HomeMy WebLinkAboutDrainage Reports - 02/17/1994LIDSTONE & ANDERSON, INC.
Water Resources and Environmental ConsultantjMOPMTY OF
736 Whalers Way, Suite F-20YORT COILMS U-1 91d1'l 3
Fort Collins, Colorado 80525
(303) 226-0120
January 27, 1994 a'2
Mr. Glen Schlueter
City of Fort Collins
Stormwater Utility
235 Mathews Street
Fort Collins, CO 80524
Re: Final Drainage Report for the Finch Court Minor Subdivision of Paragon Point
(LA Project No. CO-TST-19)
Dear Glen,
Lidstone & Anderson, Inc. (LA) is pleased to submit herewith the Final Drainage Report
for the Finch Court Minor Subdivision of Paragon Point. The subdivision is a small parcel
adjacent to the Paragon Point Phase 4 Development. The final drainage report for Phase 4 was
completed by LA, and approved by the City on September 9, 1993. The platted area consists
of a total of 0.12 acres which would be an extension of Finch Court approximately 100 feet
south of Hawkeye Street. The purpose of this report is to evaluate the drainage facilities
designed in association with the Phase 4 Development in order to: (a) determine whether they
are adequate in light of the refined drainage configuration; and (b) modify the previous design,
as necessary, to accommodate the Finch Court extension. All analyses presented herein were
conducted in accordance with the City of Fort Collins Storm Drainage Design Criteria (SDDC)
Manual.
Hydrologic Evaluation
The proposed extension of Finch Court would result in the modification of Subbasins E
and I from the Phase 4 report. A total of 0.41 acres would be added to Subbasin I; 0.23 acres
would be transferred from Subbasin E, while 0.18 acres would be new area added as a result
of the street extension. The Rational Method calculations from the Phase 4 report were revised
for two design points along the southern boundary of the development. The major and minor
storm discharges were calculated for Design Point 14, which includes a portion of Subbasin 1;
and for Design Point 15, which includes all of Subbasins E, F, G, H and I. Figure 1 shows the
Finch Court modifications to the Grading and Drainage sheet from the Phase 4 report. The
figure shows all proposed drainage facilities affected by the Finch Court extension; these
Branch Office: Box 27, Savery, Wyoming 82332
Mr. Glen Schlueter
January 27, 1994
Page Two
include: (a) the Finch Court extension, and (b) the extension of the southern perimeter swale
west to the Finch Court extension.
The results of the analysis indicate a discharge of 1.6 cfs at Design Point 14 during the
100-year event; this represents in an increase of 0.9 cfs compared to the Phase 4 analysis. The
100-year discharge at Design Point 15 would be 24.7 cfs, which is 0.5 cfs higher than the
discharge given in the Phase 4 report. It is noted that the reduced area within Subbasin E would
result in a reduction in discharge at the low point on Hawkeye Street, which is represented by
Design Point 13. Therefore, hydrologic calculations were not performed for the modified
Subbasin E. All hydrologic and hydraulic calculations associated with this analysis are included
in the appendix.
Street Capacity Analysis
Finch Court would be classified as a local street and have a slope of 0.4 percent. The
street would be characterized by a 2 percent cross slope and would incorporate a Fort Collins
standard 4.75-inch rollover curb. City of Fort Collins street capacity criteria requires that flows
do not top the curb for the 2-year event.
A normal depth analysis of the allowable street capacity was performed using HEC-2
[U.S. Army Corps of Engineers, 1991]. The normal depth option for a single cross-section was
used to find the flow rate associated with the allowable depth. The results of the street capacity
analysis indicate that the 2-year allowable discharge on the Finch Street extension is 2.3 cfs.
The hydrologic calculations indicate that the 100-year flow to Finch Street would be 0.9 cfs.
Therefore, the street capacity would not be violated for either the 2- or 100-year events. It is
noted that riprap design calculations were performed for the flows at the southern terminus of
Finch Court. It was found that riprap protection is not required for the relatively small amount
of flow conveyed along the street.
