Loading...
HomeMy WebLinkAboutStorm Water management & Engineering Drainage Report , • I HI r I.ANI) Pe } vI" Touchmark at Meadow Lake Village ELKHORN Meridian, Idaho Storm Water Management & Engineering Drainage Report ELKHORNz 4037 E. Clocktower Lane Meridian, ID 83642 Contact: Ph: ���Ot AL , 0-G\ST .,$ i,�,• 40 Engineer 4 The Land Group, Inc.z 10961. 462 East Shore Drive, Ste. 100 Eagle, Idaho 83616 %.3) �fl Contact: Jason Densmer, PE to 'it OF \©P Ph: 208.939.4041 D Sew March 19, 2014 Project No. 114019 Site Planning• Landscape Architecture•Civil Engineering°Golf Course Irrigation&Engineering•Graphic Design•Surveying 462 E.Shore Drive,Suite 100•Eagle, Idaho 83616•P 208,939.4041•F 208.939,4445•www.thelandgroupinc.com •4, Elkhorn Building iimio Meridian, Idaho THELAN GROUP, NC. Storm Water Management Report Report Purpose The following report addresses the storm drainage systems proposed for the Elkhorn Building is located, South of E. Clocktower Dr. and NW. of S. Arbor Circle, Meridian, Idaho. Calculations are provided demonstrating that the project provides suitable drainage systems to accommodate anticipated stormwater flows. Peak Precipitation Rates The drainage systems have been designed to store the 100-year, 1-hour event. The drainage calculations are shown in Appendix A. Peak Stormwater Flows & System Performance Site Drainage Areas The site is divided into tributary areas, each into one drainage system. An overview of the site is given in Appendix B. Generally,the drainage from the parking lot area will sheet flow across the asphalt surface to inlets and seepage beds designed to hold the 100-year event storm runoff and will allow the runoff to infiltrate into the natural sub-soils. The drainage from the building is anticipated to discharge their roof drainage to splash block then sheet flow to the drainage system in the parking lots. Finished surface grading in these areas has been designed to result in finished landscape slopes which are flat or nearly flat to prevent this storm water from being discharged off the project site. The following calculations show that the proposed facilities are adequately sized to accommodate the expected storm water runoff from the site. • Site Planning Landscape Architecture Civil Engineering Golf Course Irrigation&Engineering•Graphic Design•Surveying 462 E,Shore Drive,Suite 100•Eagle,Idaho 83616•P 208.939.4041•F 208.939.4445°www.thelandgroupinc.com row.; Elkhorn Building Meridian, Idaho THE LAND GROUP, INC. Storm Water Management Report Appendix A Stormwater Calculations Site Planning• Landscape Architecture •Civil Engineering•Golf Course Irrigation& Engineering•Graphic Design • Surveying 462 E.Shore Drive,Suite 100• Eagle, Idaho 83616•P 208,939.4041•F 208.939.4445 www.thelandgroupinc.com lin. LAND Glitoup iNc. Elkhorn Drainage Area Characteristics: Basin A9 Total Area= 32,802 s.f. (0.75 ac) Pervious= 5,302 s.f. C= 0.25 Q100= 1.86 cfs Impervious 27,500 s.f. C= 0.90 Vioo= 2,478 cf Weighted'C = 0.79 Storage Volume Required: Bowstring Method REQUIRED STORAGE&IMILTRATION VOLUME(24 hour.