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HomeMy WebLinkAboutDrainage Reports - 10/09/1991Fmal Approved Report 4 D. r . DRAINAGE REPORT AND EROSION CONTROL REPORT FOR SOUTH .GLEN SUBDIVISION, FIRST FILING FORT COLLINS, COLORADO September 1991 Stewart & Associates, Inc. 214 North Howes Street Fort Collins, Colorado 80521 DRAINAGE REPORT AND EROSION CONTROL REPORT SOUTH GLEN SUBDIVISION, FIRST FILING INTRODUCTION: .The proposed South Glen Subdivision, First Filing, is a 4.5—acre parcel of land located in the Northeast I of Section 35, Township 7 North, Range 69 West of the Sixth P.M., Fort Collins, Larimer County, Colorado. This parcel is in the McClellands and Mail Creek Major Drainageway Plan and part of what was previously called The Replat of South Glen P.U.D., Third Filing, which was a 14—acre planned unit development. All the runoff in this 14— acre development was designed to go into a detention pond in the Northeast corner of the site. This pond has been constructed. EXISTING CONDITIONS The proposed site has been developed according to the South Glen P.U.D., Third Filing, with sewer, water, storm drains, and the detention pond. Some grading work has been completed in the street areas. There are not offsite flows that cross the proposed site. Manhattan Avenue flows North and has been constructed. The remaining land slopes West to -East at about 0.6 per cent (0.6%) grade. Most of the original vegetation on the site has been removed. DEVELOPED CONDITIONS There are 18 single—family homes planned on this site. One cul—de—sac, Mapleton Court, begins at Manhattan Avenue and runs east about 600 feet. The drainage is designed to flow to an existing curb inlet 70 feet East of this site. The site has been divided into four subbasins: Subbasin I is 0.30 acres: The flow from this subbasin is North along Manhattan Avenue. Subbasin II is 1.3 acres. Flow from this Subbasin is East along the South property line in a grass swale. - Subbasin III is 1.3 acres. Flow from this subbasin is East along the North property line is a grass swale. The last 135 feet of the swale will have a 2.0 foot concrete pan. Subbasin IV is 1.8 acres. Flow from this Subbasin is East along Mapleton Court to the end of the cul—de—sac, then East to the property line in a concrete pan and grass swale. A temporary dirt swale will then carry the flow to the existing 4—foot curb inlet. This Swale will need to be reseeded with grass. The area around the 4—foot inlet will need to be built up to elevation 5048 to force the water into the inlet. Flows that overtop this elevation will run North in the existing rough cut street to the existing detention pond. This pond is about 270 feet North of the inlet. The developer of this site will be required to maintain the temporary swale and 4—foot curb inlet East of said site. Drainage Report and Eroson Control Report South Glen Subdivision, First Filing