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HomeMy WebLinkAboutStormwater Report - 980 OSGOOD STREET 2/1/1996 DRAINA GE,ANAL YSIS REPORT PREPARED FOR: JOHN FERREIRA FEBRUARY , 1996 iuLMERRIMACK ENGINEERING SERVICES, Inc. 66 Park Street Andover, Massachusetts 01810 planners 0 engineers 0 surveyors DRAINAGE ANALYSIS REPORT PREPARED FOR: JOHN FERREIRA FEBRUARY, 1996 DALE" PI, G Merrimack Engineering Services, Inc. DRAINAGE ANALYSIS FOR THE DESIGN OF THE ON-SITE SUBSURFACE STO DRMW RMIN ON OF ON AND DETENTION FACILITY AND HYDRAULIC CAPACITY OF THE STATE DRAINAGE SYSTEM N= The project site is located at 980 Osgood Street (Route 125) in North Andover, Massachusetts, north of Sutton Street, and east of Old Clark Road. e existin site is proposed to be further developed. A building addition of 2560 A portion of th g square feet and paved driveway and parking area wili _ -ion, which has been in continuous operation or more than 10 years. PRE-DEVELOPMENT CONDITIONS altered over these years from its natural state to The area to be developed has been previously provide space for storage of vehicles and other related uses consistent with automotive repair and ub growth are service facilities. Most of the vegetated cover has been stripped. Weeds and scr prevalent. the site is underlain with Paxton Soil which is Hydrologic Soil From the USDA Soils Map, et depth, and a permeability of soil at Gr ou p "C", with Seasonal High Water Table at greater than 6 fe less than 0.2"/hour. A test pit was done at the site to confirm this description. Route 125, The topography of the site and its watershed extends from Old Clark Street toward Osgood Street. Refer to the Site Plan for grading. For the drainage analysis, the following criteria is obtained by measurement and calculation. The watershed area is 0.42 acres, that being the limit of work in the area to be within the proposed construction activities. Then, the weighted curve number, using the TR-55 method for drainage analysis, is determined for the pre-development conditions. The wooded areas (CN = 7'-)), crass etated (CN = 79), and gravel or disturbed areas (CN = 93) are combined by percentage of a reas-ve g total area, to determine "Wt CN": WtCN = 19% @73 + 43% @79 + 38% @93 = 83 The Time of Concentration is estimated at 20 minutes, to account for on-site puddling, ) within the evaporation, as "initial abstraction", occurring along the hydraulic length(flow p ath �analysis, the subcatclunent hydrographs for the 2 watershed. Using the "Drain Calc" Program for the an Y er 24 hours, using 10 year and 100 year storms, where i=3.1, 4.5, and 6.5 inches respectively, p ye ar Y a Type IR statistical storm, are computed and graphically shown herewith. See hydrographs for Subcatchments 1, 2 and 3. POST-DEVELOPMENT CONDITIONS The curve number is The post development analysis is done by using the same methodology. P pavement areas as rimary il affected due to the addition of impervious surfaces,being the roof and pa d peak proposed. There will also be a resulting increase in the runoff velocity as well as volume an p rate