--p0 Year Design:Sten* Time Time Time Intensity Q dev. V dev. V inf. Vs (hr) (min.) (sec.) (in./hr) (cfs) (cf) (cf) (cf) 0.17 10 600 3.11 1.86 1,117 67 1,050 0.25 15 900 2.62 1.57 1,412 100 1,312 0.50 30 1,800 1.82 1.09 1,961 200 1,761 1 60 3,600 1.15 0.69 2,478 400 2,078 2 120 7,200 0.66 0.40 2,845 800 2,045 3 180 10,800 0.48 0.29 3,103 1,200 1,903 6 360 21,600 0.30 0.18 3,879 2,400 1,479 12 720 43,200 0.19 0.11 4,913 4,800 113 24 1,440 86,400 0.12 0.07 6,206 9,600 -3,394 V5 max= 2 078 c.f. a System Size: Seepage Bed L=40 ft length W= 15 ft width D= 9.00 ft depth k= 8.0 in/hr percolation rate per geotech report Aperc= 600 s.f. infiltration area(L x W) Qperc= 400 c.f./hr infiltration flow rate(Aperc X k) Vv= 2,160 c.f. void volume(40%voids) VT= 2460 c.f. TOTAL facility capacity Ni,- V,max? Yes Trec= 5.2 hrs facility recovery time Trec<24 hrs Yes Site Planning I andscape Architecture'Civil Engineering'Golf Course Irrigation& f ngineering Graphic Design. Surveying 462 E. Shore()rive,Suite 100 Eagle,Idaho 83616- P 208.939,4041 ° F 208.939,4445, wwvv„thelancigroupinc.com 1 of 4 TUE LAND GROUP,. INC. Elkhorn Drainage Area Characteristics: Basin A10 Total Area= 9,015 s.f. (0.21 ac) Pervious= 65 s.f. C= 0.25 Qioo= 0.58 cfs Impervious 8,950 s.f. C= 0.90 Vioo= 767 cf Weighted 'C = 0.90 Storage Volume Required: Bowstring Method REQUIRED STORAGE&If4fILTRATIONVOIMME(24 hour-100 year Desi o Storm): Time Time Time Intensity Q dev. V dev. V inf. V, (hr) (min.) (sec.) (in./hr) (cfs) (cf) (cf) (cf) 0.17 10 600 3.11 0.58 346 22 324 0.25 15 900 2.62 0.49 437 33 404 0.50 30 1,800 1.82 0.34 607 67 540 1 _ 60 3,600 1.15 0.21 767 133 634 2 120 7,200 0.66 0.12 881 267 614 3 180 10,800 0.48 0.09 961 400 561 6 360 21,600 0.30 0.06 1,201 800 401 12 720 43,200 0.19 0.04 1,521 1,600 -79 24 1,440 86,400 0.12 0.02 1,921 3,200 -1,279 V max= 634 c f. 5 . System Size: Seepage Bed L= 20 ft length W= 10 ft width D= 8,00 ft depth k= 8.0 in/hr percolation rate per geotech report Aperc= 200 s.f. infiltration area(L x W) Qperc= 133 c.f./hr infiltration flow rate(Aperc x k) V„= 640 c.f. void volume(40%voids) VT= 640 cf. TOTAL facility capacity VTVs max? Yes Trec= 4.8 hrs facility recovery time Trec<24 hrs Yes • 0 Site Planning, Landscape Architecture Civil Engineering Golt Course Irrigation&Fngineering .Graphic Desqn, Surveying 462 E. Shore Drive,Suite 100, Eagle,Idaho 83616- P 208.939,4081 ' E 208.939.4445, wwwthelandgroopinc.corn 2 of 4 •, *-'?''' Ili ii LANA) GattitIP. Mt. Elkhorn Drainage Area Characteristics: Basin Al2 Total Area= 13,161 s.f. (0.30 ac) Pervious= 59 s.f. C= 0.25 Qioo= 0.84 cfs Impervious 13,102 s.f. C= 0.90 Vioo= 1,122 cf Weighted'C = 0.90 Storage Volume Required: Bowstring Method ROMIRED STORAGE&INFILTRATIOkVOLUME(24 heUt.,14:M Year Deeign6terre): Time Time Time Intensity Q dev. V dev. V inf. V5 (hr) (min.) (sec.) (in./hr) (cfs) (cf) (cf) (cf) 0.17 10 600 3.11 0.84 506 27 479 0.25 15 900 2.62 0.71 639 41 598 0.50 30 1,800 1.82 0.49 888 82 806 1 60 3,600 1.15 0.31 1,122 163 959 2 120 7,200 0.66 0.18 1,288 327 961 3 180 10,800 0.48 0.13 1,405 490 915 6 360 21,600 0.30 0.08 1,756 980 776 12 720 43,200 0.19 0.05 2,225 1,960 265 24 1,440 86,400 0.12 0.03 2,810 3,920 -1,110 V5 max a 961 c.f. System Size: Seepage Bed L= 35 ft length W= 7ft width D= 10.00 ft depth k= 8.0 in/hr percolation rate per geotech report Ape,= 245 s.f. infiltration area(L x W) Qperc= 163 c.f./hr infiltration flow rate(Ape,x k) V,= 980 c.f. void volume(40%voids) VT=980 c• ty capacity VT- Vs max? Yes Trec= 5.9 hrs facility