Drainage Swale Design
Runoff from the Finch Court extension would be conveyed to the lower pond on Stone
Creek by the perimeter swale along the southern boundary of Phase 4. Section F-F of this swale
was classified as a minor swale in the Phase 4 report; it would convey flows from Finch Court
and all flows tributary to Design Point 14 (western portion of Subbasin 1). At Design Point 14,
Mr. Glen Schlueter
January 27, 1994
Page Three
flow would also be collected from the low point on Hawkeye Street (Design Point 13). All flow
would then be conveyed in the major drainage swale identified as Swale D-D.
Swale F-F, as designed in the Phase 4 report, would have to be enlarged to convey the
additional flow contributed by the Finch Court extension. As documented in the previous report,
the section was designed to be 0.5 feet deep with 6H:1V side slopes. For this study, the swale
was designed for the 100-year discharge with an additional one-third capacity for freeboard. The
results of this analysis indicate that the grassed swale would need to be 0.7 feet deep with 611:1V
side slopes. It is noted that the velocity in swale F-F is less than the allowable minimum. It
is requested that the variance which was previously granted for the Phase 4 Development be
broadened to include the extension of swale F-F to the terminus of Finch Court. The revised
swale section F-F is shown in Figure 2.
The hydraulic analysis from the Phase 4 report for Swale D-D was repeated with the
higher 100-year discharge determined in the revised hydrologic analysis documented herein. The
results of the hydraulic analysis indicate that the swale, as previously designed, is adequate to
convey the excess flow generated by the Finch Court extension.
In conclusion, the results of the analysis indicated slightly higher discharges compared
to the findings in the Paragon Point Phase 4 Development. The perimeter swale along the
southern boundary of Phase 4 would have to be extended to Finch Court and expanded to carry
additional runoff. All other drainage facilities are adequate as previously designed for Phase 4.
If you have any questions regarding the procedures and results given in this report, please feel
free to call us.
Sincerely,
Christophe L. Doherty, EIT
iProjectE 'neer
J och, PE
gineer
CLD/tlt
Attachments
300 FT. TO TRILBY ROAD
. � u i
000
,..
40
0000
I
SQ
'H
' 1-44
'- SCALE: 1 "=50'
Figure 1. Finch Court Modifications to
the Paragon Point Phase 4
Grading and Drainage Plan.
100— YR W. S.
0.7 ft. 0.6 ft. I� GRASS LINED
6 =°' n = 0.060
SWALE E-F- CROSS SECTION
NOT TO SCALE
Figure 2. Typical Cross Section for Swale F-F.
APPENDIX
SUPPORTING CALCULATIONS FOR THE FINCH CT. EXTENSION
- finch Minor5ob
CAD
FEATURE l- �nccRcu n
Raborlal Megod Calcola7rJ�5 - f aye �I Qev�5�a�5. G
1-Iq-19q
I SHEET
3, 8
OF
k+oQ of 0•11acre5 will b6adAeJ fo 5L)bb,5,w 1; 0,23 acre-) could came doer►
Sobhasin F while k rBmain� o.18a�rP� con5tre5 U�acldi�oi fo the
IPorc�o✓I Pbiv4 ,PAc,5e 4 Jrair?;e grew.
5vbkx,5i� S
-Pkute 4 : A = a•oa AUeS
C = 0,95
t� (�yr)= la I mir► L (aye)=a. 35inihr spa ?4(101'Pbsn�
i e 6rv-yr) = II-Smm -5, G ODOjr) =6,75 m ItirQ m : H•3efs �hase�I rnpor+.
Reined = aA3 acre5
r(o.�s)(ayl)��a.�13 = 0,43
tc (a-yo :19.l min -9 (a-yr)
Qa= Cb H = (C).a8)(d 35n/h.�( •�13ac) 1 (oCfs
5, 7 A
1�e5 �
- X1,5e Li ; A = 7,qb. acres �oM�u, rlfo�n�
76,, = la• I min [ (a yr: a,3 5,n'hr LQ7 Cf5 � P{wet itPoi4.
= m II,Son -� L (IDv-ri)=%•75,n1ti� -i atoo z dIl,;cf5 (G?,00-xl•33 • .acfS)
RevISed A = 7,q& 4C_)4 (6,18 Gt) = 8. I `i acres
C= 1,100,304.
tG (d-yr), la,lmina-yr�- a•35^ �hr
ec boo -It) °11,5msn Gao-rr) = b, 75,r lhr
(6, 56) (a, 35) (g, l 4 q c-75
Qoo=�� A= (0,36)(�.a5)((�•75)(8./4) = aci,7 cf5, (Q,o�1.33 > 3a•R�)
IA
. .
ruw •o•r••..r .o.•..uw c•u•nr..
