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Home My WebLink About17 - Design Report - Osterman Commercial Condos - Stormwater ENGINEERING CONSULTING p� p� � PLANNING i�[GINEER1NG� INC DESIGN 204 NORTH 11t11AVENUE,BOZEM1AN,MT59715 204N 11"'Ave. BOZEMAN,MT 59715 406-581-3319 WWW.g-e-i.net Storm Water Management Design Report Osterman Commercial Condos 660&670 Osterman Drive Lot 1A-5A, Minor Sub 41-C Bozeman, Montana April 2017 Prepared By: Genesis Engineering, Inc. GEI Project#: 1086.010 Prepared For: Longshot Equity, LLC 510 W. Hemlock Bozeman, MT 59718 11`h 204 N. Ave.,Bozeman,MT 59715 Cell:(406)581-3319 www.q-e-i.net Page 1 of 7 NGtNE�filNG,li�lc Storm Water Management Design Report Table of Contents I. Project Background.............................................................................................................. 3 1. Introduction............................................................................................................................... 3 2. Soil and Groundwater.............................................................................................................. 3 3. Land Use..................................................................................................................................... 3 II. Existing Conditions.................................................................................................................. 3 1. Drainage Basins and Pre-Development Peak Flows............................................................ 4 III. Proposed Drainage Plan and Post-Development Peak Flows........................................ 4 1. Major Drainage System........................................................................................................... 5 2. As-Built Storm Main ............................................................................................................... 5 3. Minor Drainage System........................................................................................................... 5 4. Maintenance............................................................................................................................. 6 IV.Conclusion................................................................................................................................ 6 List of Tables Table 1. Estimated Pre-Development Peak Flows................................................................................... 4 Table 2. Estimated Capacity of Existing Drainage Conveyance Structures........................................ 4 Table 3. Estimated Post-Development Peak Flows................................................................................. 5 Table 4. Proposed Storm Detention Pond..................................... ............................................................5 Table 5. Proposed Drainage Conveyance Structures Capacities............................................................6 Appendix A—Exhibits and Calculations Grading and Drainage Exhibits Pre/Post Development Drainage Basin Flows Conveyance Structure Modeling List of References City of Bozeman Design Standards and Specifications Policy, March 2004,and all addenda. 204 N. 11'h Ave.,Bozeman,MT 59715 Cell:(406)581-3319 www.g-e-i.net Page 2 of 7 ' � NCYtN�ERiNG,1NC YF.Y�yien�yn;el•xu.5�u�.fvjf.a.Nwno I. Project Background Introduction The Osterman Commercial Condo project consists of two commercial buildings, located at 660&670 Osterman Drive on Lot 1A-5A of Minor Subdivision 41-C. The existing lot covers approximately 1.6 acres in Section 9,T2S, RISE, PMM in Bozeman, Montana. The property lies north of Interstate 90,south of Frontage Road and southeast of the cul-de-sac on Osterman Drive. This design report outlines the storm water analysis conducted for the site and describes the storm water drainage and management facilities required for the Site by state and local regulations. The storm water plan follows the design standards set forth by the City of Bozeman in Design Standards and Specifications Policy, March 2004 and three subsequent addenda. Soil and Groundwater The NRCS Soil Survey identifies the major soil type on the site to be Enbar-Nythar loams(532A). This soil belongs to hydrologic soil group C as it is comprised primarily of loam covering deep alluvium gravels. A geotechnical investigation was completed by a geotechnical engineer,and evidence of groundwater was found as shallow as 4'below existing grade,which is close to what the NRCS report estimated. The presence of groundwater will not likely affect pond construction methods. However, based on this information any proposed ponds should likely have dry,vegetated pond bottoms. Land Use The pre-development land use on the site was a vacant lot from the Minor Subdivision. The land is currently zoned M-1 and the proposed use is two commercial buildings. II. Existing Conditions The Project Site lies north of Interstate 90 and at the end of the Osterman Drive cul-de-sac. The project's land slopes generally to the north at an approximate average grade of 3.0%. The existing high point of the property is located at the southeast corner,with the low point being on the north property line. The existing topography of the overall site conveys runoff to the north and eventually to the irrigation ditch along the south side of the Frontage Road. Drainage Basins and Pre-development Peak Flows Genesis identified the onsite drainage basins as shown on exhibit GD1 found in Appendix A. The offsite flows are limited by a flow split after the waterway flows under the interstate. The channel of the flow split that comes east towards the subject property is limited to what fits within the small channel with the remaining flow traveling north or east. Estimates of runoff and their respective calculations for the more local existing drainage basins were completed using the Modified Rational Method. The local basin also uses the required pre-development runoff coefficient of C=0.20. Genesis looked at storm return intervals such as the 10-year,25-year and 100-yr during