The URL can be used to link to this page

Home My WebLink About13 - Design Report - South University District Ph 1 & Stadium View Apartments - Sewer0nSewer Main Extension Engineer's ReportSouth University District - Phase 1, andStadium View ApartmentsFebruary 2013Submitted to:City of Bozeman Engineering Department20 East OliveBozeman, MT 59715Montana Department of Environmental QualityPermitting and Compliance DivisionPublic Water and Subdivisions BureauPO Box 200901Helena, MT 59620-0901Prepared by:Stahly Engineering and Associates7585 Shedhorn DriveBozeman, MT 59718(406) 522-9526^w^^yEST.STAHLY^^^ 0r-iEngineer's ReportContentsNote: The Engineer's Report format for the South University District Phase 1,and Stadium View Apartments Sewer Main Extension follows DEQ-2organization. Additional information required by the City of Bozeman DesignStandards is added where required.Report NarrativeChapter 10 - Engineering Reports & Facility Plans11.1 Engineering Report11.11 Problem Defined11.12 Design Conditions11.13 Impact on Existing Wastewater Facilities11.14 Project Description11.15 Design Criteria11.16 Site Information11.17 Environmental ImpactsFigures and TablesFigure 1. Vicinity MapFigure 2. Sewer Site Plan (C3.0 - included separately)Table 1. Estimated Water Use DataTable 2. Capacity of 8" SDR 35 PVC Sewer MainSewer Mains12/6/2014 n11.1 Engineering ReportThe South University District - Phase 1 subdivision is located within theCity of Bozeman adjacent to South 11th Street and south of KagyBoulevard. The subdivision is located west of Bobcat Stadium and issouth of the existing Stadium Center Subdivision. The subdivisionconsists of 3 lots, road right-of-way, and park. Lot 1 is a proposed 9.82acre site for the Stadium View Apartments, a 499-bed student housingfacility which is currently under review. Lots 2 and 3 are futuredevelopment tracts and are not proposed for development with thissubdivision.The property developer's contact information is:Fountain Residential Partners2626 Cole Ave, Suite 620Dallas, TX 75204Water supply and wastewater treatment will be provided by the City ofBozeman's municipal systems. The system owner's contact informationis:City of Bozeman Public Service DepartmentPO Box 1230Bozeman,MT 59771-1230The location of the South University District - Phase 1 is shown on theVicinity Map in Figure 1 .Sewer Mains22/6/2014 nnfsjtt^y-tt4TW-J>'»>••7i:!p%S»»rVwwIE/.k"-f.^^•)5I/I^^'•*!^v^^*•eti^.1\PHASE 1SUBDIVISION28.06 ACRESt"S:k., -STADIUM VIEWI 9.82 ACRES(HATCHED)'t^^,\"K[i1^^?N1i?<3.(HI-•iy>'A.SOUTti UNIVERSHY DISTPICT126.9,3 ^CRESM-. sIttFigure 1. Vicinity Map, Bozeman, Montana11.11 Problem DefinedCity of Bozeman sewer mains currently extend to the northern boundary ofthe property. Connection to the existing sewer infrastructure will takeplace at this point. The location of the existing mains and proposedextensions to the sewer system are shown in Figure 2, a large mapincluded separately.An 8" trunk sewer main flows from south to north through the center of theStadium Center Subdivision and continues north eventually reaching theBozeman Wastewater Treatment Plant. Separate analysis of the ability ofthe existing sewer to convey the additional sewer flow was conducted inSeptember, 2011 and showed the existing infrastructure has capacity toserve Lot 1. The proposed Stadium View Apartments in Lot 1 will beserved by 8" sewer mains which will connect to the existing 8" sewer mainon the northern border