OWNER -PROJECT
+?w on ���f -finch Minor Sub-
Y
C'LD
DATE
1-av-19G�
PROJECT NO.
COT57 9.8
FEATURE
�irv�o �� �I��(��on�
CHECKED BY
DATE
SHEET OF
a /►1
D!5,q n T)o, r.+ SoL4 Fnd of rf nd� Coo(4�
IribLiaev Area (wAiri Sobba's,h S) : 0-gac(e5
IAal A- eq (W(ih,n5L)b",l T) = �Mncrei
04cv)= l,bef-5 ; aou CT = 5,7 e�5 Froa,?49e 1411
�a (aP, iqp) = (°,��3) (I,(cD. 3C Fs
(�ioo(D�D,I�IA�=(°'��a•H5�(5.7c;��= O.q��s
(�,00+1�33= I,ac�s
L�s�n {Poinf 14 (ezfloence wi*50ale D-A)
Tri bo+ail 4re61 6,,h ,n 5vbbasml) = 0,34cee5
io+al Arlq (r/�f17�� 5�bb �,n S) = a, q 5 acro
0,(,c�s�
� c-;
0100 1, 33 = a.a cf-5
jFe- �l PQIIQ9ano,J Phkse Qioo (A.R lei) = b c�5
3/1
24JAN94 14:33:12 rm- O U I
'Parayou mA AW4
x+++xxwwxxww+w+++xwwwxwwxx++ww+++wwwx /J�
HEC-2 WATER SURFACE PROFILES
Version 4.6.0; February 1991
xww++wxxwxwx+++wxwwwx+++++++x+wwxxwxw
PAGE 1
THIS RUN EXECUTED 24JAN94 14:33:12
T1 PARAGON POINT FINCH CT. MINOR SUBDIVISION - STREET ANALYSIS 1/20/1994
T2 FLOW FOR THE ALLOWABLE 2-YR DEPTH (CURB FULL) LIDSTONE & ANDERSON, INC.
T3 FINCH CT. (1/2 LOCAL)
J1 ICHECK ING NINV IDIR STRT METRIC HVINS 0 WSEL F0
2 0 0.004 1.0
J2 NPROF IPLOT PRFVS XSECV XSECH FN ALLDC IBW CHNIM ITRACE
1 -1
02aLL 0100act
OT 2 4.6 0.9
NC 0.016 0.016 0.016 0.1 0.3 -
X1 1 6 98.58 118.01 10 10 10
GR 2 98.58 0.39 98.59 0 100.00 0.11 101.17
GR 2 118.01
24JAN94 14:33:12
0.45 118.00
SECNO
DEPTH
CWSEL
CRIWS
WSELK
EG
HV
HL
OLOSS
L-BANK ELEV
0
GLOB
OCH
GROB
ALOB
ACH
ARDS
VOL
TWA
R-BANK ELEV
TIME
VLOB
VCH
VROB
XNL
XNCH
XNR
WTN
ELMIN
SSTA
SLOPE
XLOBL
XLCH
XLOBR
ITRIAL
IDC
ICONT
CORAR
TOPWID
ENDST
*PROF 1
CCHV= .100 CEHV=
.300
*SECNO 1.000
1.000
.00 1.00 .44 .05 .00
4.6
.0 .0 2.7 .0 .0
.00
%.04.6
.00 .000 .016 .000 .000
.0013977
10. 0 0 8 .00
;-year A(low4webepfh
a-ye4r Mjo.Aa le Dochzje 0eotebcat)
kejo(e. (0,S) (q,& r-A)-
lPelxfw Fuclor
.00 2.00
.0 2.00
.00 98.59
16.62 115.21
PAGE 2
24JAN94 14:33:12
71 PARAGON POINT FINCH CT. MINOR SUBDIVISION - STREET ANALYSIS 1/20/1994
T2 FLOW FOR THE ACTUAL 100-YR DEPTH LIDSTONE & ANDERSON, INC.
