HomeMy WebLinkAbout99 - Design Report - Allison Minor Subdivision - Water, Sewer, Streets1111111]1DESIGN REPORTforALLISON MINOR SUBDIVISIONWater, Sewer, and Street ImprovementsApril, 1999J]]J|^ 1G692ES J^J"-^yIJJPrepared by:MORRISONMAIERLE,INC.An J^mpioyev—OTj^Ttsd. Compa.n'yENGINEERSSCIENTISTSSURVEYORSPLANNERSSiNCE 18d5^opv?;g?lt !&<i«RECEIVED MAY 2 ^ 1999
INTRODUCTIONAllison Minor Subdivision contains 1.18 acres and is located just north of Morning Star School inthe Northeast comer of Section 24, Township 2 South, Range 5 East P.M.M.. Arnold Street makesup the South boundary of the minor subdivision. The purpose of this report is to provide the basisfor the design of the water, sewer, and streets improvements.WATER SUPPLYThere in an existing 10" water main running 11' north of the centerline of Arnold Street. Four (4)water services and a fire hydrant will be tapped into the existing main. With these minor additionsthe existing main provides adequate service to meet the consumptive demands for this development.SEWAGE DISPOSALA 8" sewer main currently exists in Arnold Street. The proposal is to extend the 8" main to the westapproximately 205 LF. The only effluent flowing through the existing manhole in Arnold Streetcomes from the elementary school.The following assumptions are the basis for wastewater demand calculations:1. 3-bedroom homes having daily wastewater flow of 350 gallons/day2. 4 persons per home3. Peak Flow Factor = 18 + v^P where P = population in thousands4+^PNOTES:1.2.3.LOTS 1-4WASTEWATER FLOW (GPM)PERSONSAVE. FLOWPEAK FLOW160.97224.273PF=18+v/.016=4.394+V/.0164 homes x 350 gpd/home = 1,400 gpd = .972 gpm4.39 x .972 = 4.27 gpmAllison Minor Subdivision1
Capacity CalculationManning's Equation Qcfs=(1.49/n)*(A)(R)A.6667(S)A!/2Qcfs=(l.49/0.013)(3.14*.667A2/4)(.667/4)A.667(.004)A1/2n= 0.013 (PVC)S = 0.4% minimum sloped = 8 inchesQ^ = 343 gpmConclusionThe peak wastewater flow generated by the four lots is much less than the capacity of a minimumgrade 8" PVC sewer. The existing manhole at the intersection ofWestridge Drive and Arnold Streetis flowing at a rate of 0.06 CFS. The addition of this subdivision will increase the flow in thismanhole to 0.07 CFS. This increase accounts for 1.3% of the total capacity of the existing pipe.JPAVEMENT SECTION DESIGNFour test pits were excavated on December 14, 1998 to evaluate the groundwater and soilcomposition on the property. The following is a summary of the investigation for each of the fourtest pits: (See sheet E-l for locations).Test Pit #1Location: 45' west of southeast comer of lot 4 and 30' north of the south property line.0' to 1.5' waste material1.5'to3.4'topsoil3.4' to 7.5' silty/clay (gray in color)7.5' to 8.6' poorly graded gravelwater @ 8.6' below ground levelsampled silty/clay layerTest Pit #2Location: 45' west of southeast comer of lot 3 and 30' north of the south property line.0' to 3.1' waste material3.1'to 5.1'topsail5.1'to7.9'silty/clay7.9' to 8.7' poorly graded gravelAllison Minor Subdivision2J