of flow due to the development. gg will be 66% and wooded area. The WtCN is determined, where the impervious area(CN= ) and ve etated areas lawn, landscaped, etc. (CN=79)will be 18% of the 0.42 (�=73) will be 15% a g acre watershed. The weighted curve number,WtCN is computed: WtCN= 66% @ 98 + 18%@ 79 + 15% @ 72= 90 hydraulic length of the The time of concentration is estimated at 15 minutes, along th e y watershed. The subcatehiient hydrographs for the 2 year, 10 year and 100 year storms are computer-generated. eak rate of runoff from pre to Refer to Subcats 411, #12 and 413. The difference, or increase, in the p e retention/detention ost development conditions shall be mitigated on-site by the use of a subsurface storm event, as p eak rate of runoff for each sto drainage facility. This facility will be sized to detain the P ent flows. The facility will be analyzed, such that the rate is reduced to less than predevelopm wells, each shall withstand H-20 constructed using 36-8' x 4.7' precast concrete leaching pits or dry we , wheel loading where installation in paved area is necessary and whereby proposed. Refer to site plan and details. -2- this reduction in the peak rate of runoff, as outlined in the following chart, In order to achieve on-site acili will have a 6" outlet pipe which will be connected into the existing the the subsurface facility drainage system, which has been rerouted to eliminate any stormwater discharge toward and into ding Lake Cochichewick. This Town of North Andover Watershed Protection District surroun rerouting of water from the Watershed District, as directed by the Town of North Andover Planning nt of Public Works, would pose an increase in runoff into the State drainage Board and Departure osed subsurface facility prop s stem within the State Highway Layout of Route 125. However, the Y initial intense rainfall from the new project site so as to allow this runoff from the it will detain the i on the hydraulic capacity adjacent areas, due to rerouting, to occur without any significant impact up Y A separate area wide analysis of the state drainage system, using the of the state drainage s Y stem. has been done, as requested by' "Rational Method" for drainage analysis with a 10 year storm event, the District 4 Engineering Department, and is included with this report, which will be submitted to the royal and puts. Massachusetts Highway Department for app including soil 'n of the on-site subsurface drainage facility is based on several criteria, g and The sizing fume/storage capacity, outflow rate control, relative to stormwater inflow rates achieve d permeability, vo to volumes, as well as allowable vertical depth of stored water within the facility, as necessary the desired mi g will ti ation rate. The outlet flow control pipe will be 6" ductile iron. This face ntY the Refer to the site plan for configuration, elevations, and dimensions, etc. Thus is require 36 pits. Re ' um design for mitigation of peak flow as well as providing significant storm water apparent optim gn h the state detention to all ow the peak flow of the