T3 FINCH CT. (1/2 LOCAL)
J1 ICHECK INO NINV IDIR STRT METRIC HVINS 0 WSEL
3 0 0.004 1.0
J2 NPROF IPLOT PRFVS XSECV XSECH FN ALLDC IBW CHNIM
15 -1
24JAN94 14:33:12
FG
ITRACE
SECNO
DEPTH
CWSEL
CRIWS
WSELK EG
HV
HL
OLOSS
L-BANK ELEV
G
GLOB
GCH
OROB
ALOB ACH
AROB
VOL
TWA
R-BANK ELEV
TIME
VLOB
VCH
VROB
XNL XNCH.
XNR
WTN
ELMIN
SSTA
SLOPE
XLOBL
XLCH
XLOBR
ITRIAL IDC
ICONT
CORAR
TOPWID
ENDST
*PROF 2
CCHV= .100
CEHV=
.300
Velot4Y
*SECNO 1.000
twiel/ %ree+
1.000
.24
.24
.00
1.00 .26
.02
.00
.00
2.00
.9
.0
.9
.0
.0 .8
.0
.0
.0
2.00
.00
.00
1.16
.00
.000 .016
.000
.000
.00
99.12
.003979
10.
10.
10.
0 0
10
.00
8.68
107.80
�/►f
PAGE 3
PAGE 4
24JAN94 14:33:12
xwxxxxwwwwwxwwwwwwxxxxxwwxxxxxwxwxwwx
HEC-2 WATER SURFACE PROFILES
Version 4.6.0; February 1991
rrxxxxxxwxxxxxxxxxxwwwxxxxwxwwwxxwxxx
PAGE 5
THIS RUN EXECUTED 24JAN94 14:33:12
NOTE- ASTERISK (*) AT LEFT OF CROSS-SECTION NUMBER INDICATES MESSAGE IN SUMMARY OF ERRORS LIST
FINCH CT. (1/2 LOCAL)
SUMMARY PRINTOUT TABLE 150
SECNO
XLCH
ELTRD
ELLC
ELMIN
0 CWSEL
CRIWS
EG 10*KS
VCH
AREA
.01K
1.000
.00
.00
.00
.00
4.60 .39
.00
.44 39.77
1.72
2.67
.73
1.000
.00
.00
.00
.00
.90 .24
.00
.26 39.79
1.16
.77
.14
24JAN94 14:33:12
FINCH CT. (1/2 LOCAL)
SUMMARY PRINTOUT TABLE 150
SECNO
0 CWSEL
DIFWSP
DIFWSX
DIFKWS
TOPWID
XLCH
1.000
4.60 .39
.00
.00
-.61
16.62
.00
1.000
.90 .24
-.15
.00
-.76
8.68
.00
24JAN94 14:33:12
SUMMARY OF ERRORS AND SPECIAL NOTES
PAGE 6
PAGE 7
OWNER -PROJECT BY DATE PROJECT NO.
+mar on �� - f'�nC (�es�b CAD 1-aU-Igq�( CoTST�`► S
FEATURE CHECKED BY DATE SHEET OF
p re, a De5,cgh
70c-eAqri 'join% WA &LAem End v� 1;r6 Cloo(f)
T14100=
IvS
�e� �f C'ollrm SADC M4h� Gy'drslox
(o,17)4
D. � � l No praa r, re rej
-7
Table 8-1 lists several gradations of riprap. The minimum average size designation for loose riprap
shall be 12 inches. Smaller sizes of riprap shall be either buried on slopes which can be easily
maintained (4 to 1 minimum side slopes) or grouted if slopes are steeper. Grouted riprap should meet
all the requirements for regular riprap except that the smallest rock fraction (smaller than the 10 per-
cent 18 inchesshould
to 12 incheseliminated
or from 24 inchestion. A reduction of to 18 inches) is permitted d forsize
grouted one nprapesignation
Table 8-1
CLASSIFICATION AND GRADATION OF ORDINARY RIPRAP
% of Total Weight
Smaller than the
Stone Size
dwt
Riprap Designation
Given Size
(in pounds) (inches)
70-100
85
Class 6 tt
50-70
35
10
6
35-50
2-10
<1
70-100
440
Class 12
50-70
275
85
12
35-50
2.10
3
100
1275
Class IS
50-70
655
275
18
35-50
2-10
10
100
3500
Class 24
50-70
1700
655
24
35-50
2-10
35
t dso = Mean Particle Size. At least 50 percent of the mass shall be stones equal to or larger than this dimension.
tt Bury on 4 to 1 side slopes or grout rock if slopes are steeper.
