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HomeMy WebLinkAboutDrainage Reports - 02/03/1994STEWART&kSSOC[ATES Consulting Engineers and Surveyors January 28, 1994 STORMWATER UTILITY Mr. Glen Schlueter CM Storm Water Utility City of Fort Collins P.O. Box 580 Fort Collins, Colorado 80522 Dear Glen: Re: The First Assembly of God Church 1800 South Lemay Avenue :N I I have attached a copy of the 1988 drainage report, a copy of my February 1993 letter and calculations of the theoretical pond volumes and allowable additional hard surface, and a copy of the October 1993 as —constructed pond volumes and calculation of allowable hard surface. The existing detention pond volume is 874 cubic feet greater than the required volume. I have calculated that this 874 cubic feet of detention volume will accommodate an additional 4879 square feet of hard surface. The church desires to construct a garage with a hard surface area of approximately 2000 square feet. My calculations indicate that the existing detention ponds have the capacity to hold the runoff from the proposed new garage as well as 2800 square feet more hard surface. Should the church decide to expand more in the future, it is possible the west pond along Lemay can be enlarged by regrading the lawn area along the west side of the building. Please call if you require any additional information regarding this proposed garage addition. Sincerely, Ph i l l i.p I. Robinson, P.E. & L.S. Vice President jrr u enclosures James H. Stewart and Associates, Inc. 103 S. Meldrum Street P.O. Box 429 Ft. Collins, CO 80522 303/482-9331 Fax 303/482-9382 ri No Text STEWART&ASSOCIATES Consulting Engineers and Surveyors October 25, 1993 Mr. Frank Estep First Assembly of God'Church 1800 South Lemay Avenue Fort Collins, Colorado 80525 Dear Mr. Estep: I have surveyed the existing storm water detention ponds located on the east and west sides of the First Assembly of God church site at 1800 South Lemay Avenue: From the results of this survey, the calculated detention pond volumes are 32010 cubic feet of storage in the east pond and 1782 cubic feet of storage in the west pond. This compares to the originally designed volumes of 27640 cubic feet in the east pond and 7080 cubic feet in the west pond. The top of the berm and overflow of the east pond is about 2 inches higher than orginally planned, which accounts for the additional volume. It appears that during construction of the walk along Lemay and during landscape grading procedures, the west pond was filled in and made smaller. Also, the, proposed ridge in the west parking lot, which was to raise the high water line, was not constructed. The west pond is 5298 cubic feet smaller than originally proposed, and the east pond is 4370 cubic feet larger than originally proposed. The required total detention volume for the entire site is 32918 cubic feet, compared to the existing total volume of the east and west ponds combined of 33792 cubic feet. .There is now an excess detention volume of 874 cubic feet, which will contain runoff from an additional 4879 square feet of new hard surfaced area. It looks like the west pond can be enlarged by regrading the west lawn area without