the analysis of the existing storm water conveyance structures in or near the site. A summary of estimated pre-development peak runoff rates as well as existing drainage conveyance structure capacities can be found in Tables 1 and 2. Detailed calculations are available in Appendix A. 204 N. 11`"Ave., Bozeman,MT 59715 Cell:(406)581-3319 www.q-e-i_net Page 3 of 7 NGtrilEl~R[htC�,iNC Table 1. Estimated Pre-Development Peak Flows(see GD-1) Sub Area Description Area Tc Q10 Q25 Q100 (acres) (min) (cfs) (cfs) (cfs) Offsite Offsite Basin 0.50 11 0.2 0.2 0.3 A Onsite Basin 0.04 9 0.02 0.02 0.03 B Onsite Basin 0.91 15 0.3 0.3 0.5 C Onsite Basin 0.46 13 0.2 0.2 0.3 Table 2. Existing Drainage Conveyance Structure Capacities Description Depth Slope Struct.Cap. (ft) M (cfs) 2'x3'Box Culvert 4 0.5 40.0 West Channel Split 1.4 0.5 16.6 Irrigation Ditch at NE Cnr 2.5 0.4 52.0 III. Proposed Drainage Plan and Estimated Post-Development Peak Flows The proposed drainage plan shall build off of the existing or natural drainage system in place. Genesis' drainage plan consists of two separate drainage systems. First,the major drainage system or backbone is designed to have a much higher conveyance capacity and shall convey the excess runoff from the 100-year storm without inundating any building structures. Secondly,the minor drainage system fits within the major drainage system and feeds into it. The minor drainage system(s)are designed to accommodate moderate and relatively frequent storm events without inconveniencing the public. The minor system is comprised of the streets,inlets,and swales designed to convey runoff from the 25-year event,and the detention pond designed to attenuate the 10-year storm event. Table 3 presents a summary of the expected post-development peak flow rates passing through the proposed project. Table 3. Estimated Post-Development Peak Flows(see GD-1) Sub Area Description Area C Tc Q10 Q25 Q100 (acres) (min) (cfs) (cfs) Icfs) Offsite Mite Basin 0.5 0.41 10 0.4 0.5 0.7 A Onsite Basin 0.04 0.90 9 0.08 0.09 0.1 B Onsite Basin 0.91 0.74 13 1.2 1.4 1.9 C Onsite Basin 0.46 0.60 11 0.5 0.6 0.9 Major Drainage System The major drainage system in the area is comprised of the unnamed ditch to the east of the subject parcel. The existing ditch has adequate capacity to convey the 100-yr event through the development in addition to the existing flows without inundating the first floor of the proposed structures. Based on the proposed first floor elevations and capacity of the unnamed ditch to the east as,we do not anticipate the structures being inundated by storm events up to and including the 100-yr event. Minor Drainage System The proposed minor drainage system for the Osterman Commercial Condos includes an interior parking lot with sheet flow directed into either Pond C or curb inlet which empty to Pond B,generally located in north part of the project. Curb is proposed to direct runoff from the parking area into the above mentioned ponds. The detention ponds are sized to detain the onsite, 10-year storm flows as required.Discharge from the ponds is to be conveyed through the outlet structure, into a storm pipe emptying into the existing irrigation ditch. A 204 N.11" Ave.,Bozeman,MT 59715 Cell:(406)581-3319 vvww.g-a-i.net Page 4 of 7 NGIN�CRING,IC�C Swale,located in the southeastern corner of the project will convey runoff from the south building and offsite, around the south building and into ponds B or C. The existing irrigation ditch at the west split has the capacity of 16.6 cfs, but then almost disappears. The irrigation ditch will be relocated and increased in size in order to handle the 16.6 cfs that is received from the flow split. The 16.6 cfs is combined with the onsite flows and the flows from the 2'x3'culvert and flow down the existing irrigation ditch to the north. The catch curb and gutter of each of the parking lots will convey an estimated 5 cfs before inundating the adjacent sidewalk which is many times greater than the 100-year flow rate contributed by impervious area on site. The pipe leaving detention pond B is a 10" HP Storm pipe has a capacity of 2.0 cfs,which is greater than the 100 year storm flows for that basin.The pipe leaving detention pond C is a 8" PVC Storm pipe has a capacity of 1.1 cfs,which is greater than the 100 year storm flows for that basin. Each of the proposed inlets at the approach have a capacity of 3 cfs,with a 10"pipe capacity of 2.0 cfs which exceeds the contributing Basin B, 100-year post development event. Storm Pond A is a retention pond that is design to handle a portion of the roof flows from the D&R Warehouse Building. Table 4. Detention Pond Volume(See GD-2) Pond Type Depth Contributing Q10 Pre Req.Vol. Avail.Vol. Retains/Detains Subarea (cfs) (cft) (cft) Design Storm A Retention 0.5' A 106 110 Y B Detention(Underground) B 0.3 745 750 Y C Detention 1.0' C 0.2 246 270 Y Table S. Proposed Drainage Conveyance Structure Capacities(See GD-2) Description Contributing Depth Slope Q10PST Q2SPST Q10OPST Qcap Passes Subareas (ft) N (cfs) (cfs) (cfs) (cfs) Design Storm Curb Inlet Pipe B 1.0 0.50 1.2 1.4 1.9 2.0 Y Pond B Outlet Pipe B 1.0 0.50 1.2 1.4 1.9 2.0 Y Pond C Outlet Pipe C 1.0 0.50 0.5 0.6 0.9 1.1 Y Outlet Structure Weir(B) B 1.0 Q10pre=0.29 0.29 Y Outlet Structure Top Inlet(B) B 2.0 Y Outlet Structure Weir(C) C 1.0 Q10pre=0.16 0.16 Y Outlet Structure Top Inlet(C) C 2.0 Y Maintenance Regular maintenance of storm water facilities is necessary for proper functioning of the drainage system. In general, regular mowing of any grass swales and storage ponds and unclogging of inlets and outlet works will be required to prevent standing water,clogging,and the growth of weeds and wetland plants. More substantial maintenance,such as sediment removal with heavy equipment, may be required in coming decades to restore detention pond volume. All maintenance and repair should be prioritized and scheduled in advance. Inlets&pipes should be visually inspected yearly. Typical maintenance items include removing obstructions,cleaning and flushing pipes, mowing grass and weeds,tree maintenance to prevent limbs from falling and blocking swales,and establishing groundcover on bare ground. 