Page 2 When the property East is developed, our offsite flows will need to be incorporated into that final design. The maintenance will be the responsibility of the developer. Drainage calculations and drawing for this site are attached. P Franklin D. Blake, P.E. & L.S. EROSION CONTROL *on 7339 WIND EROSION The South Glen Subdivision, First Filing, is located in a moderate wind erodibility zone, requiring a wind barrier spacing of 200 feet. The installation of the curbs and pavement and the leaving of undisturbed vegetation will provide adequate wind barriers, so no further wind erosion control procedures will be needed. RAINFALL EROSION The South Glen Subdivision, First Filing, is divided into four subbasins. Subbasin I is the existing pavement on Manhattan Avenue and a small portion of the sideyard of Lots 1 and 18 which will be undisturbed. No rainfall erosion control procedures are required for Subbasin I. Subbasins II, III and IV drain to the East into an existing catch basin. A sediment trap will be constructed at the existing catch basin. Subbasin II is the rear yard of Lots 10 through 18, and some of the area will be left undisturbed. Subbasin III is the rear yards of Lots 1 through 9, and some of the area will be left undisturbed. Subbasin IV is Mapleton Court and the front yards. The Rainfall Performance Standard Evaluation of the existing site and the Effectiveness Calculations of the proposed erosion control methods are shown on the attached sheets. Phillip'V Robinson, P.E. & L.S. *' 4502 b' No Text SUBJECT DATE_lL�j I/Yl _-=✓/T���/_7 --------- SHEET NO.--`/----- //� �� �J - �J�----�-�----------�PROJECT NO.---------- �STm2lCc ice f 1za Zn✓�2o�L- �i�j F1�ir 3_2 vso y, 3-Z z3 SUBJECT __-__-_ SHEETNO.__ G---_ SO✓��Gsvd�-=�i/N�. _.. PROJECT NO_ 97 le le- e4 CD eye o, 9S) 4. re la. 9s> ,.4- �o. G'= ©-¢,,,q. SUBJECT f /L!�_ �-_ _--_ BY__�=�<_/ _,_. DATE._//9� 1/Y� --- 1:%J✓'.'_7 _,ems-�i✓J ��_ll L'_------ SHEET NO.- - �.-__---______.PROJECT NO.---------- Ci ��r�/a>o /ram/ 2� •iL�Cfs /5�/ ,g 4_�7v/Z2aco�7 6-ro �'/vatio�7 ¢80. /� . r aii�c�.J>✓mod 117le 7-1 ' I i SUBJECT' `__,G/�✓���,___ C ..Jl�` '"i____ BY �('q=/-___. DATE SHEET NO.- -t2� ---- .G__CL � __ PROJECT NO.-----__--_ sa - 1, 7 qz = p, ssB x / 7 �,,//,/ SUBJECT,--�i`��/JaT�/C _i; --- BY_�"�'= ___. DAIEJ��� ®/T1 ---- _ __----- SHEET NO.-- --- ---- - �? _� PROJECT NO.---_---__- -I.- zl�117. f�rra �. 30 aci�s: 95) T /71771/7 `,C;9 vrc J CifY SUBJECT__-�%?i%7..`.'.:y_„`__� /__'__. BY__� /w7.:•/'_-. DATE_:/-/ SHEET NO.---<�--- `J/����� PROJECTNO.---------- /�ir� �_ Y13 /Sca �2 = �% 2C �C /. to �C • /. ,�' - �' � �?. �,s , n SUBJECT �r!�%��Gi "� C _✓ C'_�BY /9� SHEET NO_ ---- _�_��%CH �fJ����`/."'y. PROJECT NO.-_-_------ G = 71iO S7 cis SUBJECT _r%l _`�=�o�nc��_%/:J7/G/'a" - J.:✓��`/ ,,.r-- BY—_----___. DATE I�/l — '__•W j i—_ SHEET NO.__�_—__ PROJECT NO.__________ i. t Ve- 71 - .D7/X 7/ C�4f G Z !