of the development at South 12th Avenue (AriannaWay).Sewer Mains32/6/2014 nFi11.12 Design ConditionsThe sewer flow contributed by the proposed Stadium View Apartmentswithin South University District - Phase 1 was determined in accordancewith the City of Bozeman Design Standards. The site for Stadium ViewApartments (Lot 1) consists of a gross lot area of 9.82 acres. The net lotarea includes the student housing development with an 1800 SFcommercial shell. The peaking factor used was based on the totalpopulation at the north connection to the existing sewer at South 12thAvenue. The sewer flow estimates for the Stadium View Apartmentswithin Phase 1 are shown in Table 1, below.Table 1 Stadium View Apartments Sewer Flow EstimateTotal Site Area (acres)9.82l&l rate gpd/acre150l&l Flow (gpd)1473Student Housing Residents499per capita flow (gpd)89Student hlousing Flow (gpd)44,411Non-residential Employees4per capita flow (gpd)15Non-residential Employee Flow (gpd)601800 SF Commercial Shell1Estimated Flow (gpd/unit)400Phase 1 Commercial Flow (gpd)400Total Daily Flow (gpd)46,344Total Daily Flow (gpm)32.2Peaking Factor3.97Peak Flow (gpm)127.6The proposed 8" SDR 35 PVC sewer mains installed at the minimumslope of 0.4% have a flow capacity of 309 gpm using 75% of the flowdepth of the pipe as required by the City of Bozeman Design Standardsand Specifications Policy. See Table 2 below for the parameters used inthe flow calculation.Sewer Mains42/6/2014 n0Table 2. Capacity of 8" SDR 35 PVC Sewer MainStatusLocationPipe MaterialPipe Diameter (in)Minimum Pipe Slope (Wft)Coefficient of Roughness (n)Depth in Pipe at 75% Full (in)Depth of Flow (ft)Pipe Radius (in)Pipe Radius (ft)Wetted PerimeterArea of Flow (ft2)Hydraulic RadiusVelocity (ft/sec)Maximum Pipe Flowrate (gpm)Avg Flow % of Max CapacityProposedPhase 18" SDR 35 PVCPeak Flow % of Max Capacity80.0040.01360.5040.331.400.280.202.45308.910.4%41.3%The minimum allowed slope in the minimum pipe size allowed hassufficient capacity to convey the peak flow from Lot 1 .To allow easier maintenance 6" sewer services are provided for Buildings1 through 8. The maintenance building and outdoor amenity building willbe served by 4" lines.11.13 Impact on Existing Wastewater FacilitiesAs previously described, Lot 1 consists of a proposed student housingdevelopment on 9.82 acres of the 127-acre South University Districtproperty. An existing city sewer main is stubbed to the north property lineof Lot 1 at South 12 Avenue. In an effort to utilize existing infrastructure,the capacity of this line to serve Lot 1 was evaluated. The existing servicearea of this line was determined and peak flows estimated based onexisting land use. An initial review of pipe capacity showed the limitingsection of this sewer to be located in the alley between 19th and 20thbetween Olive and Babcock streets. The flows were monitored for 33days between August and September of 2011 and correlated to wetweather peak flows measured at the treatment plant in early summer.Sewer flow contributions were determined for the proposed developmentusing the City's design standards. The existing pipe's capacity wasevaluated with the existing wastewater flows adjusted to wet weatherconditions and the addition of Lot 1 contributions. The existing pipe is atapproximately 66% of its 75% flow depth capacity under wet weather peakSewer Mains52/6/2014 nnflows. Lot 1 will contribute flows equivalent to an additional 21% of theexisting pipe's 