having to do any modification to the existing west parking lot. I am enclosing copies of maps and calculations regarding this matter. Please call if you need further information. Sincerely, Phillip I. Robinson, P.E. & L.S. Vice President jrr enclosures James H. Stewart and Associates, Inc. 103 S. Meldrum Street P.O. Box 429 Ft. Collins. CO 80522 303/482-9331 Fax 303/482-9382 STEWART&ASSOCIATES 103 . MEL 1RUM,FAX FORT gOLLINS, CO 80521 PH.Consulting Engineers and Surveyors By: P/ R Date: lO�q 3 Client: Firs i Arre,-ihI v of 6-14 vrc� Sheet No. —of _ Project:/000 s, Lema e' II Subject: ✓o r-, . s�i n 4" r Ln/ a 7 1_ r' e i e n i or ey n As surveye /0 zj 13 / l / eS r'O h Gon�Qvr area Vo(vme �afGk/ol/MC 71. 43 0 7 Z. O P75 l ¢� 75 3 ; 72. S zs Zo SF4 g fi Pv 77.7 6Z5S 17P�2 Coalovr uraa ✓OwMe f via) volvhf - 32� 70.0 14zz 321 70 1'754-9 soF9 1¢g23 71. 0 ¢214-1 r 4 757 IZO23 7/. Zs S404Z sz010 %T/aL _ 337 �(a GF OrSs i ti�f T7ru�OSC� wes7 �70 - 70(9 D 7'07/1-L� _ .3 4- 7 2 0 c r STEMRt&kSSOCIATES 103 . MEL 1RUM,FAX FORT gOLLINS, CO 80521 PH.Consulting Engineers and Surveyors . REV 1S E f7 By: P1 FK Date: U 2 Client: ElTs " AssenkIle o� 6vc 64tlmj Sheet No. JA of Project: 1800 S, Lcry — �r 000.5-e-� ioir't• Q�c�i lionf Subject: EY-C- e4en4oh ✓oItIme k/G01'4,Lie over +hai- i e�vired for resew si�e 33 7 7 Z - 3 2-1 = 67 cy, �• �/e,,,/ 1'lar� svr�acc �c�io„�a,b(� -%r' eZ� cv. �'�• �e7�C�Y-io� f(�ir �AW1M = O, 2S� G tGr� cLciC 4) einS - O• `r S V = (TW6(,')(I� (C t CA) (100)(-o)(1•05)(1.2-*Vx,2s-x^) 8 7¢ = l 13 4-0 3 544- A 679- = 77Q6 A ices(x 1=7• STEWART&ASSOCIATES Consulting Engineers and Surveyors February 26, 1993 Mr. Glen Schlueter Stormwater Utility City of Fort Collins P.O. Box 580 Fort Collins, Colorado 80522 Dear Glen: Re: The First Assembly of God Church The First Assembly of God Church has asked me to calculate the maximum size of building addition they can construct based on the excess detention pond volume now existing on their site. Based on a plan and drainage report prepared by Stewart and Associates in 1989, the required detention for the existing site is 32918 cubic feet, and the detention provided in the ponds is 34720 cubic feet. From the information in the report, the larger pond on the east side has an excess volume of 224 cubic feet, and the small pond on the west has an excess volume of 1578 cubic feet. The church proposes to build a garage on the east, which will be 1200 square feet of hard surface over existing gravel. This additional runoff will flow to the large pond on the east. They also plan to add to the northwest side of the existing church building. This addition, by the use of downspouts,can be made to drain to the west pond. I have included a copy of our 1989 drainage report, along with prints of the grading and drainage plan on which I have shown in red the approximate building additions. Also, I am attaching calculation sheets prepared at this time which show the following: Sheet IA shows a calculation of the approximate new hard surface allowable based on a calculation of the total additional runoff generated by the new hard surface area only. Sheet 2A is the calculation of a new composite C factor for the entire site