no water in test pitTest Pit #3Location: 45' west of the southeast comer of lot 2 and 30' north of the south property line.0' to 3.6' waste material3.6' to 5.5' topsail5.5' to 7.3' silty/clay7.3' to 8.7' poorly graded gravelno water in test pitJJTest Pit #4Location: 45' west of the south east comer of lot 1 and 30' north of the south property line.0' to 4.4' waste material4.4' to 5.4' topsail5.4' to 7.3' silty/clay (brown in color)7.3' to 9.4' poorly graded gravelsample taken and nuclear compaction test of silty/claywater at 9.4' below ground levelThe samples taken from Lots 1 and 4 were brought back to the laboratory at Morrison-Maierle Inc.to perform Moisture-Density Relations of Soil, AASHTO T-99, Method A and compare thelaboratory maximum dry density to the in-situ density of the silty/clay soil in test pit #4. Themoisture-density tests results are as follows:Test Pit #1Laboratory Maximum Dry Density: 100.1 Ibs./cubic footLaboratory Optimum Moisture Content: 20.1%Test Pit #4Laboratory Maximum Dry Density: 96.9 Ibs./cubic footLaboratory Optimum Moisture Content :20.5%In-situ Wet Density: 104.9 Ibs./cubic footIn-situ Dry Density: 84.4 Ibs./cubic footIn-situ Moisture Content: 24.3%Relative Compaction In-situ: 87.1%Allison Minor Subdivision3J
1111A pavement section design was prefonned using Amoco, a pavement section design program basedon the AASHTO Guide for Design of Pavement Structures. The recommended section is as follows:1) 3" - Hot Plant Mix Asphalt Concrete (type B) Surface Course2) 3" - 1" Minus Cmshed Base Course3) 18" - 3" Minus Select Sub-Base Course4) Amoco 2002 fabricSee the Appendix for the Amoco design parameters and results.SITE GRADING & DRAINAGE PLANThe storm drainage ponds and collection system calculations can be found in the Appendix. Thesefacilities were sized to handle the ten year two hour storm post development flow. See plans forlocations.Three ponds will be constructed to meet the storm water discharge requirements for the project. Theponds are as follows:PondContributoryArea (Acres)DescriptionPond Volume(CFT)#10.762/3 of Lots614#20.701/3 of LotsN. '/2 Arnold Street1088#30.16S. /2 Arnold Street370JMAINTENANCE PLANDuties shall include routine inspections to ensure that debris, yard waste, and seasonal icedoes not impede operation of the detention ponds, and discharge structures. These inspections shalloccur after each major mnoff event and on a monthly basis throughout the year. All results shall berecorded and kept on file for future verification by regulatory agencies. In addition to the routineinspections, annual inspections shall assess and mitigate, if necessary, performance of the detentionponds, and release structures. Criteria shall include accumulation of sediment and debris in thedetention ponds, and release structures as well as any weather or vandalism related damage.Detention ponds shall be mowed on a regular basis during the growing season so as to remain freeof vegetation that might impede their storage capacity.Allison Minor Subdivision4J
11111]AppendixJjJJAllison Minor SubdivisionJ
1-ijiJJProject: AllisonThis is the Amospec paved road design output. This output is madeup of two parts. The first part provides the pavement sectiondesign. The second part provides the geotextile selection based onsurvivability criteria.The pavement design parameters are:1. Estimated total traffic = 100000 18-kipESALS2. Standardized normal deviate = -1.653. Standard deviation = .44. Subgrade resilient modulus = 4.5 ksi5. Initial serviceability = 4.2 PSI6. Terminal serviceability = 2 PSIThis is a flexible pavement design.The unit cost of the pavement is $ 18.51/sq. yd.The cross-section is as follows:1. 