204 N. 11`h Ave.,Bozeman,MT 59715 Cell:(406)581-3319 www.q-e-i.net Page 5 of 7 NG[NEERiNG,INC IV. Conclusion Storm water analysis and calculations indicate that the proposed storm water management plan for the proposed site plan is adequate to safely convey the 10-year,25-year,and 100-year storm events while satisfying state and local regulations for peak attenuation and storm water storage. No hazardous backwater affects from downstream structures have been observed to affect the proposed site plan. The project as planned and described within this report will not have any significant adverse effects on any neighboring properties. Furthermore,the proposed first floor elevation for the proposed structures are above the estimated 100-yr Base flood Elevations as estimated by Genesis Engineering. H:\1086\010\DOCS\Design\STORM\StormwaterDR.doc 204 N. 11"'Ave.,Bozeman,MT 59715 Cell:(406)581-3319 www.g-e-i.net `1 Page 6 of 7 NGtNE�RE�tG,ANC Appendix A Exhibits & Calculations "1 204 N. 11"'Ave.,Bozeman,MT 59715 Cell:(406)581-3319 www.o-e-i.net Page 7 of 7 _ FEi _ EXIsnNGCONCNErE _ \�\\\ RETAINING WALL 1 / PROPlzRf-BOUNDA Y�--__ ti yak < '// / XCII r W P'ROPO D 8,6140 SF BUILDIN�a 3TERMAN-DRIVE fin' I II / // I ' \ \\ \•/ \ I I I FFE=4629.20' rn\ 1 \ l r \ n \ a\\ LL LL FUTURE BUILD G SITE\\ I W ® / ADDITIONAL SI PLAN I I 1 / — REVIEW REQUI\ED F_FE=4632.00'\ AT l C-2 \ aw Ws w w w aw OSTERMAN DRIVEPROPERfl'Ap NDARY\ 1 \ / \\\ GRAPHIC SCALE 9 7.5 75 IN FEET) 30 I inch=———————————————— = t i VERIFY SCALE REVISIONS \ DRAWN BY:JRM PROJECT NUMBER THESE PRIMS MAY BE NO. DESCRIPTION DATE BY - OSTERMAN COMMERCIAL CONDOS 1086.010 REDUCED.LINEBELOW CHK'D.BY: MEASURES ONE MMN ON BOZEMAN 760&770 OSTERMAN DRIVE SHEETNUMBER oRCINu BRAwINc. ��1 �m�� 204 N.111h Ave. APPR.BY: MT -- Consulting Design Bozeman,MT 59715 DATE:03/2018 DRAWING NUMBER Phane:(406)581-3319 MODIFY SCALEACCOROINGLY ,,ENGINEERING, INC Planning Q.A.REVIEW STORM BASINS GD-1 BY: H:11 0 8 6101 0V\CADISHEETSIMASTER SITEPLANIISTORM BASINS.dwg Plotted by ohdstopher wash on 4lM0186:14 PM 75e 11r irnrn o u;5`ra�,SturtQur�n Bmmilmrrtt OOPYRIGHfOGENE55 ENGINEERING,INRNt9 DATE: _—_—_--_—— nsnN7lrc"wGNmEru--- 'I _--— -- //Q/ _ __ _ __ � 1\\ EXISTING CONCRETE / — ——'�— `�' c: .�'•ay.cnuT�.�:...v..-...�......f———.———— —-_.———— —— — — '� RETAINING WALL 1 / // / / / i PROPkRfYY BOUNDA Y—— PRdPOSE0110 CF RET TIONPONDA ZONE2NNE----------------- \ \ \\ \ UTIL D-S\E ENT 35 WATERCOURSE \\ 35'WATERCOURSE SETBACK O POSED 270 CF \ \ \ \ \ \ O B \N .75 \ \ SE I \ \ �' \ _ //� ———— \ I \ \ TOP-626,75 ———— I11 \ I I PROPOSED 8,640 SF BUILDIN� / INSTALLS'X4' 760 OSTERMAN DRIVE / SIDEWALK FFE=4�629.20' INSTALL-4r HP STORM PIPE W1 CONCRETE CbLLAR ON END I I I I I I INSTALL S XTHICKENED E6-/ SIDEWALK/ GE I \ \ / I I I \ T 1 I I I I .0%I INSTALL OUTLET STRUCTURE 11 1 a7a I I I ( l 3 I III 11 RAMP I C NB \RTOF T \\ \\\\ \ \ sloEwLnL3)X4 I / !/ za'DRIv AISLE / \\ _ / 1 IIK \\ fr a t / l l l I \ \ \ 1 I I I f I 1 / \\\\ \ \ I o I I I / / N/ N / \ \ \ 1 I I 1 1 \\ GRAPHIC SCA 15 P 777 5 15 / i ITRU CURB SEE / 4O lel I r \, \\\ \ \ '. 0k UEg FUTURE BUILDING SITEINSTALL II II II i' INFILTRATIONNNDERGROUND/ / / / ADDITIONAL SI#PLAN i' STORAGE SYSTEM PER SHEET C4 1 I I I REVIEW REQUIRED \ STORAGE CAPACITY 7&(CFT _FFE=4632.00' \ 5..0% / / / / ✓ / / �¢ / \ INSTALL 48' ZRM 'MAN M NMOLE \ T TAPERSM1YIN 4W _ \ / INSTALL I y aW Ws W W 4W 26'DRIVE ISLE `\\�, — CONCRETE STORM P \PE \. \S IVI+� FLAG-2 ReINLET I \ 4.4% I \ 26.m m \\\ \\\ NCLO XTAPE NG9 10'UTIL 1.NOTES: ALL 7BC DII ARE 3.0'UNLESS OTHERWISE NOTED. ss I \ \ I I \ / 2.ALL CU, GUTTER SHALL INSTALLED PER DETAIL ON OSTERMAN DRIVE I J \ —1 — �J / SHEETC-� \ L I P OPERTi'Ap DAR / 3.SEE LANDSCAPE PLAN FOR LOCATION OF PROPO ED LANDSA� AA \ I \\\ \\\ /` \\ \\\ `\ I� \ \\ I \ T l\ / 4.ALL LAST C PIPE ENDS THAT W ILL BE EXPOSE TO \\ \\ \.\ 1 \ \\\\�' \ 1 1 \ \ / SUNLI HT SHALL HAVE PREFABRICATED END SE IONS OR III CON ETE COLLARS POURED TO PROTECT THE PIPE. 5.C TCH TBC=FLAG+0.38' —I--- I 6.S ILL TBC=FLAG+O-52' 7.TRANS TBC=FLAG+0.45 B. P=SPILL,LOW=LOW POINT,HI=HIGH POINT,VG=VALLEY PUTTER,GB=GRADE BREAK,CA=CATCH. B RGARO'HULLDING \\ \\ \\ I / / / / VERIFYSCALE REVISIONS DRAWN BY:JRM PROJECT NUMBER THESEPAWSMAYBE NO. DESCRIPTION DATE BY OSTERMAN COMMERCIAL CONDOS 1Dss.D10 AEOUCED.LINE BELOW CHICO.BY: MEASURES ONE INCH ON !, ORIGINALDMWING, , �e;,mrmg APPR.BY: BOZEMAN 760&770 OSTERMAN DRIVE SHEETNUMBER I consBmng 2a N. xn Ave. MT > m Bozeman,MT 59715 DATE:03/2018 Design Phone: DRAWING NUMBER MODIFY SCAIEACCORgNGLV Plenning (406)581-3319 q.A.REVIEW XNGINEERING, INC BY: GRADING&DRAINAGE GD-2 H:NO66\0101ACAD\SHEETSSMASTER SITEPLAN\GRADING-DRAINAGE.dwg Plotled by chds4opher wasW Dn 4I2RD16 fi:15 PM ''gTivOr innin o a;tirm,S'tanCarfo Dmmilmrnt COPYRIGHTOGENESKENGINFERING M.201B DATE: GEI#: 1086.01 DATE: 3/19/2018 ENGINEER: JRM RET-Pond-A-lOyr NESIS MODIFIED RATIONAL METHOD NGINEERING, INC Qp=CiA 2')IN 1!1,,a 9Ci>i1A>:.sYr!+'.9"l� , 4C76i!.sI:?a.lS, PRE-DEVELOPMENT RAINFALL FREQ= 10 YR(DURATION=1) 1=A*(Tc/60)_B (CITY OF BOZEMAN) BASIN AREA PRE= 0.04 AC STORM EVENT STORM i COEFF INTENSITY YR A B IN HR PRE-DEV Tc= 10.0 MIN 2 0.36 0.6 1.05 5 0.52 0.64 1.64 PRE-DEV C= 0.20 10 0.64 0.66 2.09 25 0.78 0.64 2.46 STORM A= 0.64 50 0.92 0.66 3.00 B= 0.66 100 1.01 0.67 3.35 STORM INTENSITY= 2.09 IN/HR PRE-DEV Qp= 0.02 CFS POST-DEVELOPMENT POND VOLUME: GONST:RELEASE (CF) BASIN AREA PRE= 0.04 AC POST-DEV Tc= 9.0 MIN TRIANGLE RELEASE DETENTION ( F} POST-DEV C= 0.9 STORM INTENSITY= 2.24 IN/HR AVERAGI V(11 UME' (CF) POST-DEV Qp= 0.08 CFS 39,8 " OUTLET STRUCTURE DESIGN RETENTION (Cf) POND: RET-Pond-A-10yr REQUIRED VOL= 39.86 CF (AVG.B/W CONST.