¢ D 71- /•ZS•�G.7 .x /. �'= A), 7, c. s p,/s! tlui3jliC'Y __L�,-J�,%'�/ �/°s+`•r�• /� / --- BY _5./-'_' _. UAfi@J�e� /�- - - - - - SHEET NO.-- ---- . PROJECT NO.---------- Ny f � 1j� i }YkK• �.1�n�.... . K�`�4.1� � 4 .'t J �5 t� . O /G _ JJ p,2s X. p,pG le- /54 7oJ •yP}�qq,p/ SUBJEC'��_��%/��� G-��/-"BY_SG/•='�__. UAT[��� SHEETNO.__ --_ i =`--_?>.l �•�7/Y/✓ 1>;�______ PROJECT NO.---------- s' r �� •/S ,r3,00s�ZK4.3, / 3 Z.. X2 , � D. -5, . f'�/ass scJo/t P"7 �/25 S JSga�s t��49X 0.2��,00s'�x3,51 �_ /z iP=P= 0,29 o� z' vZx �.?9 Q,4G 7�1 72; s Ile�,o SUUJECrsr—r:/?�-<� SHEET NO._��-_-- _//r/ %✓ice_ �� PROJECT NO._ Cd�G'2�7�� .zJtli(J G'il/�fiG/T� t . �-= x p.25 7 3�• 79 8, c3 g-2�cicfs f F1x p,OG e Cs T �• 3 � 90' zo, � ' So.S h �f9.o =LG3xD•75') f (4X/.S) �ZD.7X O.75> 3.35 B9G p�B ,o= /S.so �= `D•r! ��vs"�. ��i "ice/r 7�, G Dr � f � // 1g,,5t SUBJECT—_�.�'rJc'•_aIC �J __ BY—��G�` ---. UAIG SHEET NO.__LZ--__ PROJECT NO._—___—_—__ goy AA 70c�5f' SwAE_AcA_PA.G_/_.-r-Y Ic�_q..- /Z..L0 X l•33 /7 dDG 9•s n /7\08 GQv 1- 33 x /00 2ar .%�O rrrt YNH aiC�. 0 DRAINAGE CRITERIA MANUAL RUNOFF 50 T t- 20 z w 0 cc w a 10 z w a of 5 to w cc 3 7 0 co 2 w F Q t 1 'ii0■1, ■■■■■il vM I IN%■%■� �MIFAMIKIII V ��=M■■■ll .2 .3 .5 1 2 3 5 10 20 VELOCITY IN FEET PER SECOND FIGURE 3-2. ESTIMATE OF AVERAGE FLOW VELOCITY FOR "I USE WITH THE RATIONAL FORMULA. f.MOST FREQUENTLY OCCURRING"UNDEVELOPED" LAND SURFACES IN THE DENVER REGION. " REFERENCE: "Urban Hydrology For Small Watersheds" Technical Release No. 55, USDA, SCS Jan. 1975. 5 -1-84 URBAN DRAINAGE & FLOOD "CONTROL DISTRICT No Text No Text COMPUTATIONS Stewart & Associates, Inc. 214 N. Howes St. Ft. Collins, CO 80521 (303) 482-9331 By: 7))Z Date_70�9/ Client: Mark Lind er Sheet No. of Chkd By: Date Project: .So (J+b 6-)en .50. , J S7 Subject EroSiGh K'rin4ro I BaSI o f To�Gi i S) e• are,I � 1 f?1 ea . dra'Infnt / 0� Ai !J' T , D; 3 f4 c I 1 IO L � ..{ I✓].....I. i 5- S = O. S� �reti cunt ✓ref..!. .!)9 L. � I j 131A51IQ 'TF - J, 3 AcIi /%r�� I UL 1� I'1*e the rovesIA'c Vq�re rOJr T3%�S)N; I j �ovn�j..,LA-� 1 rie c_ bd reovti /-� r� 1 , ' I 13H si .— 70r1 �relc ✓ini c'Gnc '- 0. �4 It I I I f I1 I , COMPUTATIONS Stewart & Associates, Inc. 214 N. Howes St. Ft. Collins, CO 80521 (303) 482-9331 By: Date Client: 10crrk / i o d er- Sheet No. of Chkd By: Date Project: SU(l{J) G I n SU cl JT Subject Erosion 'CG_Y) -to/ _ I 'S.S � Gn� IJM�• r,of ope re c7L4on, I � i RAINFALL PERFORMANCE STANDARD EVALUATION --------------------------- PROJECT: ICOMPL'ETED .Sovi�h GI ----------------------------------------- en Svbd, !STANDARD FORMA BY: F'!R DATE: 9/Ow I------------------------------------------------------------ IDEVELOPED�ERODIBILITY SUBBASIN --------- ZONE ----------- Asb (ac) I Lsb I (ft) I Ssb I (%) I Lb 1(feet) I Sb I (%) ----`-�--� I PS I (%) 7 I -------II 0. 