rerouted stormwater to flow into and through e system virtually unaffected by the runoff from this new site de velopment. drat na g Y -3- PRE-DEVELOPMENT - 4 - Merrimack Engineering Services, Inc. Merrimack Engineering Services, Inc. DATE: / / 30 9G t'1Pc _ L-7,A!JE op,.l=�'_t_F --- SHEET: 5 OF EXISTING SUBCATCHMENT DATA -------------------------- SUBCAT-#-1 SUBCAT-#-2 AREA= .42 ACRES AREA= .42 ACRES CN= 83 CN= 83 TC= 20 MIN TC= 20 MIN PEAK FLOW= 1 .5 CFS PEAK FLOW= .9 CFS RAINFALL= 6.5 INCHES RAINFALL= 4.5 INCHES VOL= . 14 AC.FT. VOL= .08 AC.FT. SUBCAT-#-3 AREA= .42 ACRES CN= 83 TC= 20 MIN PEAK FLOW= .5 CFS RAINFALL= 3. 1 INCHES VOL= .03 AC.FT. POS T G t v Li�r SUBCAT # 11 AREA= .42 ACRES CN= 90 / TC= 15 MIN PEAK FLOW= 1 .9 CFS RAINFALL= 6.5 INCHES VOL= . 17 AC.FT. POND._ # 1 PEAK OUTFLOW= . 79 CFS MAX. WATER STORED= .07 AC.FT. 6 DATE. / 3 a/ Me,ma�ck Enpneenng Services, Inc. SHEET: G OF 29 HYDROGRAPH-FOR eSUBCATCHMENT CUBI*********PER ****SECOND DUp 0.0 5 .0 . 2 0 .0 .0.4 0 .0 L0. 6 0 .0 L0.8 **** 0. 1 11.0 **** 0. 1 L1.2 **** 0 .1 11 .4 **** 0. 1 L1 .6 ******** 0.2 11 .8 ************* 0.3 0.7 12 .0 ****, ******************* **************** 1.3 12 .2 *********** L2 .4 *********************************O*?*** .2 .6 ********* 3 .0 ************* 0.3 .3.2 ******** 0.2 .3 .4 ******** 0 .2 .3.6 ******** 0.2 .3.8 ******** 0 .2 .4.0 ******** 0 .2 .4.2 **** 0.1 .4.4 **** 0.1 .4.6 **** 0.1 .4.8 **** 0.1 .5.0 **** 0. 1 ,5.2 **** 0.1 5.4 **** 0 .1 5 .6 **** 0.1 5 .8 **** 0 .1 6 .0 **** 0 .1 6 .2 **** 0 .1. 6 .4 **** 0 .1 6 .6 **** 0 .1 6 .8 **** 0 .1 7 .0 **** 0 .1 7 .2 **** 0 .1 7 .4 **** 0 .1 7 .6 **** 0 .1 7.8 **** 0 . 1 8.0 **** 0.1 8. 2 **** 0 . 1 8.4 0 .0 8 . 6 0 .0 8.8 0.0 9 .0 0 .0 9 .2 0 .0 9 .4 0 . 0 9 .6 0 .0 3 .8 0 . 0 3 .0 0.0 DATE: / 3 D/ Merrimack Engineering Services, Inc.. SHEET' OF 2 1 HYDROGRAPH-FOR_SUBCATCHMENT_#--2 CUBIC FEET PER SECOND OUR 0 .0 0.0 0.2 0.0 0.4 0.0 0.6 0.0 0.8 0.0 ,1.0 0.0 .1.2 ******* 0.1 ,1.4 **** ** 0 .1 ,1.6 ******* 0.1 .1.8 **** ********* 0.2 2.0 ***** ** 0.4 2.2 ****************** *********** ***�r*00 .8* 0 .9 2.4 0.4 2.6 ** * ***************** ***** 2.8 ************** 0.2 3.0 **** ******** 0.2 3.2 ** * * 0.1 3.4 ****** 0.1 3.6 * ** * 0.1 3.8 ******* 0.1 4.0 **** ** 0.1 4.2 *** * 0.1 4.4 **** * 0.1 4.6 0.1 4.8 **** * 0.1 5.0 0.1 5.2 ******* 0.1 5 .4 ****** 0.1 5.6 * * 0.1 5.8 * **** 0.1 5.0 *** * 0.1 5.2 * *** * 0 .1 5.4 **** 0.1 5.6 0.0 5.8 0.0 7.0 0 .0 7.2 0.0 1.4 0 .0 7.6 0 .0 1.8 0 .0 3.0 0 .0 1.2 0 .0 1.4 0 .0 1 . 6 0 .0 1 .8 0 .0 1 .0 0 .0 1 .2 0 .0 i . 4 0.0 .6 0.0 .8 0 . 0 .0 0 .0 DATE neenng Services,Inc. SHEET: I OF Memn'ack Eng� SUBCATCT 3 ;;yDROGRAPH FOR_____-- CUBIC FEET PER SECOND ********************* )UR r I' 3'0 0 .0 0 '2 0 0 '4 .0 0 0 '6 .0 0 0 '8 .0 0.0 1'0 0.0 1'2 0 .0 ************* 0.1 ***** 0 .1 **** 0.2 *****************0 .4******** 0 • 1.6 1.8 ******** ******** ******* ****** ****** ************** 2 .2 ******** ******** **************** 0.2 ******************** 2 .6 ************************* 2.8 ************* 0.1 3.0 *********** * 0.1 3.2 ************* 0.1 3.4 **** 3.6 0.1 0.1 3.8 ************* 