0.94 0.15 113.58 3.397
1.428 36.78 33.40 36.93 0.94 0.15 113.41 3.396
1.427 36.76 33.36 36.91 0.93 0.15 113.24 3.395
CHECK FOR FLOW DEPTH AND VELOCITY
FOR Q = 22.70 cfs
STARTING DEPTH = 0.647 INCREMENT (ft) = 0.001
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V
(s.f.) (ft) (s.f.) (ft) (A/P) (cfs) (ft/sec)
0.647. 22.13 10.39 22.20 0.60 0.15 22.76 2.189
0.646 22.11 10.37 22.18 0.60 0.15 22.69 2.188
0.645 22.09 10.35 22.17 0.60 0.15 22.62 2.186
CHECK FOR FLOW DEPTH AND VELOCITY
FOR Q = 41.05 cfs
STARTING DEPTH = 0.874 INCREMENT (ft) = 0.001
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V
(s.f.) (ft) (s.f.) (ft) (A/P) (cfs) (ft/sec)
0.874 26.39 15.90 26.48 0.71 0.15 41.10 2.584
0.873 26.37 15.87 26.47 0.71 0.15 41.00 2,583
0.872 26.35 15.85 26.45 0.71 0.15 40.91 2.581
CHECK FOR FLOW DEPTH AND VELOCITY
FOR Q = 67.83 cfs
STARTING DEPTH = 1.119 INCREMENT (ft) = 0.001
DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V
(s.f.) (ft) (s.f.) (ft) (A/P) (cfs) (ft/sec)
1.119 30.98 22.93 31.11 0.82 0.15 67.95 2.963
1.118 30.96 22.90 31.09 0.82 0.15 67 8Z---LZ2._
1.117 30.94 22.87 31.07 0.82 0.15 67.70 2.960
5020
5018
5016
5014
5012
SECTION A -A
AVERAGE SLOPE=2.15%
From To L. S.
ELEV.5014 ELEV.5012 80' 2.5%
ELEV 5012 ELEV. 5010 110' 1.81 %
9
CHANNEL SUMMARY
'W = 0.06 (FOR FLOW DEPTH LESS THAN 2.0 FEET)
S = 2.15%
A = 190.00 sf P = 85.44 ft
R = 2.22
Q,p = 1175.54 cfs
Vr�u = 6.19 fps
2
10
50
100
1.33*Q,00
YEAR
YEAR
YEAR
YEAR
********
********
********
********
********
Qpeak (cfs)
22.70
41.05
67.83
85.24
113.27
Velocity (fps)
2.19
2.58
2.96
3.15
3.39
Depth (ft)
0.65
0.87
1.12
1.25
1.43