&TRIANGLE RELEASE) DIAMETER= 6.00 IN LENGTH OF PIPE= 10.00 FT QPRE= 0.02 CFS HEAD WATER= 0.50 FT AREA= 0.01 SF N= 0.012 ORIFICE= 4 1/2 IN Ke= 0.50 ORIFICE FLOW= 0.04 CFS SLOPE OF PIPE= 0.010 FT/FT FLOW OUT= 0.34 CFS **NEED ORIFICE AVE SURF AREA= 62.55 SF H:\1086\010\DOCS\Design\STORM\POND A.xls 1 OF 2 PRINTED: 4/9/2018 RET-Pond-A-10yr POND VOLUME CALC'S OUTLET STRUCUTRE CALC'S Triangle Release Constant Release SLOPE OF ENERGY ORIFICE DURATION INTENSITY Qp POND VOLUME POND VOLUME PIPE FLOW OUT (MIN) (IN/HR) (CFS) (CF) (CF) (FT/FT) (CFS) (CFS) 8.55 2.32 0.08 33.97 26.98 0.000 0.000 0.042 9.55 2.15 0.08 35.11 27.76 0.001 0.107 10.55 2.02 0.07 36.13 28.41 0.002 0.151 11.55 1.90 0.07 37.07 28.98 0.003 0.185 12.55 1.80 0.06 37.93 29.45 0.004 0.214 13.55 1.71 0.06 38.71 29.86 0.005 0.239 14.55 1.63 0.06 39.44 30.20 0.006 0.262 15.55 1.56 0.06 40.11 30.48 0.007 0.283 16.55 1.50 0.05 40.73 30.72 0.008 0.303 17.55 1.44 0.05 41.30 30.90 0.009 0.321 18.55 1.39 0.05 41.84 31.05 0.010 0.338 19.55 1.34 0.05 42.34 31.15 0.011 0.355 20.55 1.30 0.05 42.81 31.23 0.012 0.371 21.55 1.26 0.05 43.25 31.26 0.013 0.386 22.55 1.22 0.04 43.66 31.27 0.014 0.400 23.55 1.19 0.04 44.04 31.25 0.015 0.414 24.S5 1.15 0.04 44.40 31.21 0.016 0.428 25.55 1.12 0.04 44.73 31.14 0.017 0.441 26.55 1.10 0.04 45.05 31.05 0.018 0.454 27.55 1.07 0.04 45.34 30.94 0.019 0.466 28.55 1.04 0.04 45.62 30.80 0.020 0.479 29.55 1.02 0.04 45.87 30.65 0.021 0.490 30.55 1.00 0.04 46.11 30.48 0.022 0.502 31.55 0.98 0.04 46.34 30.30 0.023 0.513 32.55 0.96 0.03 46.55 30.09 0.024 0.524 33.55 0.94 0.03 46.74 29.88 0.025 0.535 34.55 0.92 0.03 46.93 29.65 0.026 0.546 35.55 0.90 0.03 47.10 29.40 0.027 0.556 36.55 0.89 0.03 47.25 29.14 0.028 0.566 37.55 0.87 0.03 47A0 28.87 0.029 0.576 38.55 0.86 0.03 47.53 28.59 0.030 0.586 39.55 0.84 0.03 47.65 28.29 0.031 0.596 40.55 0.83 0.03 47.77 27.98 0.032 0.605 41.55 0.82 0.03 47.87 27.67 0.033 0.615 42.55 0.80 0.03 47.96 27.34 0.034 0.624 43.55 0.79 0.03 48.05 27.00 0.035 0.633 44.55 0.78 0.03 48.12 26.66 0.036 0.642 45.55 0.77 0.03 48.19 26.30 0.037 0.651 46.55 0.76 0.03 48.25 25.94 0.038 0.660 47.55 0.75 0.03 48.30 25.57 0.039 0.668 48.55 0.74 0.03 48.34 25.19 0.040 0.677 H:\1086\010\DOCS\Design\STORM\POND A.xls 2 OF 2 PRINTED: 4/9/2018 GEI#: 1086.01 DATE: 3/19/2018 ENGINEER: JRM DET-Pond-B-10yr NESIS MODIFIED RATIONAL METHOD NGINEE RING, INC Qp=CiA 20�N,Ii"I Avf:. PRE-DEVELOPMENT RAINFALL FREQ= 10 YR(DURATION=1) i=A*(Tc/60).g (CITY OF BOZEMAN) BASIN AREA PRE= 0.91 AC STORM EVENT STORM i COEFF INTENSITY YR _ A B T (IN HR PRE-DEV Tc= 15.0 MIN 2 0.36 0.6 0.83 5 0.52 0.64 1.26 PRE-DEV C= 0.20 10 0.64 0.66 1.60 25 0.78 0.64 1.89 STORM A= 0.64 50 0.92 0.66 2.30 B= 0.66 100 1.01 0.67 2.56 STORM INTENSITY= 1.60 IN/HR PRE-DEV Qp= 0.29 CFS POST-DEVELOPMENT POND VOLUME: 'tbNST.RELEASE . lcF BASIN AREA PRE= 0.91 AC 575,18 POST-DEV Tc= 13.0 MIN TRIANGLE RELEASE DETENTION POST-DEV C= 0.74 91A.6fi' STORM INTENSITY= 1.76 IN/HR AVERAGE VOLUME POST-DEV Qp= 1.18 CFS 744.92 OUTLET STRUCTURE DESIGN RETENTION POND: DET-Pond-B-10yr 19gy;gg , REQUIRED VOL= 744.92 CF (AVG.B/W CONST.&TRIANGLE RELEASE) DIAMETER= 6.00 IN LENGTH OF PIPE= 10.00 FT QPRE= 0.29 CFS HEAD WATER= 0.50 FT AREA= 0.05 SF N= 0.012 ORIFICE= 4 1/2 IN Ke= 0.50 ORIFICE FLOW= 0.16 CFS SLOPE OF PIPE= 0.010 FT/FT FLOW OUT= 0.34 CFS **NEED ORIFICE AVE SURF AREA= 1150.37 SF H:\1086\010\DOCS\Design\STORM\POND B.xls 1 OF 2 PRINTED: 4/9/2018 DET-Pond-B-10yr POND VOLUME CALC'S OUTLET STRUCUTRE CALC'S Triangle Release Constant Release SLOPE OF ENERGY ORIFICE DURATION INTENSITY Qp POND VOLUME POND VOLUME PIPE FLOW OUT (MIN) (IN/HR) (CFS) (CF) (CF) (FT/FT) (CFS) (CFS) 12.35 1,82 1,22 685.30 518.07 0.000 0.000 0.156 13.35 1.73 1.16 700.90 527.78 0.001 0.107 14.35 1.65 1.11 715.31 536.24 0.002 0.151 15.35 1.57 1.06 728.69 543.60 0.003 0.185 16.35 1.51 1.02 741.14 549.97 0,004 0.214 17.35 1.45 0.98 752.74 555.45 0.005 0.239 18.35 1.40 0.94 763.59 560.11 0.006 0.262 19.35 1.35 0.91 773.75 564.04 0.007 0,283 20.35 1.31 0.88 783.27 567.29 0.008 0.303 21.35 1.27 0.85 792,21 569.92 0.009 0.321 22.35 1.23 0.83 800.61 571.97 0.010 0.338 23.35 1.19 0.80 808.52 573.49 0.011 0.355 24.35 1.16 0.78 815.96 574.51 0.012 0.371 25.35 1.13 0.76 822.96 575.06 0.013 0.386 26.35 1.10 0.74 829.57 575.18 0.014 0.400 27.35 1.07 0.72 835.79 574.90 0.015 0.414 28.35 1.05 0.71 841.66 574.23 0.016 0.428 29.35 1.03 0.69 847.19 573.19 0.017 0.441 30.35 1.00 0.68 852.40 571.82 0.018 0.454 31.35 0.98 0.66 857.32 570.12 0.019 0A66 32.35 0.96 0.65 861.95 568.11 0.020 0.479 33,35 0.94 0.64 866.31 565.81 0.021 0.490 34.35 0.92 0.62 870.41 563.24 0.022 0.502 35.35 0.91 0.61 874.27 560.40 0.023 0.513 36.35 0.89 0.60 877.90 557.31 0.024 0.524 37.35 0.88 0.59 881.30 553.98 0.025 0.535 38.35 0.86 0.58 884.50 550.41 0.026 0.546 39.35 0.85 0.57 887.49 S46.63 0.027 0.556 40.35 0.83 0.56 890.28 542.64 0.028 0.566 41.35 0.82 0.55 892.89 538.44 0.029 0.576 42.35 0.81 0.54 895.31 534.04 0.030 0.586 43.35 0.79 0.53 897.57 529.46 0.031 0.596 44.35 0.78 0.53 899.66 524.70 0.032 0,605 45.35 0.77 0.52 901.59 519.76 0.033 0.615 46.35 0.76 0.51 903.36 514.66 0.034 0.624 47.35 0.75 0.50 904.99 509,39 0.035 0.633 48.35 0.74 0.50 906.48 503.97 0.036 0.642 49.35 0.73 0.49 907.82 498.40 0.037 0.651 50,35 0.72 0.48 909.03 492.68 0.038 0.660 51.35 0.71 0.48 910.12 486.82 0.039 0.668 52.35 0.70 0.47 911.07 480.82 0.040 0.677 H:\1086\010\DOGS\Design\STORM\POND B.xls 2 OF 2 PRINTED: 4/9/2018 GEI#: 1086.01 DATE: 3/19/2018 ENGINEER: IRM DET-Pond-C-10yr MODIFIED RATIONAL METHOD x NGINEERINGS INC Qp=CIA 704 N.1][ t+v?t. 9:Ssi'ntan:,.MT SS')75 PRE-DEVELOPMENT RAINFALL FREQ= 10 YR(DURATION=1) i=A*(Tc/60)_e (CITY OF BOZEMAN) BASIN AREA PRE= 0.46 AC STORM EVENT STORM i COEFF INTENSITY YR A _ B IN HR PRE-DEVTc= 13.0 MIN 2 0.36 0.6 0.90 5 0.52 0.64 1.38 PRE-DEV C= 0.20 10 0.64 0.66 1.76 25 0.78 0.64 2.08 STORM A= 0.64 SO 0.92 0.66 2.52 B= 0.66 100 1.01 0.67 2.81 STORM INTENSITY= 1.76 IN/HR PRE-DEV Qp= 0.16 CFS POST-DEVELOPMENT POND VOLUME: `CONSTsRELEASE F} �ic }BASIN AREA PRE= 0.46 AC ,2i POST-DEV Tc= 11.0 MIN TRIANGLE RELEASE DETENTION POST-DEV C= 0.6 30fi,94 STORM INTENSITY= 1.96 IN/HR AVERAGE VOLUME POST-DEV Qp= 0.54 CFS '246,09 OUTLET STRUCTURE DESIGN `RETENTION'. POND: DET-Pond-C-10yr 814.75 REQUIRED VOL= 246.09 CF (AVG.B/W CONST.