75% flow depth capacity, for a total pipe utilized capacity of87% of the 75% flow depth. This evaluation shows the existing pipe hascapacity to serve the Stadium View Apartments within its 75% flow depthat peak flow conditions.11.14 Project DescriptionThe Stadium View Apartments project is the first development phasewithin the Master Planned SUD Residential Emphasis Mixed Use (REMU)zoning district. The first subdivision phase of the South University Districtis proposed simultaneously with the Stadium View Apartments project.The subdivision will create the 9.82-acre student housing lot as well asprovide public streets and parkland.Eight major structures are proposed within the Stadium View Apartmentproject: two "mixed use" buildings along South 11 Avenue, and sixstudent residential buildings. The mixed use buildings along 11l will beconstructed to provide ground floor commercial uses with residential unitsabove. The northern building will house the leasing office, clubhouse, anda small commercial tenant space. The southern building will haveresidential ground floor uses until market conditions support re-purposing.Altogether, the eight buildings provide 139 living units and 499 studentbedrooms.Lot 2 and Lot 3 are not being developed at this time11.15 Design CriteriaThe South University District - Phase 1 and Stadium View Apartmentssewer main extensions were designed in accordance with MontanaDepartment of Environmental Quality Circular 2, Montana Public WorksStandards and Specifications, City of Bozeman Modifications to MontanaPublic Works Standards and Specifications, the Uniform Plumbing Code,and the City of Bozeman Wastewater Facility Plan.11.168itelnformationThe site is typical of Bozeman with fine grained soils overlying graveldeposits. Geotechnical borings have determined the depth to gravelranges from 7 to 10 feet. Estimated depth to groundwater obtained fromthe geotechnical borings is 6-13 feet. If mains are installed during highgroundwater times dewatering may be required.Sewer Mains62/6/2014 nn11.17 Environmental ImpactsContinued use and new extensions of City of Bozeman municipal sewermains has the least environmental impact. No new environmental impactswill be caused by these sewer main extensions.Sewer Mains72/6/2014 r-!„„^vh—"T-IE,Tr-rSTAHLYPROJECT BEKCHMARKARROW BOLT ONHYDRANT ELi 49.35.33</<SJ"»-L-—_________.._.L_'STADrUM''CENTERSU~BDMSiONL—-1-J„-}.CONNECT TOEXISTING SEWEREST INV 4922.00(0»UJi»4 yQrI-ssHASE 1 BOUNDARY°jsl!<I^SII'ill0^lt!s^STATE ST.\ni5>2^-" ^^^BUILDING 333 UNFTS /105 BDRMS.BUILDING 512 UNFTS /48 BDRMS.BLDG712 UNITS/4S BDRMS.6'^)5'GREASE|TRAE1?-^{^-^^E "" SJss^£wQuSE'AER SIZEyft•^•r^^"1'-'7 (JSF.)^^ftnft3 S^KeBRlros I'?;o£—Iew i ururMj/iUR-INIMUuiNI^-STUB FOR FUTUREMAIN EXTENSION-^§^?a"K8'CD^-+&4&^1-UI>-^>-105 SPACES Is85 SPACES^itlis I It!CD^li^<a^1(03n'rmiiun•+0FUTURE PHASE LOTmsl^l^lsrePHASE 1 LOT9.82ac.^LUco4-^?--Ii<§^Si-IIEsU3'sQ-1gs5^^sLUfflKuU i I I'-i-J I i ^ U'sy.Li'i"u></jLLJ:>"><•.!''1.^105 SPACES•t?T3'I85 SPACESh-PHASEg\-1rM^.~7-rorPARK"sSTORMWATERDETENTIONz81ffi8-8-nnim-^sSTUB FOR FUI'UREMAIN EXTENSION-31.E3gBUILDINGSERVICE(TW).-.0>"\BJs'CQ usftV)R<s<SSBLDG8L;uBUILDING 4BUILDING 612 UNITS /48 BDRMS,1U12UNFTS/u.33 UNITS/105BDRMS.??48 BDRMS.<25QU<^IIJIw cam<wCAMPUS BLVD.(STUCKYROAD)o'mgl<z°5T-3^<uj i ° sw E z Pl3a 3Q F Qa. w a coa.--jy—^i"rma;FUTURE PHASE LOT''«.~<<^IUsm^'•'^r^i^li;73^i&3®!^&iiyCDPCDPPAWN0 25 50100CDPHECKED.,TE 11/13/13aau—-SCALE IN FEETSHEETAC3.0