recovery time Trec<24 hrs Yes Site Planning Landscape Architecture Civil Engineering'Golf Courst,Irrigation& Engineering 'Graphic 0es4gn Surveying 462 E. Shore Drive,Suite 100'Eagle,Idaho 83616' P 208.939.4041,- F 208.939 4445, www.thelandgroupinc.corn 3 of 4 .., ''.1''') Ii ID 1,. LAN t) Gat/VP. Elkhorn Drainage Area Characteristics: Basin A15 Total Area= 8,885 s.f. (0.20 ac) Pervious= s.f. C= 0.25 Qi.00= 0.57 cfs Impervious 8,885 s.f. C= 0.90 Vioo= 760 cf Weighted'C = 0.90 Storage Volume Required: Bowstring Method REQUIRED STORAGE&INfILTRATIOU VOLUME(24 hour-100 Year Design Storm): Time Time Time Intensity Q dev. V dev. V inf. V5 (hr) (min.) (sec.) (in./hr) (cfs) (cf) (cf) (cf) 0.17 10 600 3.11 0.57 343 19 324 0.25 15 900 2.62 0.48 433 28 405 0.50 30 1,800 1.82 0.33 601 56 545 1 60 3,600 1.15 0.21 760 112 648 2 120 7,200 0.66 0.12 872 224 648 3 180 10,800 0.48 _ 0.09 952 336 616 6 360 21,600 0.30 0.06 1,190 672 518 12 720 43,200 0.19 0.03 1,507 1,344 163 24 1,440 86,400 0.12 0.02 1,903 2,688 -785 V rnax gt 648cf. s • System Size: Seepage Bed i.= 21ft length W= 8 ft width D: 10.00 ft depth k= 8.0 in/hr percolation rate per geotech report Aperc= 168 s.f. infiltration area(L x W) Ciperc= 112 c.f./hr infiltration flow rate(Ape,x k) Vv= 672 c.f. void volume(40%voids) VT= 672 c.f. TOTAL facility capacity VTVs max? Yes Trec= 5.8 hrs facility recovery time Trec<24 hrs Yes Site Planning Landscape Architecture Civil engineering Golf Course Irrigation&Engineering Graphic Design, Surveying 462 E.Shore Drive,Suite 100' Eagle,Idaho 83616.. P 208.939,4041 , F 2O8994445' www.thelancigroupinc.corri 4 of 4 voik orouN" fir.t1 Elkhorn Building al Meridian, Idaho THE LAND GROUP, INC. Storm Water Management Report Appendix B Drainage Areas Exhibit Site Planning Landscape Architecture Civil Engineering•Golf Course Irrigation& Engineering•Graphic Design Surveying 462 E.Shore Drive,Suite 100• Eagle,Idaho 83616•P 208,939.4041• F 208.939,4445 www.thelandgroupinc.com e • ,BE) ' O I v 1 o U U ° L.rs l �"" ) �' 4 �r 0 ._. rE 00 1 1 ® e o, . � y 1 tr \ I Mei/ / \ j,ss‘ ,,,, 0:7-A, 0 •, , ',,<C),,.‘ \ - -..._.— /�/ tet /''`4*, 11 , , _ ,dri,mil ,,,,_,\:\ , : ,,,,,,,,, .;. ..:--3.,.........4..._,.........,.,,,,,,,, , 40 ,„.`fir • —' -- "�,..11. I. __. t,IfA•• :.I ����,f f '� > +n ;;/ MAMIEW1rN ,.,a,.,,..., '44' .4„,'4 kncoJS-x at 1.11 wi11aNC 'MY:"� Wv / 4MIn: ax.ulch ruucamark of �♦ .;f/` Allah*,ia�i 1111 ells 4� \ ��r / I Meadow Oke Village <l`11i 7 ,,,,„,,.,%---2,"'": ELKHORN �," .al iY�a.nr •..��� O Seepage Mt L=ar.W=ti. \ d \ N%.at.raW H.1rpercWtl.n M. �, � ��! u� ,�^� .��.•, � `�i ,3S \,� Ya..e+=1,1N e1 u.rw.n.ro nue (124 U-1 �g k' "kr..:ut-Nnalo..Nwlr • I _ A. _,� I � Mlxm 4x.157 ea /�/ \ J Y...-.Nat // !i .� � .,1 a 4,, --7.-.- -7.-.- /�// / �''f�, .'v<,"� i\Yr'� t , -" 4iM.rx/xwnx.neEx bits q ,fi/•• / ♦ ���� /111i� ��il_IM .1. IN...W.4 t Existing 8 Proposed , _� ���� ♦� , �_`rImo -!J' "" � Drainage Basins yam`: -„v"y�Q ** ♦ a.- .I NUMMI wrkts 1.1Iera. 010.11.4.de 'a YsueMlel 1� WWI.Nt E_YV:w.lmu.r S 1 P I ux.wMI. 114.1.percolation rata 1 a Yo.vu.YN of iem 4 LEGEND MIME MIN NS aN:I ax.Wx.Mel Mel .4� _ 4.4.46011el / `""mow,„`"°. amp n.di.t SC axu..4c w:..sv Sawn. l.Sl',e=1'1.14.r N%...kerma. Il w...ceixxEuw .en .-WI.pereatan.n.ate 144.44=1114 H Existing&Proposed Drainage Basins