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HomeMy WebLinkAbout1997-05-21 Stormwater Mitigation Report CH RISTIA NS E N & S E R GI, IN C. . PROFES LE GREEC AND LANDS URVEYORS 160 SUIAMm 7gR HAVERH ELL MAC qAe4�U w;'% S20 (5M373fj310 q» (5m) yzmq REPORT ON STORMW&TER MITIGATION PREPARED FOR: LOT 2A ORCHARD IULL ROAD . IN NORTH ANDOVER, MASS . PREPARED FOR: GEORGE R. BARKER, jIL ~ DAT APRIL \ ! 7 n m � a■���� 5TORMVVAJj,�R MITIGATION The inereasc in raInfalI runoff crcated by the iinpervious buiIdIng, di'iveway, acid pal-king areas will be mitigated by [lie use of infiltration areas and feaQhing bashes. the runt)ff€'min the 9,goo &I' mof will be direeted to one inflitratim ai-ea, which has snffi ienL capacity to recharge all of the runoff 1Fum [lie roof into the ground for st01-ms up to tine 100 year even I- The runof from the di'ivmays and parking ai-eas wiff be Col Ieeted iIi leaching "ch basins loeated thi-OUghOLIt the paved areas and recharged iwo 0 e gronnd- The leaching basins have sufficient capacity to rechavge all of the F-Unoff from the paved ai-eas iilto tfie grouvd C()r storms up to the 100 year event. Singe aft t�f'the i-11rio fftfurai tl3e proposed impervious areas a total of 29,550 s-f will be re urged into the ground, the overall rate o!'i-unofl'from the site wiII decrease- The attached data and calcuLitions are provided to support the mitigation pi an. SITE SO . The Soil ConservaLion Service Soil Survey indicates that the soils on site Consist of Wind; or Loamy Sands. These cheep, excessively drained soils are fbi'med in SEIndy glacial outwash. The permeability of the soils typically ranges from 6 inches per hour to greater than 20 inches per hour. The i er end of'the range of permeabiiities, 6 irQht# s per hour, was Uscd in the design of the Infiltmtion stnic.ties on the site. This assumpti0F1 sflould provide an arapie Factor of safety for the deSIP of the structuvesVVnU `1_ ti [ • `. - ..,y. / e .Y f �'f �� � �* .� d.. � �Ff x� w,r �?,;.f.,�'y { �' � ' �y•���" 4ti • .�kx, lk+ f> # e,r-Y*4.r .;..`�rP v �• S` ..}} - nf -3 , `} .. y' 1_ j.._i`!h A. i.A��k.=•, .• f k}�?;.�. �� ��. �s f u_rw•�� jr• `1' ..�° :, r Imo. if iSfqW ,ti XVk •k- a 'N ' '_ ':a..}�" 43` r, '.'a5 . ' '.4 `, �r ,� ►'. * { } :7. �` �5*yPb #Ffy����.�t T 7 l :Y�•,xg�' ,�.*.sS.', •xr �t i. {-M1r�. .i' '� ^4 r.i!'• _,�M1F .•y ry��.