&TRIANGLE RELEASE) DIAMETER= 6.00 IN LENGTH OF PIPE= 10.00 FT QPRE= 0.16 CFS HEAD WATER= 0.50 FT AREA= 0.05 SF N= 0.012 ORIFICE= 4 1/2 IN Ke= 0.50 ORIFICE FLOW= 0.16 CFS SLOPE OF PIPE= 0.010 FT/FT FLOW OUT= 0.34 CFS **NEED ORIFICE AVE SURF AREA= 370.47 SF H:\1086\010\DOCS\Design\STORM\POND C.xls 1 OF 2 PRINTED: 4/9/2018 DET-Pond-C-10yr POND VOLUME CALC'S OUTLET STRUCUTRE CALC'S Triangle Release Constant Release SLOPE OF ENERGY ORIFICE DURATION INTENSITY Qp POND VOLUME POND VOLUME PIPE FLOW OUT (MIN) (IN/HR) (CFS) (CF) (CF) (FT/FT) (CFS) (CFS) 10.45 2.03 0.56 247.04 173.85 0.000 0.000 0.156 11.45 1.91 0.53 253.27 177.15 0,001 0.107 12.45 1.81 0.50 258.88 179.77 0.002 0.151 13.45 1.72 0.47 263.95 181.80 0.003 0.185 14.45 1.64 0.45 268.55 183.30 0.004 0.214 15.45 1.57 0.43 272.72 184.35 0.005 0.239 16.45 1.50 0.41 276.51 184.98 0.006 0.262 17.45 1.45 0.40 279.96 185.24 0.007 0.283 18.45 1.39 0.38 283.11 185.15 0.008 0.303 19.45 1.35 0.37 285.97 184.76 0.009 0.321 20.45 1.30 0.36 288.58 184.08 0.010 0.338 21.45 1.26 0,35 290.95 183.14 0.011 0.355 22.45 1.22 0.34 293.10 181.95 0.012 0.371 23.45 1.19 0.33 295.05 180.54 0.013 0.386 24.45 1.16 0.32 296.81 178.92 0,014 0.400 25.45 1.13 0.31 298.40 177.10 0.015 0.414 26.45 1.10 0.30 299.81 175.10 0.016 0.428 27.45 1.07 0.30 301,08 172.93 0.017 0.441 28.45 1.05 0.29 302.20 170.59 0.018 0.454 29.45 1.02 0.28 303.18 168.10 0.019 0.466 30.45 1.00 0.28 304.04 165.47 0.020 0.479 31.45 0.98 0.27 304.77 162.69 0.021 0.490 32.45 0.96 0.27 305.38 159.79 0.022 0.502 33.45 0.94 0.26 305.89 156.76 0,023 0.513 34.45 0.92 0.25 306.29 153.62 0.024 0.524 35.45 0.91 0.25 306.59 150.36 0.025 0.535 36.45 0.89 0.25 306.79 147.00 0.026 0.546 37.45 0.87 0.24 306.91 143.53 0.027 0.556 38.45 0.86 0.24 306.94 139.97 0.028 0,566 39.45 0.84 0.23 306.88 136.31 0.029 0.576 40,45 0.83 0.23 306.75 132.56 0.030 0.586 41.45 0.82 0.23 306.54 128.73 0.031 0.596 42.45 0.80 0.22 306.26 124.81 0.032 0.605 43.45 0.79 0.22 305.90 120.81 0.033 0.615 44.45 0.78 0.22 305.48 116.73 0.034 0.624 45.45 0.77 0.21 305.00 112.58 0.035 0.633 46.45 0.76 0.21 304.45 108.36 0.036 0.642 47.45 0.75 0.21 303.84 104.07 0.037 0.651 48.45 0.74 0.20 303.17 99.71 0.038 0.660 49.45 0.73 0.20 302.44 95.29 0.039 0.668 50.45 0.72 0.20 301.66 90.80 0.040 0.677 H:\1086\010\DOCS\Design\STORM\POND C.As 2 OF 2 PRINTED: 4/9/2018 GEI#: 1086.01 DATE: 3/9/2017 ENGINEER: JRM BASIN Mite NESIS MODIFIED RATIONAL METHOD ��. I EERI Gy INC Qp=CiA 2Q>a"J.1±Iei:.uL •, 9:I�T.1'h�.M'f'S'i:7"x :R nCf.:?5�.33t9 PRE-DEVELOPMENT RAINFALL FREQ= 10 YR(DURATION=1) i=A*(Tc/60)_e (CITY OF BOZEMAN) BASIN AREA PRE= 0.495409 AC STORM EVENT STORM i COEFF INTENSITY YR A _ B IN HR PRE-DEVTc= 11.0 MIN 2 0.36 0.6 1.00 5 0.52 0.64 1.54 PRE-DEV C= 0.20 10 0.64 0.66 1.96 25 0.78 0.64 2.31 STORM A= 0.64 50 0.92 0.66 2.82 B= 0.66 100 1.01 0.67 3.15 STORM INTENSITY= 1.96 IN/HR PRE-DEV Qp= 0.19 CFS POST-DEVELOPMENT BASIN AREA PRE= 0.495409 AC POST-DEV Tc= 10.0 MIN POST-DEV C= 0.41 STORM INTENSITY= 2.09 IN/HR POST-DEV Qp= 0.42 CFS H:\1086\010\DOCS\Design\STORM\Basin Offsite.xls 1 OF 1 PRINTED: 4/9/2018 GEttt: 1086.01 DATE: 3/9/2017 ENGINEER: 1RM BASIN Offsite MODIFIED RATIONAL METHOD NGINEERING, INC Qp=CiA M4"'9,ittei A, _. DC,1111.i1,MT°S0715 1 100,..tsi 3.1 1:2. PRE-DEVELOPMENT RAINFALL FREQ= 25 YR(DURATION=1) i=A*(Tc/60)_e (CITY OF BOZEMAN) BASIN AREA PRE= 0.495409 AC STORM EVENT STORM i COEFF INTENSITY YR A B IN HR PRE-DEVTc= 11.0 MIN 2 0.36 0.6 1.00 5 0.52 0.64 1.S4 PRE-DEV C= 0.20 10 0.64 0.66 1.96 25 0.78 0.64 2.31 STORM A= 0.78 50 0.92 0.66 2.82 B= 0.64 100 1.01 0.67 3.15 STORM INTENSITY= 2.31 IN/HR PRE-DEV Qp= 0.23 CFS POST-DEVELOPMENT BASIN AREA PRE= 0.495409 AC POST-DEV Tc= 10.0 MIN POST-DEV C= 0.41 STORM INTENSITY= 2.46 IN/HR POST-DEV Qp= 0.50 CFS H:\1086\010\DOGS\Design\STORM\Basin Offsite.xls 1 OF 1 PRINTED: 4/9/2018 GEIM: 1086.01 DATE: 3/9/2017 ENGINEER: 1RM BASIN Mite NESIS MODIFIED RATIONAL METHOD NGINEERING, INC QP=CIA PRE-DEVELOPMENT RAINFALL FREQ= 100 YR(DURATION=1) 1=A*(Tc/60)_e (CITY OF BOZEMAN) -- BASIN AREA PRE= 0.495409 AC STORM EVENT STORM i COEFF INTENSITY YR A B IN HR PRE-DEV Tc= 11.0 MIN 2 0.36 0.6 1.00 5 0.52 0.64 1.54 PRE-DEV C= 0.20 10 0.64 0.66 1.96 25 0.78 0.64 2.31 STORM A= 1.01 50 0.92 0.66 2.82 B= 0.67 100 1.01 0.67 3.15 STORM INTENSITY= 3.15 IN/HR PRE-DEV Qp= 0.31 CFS POST-DEVELOPMENT BASIN AREA PRE= 0.495409 AC POST-DEVTc= 10.0 MIN POST-DEV C= 0.41 STORM INTENSITY= 3.35 IN/HR POST-DEV Qp= 0.68 CFS H:\1086\010\DOCS\Design\STORM\Basin Offsite.xls 1 OF 1 PRINTED: 4/9/2018 GEM 1086.01 DATE: 3/9/2017 ENGINEER: JRM 4 BASIN A E S I S r MODIFIED RATIONAL METHOD 1'�GINEERIN , INC; QP=CIA 2U.N.1! Alt HeSerxt+n,`n7 ;�37.9°: fCki a.�it :&i„! PRE-DEVELOPMENT RAINFALL FREQ= 10 YR(DURATION=1) i=A*(Tc/60)_B (CITY OF BOZEMAN) BASIN AREA PRE= 0.04 AC STORM EVENT STORM I COEFF INTENSITY YR A 8 IN/HR PRE-DEVTc= 10.0 MIN 2 0.36 0.6 1.05 5 0.52 0.64 1.64 PRE-DEV C= 0.20 10 0.64 0.66 2.09 25 0.78 0.64 2.46 STORM A= 0.64 50 0.92 0.66 3.00 B= 0.66 100 1.01 0.67 3.35 STORM INTENSITY= 2.09 IN/HR PRE-DEV Qp= 0.02 CFS POST-DEVELOPMENT BASIN AREA PRE= 0.04 AC POST-DEVTc= 9.0 MIN POST-DEV C= 0.9 STORM INTENSITY= 2.24 IN/HR POST-DEV Qp= 0.08 CFS H:\1086\010\DOCS\Design\STORM\Basin A.xls 1 OF 1 PRINTED: 4l9l2018 GEI#: 1086.01 DATE: 3/9/2017 ENGINEER: 1RM BASIN A E zo:34 1 S MODIFIED RATIONAL METHOD NGINEERING, INC Qp=CiA 2b4 PRE-DEVELOPMENT RAINFALL FREQ= 25 YR(DURATION=1) i=A*(Tc/60)_e (CITY OF BOZEMAN) BASIN AREA PRE= 0.04 AC STORM EVENT -STORM i COEFF INTENSITY YR A B IN HR PRE-DEVTc= 10.0 MIN 2 0.36 0.6 1.05 5 0.52 0.64 1.64 PRE-DEV C= 0.20 10 0.64 0.66 2.09 25 0.78 0.64 2.46 STORM A= 0.78 50 0.92 0.66 3.00 B= 0.64 100 1.01 0.67 3.35 STORM INTENSITY= 2.46 IN/HR PRE-DEV Qp= 0.02 CFS POST-DEVELOPMENT BASIN AREA PRE= 0.04 AC POST-DEV Tc= 9.0 MIN POST-DEV C= 0.9 STORM INTENSITY= 2.63 IN/HR POST-DEV Qp= 0.09 CFS H:\1086\010\DOGS\Design\STORM\Basin A_xIs 1 OF 1 PRINTED: 4/9/2018 GEW 1086.01 DATE: 3/9/2017 ENGINEER: 1RM BASIN A MODIFIED RATIONAL METHOD NGINEERING, INC Qp=CiA 2Gn*.. I 4i6 461330 PRE-DEVELOPMENT RAINFALL FREQ= 100 YR(DURATION=1) i=A*(Tc/60)_B (CITY OF BOZEMAN) BASIN AREA PRE= 0.04 AC STORM EVENT STORM i COEFF INTENSITY YR A B IN HR PRE-DEV Tc= 10.0 MIN 2 0.36 0.6 1.05 5 0.52 0.64 1.64 PRE-DEV C= 0.20 10 0.64 