3 u - -I------- i Z6 s 11 c ------- I Z.6 �, I ----- 1 p. s I -------I iz�.3 � - � --- -- 1,30 _ i. eo _70.0 1_0.3 I I I I _ 700 ' I �. a I 78.0 1 I 71 sb= �1,30)� I I 1,l,fi 1.3o�(O.y� t�/.f',0 I I I � I I /.o> I I I j I I III I I I I I I I I I I I I I I I I I I -------------------------------- DI/SF-A:1989 JANU RV 1991 8-18 DESIGN CRITERIA EFFECTIVENESS CALCULATIONS ---------- 7----------------------------------------------------------- PROJECT: Sou }h Glen S Ub j . / 57 STANDARD FORM B P4<C COMPLETED BY:' DATE: y 1GJ 191J Erosion Control C-Factor P-Factor Method Value Value Comment - -------------------------------------------------------- OCA-r-e Grouted 1.00 1.00 pu^-IF 4- conc 0.01 1.00 .Sedirnenl -Yap / /.C20 0.50 Sera .bales 1, o0 0.60 u nd ts4urbe�J 54-ound 0.03 160 ------------------------ MAJORI PS. I SUB I AREA BASIN (o) BASINI (Ac) i CALCULATIONS ----- ------ ----- ------------=-------- ----------------------------- Tv7AL 7b, O Z 0.30 I WAA G 517E I I (D.IS'� a-0 tjO.IZxo-3 O.3 -6.oZ ly 1.3 EFF = )-(o.Oz;(I.w)x 100 `l(? 7 ((1. (0.0 3)-h= 0.27 Wed P= 0,50 (0 Z7�0-�0)xibu- ss6.S (0. 100, 03�a..o2�(0.01 0.37)(1 ) = 0,31 I.3 W4-d 7 = G. 5-0 FFP : I - �0.31)(0.)x1w = S-4•5- 1---------------- HDI/SF-B:1989 i1Nir-'Pv.Ia01 8-19 n=STC,V CRT--RT EFFECTIVENESS CALCULATIONS ----------------------------------------- - - --------------------------- PROJECT: sa Ui �, �r e h S U / ST STANDARD FORM B 5e 7 COMPLETED BY: p/7Z DATE: y / Erosion Control C-Factor P-Factor Method Value Value Comment ---------------------------------------------------------- MAJORS PS. SUB AREA BASIN (%) BASIN (Ac) CALCULATIONS ----- ------ ----- ------ ------= ------------------------------------- w-W -p Z. v, SO EFF- :-- l-(0-G7)(0.S)xrv1-v= �(.s lTF I ��F I = 3)(er.S)}�1.3)(9c 1 ¢, 7 ----------------------- _---------- _____�_ _____________________________ DI/SF-B:1989 T ,.,,,, n- 1GI! O I ff 0 A JANUARY 1991 UAU 0.35 0.30 0.25 0.20 0.15 0.10 0.05 nm ESTABLISHED GRASS AND C-FACTORS FORT COLLINS, COLORADO ............. I ............. I; ............. ............. I ............. I ............. I .............. I .............. i --...........I............. ............. ............ ....... . .. ............. .............. ............. ........ . ... .. I I ..... . ............. ............ ... ....... .... .... ... .......... .. I .......... "T ......... .... ........ .... ............. ............. . .... ..... ............. ........ ............. ............. ............. l ............. ............. . ........... T ............. .......... ............. ... . ........ I - . . .......... .... ........ ............. f i .............. i ........... ..... ........ 1 . ....... ...... ............. ........ ........... ....... . ... ..... ............. ............. i ............. ...... ... . ...... . ........ . ............. � ............. .............. T 0. 10 20 30, 40 50 60 � 70 80 90 100 E.STABM GRASS GROUND COVER (7o) .FIGURE 8-A 8-10 DESIGN CRITERIA