}.: �} '�: "��` �w i�,+_` •; �4 '7' T'F } 'SLS �• vk y ' C. rLl .i 1 CFU .T' 4 �Ar� ' s � �.Y 7!1., '� r M1� + r {`'si•..�', .r�i i� .4# r+ SF4 W +y .; _ yti• .. ^rx71 5 }=;'�l r#_ f sky :_ _ :: ',� �-•...nF--'�y V. e=}'�� ja�f�y.(,*Si"' y K �'•,}-' 5.t, , _ YS# ..c '`. tiik #' A'd Data for LOT 1.2A ORCHARD HIS ROAD, NORTH AND OVER Page 1 TYPE II 24-HOUR a N &L_ 6.4 IN Prepared Sm1STTANA2§ & QGI. INC . Apr 92 Hs d oQ ■ . 0 1O§7 fie] LIL -1? A Sy SUBS TcHM T 1 LOT 1-2A, pRopoSED CONDITIONS De&z 5 ,61 CPS e 11,82 IRS, 1IME= .27 a9 3 ps J SCS mR-20 M2710Q .65 9E3 IMPERVIOUS TypR II 24 q mqR R?�LT mbar= 6 -4 IN SPAN= 1l-20 KRS, aL= .l Ims Me r 22 Cofformt. 2: ni TR-55 SHEET FLOW 1 .4 S oth _£ e2 n-.0.1 G=50' =6 ,4 in � .04 SUBEA NAME 1 1 RUNOFF LOT 1 -2A : PROPOSE) CONDITIONS 5.s 5.0 - _ .4 MIN 4 5 E1w 1:3T� 4 .0 5 TRH ME1'H00 J.s 1'Y E II - OU J.e lF L: 6.11 IN 2.5 - READ b.b] EFS ® « , 1 .02 HRB q 2,0 V(Q �NC . zZ Ar b I ti 1 .8 .5 2 L - .-I �. �. �,�.. .�. . a : z . M ± S f ? q IIME Q,m r e) Uj�l rHMwN-2 Ion $0 r 9_al QR9 e 1 B7 Io! Ul� R a0§R D.aO .2 .a _40 .50 _Go -70 lo. 00 | .I7 .IS . 19 .20 ,21 ,22 .e« .25 .29 .29 11 .00 .37 .35 .40 .&4 _48 . 93 1 .92 3 , R3 1j .56 1 .35 12 .00 ,al .70 .§I .51 -12 As _33 , a1 .29 .717 ' 3, 00 | .25 .24 ,23 .22 .20 .19 . 19 -18 .17 . 16 14 .00 . I§ .15 . 15 .1& , 14 , 14 .l4 . la .Is .13 15 .0o . I: .12 . 12 .12 _11 , 11 . 11 , 10 .!G .ID 16 ,00 l .fo .09 . 09 .09 _09 - 09 .09 ,g9 '09 .09 17 .0n - 09 .ea .09 .08 .oa .aa .0a ' 06 .ea -08 IB .oa _ov .A7 .07 ,07 .07 .07 .09 . 07 .g7 .ov 19 .04) .gG .or . 06 .06 - 06 -06 , 06 ,g6 .0a . 06 20 ,00 . Bs Data for LOT 1-2A ORCHA9D HILL ROAD, NORTH ANDCOVER Page 2 TYPE 11 24-HOUR RAINFALLn 6.4 IN 0 Prepared by CHRTSTTANSEN & SERCT, INC. 3 Apr 97 HY!Ll. 11,0105y (011,11-2986-1996 Anulk-A misrucamulzi- sYste-M8 POND I INFILTRATION BASINS QQ = 531 CF8 A 11 .82 URS, VOLUME= 27 AF QOUL= .47 CFO a 11.50 mRS, VOLUME= 27 AF, ATTEW 92t, LAG= 0 ,0 MIN 0 FTRVATION AREA INC'.STOR CUM.S"TOR STOR-IND METROD (SF) (C F) PEAK STORAGE - 5251 CP 0 .0 1350 0 PEAK ELEVATION= 3 .9 PIT 1 .0 1350 1350 1350 IFTOOD ELEVATION= 4 ,0 F 2 . 0 135D 1350 2700 SIART ELEVATION- 0,0 FT 3.0 13bo 3350 4050 SPAN= 10-ZU HRS. dt= .l URS 4 .0 1350 3350 5400 Tdot 88 .7 MIN ( .27 AF) INVERT ,,QgTLET DSVICSS, -- gn - I P 0 , 01 3WILTRATION Q= 47 CFS at and above lu,0 CA cl; 3,6 i if Tl s x s 3 I TOTAL DlSQBARGK..