0.66 2.09 25 0.78 0.64 2.46 STORM A= 1.01 SO 0.92 0.66 3.00 B= 0.67 100 1.01 0.67 3.35 STORM INTENSITY= 3.35 IN/HR PRE-DEV Qp= 0.03 CFS POST-DEVELOPMENT BASIN AREA PRE= 0.04 AC POST-DEV Tc= 9.0 MIN POST-DEV C= 0.9 STORM INTENSITY= 3.60 IN/HR POST-DEV Qp= 0.13 CFS H:\1086\010\DOCS\Design\STORM\Basin A.xls 1 OF 1 PRINTED: 4/9/2018 GEIN: 1086.01 DATE: 3/9/2017 ENGINEER: JRM BASIN B NESIS MODIFIED RATIONAL METHOD NGINEERINC., INC QP=CiA PRE-DEVELOPMENT RAINFALL FREQ= 10 YR(DURATION=1) i=A*(Tc/60) ° (CITY OF BOZEMAN) BASIN AREA PRE= 0.91 AC STORM EVENT _- STORM i COEFF INTENSITY YR A B IN HR PRE-DEVTc= 15.0 MIN 2 0.36 0.6 0.83 5 0.52 0.64 1.26 PRE-DEV C= 0.20 10 0.64 0.66 1.60 25 0.78 0.64 1.89 STORM A= 0.64 50 0.92 0.66 2.30 B= 0.66 100 1.01 0.67 2.56 STORM INTENSITY= 1.60 IN/HR PRE-DEV Qp= 0.29 CFS POST-DEVELOPMENT BASIN AREA PRE= 0.91 AC POST-DEV Tc= 13.0 MIN POST-DEV C= 0.74 STORM INTENSITY= 1.76 IN/FIR POST-DEV Qp= 1.18 CFS H:\1086\010\DOCS\Design\STORM\Basin B.xls 1 OF 1 PRINTED: 4/9/2018 GEI✓;: 1086.01 DATE: 3/9/2017 ENGINEER: JRM BASIN B NESIS MODIFIED RATIONAL METHOD ", NGINEERIN , INC QP=CiA „F 'I.CiA N.ii't x+hvs_ .F :?cirrf.sa�l'*n7'+ii'�1S , flfi6`.i513:st� PRE-DEVELOPMENT RAINFALL FREQ= 25 YR(DURATION=1) i=A`(Tc/60) ° (CITY OF BOZEMAN) BASIN AREA PRE= 0.91 AC STORM EVENT STORM i COEFF INTENSITY YR A B IN HR PRE-DEV Tc= 15.0 MIN 2 0.36 0.6 0.83 5 0.52 0.64 1.26 PRE-DEV C= 0.20 10 0.64 0.66 1.60 25 0.78 0.64 1.89 STORM A= 0.78 50 0.92 0.66 2.30 B= 0.64 100 1.01 0.67 2.56 STORM INTENSITY= 1.89 IN/HR PRE-DEV Qp= 0.34 CFS POST-DEVELOPMENT BASIN AREA PRE= 0.91 AC POST-DEV Tc= 13.0 MIN POST-DEV C= 0.74 STORM INTENSITY= 2.08 IN/HR POST-DEV Qp= 1.40 CFS H:\1086\010\DOGS\Design\STORM\Basin B.As 1 OF 1 PRINTED: 4/9/2018 GEI#: 1086.01 DATE: 3/9/2017 ENGINEER: JRM BASIN B NESIS MODIFIED RATIONAL METHOD NGINEERINGf INC Qp=CiA 2f).:^i.7!'[sF i+•ts'. v+,�XF�,4rn�:.^.9T?i<i71`5 :. '.Si¢i'!i:31.-�:31$ PRE-DEVELOPMENT RAINFALL FREQ= 100 YR(DURATION=1) i=A*(Tc/60)_e (CITY OF BOZEMAN) BASIN AREA PRE= 0.91 AC STORM EVENT STORM i COEFF INTENSITY YR A _ 8 IN/HR PRE-DEV Tc= 15.0 MIN 2 0.36 0.6 0.83 5 0.52 0.64 1.26 PRE-DEV C= 0.20 10 0.64 0.66 1.60 25 0.78 0.64 1.89 STORM A= 1.01 50 0.92 0.66 2.30 B= 0.67 100 1.01 0.67 2.56 STORM INTENSITY= 2.56 IN/HR PRE-DEV Qp= 0.47 CFS POST-DEVELOPMENT BASIN AREA PRE= 0.91 AC POST-DEV Tc= 13.0 MIN POST-DEV C= 0.74 STORM INTENSITY= 2.81 IN/HR POST-DEV Qp= 1.90 CFS H:\1086\010\DOCS\Design\STORM\Basin B.xls 1 OF 1 PRINTED: 4/9/2018 GEI#: 1086.01 DATE: 3/9/2017 ENGINEER: IBM BASIN C H MODIFIED RATIONAL METHOD NGINEERING, INC�°_,; �" Qp=CiA 2t7v h3.t!rtt Au4. <M l7t�r[r,tau!N't'?i5i::5 :� af;�',;57..�,:s;R PRE-DEVELOPMENT RAINFALL FREQ= 10 YR(DURATION=1) i=A*(Tc/60)_a (CITY OF BOZEMAN) BASIN AREA PRE= 0.46 AC STORM EVENT STORM i COEFF INTENSITY YR A B IN HR PRE-DEV Tc= 13.0 MIN 2 0.36 0.6 0.90 5 0.52 0.64 1.38 PRE-DEV C= 0.20 10 0.64 0.66 1.76 25 0.78 0.64 2.08 STORM A= 0.64 50 0.92 0.66 2.52 B= 0.66 100 1.01 0.67 2.81 STORM INTENSITY= 1.76 IN/HR PRE-DEV Qp= 0.16 CFS POST-DEVELOPMENT BASIN AREA PRE= 0.46 AC POST-DEV Tc= 11.0 MIN POST-DEV C= 0.6 STORM INTENSITY= 1.96 IN/HR POST-DEV Qp= 0.S4 CFS H:\1086\010\DOCS\Design\STORM\Basin C.xls 1 OF 1 PRINTED: 4/9/2018 GEI#: 1086.01 DATE: 3/9/2017 ENGINEER: JRM BASIN C NESIS MODIFIED RATIONAL METHOD NGINE RING, INC Qp=CIA n'.04^i.712e£Xuk.. .. f:7zE�.taa.',!NT?*<'➢31� .. F:;t4:igi.,?3 tL+ PRE-DEVELOPMENT RAINFALL FREQ= 25 YR(DURATION=1) i=A*(Tc/60)-B (CITY OF BOZEMAN) BASIN AREA PRE= 0.46 AC STORM EVENT STORM i COEFF INTENSITY YR A B IN HR PRE-DEV Tc= 13.0 MIN 2 0.36 0.6 0.90 5 0.52 0.64 1.38 PRE-DEV C= 0.20 10 0.64 0.66 1.76 2S 0.78 0.64 2.08 STORM A= 0.78 50 0.92 0.66 2.52 B= 0.64 100 1.01 0.67 2.81 STORM INTENSITY= 2.08 IN/HR PRE-DEV Qp= 0.19 CFS POST-DEVELOPMENT BASIN AREA PRE= 0.46 AC POST-DEV Tc= 11.0 MIN POST-DEV C= 0.6 STORM INTENSITY= 2.31 IN/HR POST-DEV Qp= 0.64 CFS H:\1086\010\DOGS\Design\STORM\Basin C.xls 1 OF 1 PRINTED: 4/9/2018 GEI#: 1086.01 DATE: 3/9/2017 ENGINEER: 1RM BASIN C :, w ifflEsis MODIFIED RATIONAL METHOD N INEERING, INC Qp=CiA ?Q) 11 1111,AVS.. PRE-DEVELOPMENT RAINFALL FREQ= 100 YR(DURATION=1) i=A*(Tc/60)_e (CITY OF BOZEMAN) BASIN AREA PRE= 0.46 AC STORM EVENT STORM i COEFF INTENSITY YR A B IN HR PRE-DEV Tc= 13.0 MIN 2 0.36 0.6 0.90 5 0.52 0.64 1.38 PRE-DEV C= 0.20 10 0.64 0.66 1.76 25 0.78 0.64 2.08 STORM A= 1.01 50 0.92 0.66 2.52 B= 0.67 100 1.01 0.67 2.81 STORM INTENSITY= 2.81 IN/HR PRE-DEV Qp= 0.26 CFS POST-DEVELOPMENT BASIN AREA PRE= 0.46 AC POST-DEV Tc= 11.0 MIN POST-DEV C= 0.6 STORM INTENSITY= 3.15 IN/HR POST-DEV Qp= 0.87 CFS H:\1086\010\DOGS\Design\STORM\Basin C.xls 1 OF 1 PRINTED: 4/9/2018 81nch PVC Project Description Friction Method Manning Formula Solve For Discharge Input Data Roughness Coefficient 0.010 Channel Slope 0.00500 ft/ft Normal Depth 0.67 ft Diameter 0.67 ft Results Discharge 1.13 ft'/s Flow Area 0.35 ftz Wetted Perimeter 2.10 ft Hydraulic Radius 0.17 ft Top Width 0.00 ft Critical Depth 0.50 ft Percent Full 100.0 % Critical Slope 0.00601 ft/ft Velocity 3.19 ft/s Velocity Head 0.16 ft Specific Energy 0.83 ft Froude Number 0.00 Maximum Discharge 1.21 ft'/s Discharge Full 1.13 ft'/s Slope Full 0.00500 ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 It Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Normal Depth Over Rise 100.00 Downstream Velocity Infinity ft/s Bentley Systems,Inc. Haestad Methods Sotii&dle(CEtdwMaster V8i(SELECTseries 1) [08.11.01.03] 4/2/2018 6:13:36 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06796 USA +1-203-755-1666 Page 1 of 2 81nch PVC GVF Output Data Upstream Velocity Infinity f/s Normal Depth 0.67 ft Critical Depth 0.50 ft Channel Slope 0.00500 ft/ft Critical Slope 0.00601 ft/ft Bentley Systems,Inc. Haestad Methods SoBdfdtapidwMaster V81(SELECTseries 1) [08.11.01.031 4/2/2018 5:13:36 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 2 of 2 101nch PVC Project Description Friction Method Manning Formula Solve For Discharge Input Data Roughness Coefficient 0.010 Channel Slope 0.00500 ft/ft Normal Depth 0.83 ft Diameter 0.83 ft Results Discharge 1.99 