Table 8-2 summarizes riprap requirements for a stable channel lining based on the following
relationship:
vs() "
(d5o) (Si)o.66 = 5.6
s
in which, V = Mean channel velocity in feet per second
S = Longitudinal channel slope in feet per foot
S5 = Specific gravity of rock (minimum S5= 2.50)
d50 = Rock size in feet for which 50 percent of the riprap by weight, is smaller.
The rock sizing requirements in Table S-2 are based on the rock having a specific gravity of 2.5 or
more. Also, the rock size does not need to be increased for steeper channel side slopes, provided the
side slopes are no steeper than 2h:1v. Rock lined side slopes steeper than 2h:1v are not
recommended.
Table 8-2
RIPRAP REQUIREMENTS FOR CHANNEL LININGS tt
VS0.1Tl(S� 1)o.snt RockTypett
_--1111IN 0 to 1.4
1.5 to 4.0
4.1 to 5.8
5.9 to 7.1
7.2 to 8.2
No Riorap Required
Class 6 Riprap
Class 12 Riprap
Class 18 Riprap
Class 24 Riprap
t Use S, = 2.5 unless the source of rock and its densities are known at the time of design.
tt Table valid only for Froude number of 0.8 or less and side slopes no steeper than 2h:1 V.
MAY 1984
8-2 DESIGN CRITERIA
PARAGON POINT; FINCH MINOR SUB -- SWALE F-F NORMAL DEPTH CALCULATIONS
INPUT DATA:
DISCHARGE
= 1.600000 CFS Qoo �•����
BOTTOM WIDTH
= 0.000000E+00 FT
BED SLOPE
= 4.000000E-03 FT/FT
SIDE SLOPE
= 6.000000
MANNINGS N
= 6.000000E-02
RESULTS:
NORMAL DEPTH -
6.142979E 01 FT
FLOW VELOCITY =
7.064316E-01 FPS
HYDR. DEPTH =
3.072484E-01 FT
TOP WIDTH =
7.371575 FT
FROUDE NUMBER =
2.245936E-01
SPECIFIC ENERGY= 6.220471E-01 FT
INPUT DATA:
0100*1'33
DISCHARGE
= 2.200000 CFS -
BOTTOM WIDTH
= 0.000000E+00 FT
BED SLOPE
= 4.000000E-03 FT/FT
SIDE SLOPE
= 6.000000
MANNINGS N
= 6.000000E-02
RESULTS:
NORMAL DEPTH =
6.922267E-01 FT
f7 Q!(�$
FLOW VELOCITY =
7.650340E-01 FPS
HYDR. DEPTH =
3.461883E-01 FT
UV
TOP WIDTH =
8.306721 FT
FROUDE NUMBER =
2.291377E-01
SPECIFIC ENERGY= 7.013149E-01 FT
20JAN94 11:08:52
*#****#**#********************#******
HEC-2 WATER SURFACE PROFILES
Version 4.6.0; February 1991
SWriL;' oi•OPT PAGE 1
Rana
yqgcn Poufsn'1� ha5e
Fi►tlil �% 1�Gv 151 or1
- Swale 1J-D (S�bhasln.2)
THIS RUN EXECUTED 20JAN94 11:08:52
Hyjraullc "CP15
T1 PARAGON POINT PHASE 4 FINAL DRAINAGE PLAN L&A, INC. 1-19-94 CLD
T2 SWALE DEPTH AND VELOCITY CALCULATIONS -- FOR FINCH COURT MINOR SUB.