using an estimated new hard surface area. The estimated new building area is 7000 square feet, and the garage area is 1200 square feet. James H. Stewart and Associates, Inc. 103 S. Meldrum Street P.O. Box 429 Ft. Collins, CO 80522 303/482-9331 Fax 303/482-9382 Mr. Glen Schlueter Re: First Assembly of God Church February 26, 1993 Page 2 Sheet 3A is a mass diagram calculation using the newly calculated composite C factor. The required detention volume per this new mass diagram calculation is 34653 cubic feet which is slightly less than the 34720 cubic feet provided, so the maximum building addition of 7000 square feet, and the garage addition of 1200 square feet will not generate more runoff than can be handled by the existing detention ponds. There is an existing overflow spillway into Stuart Street from the east pond, and any overflow from the west pond is onto Lemay Avenue, so any possible overflow will not cause flooding of adjacent buildings. Please call if you have any questions or comments regarding my analysis of this situation. Sincerely, //�< Ph i l l i i p I. Robinson, P.E. & L.S. Vice President ° to 4 '02 jrr ° enclosures �nnnntn�• STEWARTSSOCIATES Consulting Engineers and Surveyors By: P! R Date: Z-2 S 73 Project: ' ro ose c' I Subject: 103 S. MELDRUM, FORT COLLINS, CO 80521 PH. 482-9331 FAX 482-9382 Client: First /4rse,�6Iv df- /Go/ SheetNo.LI!-of cnG �JV it Jf'rc G. c4 f on r EXG SS S-�O!'r-, 1,11ck er- de en h a✓cr ia ar (��� ve t/�a>�: re�vi red �o� �r�se•�f s,(TP , 3.¢72-0 - 3zq! = 180Z cv. ' j t Drp �.QSC� Gr a�e =: 3Gx 4Y' /2�0 ;sT-/I /= 0.0r27-r. G/CG� G(I/C'/ (Pi[lTtinS �ra✓P(t1 JS(i/TOC/' 1�%Oncil rv^cll 70r 100- yt-. .3 ! i70Vr- sTOflv\l - e ICor l n e J PaCIS% 0. 9 • G Fay. 5,-a✓eI= 0. S0 ' r x I'sI-I'.,� V = �s-dlco 0.0s .zo.s0 0.0 Z�s = i l/e� GAroSc ; �((t ono( VP(VMe re�v1' red = ! /1� �� f e.x cesr VOI (iMc 6z v a 11 �S(c. 0 bV i(Jth5 add i �-J oK = IeOI - ll7 'New o�d�%�i G �✓�l( ID el c.oKS �r vC-�-P cj ova/ G d ot r�l C -far .c9� G -for- / a Vrr\ rr j V = Kv rio�� voj✓MG FAG... r76W agd I tlo 1 rA i n uS I vn " V = (10e0o)(1'0Yx))(A) o i i i evi S�in..l (o�h ��icr� exis��n5 STEWART�SSOCIATES 10 S- MEL9331DRF�M, FORT COLLINS, CO 80521 82 Consulting Engineers and Surveyors By: V- ) 7-1� Date: Z 2:� 7 3 Client: E rl' ksel b , II Of (6W Sheet No. ZA of Project: 1;,-OJ;�r.So0ra�c 'T �uC' i�c+ f� Gd�i7l Subject: ColcVlG�i aVk COM QSf-11e C 4r- errrj re .s ! r FT -Off -se 7000 .5F OVer 01161 -, n Y r-O Dos e IZ00 SF SG r-a GUrrrave - 0.0L7� �c lie v 1 se carte os 4r e-� _ jaiQ� sl C a�e!�. ¢.07 A + 0,23 oS�s1 _ �,30 AG, Ga�c 0� GUM��os! C G �ror. 19d� re G �0.2s 3G Z. 9385 1.3Cl5 �0.95�(2.757+,)6/.+,0271) t �61.Kk1,55 -.1 -.02-7 = 4.7Z8 STEWART&ASSOCIATES 10 DRUM( T COLLINS, CO 80521 PH.82 82 g3 431 82 Consulting Engineers and Surveyors By: P/ 7 Date: Z ZG 3 Client: Fi t-d- -(J �,n fl'� o i Goa Sheet No. 3 A of _ Project: Fra cal Subject: n i ov\ /(/NIe rep L) I Mess 171A6ZA - Fele6,Se F<a:�e = 0, f0 � �s 107 20(0,7z8)f4-.3) 2-7,¢ 1G4-3 59-O 9¢ 'zo 5,1 3.17/3 zo, Z441 1OB0 Z333 7 3o ¢.1 S /C. Z Z 1 Z3 0 4 zo !4-0 3.5 13.7 3 9 30709 150 3.0 l /.) 3`�- Z l 7 Z70a _3 7 !G z.� /0,2 36C2c" 3Z44 333d-S' 70 2. 