ft'/s Flow Area 0.54 ft2 Wetted Perimeter 2.61 ft Hydraulic Radius 0.21 ft Top Width 0.00 ft Critical Depth 0.63 ft Percent Full 100.0 % Critical Slope 0.00577 ft/ft Velocity 3.68 ft/s Velocity Head 0.21 ft Specific Energy 1.04 ft Froude Number 0.00 Maximum Discharge 2.14 ft'/s Discharge Full 1.99 ft'/s Slope Full 0.00500 ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Normal Depth Over Rise 100.00 Downstream Velocity Infinity ft/s Bentley Systems,Inc. Haestad Methods SoBdidlepEldwMaster VBi(SELECTseries 1) [08.11.01.03] 4/2/2018 6:13:59 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 2 101nch PVC GVF Output Data Upstream Velocity Infinity ft/s Normal Depth 0.83 ft Critical Depth 0.63 ft Channel Slope 0.00500 ft/ft Critical Slope 0.00577 ft/ft Bentley Systems,Inc. Haestad Methods SoHdidlepElriwMaster V8i(SELECTseries 1) 108.11.01.031 4/2/2018 6:13:59 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203.755-1666 Page 2 of 2 Irrigation Ditch NE Corner Project Description Friction Method Manning Formula Solve For Discharge Input Data Channel Slope 0.00400 ft/ft Normal Depth 2.64 ft Section Definitions Station(ft) Elevation(ft) 0+00 4827.48 0+08 4827.12 0+11 4824.05 0+13 4824.64 0+19 4826.69 Roughness Segment Definitions Start Station Ending Station Roughness Coefficient (0+00,4827.48) (0+19,4826.69) 0.030 Options Uurrent rtougnness vveigntea Pavlovskii's Method Method Open Channel Weighting Method Pavlovskii's Method Closed Channel Weighting Method Pavlovskii's Method Results Discharge 51.67 ft'/s Elevation Range 4824.05 to 4827.48 ft Flow Area 14.70 ft2 Wetted Perimeter 12.37 ft Hydraulic Radius 1.19 ft Top Width 10.92 ft Normal Depth 2.64 ft Critical Depth 2.04 ft Bentley Systems,Inc. Haestad Methods So89idlefftdwMaster V8i(SELECTseries 1) [08.11.01.031 4/2/2018 3:56:56 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 2 Irrigation Ditch NE Corner Results Critical Slope 0.01522 ft/ft Velocity 3.52 ft/s Velocity Head 0.19 ft Specific Energy 2.83 ft Froude Number 0.53 Flow Type Subcritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Normal Depth 2.64 ft Critical Depth 2.04 ft Channel Slope 0.00400 ft/ft Critical Slope 0.01522 ft/ft Bentley Systems,Inc. Haestad Methods So6didlePEldwMaster V8i(SELECTseries 1) [08.11.01.03] 4/2/2018 3:56:56 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-765-1666 Page 2 of 2 West Split Project Description Friction Method Manning Formula Solve For Discharge Input Data Channel Slope 0.00500 ft/ft Normal Depth 1.40 ft Section Definitions Station(ft) Elevation(ft) -0+02 36.30 0+00 36.00 0+05 35.64 0+07 34.75 0+09 35.04 0+10 35.96 0+13 36.18 Roughness Segment Definitions Start Station Ending Station Roughness Coefficient (-0+02,36.30) (0+13,36.18) 0.030 Options current ttougnness vveignteo Pavlovskii's Method Method Open Channel Weighting Method Pavlovskii's Method Closed Channel Weighting Method Pavlovskii's Method Results Discharge 16.58 ft'/s Elevation Range 34.75 to 36.30 ft Flow Area 7.29 f(Z Wetted Perimeter 13.91 ft Hydraulic Radius 0.52 ft Top Width 13.27 ft Bentley Systems,Inc. Haestad Methods SoG&dh!PEh1wMaster V8i(SELECTseries 1) [08.11.01.031 4/2/2018 3:45:17 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 2 RECONSTRUCTED CHANNEL Project Description Friction Method Manning Formula Solve For Discharge Input Data Roughness Coefficient 0.030 Channel Slope 0.02500 ft/ft Normal Depth 0.87 ft Left Side Slope 2.00 ft/ft(H:V) Right Side Slope 2.00 ft/ft(H:V) Bottom Width 2.00 ft Results Discharge 17.15 ft'/s Flow Area 3.25 ft2 Wetted Perimeter 5.89 ft Hydraulic Radius 0.55 ft Top Width 5.48 ft Critical Depth 0.96 ft Critical Slope 0.01677 ft/ft Velocity 5.27 ft/s Velocity Head 0.43 ft Specific Energy 1.30 ft Froude Number 1.21 Flow Type Supercritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 f: Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Normal Depth 0.87 ft Critical Depth 0.96 ft Channel Slope 0.02500 ft/ft Bentley Systems,Inc. Haestad Methods So6&dtef&EMarMaster VSi(SELECTseries 1) [08.11.01.03] 4/2/2016 7:45:01 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06796 USA +1-203-755-1666 Page 1 of 2 RECONSTRUCTED CHANNEL GVF Output Data Critical Slope 0.01677 ft/ft Bentley Systems,Inc. Haestad Methods SoRdidlef&EfderMaster V8i(SELECTseries 1) [08.11.01.031 4/2/2018 7:45:01 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06796 USA +1-203-755-1666 Page 2 of 2 NESIS ISIGI EERING, INC ?fir+sgvwingofa�5irl.StartderdgF�unnsitatnt Osterman Commercial Condos/D&R Warehouse Storm Pond C Engineer: J. May 04/02/18 36" Round Outlet Structure - Pond B 10 year pre 0.16 cfs 25 year post 0.6 cfs Weir Height 1 ft Using COB Weir Equation 10 yr flow through slot = CLHA(3/2) Q= 3.33*L'1.0(3/2) 0.16 cfs L=0.048' Qr� wide During storms greater than the 10 year, some additional flow will overtop the weir and flow through the outlet pipe. Remainder of flow up will enter the inlet on top of the structure. NESIS NGINE RING, INC "" :....,.p- 'Ihe31r�sexro,»gnfx..`.Yeu,Sfare,farlu}'fomttitwr»E Osterman Commercial Condos/D&R Warehouse Storm Pond B Engineer: J. May 04/02/18 36" Round Outlet Structure - Pond B 10 year pre 0.29 cfs 25 year post 1.4 cfs Weir Height 1.33 ft Using COB Weir Equation 10 yr flow through slot = CLHA(3/2) Q= 3.33*L*1.5(3/2) 0.29 cfs L=0.057' 0 irk ,, wide During storms greater than the 10 year, some additional flow will overtop the weir and flow through the outlet pipe. Remainder of flow up will enter the inlet on top of the structure. D&R Warehouse 3/19/2018 BASIN Offsite BASIN A Weighted C Weighted C Area(sf) 21580 Area(sf) 1942 Area(Acres) 0.50 Area(Acres) 0.04 Area Impervious(0.9) 6528 Area Impervious(0.9) 1942 Area Grass(0.2) 15052 Area Grass(0.2) 0 Weighted C= 0.41 Weighted C= 0.90 BASIN B BASIN C Weighted C Weighted C Area(sf) 39667 Area(sf) 19960 Area(Acres) 0.91 Area(Acres) 0.46 Area Impervious(0.9) 30754 Area Impervious(0.9) 11509 Area Grass(0.2) 8913 Area Grass(0.2) 8451 Weighted C= 0.74 Weighted C= 0.60 Typical Values for the Rational C Coefficient (McCuen, Richard H., Hydrologic Analysis and Design, 3rd Ed.,Pearson Prentice Hall, 2005. TABLE 7,9 Runoff Coefficients for titer Rational Formula versus Hydrologic Soil Gtoup 1R,8,C,t)i and Slope Annge A B C 1) lams tJse, O 2% 2-5, fi' to 2M, -2-6T, iml fir 2":1 2 G`,> G-2% 2-4Y%_.6__ Cultivatz;d land 0,0V 0.13 0.lfi (.Bat 0115 0.21 0.14 4.199 0.216 0.18 0?3 031 0,14e 0.18 0.22, 0,16 0;2' 0,28 UO 0.25 0,34 0.24 0.29 0.41 P"mare. 0.12 ON 0,30 OAS 0.2s 0,37 U4 0:34 0,44 0.30 0.40 0,50 OM Q25 0.37 0.29 g.34 U.45 0,30 (w'z 0.52 0.17 01.50 0.62. Meadow 0,10 0,16 US 0.14 0,22 0.30 ON 0.28 £1-36 0,24 030 0,40 014 0,22 0.30 £320 0.28 0.37 UO 0,35 Q.44 0.30 OAO 0,50 forest 0.05 0.18 0.11 010S tt.ft 414 0,10 013 Q.16 0.12 0,16 010 0.08 Oil 0.1.1 0AO 0,14 0.t,S 0,11 0,16 0,20 0,15 0.110 0,25 ReSid(Craia) lot 025 028 (01 £i,,'.7 Usti 035 0.30 e3."53 111,38 033 0,36 0,42 siac 1:9 av're 0.33 U. ' 0140 0. 