4.0 ************* 4 .2 0 .0 4 .4 0.0 4 .6 0.0 4.8 0.0 5 ,Q 0.0 5.2 0 .0 5.4 0 .0 5.6 0 .0 5.8 0 .0 5 .0 0 .0 5 .2 0 .0 5 .4 O.Q 5 .6 0.0 , � .0 0 .0 7 .2 0 .0 7 .4 0 .0 7 .6 0 .0 7 .8 0 .0 i .0 0 .0 1 .2 0 .0 1 .4 0.0 3 .6 0 .0 1.8 0 .0 1 .0 0 .0 1 .2 0 .0 1 .4 0.0 i .6 0 .0 1 .8 0 .0 1 .0 0.0 - 8 POST-DEVELOPME""41 _ g — Inc. Merrimack Engineering Services, Vfe:nmack Engineenng Services, Inc. DATE: I / ;o SHEET: /° OF 2y HYDROGRAPH FOR SUBCATCHMENT ## 11 CUBIC FEET PER SECOND ********************* HOUR 10.0 0.0 po .5 D 10.2 0.0 10.4 0.0 10.6 *** 0. 1 L0.8 *** 0. 1 L1 .0 *** 0. 1 L1.2 *** 0. 1 L1 .4 *** 0. 1 L1 .6 ****** 0.2 L1.8 ***************** 0.5 .2.0 ************************************** 1. 1 .2 .2 ****************************************************************** 1 . 9 .2.4 1.3 .2. 6 ******************** 0. 6 .2.8 ************* 0.4 .3.0 ********** 0.3 ,3.2 ********** 0.3 0.2 3.6 ****** 0.2 3.8 ****** 0.2 4.0 ****** 0.2 4.2 ****** 0.2 4.4 ****** ' 0.2 4. 6 *** 0.1 4.8 *** 0.1 5.0 *** 0 . 1 5.2 *** 0 . 1 5.4 *** 0 . 1 5. 6 *** 0 .1 5.8 *** 0. 1 6.0 *** 0 .1 6.2 *** 0. 1 6.4 *** 0.1 5. 6 *** 0. 1 5.8 *** 0.1 7.0 *** 0. 1 7.2 *** 0. 1 7. 4 *** 0. 1 7. 6 *** 0. 1 7. 8 *** 0. 1 3 .0 *** 0. 1 3 . 2 *** 0. 1 3 .4 *** 0. 1 3. 6 *** 0. 1 3. 8 *** 0. 1 ► . 0 *** 0. 1 1 .2 *** 0. 1 1 . 4 0. 0 1 . 6 0. 0 � . 8 0 . 0 1 .0 0 . 0 -io- ue`^mack Engineenng Services, tnc. DATE: / 3 3� 'j C SHEET:-// OF 29 STORAGE POND # 1 DATA ------ ------ ----- PEA 7Y, SuBCAT p// --------------------------- TIME INFLOW OUTFLOW ELEVATION HR. CFS CFS STORAGE -------------------- ACRE-FT. 10.0 ------------- 10.2 0.0 0.0 140.9 0.00 10.4 0. 0 0'0 140.9 0.00 0.0 10.6 0. 1 140.9 0. 00 10.8 0. 1 0.0 140.9 0.01 11.0 0.0 141.0 0 01 11.2 �:i 0.0 141. 0 0. 01 11.4 0.1 0.0 141. 1 0. 01 11 .6 0.2 0.0 141. 1 0.01 11 .8 0.5 0'0 141.2 0. 01 12 .0 1 . 1 0'0 141.3 0.02 12.2 1.9 0. 1 142, 1 0. 03 12 .4 0.8 142.6 0.06 12.6 143. 12.8 0.4 0.7 143.0 10.071 13.0 0.3 0. 6 1­ - 13.2 0.3 0.5 14 �° 13.4 0.2 0.5 142. 7 0.06 13. 6 0.2 142.6 0.05 13.8 0.2 0.4 142.5 0.05 14.0 0.2 0.3 142.4 0.04 14:2 02 0.3 142.4 0.04 . 14.4 0.3 142.4 0.2 0.04 14.6 0. 1 0.3 142.3 0.04 14.8 0. 1 0.2 142.3 0.04 15.0 0. 1 0.2 142.3 0.04 15.2 0. 1 0.2 142.2 0.03 15.4 0.1 0.2 142.2 0.03 15.6 0. 1 0.2 142.2 0. 03 15.8 0.1 142 .2 O.I 0.1 142.2 0. 03 16.0 0. 1 0. 1 0. 03 16 .2 0•I 142. 1 0.03 0. 1 142. 1 16 .4 0.1 0.03 16.6 0.1 0. 1 142 . 1 0, 03 16.8 0.1 0. 1 142. 1 0.03 17.0 0.1 0. 1 142 . 1 0. 03 17.2 0.1 0. 1 142. 1 0 .03 17.4 0. 1 0. 1 142 . 1 0. 03 17. 6 0. 1 0. 1 142 . 1 0 . 03 17.8 0. 1 0. 1 142 . 1 0 . 03 18.0 0 0. 1 142 . 1 0 .03 . 1 18.2 0. 1 0. 1 142 . 1 0 . 03 18. 4 0. 1 0. 1 142 . 1 0 .03 1 0. 1 142 . 1 8. 6 0. 1 0 . 03 18. 8 0. 1 0. 1 142 . 1 0. 03 19. 0 0. 1 0.1 142 . 1 0 . 03 19. 2 0. 1 0. 1 142 . 1 0 .03 19. 4 0.0 0. 1 142 . 1 0 . 03 19. 6 0. 0 0. 1 142 . 1 0.03 19.8 0.0 0. 1 142 . 1 0. 03 142. 0 n n1 DATE: ing Services, Inc. SHEET' 2 OF % J Merrimack Engine, -° HYDROGRAPH FOR SUBCATCHMENTO#_®12 CUBIC *********PER �***SECOND :OUR .0.0 0 .0 .0. 2 0 .0 .0.4 0 .0 L0. 