-WFS) W ELLIM16119N -3 G 62. 0.0 Qf .00 47 .47 47 .47 .47 47 .47 47 -417 1 .0IV 47 .47 .47 47 .17 .47 .47 .47 -47 .41 ,3 . p .47 .4v 47 -47 .47 "47 -41 .47 -47 .411' va .47 47 .47 .47 47 '47 .47 .47 .47 47 40 .47' POND I DWICHARGE JNFTI TRATION OWNS 40 - I 3 0 2 5 - 0 2 ,0 LLJ LLI In w 0i Ln m m r') I W T ca DISCHARGE QW) Data for LOT 1-2A ORCHARD HI1.1`. ROAD, NORTH ANDOVER Page 3 HYPE II 24-HOUR "INFALLu 6 .4 IAA P.ri7g)aL'ed I)y �'I-II}IS'1'3ANSFN fi ERG1, INC, 3 App 97 F4- roCAD 4,. 57 €101{]57 Irj 19E36-1996 Applied C4ic corelps�l i v ,]�C s - PONI) 1 INFLOW X OUTFLOW TNT l'l TRATION HASTNS 5TDR.-iNU I,Tl'1GD PEOK S I'GR= 525; CF PEAK R.EU- 3,0 FT 4 [din- 5,61 CFS 0 3.5 0 )UL= .47 f=Fii 0 MIN 2.5 I R,0 s f� r an f] r, ID u, m TIME Ch �.rr ;� POND 1 INFLOW }!EAK= 5 -61 CFS .�... '11. ,El HOURS HOUR 0_00 10 ?[� 30 4Q -50 fi -70 8 10 .0Q I - 17 JB -19 .20 '21 .22 .24 .2�3 27 -29 .11 .OG 32 '35 -110 44 AB 93 1 - 92 3 .06 5-56 4 , 3� 12 ,€ G I ,8=s -70 .61 .si A2 .35 -3 3 .31 _21) .27 13 .Go ,25 ,24 ,23 -22 20 - 114 1-8 - 18 .17 ,1.6 14 ,00 15 15 - 15 .14 _1.4 4 - 13 . 1.3 -13 15, 00 -12 .'12 - 12 .12 -1.1 . 11 , 11 ' 10 . 10 -10 16 - u0 '10 -€39 .09 .C19 ' 09 '09 ' 09 '05 .09 . 09 1'7, 00 '09 ' 09 ,08 .08 '08 -08 .08 -08 .08 '09 16, 00 ; -07 . 07 07 .0`1 07 -011 .07 -€1'I .07 '07 19 .00 ,0�3 -06 06 -€ 6 .06 _G6 A6 , 06 A6 '06 20 .00 - U5 POND 1 '1'0'1'A1, QIITI?LQW PFAK= .! 7 CPS @ 11 .50 H-QaR-$ SOUR 0- 00 7i] -20 .30 4U .50 G _'!0 -90 10-00 I '06 - 15 .1.8 ' 19 .20 '7.1 -23 .74 _2, 27 11. 00 I --3€1 A3 36 .40 44 -47 .47 -47 ..17 _47 12 . 00 -117 .47 -47 .47 47 -117 47 -41 .47 -47 13 .00 I 47 -411 .47 -47 .217 47 AV 47 A 7 .47 14 .06 47 .f1'f 47 +17 ,47 -47 A7 -47 -15 .00 1 -47 .47 -117 47 47 -1? 47 -11'1 47 -4V 16 .00 [ .47 _47 ,47 47 AV 47 -47 47 -47 A? -=35 .111 , 1 0 -09 .08 - GH .08 G8 AB B '08 1r3 .00 -0 .07 07 AV .07 - 07 .07 - 07 A? %)7 1.9- GO 07 ' 06 0Ea Oc`} - 06 .06 _G6 .Ob '06 ' 06 0- 00 '05 MARY OF. LII ]YSIS OF STORM.—TER INFIL.TRAjQN A►R F_QR_RQ AND_PAVEMkUT $A%AM IAIFILTRATION —CONTRIBUTING � °�6 OF TOTAL. PEAK RATE OF" INFILTRATION AREA INFILTRATION AREA Y AREA IMPERVI0US AkEA.( .F,�r_PAVED AREA RUNOFF CFS _ REQUIRED (S F.�..- , y PROVIDED_(q_.F)_� 1 9,BGo 3.342 ;'1.71"A q,66 _-_ 3215 446 3 _ 4, 40 15.90°r rw,B9 537_ 7 4 14.86 88.06% 2-14 1,284 1296 3502 .:._TQTA,L : ...w 28,546 100.'00°la 5.61 3,375 �..,