5 (}3u 6,1111 ii x8 0.41 0,19 041 045 0,54 Residential lot 0.22 0.'6 0.20 0.2.1 0.29 0,13 0,27 101 0.36 1'1.3ti 0.314 0.40 size 114aac 0:30 0.34 017 031 037 0.42 D16 0.40 0.47 03t tlAZ 0.52 Residential lot 019 0.23 0'26 O22 0,26 0.3u 0k25 029 034 0.28 0.32 0.39 stm 1.'3 acre 0.28 032 0.35 0.30 0,35 O)IQ W33 (1 38 043 1t30 0,40 0.4) Residrnlial lot 0.16 0.20 0-4 0.19 0.23 0,29 0,22 0,27 0,31 0.26 0'30_ 0.37 size 112 acre 0.2.5 0.29 0.32 0 2S 0.32 (IM, £131 0 3S 0.42 034 0..38, OAS l~x;mdQ1[ttt lot 0.14 0.19 0,22 0.17 0.21 0.26 0,20 0.25 0.31 0,<4 029 0.3 Sig,1 sere 87.22 4}26 0.19 Q.24 0.28 034 0.2S 032 0.40 0.31 0.3j U.46 Industrial G.67 0.69 C1,68 0.t 06.K (09 0.6$ 0.69 tr(0 f169 0.69 Qi-O 0,85 0.85 0.86 0,15 ).tiE 0.156 Q,S6 0.$6 o'87 016 0.36 0.43 Commerciat 0,71 0,71. 072 031 0.72 O.i2 0.72 0.72 0.72 0,72 072 072 O's8 7.63 O.S9 0.87 0.89 0.49 0.40 0.89 0.90 0.89 0.89 0,90 Sirens 0.?11 101 0.72 031 0.72 0.74 0.72 03,1 0.76 0.73 0.75 0,IS 0.76 0.77 0.70 0.84? 11&2 0.84 0.84 0.85 0.8e) 0,89 0.91 0.95 Open space 0.05 0.10 0.14 01% 0.13 0,19 0.12 0,17 0.24 016 021 0.28 0.11 0.16 0.20 0.14 0a9 0,26 0.14 17.23 0.32 0.2-' 0127 £t,a Parkine 0.85 0.86 UP 0.=5 0.S6 0.;57 0.8,5 0.86 0.87 0,85 i7.86 01$7 (1,95 0,96 O,W 0.95 0.'% 0.97 0195 10,96 0.47 U.95 0.% t07 "Run off coefficietats for stoun.e,cu fro,ice intervals t s than 25 yests Run aif eoe fficaenis for s€orot ie atrtenc e intervals of 25 soars or hmgov Osterman Commercial Condos Storm Water Facilities Operation & Maintenance Manual Overview The HOA is responsible for maintaining all of the onsite Storm Water Facilities,including storm inlets,storm pipe and the storm water detention pond per the schedule below. Maintenance The storm inlets and pond outlet structure are to have the sediment removed from the sediment traps on a yearly basis or an updated maintenance schedule as determined by monitoring the sediment build-up of the inlets quarterly. The storm pipe between the storm inlets is to be monitored yearly for build-up of sediment or trash. If the storm system is operating correctly the build-up should be minimal and therefore maintenance schedule will be directly correlated to the yearly inspection findings. The storm water ponds shall be monitored every five years for sediment build-up. When the sediment build-up starts to decrease the capacity of the detention pond the sediment shall be removed mechanically and hauled from the site. It the extraction of the sediment removes the vegetation from the bottom of the pond, it should be reseeded or re- sodded and appropriate storm water BMPs are to be installed until the vegetation is stabilized. The underground storm water detention pond shall be monitored yearly with maintenance occurring when two inches of sediment is measured within the first lateral. The storm manhole that feeds the underground pond shall be cleaned of sediment at least yearly to reduce the sediment load going into the underground pond. The owners of the first constructed building will be responsible for maintenance of all of the above items until an HOA is in place or until a second building is constructed. If two buildings are occupied,a HOA must be created which will takeover all maintenance. Contact Information Property Manager: Association President: st ENGINEERING _.. + CONSULTING PLANNING NC # dG NEEE,BZEGy I 5 204 N.III'Ave BOZEMAN,MT 59715 406-581-3319 . �B eIGN 2Ad NOliiN iitn AVENUE,6OXFMAN,MT 55Ti5 April 41h, 2018 Griffin Nielsen City of Bozeman Engineering 20 East Olive Street Bozeman, MT 59771 Re: Osterman Commercial Condos Master Site Plan 760&770 Osterman Drive Groundwater/Storm Water Ponds Dear Griffin, This letter is to serve as the ground water monitoring information for the storm water ponds for the Osterman Commercial Condo/D&R Warehouse Site. The groundwater levels have been visually observed in respect to the deep irrigation ditch on the east property line since last summer. No groundwater has been witness entering the side walls of the irrigation ditch and there is no vegetation evidence that groundwater has historically entered the side of the ditch. The ditch bottom is below the bottom of each of the ponds and therefore acts as an adequate groundwater monitoring station.The proposed ponds are all less than one foot below native ground with the exception of the south end of the southeast detention pond. The southeast pond is immediately adjacent to the deep irrigation ditch with the bottom of the pond being over three feet above the bottom of the irrigation ditch. The geotechnical test pits found evidence of groundwater as high as four feet below ground surface which is additional proof that the ponds are above the seasonal high groundwater. We are comfortable continuing design and construction of the storm ponds with the above information but have installed a groundwater monitoring wells to be able to gather information this spring. We reserve the right to adjust the pond designs if new information is discovered. If you have any questions or comments, please contact me at 581-5730 Sincerely, Za J e riTny , P.E. Genes Engineering, Inc. w tw.g-e-i.net H:\1086\010\DOCS\Design\STORM\groundwater letter.docx 204 N. 11'h Ave.,Bozeman,MT 59715 Cell:(406)581-3319 www.q-e-i.net Page 1 of 1