6 0 .0 L0.8 0 .0 11.0 ***** 0.1 11.2 ***** 0.1 11 .4 ***** 0.1 L1 .6 ***** 0.1 0 .3 '_2 .2 *********** 0.2 .2 .8 ********** 0 .2 .3.0 ********** 0.1 .3.2 ****** *** 3.4 ***** 0 .1 .3.6 ***** 0 .1 3. 8 ****�r 0 .1 4.0 **** 0.1 4. 2 ***** 0 .1 4.4 ***** 0.1 4. 6 ** ** 0.1 4.8 ** ** 0.1 5.0 ***** 0.1 5.2 ***** 0.1 5 .4 ***** 0.1 5 .6 ***** 0.1 5 .8 ***** 0 . 1 6 .0 ***** 0. 1 5 .2 ***** 0. 1 5 .4 ***** 0 .1 5 .6 ***** 0. 1 5 .8 ***** 0.1 7 .0 0.0 7 .2 0.0 7 . 4 0.0 7 . 6 0.0 7 . 8 0 .0 3 . 0 0 .0 3 . 2 0 .0 3. 4 0 .0 3. 6 0 .0 3 . 8 0 .0 ► .0 0 .0 1 .2 0 .0 1 .4 0 .0 i .6 0 .0 , ,8 0 . 0 1 ,0 0 .0 l2 - :dmmacic , wineenng �ervlces, inc. DATE: _J.FERREIRAa SHEET: /3 OF 25_ STORAGE POND # 2 DATA E�K ELEVATION STORAGE TIME INFLOW OUTFLOW ACRE-FT. ----HR--------------CFS----------------------------------------------------- 140.9 0 .00 10.0 0.0 0.0 140.9 0.00 10.2 0.0 0.0 140.9 0 .00 ` 10.4 0.0 0'0 0 .00 10.6 0.0 0.0 140.9 140.9 0.00 10.8 0.0 140.9 0 .01 11.0 0.1 0.0 141.0 0.01 11.2 0.1 0 .01 141.0 p,01 11.4 0.1 0.0 141 .1 11.6 0.1 141.1 0 .01 11.8 0.3 0'0 141 .3 0.02 12.0 0.7 0 .0 0 .04 1.2 0.4 142.2 0.05 12.2 E O S 142.5 0.05 12.4 12.6 0.4 014 0.05 12 .8 0.2 142.5 0.04 13.0 0.2 0 '3 0.04 142.4 13.2 0.2 0.3 142.4 0. 04 13.4 0.1 0.3 142.3 0. 04 13 .6 0. 1 0.2 142.3 0.04 ' 13 .8 0.1 0.2 142.2 0. 03 14.0 0.1 0.2 142.2 0.03 14.2 0.1 0.2 142.2 0.03 14.4 0.1 0'1 0 .03 0.1 0.1 142.2 14.6 142.2 0.03 14.8 0.1 0. 1 142.1 0.03 15.0 0.1 0.1 142 .1 0 .03 15.2 0. 1 0.1 142.1 0 .03 15.4 0.1 0'1 0 . 03 142.1 15.6 0.1 0.1 142.1 0 .03 15.8 0. 1 0.1 142 .1 0 .03 16.0 0.1 0.1 142.1 0 .03 16.2 . 0.1 0.1 142 . 1 0 .03 16.4 0.1 0. 1 142 . 1 0 .03 16.6 0.1 0.1 142. 1 0 .03 16.8 0.1 0. 1 142. 1 0 .03 17.0 0.0 0.1 142. 1 0 .03 17.2 0.0 0. 1 142.0 0 .03 17.4 0 .0 0.1 141 . 9 0 .03 17. 6 0 .0 0 .1 0 .03 17.8 0.0 0.0 141 .141.8 8 0 .02 18.0 0.0 0.0 141 . 6 0 .02 18.2 0 .0 0.0 141. 5 0 .02 18.4 0 .0 0'0 0.02 141. 4 18 .6 0 .0 0.0 141. 4 0 . 02 0 .0 0'0 0 . 02 18.8 141.4 0.0 0 '0 0.02 19 .0 0 .0 0 .0 141. 4 0.02 19. 2 19. 2 0 .0 0 '0 141.4 0.02 19 .4 141 . 3 0 .0 0 '0 0.02 19 .6 141.3 19 .8 0 .0 0 .0 - 13 - Merrimack Engineering Services, Lnc. DATE:--L/ J.FERREIRAa SHEET: /'�i OF 2 F HYDROGRAPH-FOR_ HM SUBCATCENT-#__13 CUBIC FEET PER SECOND ********************* :OUR .0.0 0.0 .0. 2 0.0 .0.4 0.0 0. 6 0 .0 L0.8 0.0 L1.0 0.0 L1.2 0.0 L1.4 ******** 0.1 0 .1 .1.8 **************** 0.2 '.2.0 ************************** ****** 0.4 .2 .2 0.2 2.6 **************** .2 .8 **************** 0.2 .3 .0 ******** 0.1 .3.2 ******** 0.1 .3 .4 ******** 0.1 .3 .6 ******** 0.1 .3 .8 ******** 0.1 ,4.0 ******** 0.1 4 .2 ******** 0.1 4.4 *** **** 0.1 4.6 ******** 0.1 4.8 ******** 0.1 5 .0 0.0 5.2 0.0 5.4 0.0 5.6 0 .0 5.8 0 .0 6.0 0 .0 6. 2 0 .0 6.4 0 .0 6. 6 0 .0 6. 8 0 .0 7 .0 0 .0 7 .2 0.0 7 .4 0 .0 7 .6 0.0 7 .8 0 .0 8 .0 0.0 8 .2 0.0 8 .4 0 .0 8 . 6 0. 0 8 .8 0 .0 9 .0 0. 0 9 .2 0 .0 9 . 4 0 .0 9 . 6 0 .0 9 . 