3 inches of asphalt surface courseIn-place density of asphalt concrete = 145 pcfLayer coefficient for surface = .4Drainage modifier for surface = 12. 3 inches of graded cmshed aggregateIn-place density of base = 132 pcfResilient modulus of base = 22 ksiLayer coefficient for base ==.13Drainage modifier for surface = .83. 18 inches of subbaseIn-place density of subbase = 132 pcfResilient modulus of subbase = 13 ksiLayer coefficient of subbase = . 1Drainage modifier of subbase = .8The geotextile design parameters are:1. The max. contact pressure is 35 - 100 psi.2. The minimum lift thickness is 6 inches.3. The size of the fill aggregate is 6 inches.4. The angularity of the base aggregate is subrounded.Allison Minor Subdivision6
nr'5. Beneath the geotextile is nat. ground w/shallow depressions(<12in).6. The shear strength of the subgrade is 1000 -1800 psf.7. The inspection of construction is regular monitoring.8. Traffic will be permitted prior to paving 2 weeks.nnfl11[J[ju[JjAllison Minor Subdivision7IJ
IDIFIED RATIONAL METHODQp=CiAPRE-DEVELOPMENTSIN AREA PRE =PRE-DEVTC=I E-DEV C=STORM A=B=; 3RM INTENSITf=^nE-DEV Qp=POND#110-YR2HR STORMa'(DURATION) A-(b) (CITY OF BOZEMAN)0.76 ACRES120.00 MIN0.270.640.650.41 IN/HR0.08 CFSSTORM EVENT NTENSIT2.00 HR(YR)25102550100(IN/HR)0.240.330.410.500.580.63STORM i COEFFA B0.36 0.60.52 0.640.64 0.650.78 0.640.92 0.661.01 0.67I ST-DEVELOPMENTBASIN AREA PRE =3T-DEV TC=POST-DEV C='~TQRM INTENSITl'=I 3T-DEV Qp=0.76 ACRES120.00 MIN0.27.0.41 IN/HR0.08 CFS2.00 HR10 YR•ND VOLUME CALCULATIONS:DURATION(MIN)114.00115.00116.00117.00118.00119.00120.00121.00122.00123.00124.00125.00126.00127.00128.00129.00130.00131.00132.00133.00134.00135.00136,00137.00138.00139.00140.00141.00142.00INTENSITY(IN/HR)0.420.420.420.410.410.410.410.410.400.400.400.400.400.390.390.390.390.390.380.380.380.380.380.370.370.370.370.370.37QptCFS)0.090.090.090.090.080.080.080.080.080.080.080.080.080.080.080.080.080.080.080.080.080.080.080.080.080.080.080.080.08MAX VOLUME(CFT}:i,|,;%gi(:CFT}a|9t ^.34i:!s;iyst.^oQ 9Triangle Release i Constant ReleasePOND VOLUME(C FT)-0.35-0.24-0.15-0.09-0.04-0.010.00-0.01-0.04-0.08-0.15-0.23-0.33-0.45-0.59-0.74-0.91-1.10-1.31-1.53-1.76-2.02-2.29-2.57-2.87-3.19-3.52-3.87-4.23(CFT)4.343.642.942.22 iig@1.4&M0.750.00:i-0,76;g-1.53-2.30-3.09:-3.88-4,69-5.50-e.32-7.15-7.99-8.83-9.63;.-10-55aai-11.4Z-•t2.:3QIS']i-13-l3iiKBI|'-14,OKag|ll:'-15-833BI^ r16:81SSI||.!-17.74;||je;-18,67-:||S|DELTA DURATION1; AVERAGE VOK|:,||(CFT)^||£;gag;2.i7.:isaRETENTION VOL(CFT)605.751ss_ 3T-DEVELOPMENTlASIN AREA PRE =3T-DEV TC='OST-DEV C=)RM INTENSIT/s^JT-DEV Qp='ID VOLUME CALCULATIONS:0.76 ACRES120.00 MIN0.270.41 IN/HR0.08 CFS2.00 HR10 YRMAX VOLUMEgMAX VOLUME!:%,(CFF)a|I@|§|{CIFT},gg_:>^,,4.34_|g|i|Kooj|siTriangle Release']DELTA DURATION =gWERAG&Wg
1DIFIED RATIONAL METHODQp=CiAPRE-DEVELOPMENTSIN AREA PRE =PRE-DEVTC=E-OEV C=STORM A=B=ORM INTENSITY=, ,.E.DEV Qp=POND#210-YR2HR STORMa ' (DURATION) A -(b) (CITY OF BOZEMAN)0.7 ACRES120.00 MIN0.380.640.650.41 IN/HR0.11 CFSSTORM EVENT NTENSIT2.00 HR(YR)25102550100(IN/HR)0.240.330.410.500.580.63STORM i COEFFA B0.36 0.60.52 0,640.64 0.650.78 0.640.92 0.661.01 0.67ST-DEVELOPMENTBASIN AREA PRE0.7 ACRESST-DEVTC= 120.00 MIN-uST-DEV C= 0.45STORM INTENSITY= 0.41 IN/HRST-DEV Qp= 0.13 CFS2.00 HR10 YRPI~IND VOLUME