T3 BASIN I -- 100-YEAR EVENT SLOPE = 0.4%
J1 ICHECK ING NINV IDIR STRT METRIC HVINS D WSEL FO
2 1 0.004 1.0
J2 NPROF IPLOT PRFVS XSECV XSECH FN ALLDC IBW CHNIM ITRACE
1 -1
oT 2
24.7
32.9
NC 0.060
0.060
0.016 0.1 0.3
X1 1
5
112 114 10 10 10
GR 2.1
100
0.1 112 0 113 0.1 114
20JAN94 11:08:52
2.1 126
SECNO
DEPTH
CWSEL CRIWS
WSELK EG
HV
HL
OLOSS
L-BANK ELEV
G
OLOB
OCH OROB
ALOB ACH
AROB
VOL
TWA
R-BANK ELEV
TIME
VLOB
VCH VROB
XNL XNCH
XNR
WTN
ELMIN
SSTA
SLOPE
XLOBL
XLCH XLOBR
ITRIAL IDC
ICONT
CORAR
TOPWID
ENDST
*PROF 1
CCHV= .100 CEHV=
300
*SECNO 1.000
1.000
1.26
1.26 1.30
1.00 1.71
.44
.00
.00
.10
24.7
4.3
16.0 4.3
4.1 2.4
4.1
.0
.0
.10
.00
1.07
6.60 1.07
.060 .016
.060
.000
.00
105.02
.003929
0.
0.. 0.
0 11
5
.00
15.95
120.98
ti9•S�Cho��, r
(WO) (G•Lo�
�Avb
q, 7 Cry
PAGE 2
20JAN94 11:08:52
T1 PARAGON POINT PHASE 4 FINAL DRAINAGE PLAN L&A, INC. 1-19-94 CLD
T2 SWALE DEPTH AND VELOCITY CALCULATIONS -- FOR FINCH COURT MINOR SUB.
T3 BASIN I -- DESIGN 0 (1.33*0100) SLOPE = 0.4%
J1 ICHECK INO N1NV IDIR STRT METRIC HVINS 0
3 1 0.004
J2 NPROF IPLOT PRFVS XSECV XSECH FN ALLDC IBW
15 -1
20JAN94 11:08:52
WSEL FO
1.0
CHNIM ITRACE
SECNO
DEPTH
CWSEL
CRIWS
WSELK EG
HV
HL
OLOSS
L-BANK ELEV
0
OLOB
OCH
OROB
ALOB ACH
AROB
VOL
TWA
R-BANK ELEV
TIME
VLOB
VCH
VROB
XNL XNCH
XNR
WTN
ELMIN
SSTA
SLOPE
XLOBL
XLCH
XLOBR
ITRIAL IDC
ICONT
CORAR
TOPWID
ENDST
*PROF 2
CCHV= .100 CEHV=
.300 D
(Deswn DeA)
*SECNO 1.000
1.000
1.44
1.44
1.49
1.00 1.95
.51
.00
.00
.10
32.9
6.4
20.2
6.4
5.4 2.8
5.4
.0
.0
.10
.00
1.19
7.28
1.19
.060 .016
.060
.000
.00
103.98
.004006
0.
0.
0.
0 14
6
.00
18.03
122.02
(a If
PAGE 3 /
PAGE 4
20JAN94 11:08:52
f fff+kfff4+f****tr*rfff*++*******r+*+
HEC-2 WATER SURFACE PROFILES
Version 4.6.0; February 1991
+ffY*kffrY*Y+tY*r*fr+******k****fkYff
PAGE 5
THIS RUN EXECUTED 20JAN94 11:08:52
NOTE- ASTERISK (*) AT LEFT OF CROSS-SECTION NUMBER INDICATES MESSAGE IN SUMMARY OF ERRORS LIST
BASIN I -- 100-YEAR EVEN
SUMMARY PRINTOUT TABLE 150
SECNO
XLCH
ELTRD
ELLC
ELMIN
0
CWSEL
CRIWS
1.000
.00
.00
.00
.00
24.70
1.26
1.30
1.000
.00
.00
.00
.00
32.90
1.44
1.49
20JAN94 11:08:52
BASIN I -- 100-YEAR EVEN
SUMMARY PRINTOUT TABLE 150
SECNO
0
CWSEL
DIFWSP
DIFWSX
DIFKWS
TOPWID
XLCH
1.000
24.70
1.26
.00
.00
.26
15.95
.00
1.000
32.90
1.44
.17
.00
.44
18.03
.00
20JAN94 11:08:52
SUMMARY OF ERRORS AND SPECIAL NOTES
EG
10*KS
VCH
AREA
.01K
1.71
39.29
6.60
10.54
3.94
1.95
40.06
7.28
13.48
5.20
PAGE 6
PAGE 7