8 0 .0 0 .0 0 .0 - 14 - • �� m. DATE ernmack Engineering Services, Inc• 2 4 J.FERREIRAa SHEET• i S OF STORAGE POND # 3 DATA PEAK--------- ELEVATION STORAGE INFLOW OUTFLOW ACRE-FT. TIME CFS CFS ------------------------------- HR. --------------------- ------------------------ 140.9 0 .00 0 .0 0.00 10.0 0.0 0.0 140.9 0.00 10.2 0,0 0.0 140.9 0 .00 10.4 0 .0 0.00 10.6 0.0 0.0 140 .9 0.00 10.8 0.0 0.0 140.9 0.00 11.0 0.0 0 .01 11.2 0'0 0.0 � 140.9 0 .01 11.4 0.1 0.0 141.0 0.01 11.6 0 .1 0.0 141.0 0 .01 11.8 0 .2 0.0 141 .1 p,03 12.0 0.0 141.5 0,03 12.2 0.8 0.2 142.2 0.04 12.4 0.2 0.2 142.2 0 .04 12.6 0 .2 0 .2 1 0.03 12 .8 0•1 u•` 142.2 0 .03 13.0 0 .1 0.2 142.2 0 .03 13.2 p•1 0.1 142.2 0.03 13.4 0.1 0.03 13.6 0.1 0.1 142.2 0 ,03 13.8 0.1 0_1 142.1 0,03 14.0 0. 0.1 .1 0.1 142 0.03 14.2 0,1 0 .03 14.4 0.1 0.1 142.1 p,03 14.6 0.1 0.1 142. 1 0,03 14.8 0. 1 0.1 142.1 0.03 15..0 �:p p.l 142:1 0 .03 15.2 00 .0 0.1 142 0.03 . 15.4 0,1 0.03 15.6 0.0 0.0 141.9 0 ,03 15.8 0.0 0.0 141.8 0 .02 16.0 - 0 .0 0.0 141.7 0,02 16.2 0.0 0.0 141 .6 0 ,02 16 .4 0.0 0.0 141.5 0 .02 16.6 0.0 0 .0 141 .4 0 .02 16.8 0 .0 0.0 141.4 0 .02 17 .0 0.0 0.0 141 .4 0 .02 17.2 00 0'0 1414 0 .02 . . 17 .4 0.0 0 .02 17 .6 0 .0 0.0 141 .3 0.02 17 .8 0.0 0.0 141 .3 0 .02 18.0 0 .0 0 .0 141 . 3 0 .02 18.2 0.0 0.0 141. 3 0 ,02 18 .4 0 .0 0.0 141.3 0 .02 18.6 0 .0 0 .0 141. 3 0 ,02 18.8 0.0 0 .0 141.3 0 .02 19 .0 0.0 0 .0 141 .3 0 ,02 19 .2 0 .0 0.0 141 .2 0 .02 19 .4 0 ,0 0'0 - 15 - 141.2 0 .02 19 .6 f% 0 .0 SUMMARY CE ART OF PEAK FLOW, QP' POST-D pRE-D SUBCAT # SUBCAT # AREA= 0,42 AC POST-D AREA= 0.42 AC "POND" # CN = 90 STORM CN= 83 OUTFLOW EVENT TC =20 MIN TC = IS MIN #1 #11 100 yr 41 6.5 Q Qp = 0.8 cfs @1 = p = 1.5 cfs Qp = 1.9 cfs #2 #12 42 Qp = 0.4 cfs 10 yr Qp = 1.2 cfs @1 = 4.5 Qp = 0.9 cfs #3 #13 43 Qp = 0.2 cfs 2 yr Qp= 0.3 cfs Qp = 0.8 cfs @ 1 =3.1 hs it is shown the subsurface drainage facility will provide From the chart above and the hydrogr a p , e for each of the storm events and will provide a delay in the ample and sufficient storage volume e s stem. of the peak outflow rate from this facility into the state drainage Y occurrence P DRAINAGE ANALYSIS NARRATIVE affects of storm run-off to be e the mounts and � �North Andover. a e an iSthan OSS d Street(Route 125), The purpose of this&a age system ro osed led to the existing reach of the drainage watershed due tCurrrent y, the ad the upper of the protect site. occur in developed portion which contribute to Lake e in run-off` the existing to open lands whl edeirec�trng of storm nun-off from lover. collected and PIPed across he Town of North An rnn_off has been 1 source f addition, Cochichevvicl�,the water supply landovrner wishes to build on an In which the this�_o ff out of the Watershed source Approval of the Site Plan,owner to red As a Condition of App the land own alive impact to the water supply Board is requiring about a potential m e Property' the planning District due to the concern d occur on Protection D ill or other pollution hazard should a gasoline sp FLOW CALcj ATiON: OR DE. ,R�tATION OF PEAK a 10 year PROCEDURE F eak rate of run-off to each catch basin, y he Rational method for determining the p Using t will be used in the calculation: storm design Q=CIA(General Formula) ' 'Coefficient of Surface C Run-off elated, (Pe�ous) C=0.2 Veg envious) C:= 0.9 paved,roof(imp time