CALCULATIONS:DURATION(MIN)114.00115.00116.00117.00118.00119.00120.00121.00122.00123.00124.00125.00126.00127.00128.00129.00130.00131.00132.00133.00134.00135.00136.00137.00138.00139.00140.00141.00142.00INTENSIFi'(IN/HR)0.420.420.420.410.410.410.410.410.400.400.400.400.400.390.390.390.390.390.380.380.380.380.380.370.370.370.370.370.37Qp(CFS)0.130.130.130.130.130.130.130.130.130.130.130.130.120.120 120.120.120.120.120.120.120.120.120.120.120.120.120.120.12MAX VOLUME'(CFT)146.96Triangle ReleasePOND VOLUME(CFT) ?g^;146.96,146.49 !||g,,146.00 ;,:;:g||:1•145.50 ill:144.98 ,|g|,: ::,144.44 !.%:,^U3-89MI1:/143.33:.142'75'SB:';:.,142.16 Ifl::--:141.55 Ig140.93140.30::139.65 ySf[138.99 3lll:i.138.31,,;::137.63 ,.^Sr^36.93^11,.136.21''%%1135.49 ;!i134.75134.00:133.24^132.47,1,131.68 -S;i3@30.89^gg|lliso.os'^1:129.26 ;:g128.43'MAX^OLUMElIWRT):::,';-:^1'23.35,S^Constant ReleasePOND VOLUME(C FT)23.3523.2623.1322.9822.8122.6122.3822.1321.8621.5621.2320.8820.5120.1219.7019.2618.8018.3117.8117.2816.7316.1615.5614.9514.3213.6612.9912.3011.58DELTA DURATIONJWBW3EVOi^igl.:(CFTB|fclg!:85.16iB|RETENTION VOL(CFT)929.881ST-DEVELOPMENTBASIN AREA PRE =ST-DEV TC=30ST.DEV C=3RM INTENSITl'=ST-DEV Qp=ND VOLUME CALCULATIONS:0.7 ACRES120.00 MIN0.450.41 IN/HR0.13 CFS2.00 HR10 YRMAX VOLUME;.^ MAXiVOLUMEiKVf-n :a;. ;:,'{e:Ft)',;|:||" .;;l:146.96 Sff;,!;::1 "l;:t23;35;;g|gTriangle Retease'' Constant ReleaseDELTA DURATIONBSS,s5,asJ
MODIFIED RATIONAL METHODQp=CiAPRE-DEVELOPMENTiASIN AREA PRE =PRE-DEVTC=•RE-DEV C=STORM A=B=iTORM INTENSITY=.'RE-DEV Qp=POND #310-YR2HR STORMi = a • (DURATION) A -(b) (CITY OF BOZEMAN)0.16 ACRES120.00 MIN0.60.640.650.41 IN/HR0.04 CFSSTORM EVENT NTENSIT2.00 HR(YR)25102550100(IN/HR)0.240.330.410.500.580.63STORM i COEFFA B0.36 0.60.52 0.640.64 0.650.78 0.640.92 0.661.01 0.67'OST.DEVELOPMENTBASIN AREA PRE = 0.16 ACRES'OST-DEVTC= 120.00 MINr'OST-DEV C= 0.76STORM INTENSITY= 0.41 IN/HR'OST.DEV Qp= 0.05 CFS2.00 HR10 YRPOND VOLUME CALCULATIONS:DURATION(MIN)114.00115.00116.00117.00118.00119.00120,00121.00122.00123.00124.00125.00126.00127.00128.00129.00130.00131.00132.00133.00134.00135.00136.00137.00138.00139.00140.00141.00142.00INTENSITY(IN/HR)0.420.420.420.410.410.410.410.410.400.400.400.400.400.390.390.390.390.390.380.380.380.380.380.370.370.370.370.370.37Qp(CFS)0.050,050.050.050.050.050.050.050.050.050.050.050.050.050.050,050.050.050.050.050.050.050.050.050.050,050.040.040.04MAX VOLUMEliMAX VOLUME:iCFTj^i^^FTr^,75,87^g|syl,:.16^||Z.Triangle Release . Constant ReleasePOND VOLUME J POND VOLUME,(CFp:,;iPJ (CFT)MilateISIBi8SBB^%^1;:~: 75.87 |8g,l%75.77^1®75.66;75.55, 75.4375.31:.wjs.is;:.?i75-°4:a74.90;74^0;;gliss.'|:'74;1l3g|t,,,73.94j]73.75'aigs73.53 jggiS.,'73.39,;g^73-1g%8373.00i:72.7&'S3!,J2:59:3i|:72'37;MB,72-16rll:::;;::71:.94:Bg,S,7T.71:;;:|.;^,71.48:3s%1.24i|iB!K:^71.01:i||B16.2716.2216.1616.0916.0115.9215.8315,7215.6015.4815.3515.2015.0514.8914.7314.5514.3714.1713.9713.7613.5513.3213.0912.8512.6112.3512.0911.8211.55DELTA DURATIONAVERAGE VQi-fl^(CFr}'ig»:,^46.073|gaRETENTION VOL(CFT)358.961'OST-DEVELOPMENTBASIN AREA PRE ='OST-DEVTC=POST-DEV C=;TORM INTENSITY='OST-DEV Qp='OND VOLUME CALCULATIONS:0.16 ACRES120.00 MIN0.760.41 IN/HR0.05 CFS2.00 HR10 YRMAX VOLUME ^MAXVOLUIME'(CFr)~||i||li|(CFT}aS''Ts^yws-w^s^Triangle Released Constant ReleaseDELTA DURATION:: AVERAGE VOiil
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