3 y. 6 .377,17 37 (0 34-61 9 . p '7 (r ,126 l.gi 5.7 3�-37Z ¢¢373 t)ZG 39-�;5'3 q-o000 J 0000 e�eas e 0 a iv 20 so 40 sa 66 70 70 1zo n STEWART&ASSOCIATES Consulting Engineers and Surveyors STORM DRAINAGE REPORT FIRST ASSEMBLY OF GOD CHURCH The First Assembly of God church is located on the southeast corner of South Lemay Avenue and East Stuart Street. The site was constructed in 1978 and a detention pond was provided with an out —flow into Stuart Street. The pond lies mostly on an unpaved area, and now the church desires to pave the area for additional parking. Also, there is a drainage problem along the west side of the church building where water is undermining slabs. The church wants to pave approximately 4,500 square feet at the southwest corner of the building for parking, and to construct a detention pond along the west side of the building. This new pond will outlet into an area inlet which drains through a pipe to an existing catch basin on Lemay Avenue. At the time this new pond is constructed, adequate grading away from the building will be provided. There is 9,900 square feet of off —site flow into the church parking lot from the Day Care center. The remainder of the Day Care center drains to the south into Indian Summer Court. Sheets 2,3,4 and 5 of this report show calculations of the composite C factor, allowable outflow, required detention and pipe sizing. sheet 6 is an overall plan at the site showing existing and proposed grading and improvements. The existing pond has a 12 inch out —fall pipe, which will allow more flow than the 2 year historic run—off. We plan to decrease the outfall to the 2 year historic flow. An overflow will be constructed in the berm to direct the water to Stuart Street. James H. Stewart and Associates, Inc. 214 N. Howes Street P.O. Box 429 Ft. Collins, CO 80522 303t482-9331 / of 6 COMPUTATIONS STEWART&ASSOCIATES Consulting En3ineers and Surveyors 21.4 N. Howes St. Ft. Collins, CO 80521 (303) 482-9331 BY: Pi F -Date A(11205 Client: Efr-SL Ass-elnbl�f off- 60,4- Sheet No. of . z I Chkd By: Date- Project: /'Ora(d i 4 1'0 Y) Ck 'I I Subject -5- LO r r" - 12 1- Of i r7 C7fq -e I I ;7+? Ml rf I f Q 4-30,Ae r ic r YAC' 3( Z- /Y1. 5 4-9 i i f I, ra /J L_ i - J4 --4 All 9:54*s v Flo 5-! 'F 9 .(4 z A) D' qc� t� 0 eo r- 0 2- C)i n rwh O U 4- 7 * 0) J 5 0) OM P UTATI O N S STEWART$ASSOCIATES Conwlti gEMineersarkI Surveyors . :..... ,r_ 214 N. Howes St. Ft. Collins, CO 80521' (303) 482-9331 By: PI R Date 19 Client:O-�- GOd Sheet No. of Chkd By: Date Project: A d d I 'O" PQ ✓e N_ �G r lT r ��c� Subject- .1 C . OMPUTAT IONS STEWART&ASSOCIATES.' Consultit-3En3incersarxiSurveyccs 214 N. Howes St. Ft. Collins, CO 80521 (303) 482-9331 By: Date 4174 &4- Client: E A rre r-1 61 J 6�7,dSheet No. 4— of . I f, I LX— Chkd By: —Date Project: ddl 1 /'0 r? cr Paveel E>or4rI'r_?O Subject- FIIe4-e_)J)0'-\ Po r\'� 0', Ffc� 14 5 i'� e 0-�- c �) ur C COMO"UTATIONS STEWART&ASSOCIATES Consulting EnSineers and Surveyors 214 N. Howes St. Ft. Collins, CO 80521 (303) 482-9331 By: Date Client: of C-OcJ Sheet No. 5- of 6 Chkd By: Date- Project': �C! cl i 1 Uhal PO�Jed Pa r � t"t) Subject h 0 V) Pa n Un c G r bvilch i' I I. 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