of concentration(refer to i=Rainfall Intensity,varies as th e rainfall chart) A= area of watershed,in acres a structure or facility will or other drainage nation. xi sting or proposed catch basin w Dint which will an e records, as well as field observation and deterrrll Each drainage area to laps and r depress', at t ed based upon e�'stmg P fled as there�s a dep overflow will occur well after the be determined A is° tration. Any . system during off and provide mfi1 hydraulic capacity of the piping It should be noted that She run- the collect and retain all so as not to impact peak intensity of the storm, peals rates of run-off. —i 1" SIMCAT 41 TO DMH 11 C =20%@O.Z+ 80%@0.9` =0.76 Tc = 15 minutes i =3.7 in/hr A =27,700 sq. ft. =0.64 ac Q=0.76 x3.7 x0.64= 1.80 cfs SI CAT #2 TO DMH#3 C =20% (�0.2+ 80% @ 0.9 =0.76 Tc = 15 minutes i =3.7 in/hr A =20,000 sq. ft. =0.46 ac Q=0.76 x3.7 x0.46= 1.29 cfs CB #3 to infiltration basin, the calculations indicate and presume no en to ovlerflow drainage heg Late system. Should this subusrface infiltration system, �proposed,eriodof run-off, thereby not contributing to drainage system, this would occur well'beyond the peak p the "peak" flow., SLTBCAT#3 TO DETENTION POND AT CB #6 C = 10% @0.2 +90% @0.9 =0.83 Tc =20 minutes i =4.2 in/hr A =66,600 sq. ft. = 1.53 ac Q=0.83 x 3.2 x 1.53 =4.06 cfs into pond 3.3 cfs, use 2.0 cfs @ use use Tc=30 min for inflow= outflow, read Qp = Tc= 15 min, due to attenuation of outflow(ponding). SUBCAT #4 TO CB #6 C = 10% @0.2 + 90% @0.9 = 0.83 Tc = 15 minutes i = 3.7 in/hr A = 66,600 sq. ft. = 0.15 ac Q= 0.83 x 3.2 x 0.15 = 0.46 cfs T l e- SUB CAT 45 TO CB #8 C = 10% @0.2+90%@0.9 =0.83 Tc = 15 minutes i =3.7 in/hr A = 12,700 sq. ft. =0.29 ac Q= 0.83 x 3.7 x 0.29=0.89 cfs SUBCAT 96 TO CB #9 C = 10% @0.2+ 90%@0.9 =0.83 Tc = 15 minutes i =3.7 in/hr A = 10,900 sq. ft. =0.25 ac: Q'=0.83 x 3.7 x 0.25 =0.77 cfs SUBCAT 47 TO CB #10 C = 50% @0.2+ 50%@0.9 =0.55 Tc = 15 minutes i =3.7 in/hr A = 16,500 sq. ft. = 0.38 ac Q= 0.55 x 3.7 x 0.38 =0.77 cfs SIMCAT#8 TO CB #11 C = 10% @0.2 +90% @0.9 = 0.83 Tc = 15 minutes i = 3.7 in/hr A = 9,000 sq. ft. = 0.21 ac Q = 0.83 x 3.7 x 0.21 =0.65 cfs SUB"-AT #9 TO CB #12 C = 10% @0.2+90% 90.9 =0.83 Tc = 15 minutes i =3.7 hlir A = 10,400 sq. ft. =0.24 ac Q=0.83 x 3.7 x 0.24=0.74 cfs DMH#4+ CB #11 + CB #12 TO DMH#5 SUBCAT#10 TO DMH#7 TO DMH#4 (Bevond the Limit of the Proiect) C = 20% @0.2+ 80% @0.9 = 0.76 Tc = 15 minutes i = 3:7 in/hr A = 35,200 sq. ft. =0.81 ac Q=0.76 x3.7x0.81 =2.28 cfs 4� H Q y � 00 o � � O In F •� v1 1 1 1 1 1 1 p 1 1 I 1 � 1 1 I I � Q W A y In M N N kn ^" C � •:� O p v1 O O O •� W y C C � C kn in i�1 1"4 Q � 00 r., r r r 00 00 V _O M M 1 M M M M M 1 M M M M fV M M M M N N QI Gi,i Q r~ •- A II S. r- oorrrv, lnrn110 110 Cam] 00 N O 00 00 N l- N O [- F �D k rn d v1 O :It N_ m m as m as cg m as co as as A u U U U U U U A A U A A A U U U A A x an C� Zt At 4k k It 00 M z o., At 4t r-. .-. it J SPEncn v) virn UUV) UU v� Uv) AC/) U AA u 0 � 0 2 � $ A 0 ' § a � k k § ° 2 � ® 2 « § .§ § .2 2 c � f 4) j ƒ A .� 6 § o � (A 0 u A ■ � � � � � . § ° .B § 4) 2 « 1. � 'O 7 § 7 # o § g § :P- § / ' 2 / — 2 © 4 ; . CY -;B $ u \ « 2 � § 2 2 2 0 > t k / o 2 / § § 0 « l Q C6 0 # o § § 2 k 5 .§ 3 � k W H . O . Drainage and Erosion Control 10.0 9.0 8.0 7.0 6.0 5.0 4.2 3.7 3.2 2.0 �'qs 1.s S +� FREQUENCY (YRS. ) L 1.0 �gs 9 r.. 7 u� •6 U C 4 } F— U1 •2 F— Z .15 J J Q LL 1 Z .09 Q .08 rr .07 06 .05 .04 WF .03 I .02 .01 5 6 7 8 9 10 15 20 30 40 So 60 2 3 4 5 6 8 10 12 18 24 (MINUTES) DURATION (HOURS) Figure 10-4. Intensity — Duration — Frequency Curve for Boston, MA Drainage and Erosion Control Table 10.6 RECOMMENDED RUNOFF COEFFICIENTS (C) FOR RATIONAL METHOD (By Overall Character of Area) Description of Area Runoff Coefficients Business Downtown 0.70 to 0.95 Neighborhood 0.50 to 0.70 Residential Single-Family 0.30 to 0.50 Multi-Family, Detached 0.40 to 0.60 Multi Family, Attached 0.60 to 0.75 Residential (Suburban) 0.25 to 0.40 Apartment 0.50 to 0.70 Industrial Light 0.50 to 0.80 Heavy 0.60 to 0.90 Parks, Cemeteries 0.10 to 0.25 Playgrounds 0.20 to 0.35 1 Railroad Yard 0.20 to 0.35 Unimproved d.10 to 0.30 Woodland 0.15 to 0.25 Cultivated 0.40 to 0.60 Swamp, Marsh 0.10 to f O 0 4�0 I l i Q I CHART 3 5 04 b , W I 06 p o z I 9040; oo I ti - 001 I I 003 � �p�ry p`y ` to 7. --► I 1 W. {J ppok jh Q h i N p W m O 1 000 t e P I - a It �_.._!__..,....._ .. •' � � erg. T W �a8 'P R1 N 000 i\ V h S/O' + U Sdd -^ - 4.ZI007_?A P � O 710'-U P , )y ZO,sU P/PE FLOW CHART 12-/NCH DIAMETER p fI► YO � QI I�• i HI A�I RT 36 I C �� ut 1 O N I O O io � I 'p v> l wo 0000 y b {o Iq 0 o Ell 0 L 1 i 46 00� i p I {I� 0 In 001 0 ti .0 V I 10 ,` 000 0 i N I I CO OOw � i 1x- r i 0 W 0 J { I M1 1 1 I {� ♦ V m `{ b j i I L i i 1 I h I i C 1 � i 1 N 1 { j � 0 11 • a p ' I � a• O 00 00 o o.o 00 o 9/0' _ Sdd - A - .4l/0073A 0 0 o zu o a O I PIPE FLOW CHART 15-INCH DIAMETER 180 10,000 CHART i o 168 8,000 EXAMPLE (1) (2) (3) ` 156 0.42 inches 3.3 6. 6,000 ( Nat'l 144 5,000 0.120 ets 6, r +,000 4 S. S. 132 s. o 3,000 hat 5. 4, 120 (1) 2.5 0.e 4 2,000 (2) 2.1 7.4 108 (3) 2.2 7.7 4. 3• O�S/8,(,� 00 in Feat 3. —'F 96 1,000 3. /O YEsi2 84 800 __ Sjb/Z p►(,.." 600 / 2— 2�jr�G 4 rS' /IV 500 _ 5CWCH4,R9c N 72 400 / 2. CO,V0(7740A z 300 60 200 � 1 f a ., -. NW = 1.20 ° U. 42 ° 60 / a 1.0 1.0 0 N 4G HD ENTRANCE ° 1.0 ° SCALE TYPE 36 t- 9 W 30 (1) S4eore edge With t •9 33 Madsgll G .9 p 20 (2) Groev4 en1 nth C 30 headwall = g 8 (3) / Groeve end .9 2T / projecting 10 24 8 .7 7- .7 6 To use $4014(2) at (3)project 21 s horizontally to Seale(1).then 4 use Straight inclined line through 0 and 0 scales,or reverse as 6 3 illustrated. 6 .6 18 2 13 .3 5 1.0 .5 12 HEADWATER DEPTH FOR HEADWATER SCALES 2a3 CONCRETE PIPE CULVERTS 13UREAU OF PUBLIC ROAOe JAN. 19453 REVISED MAY 1964 WITH INLET CONTROL 181 -- OgZ ANA VISCG� CN " CF CNJ , UQ" QOK ol a �PI,, /� M •�^t� � „�• .'� ��` 1 f� °'' ► �. �• �' - _ CAT #g TJBCAT t �$ icE GSA �O _ / i �� StJgCAT #6 w �G�� � • ` fir` v� � - SJ° �� WATERSHED PLAN SCALE: 1" = 100' L) T O r0 C7 / Merrimack Engineering Services, Inc. d .• D2D �+,C�y G O < rA Vp a a° ORR s11IAGE SYSTEM PLA_ AJ f it r iz� V v Merrimack Engineering Services, Inc. Y.0