Loading...
HomeMy WebLinkAbout1989-05-05 Environmental Impact Report DEF SUB i r ENVIRONMENTAL IMPACT REPORT for.. ENGLISH CIRCLE on SALEM STREET in. NORTH ANDOVER, MASS... , GENE Li, - ENGLISH 14' - HARVARD. STREET WOBURN,.;. MASSY. - 0 180 1- . I MAY . 1989 i MERRIMAC.K ENGINEERING SERVICES, Inc. 1 BB Park Street Andover, Massachusetts 01810 ' planners ® engineers ® surveyors 1 ENVIRONMENTAL IMPACT REPORT ENGLISH CIRCLE NORTH ANDOVER, MASSACHUSETTS BACKGROUND A PURPOSE The purpose of this report is to satisfy the requirement of the Town of North Andover Planning Board relative to the preparation and submission of an Environmental Impact Report, as part of the subdivision plan and review approval process instituted by the Planning Board in North Andover. SITE LOCATION/DESCRIPTION The site consists of approximately three and one-half (3 . 5 ) acres of land located at and behind #521 Salem Street in North Andover , Massachusetts . Currently , the site is utilized with a single family home and a small horse farm , having a barn and several buildings attached to the main structure , as well as several corrals and fenced areas which contain the horses . The major portion of the site, is open pasture land with very little woods . The buildings are in generally good repair. The property is located approximately across the street from Bannon Drive and is surrounded by single family land uses . The site is serviced with Town water , having an 8" main in Salem Street, as well as a storm drainage collection system in Salem Street. Salem Street itself is a county layout and the property lines of this parcel are marked with stone walls , fences , or other monuments in the field , all as shown on the subdivision plans . WETLANDS/SOILS There are no wetlands located on the site , the site having been inspected by IEP in 1986 . In 1987 , IEP flagged wetlands located on adjacent property owned by Abbott Street Realty Trust. Those wetland flags and their locations were verified by the Conservation Commission Agent at the time of submission of a preliminary plan in 1987 to the Town of North Andover. The wetlands were field surveyed by Merrimack Engineering Services and are shown on the grading plan contained within the subdivision plan set. A two ( 2 ) page report from IEP relative to the wetland determination and location is contained within the appendix of this report. Because of the proximity of this site to the wetlands , a portion of the site is located within the 100 ' jurisdictional boundary of the Conservation Commission . MERRIMACK ENGINEERING SERVICES, INC. • 66 PARK STREET • ANDOVER,MASSACHUSETTS 01810 The United States Soil Conservation Service , in their report of the Northern part of Essex County , Massachusetts , have classified the soil on this site as Canton series soil . Generally , this soil is found in gently or steeply sloping areas , is deep and well drained in irregularly shaped areas , usually found near the bottom of hills in survey areas . Typically , the surface layer is very friable , dark-brown , fine sandy loam for about 6 " in thickness . The subsoil is very friable fine sandy loam while the substratum is loose , light brownish gray gravelly loamy sand to a depth of 60" or more . The permeability of the soil is moderately rapid to rapid and the available water storage capacity is moderate . The majority of soils of this type have been normally found in farm pasture areas but because of the stones contained within the soil , it is very difficult to raise crops . Because of the permeability of the soil , and its high bearing capacity , it is well suited to residential development with limitations being the height of the seasonal high water table . Test pits and percolation tests were taken in the field by Merrimack Engineering Services and others , in the presence of the Town of North Andover Board of Health Inspector. Copies of the soil data and percolation test data are contained within the appendix of this report. Generally speaking , the soil testing indicates that the land is suitable for the construction of single family homes , and the construction of subsurface disposal systems in accordance with the Town of North Andover requirements and the requirements of the Commonwealth of Massachusetts Title V . THE PROPOSAL The proposed subdivision involves the creation of four (4 ) lots , one of which would service the existing single family home and barn located on the premises . A portion of the existing paved area on the site , as well as one of the existing barns , would be moved in order to accomodate the construction of a roadway approximately three hundred fifty feet (350 ' ) long, to service three (3 ) additional lots , each of which would be suitable for the construction of a single family home . The zoning in this area is R3 , requiring twenty- five thousand ( 25 ,000 ) square feet of land area , and each lot within the subdivision conforms to this minimum area requirement. Each lot would have frontage on the proposed roadway . Each lot has been designed in full accordance with the Town of North Andover bylaw, including shape , size , frontage , and minimum contiguous buildable area . .. .2 MERRIMACK ENGINEERING SERVICES, INC. • 66 PARK STREET • ANDOVER,MASSACHUSETTS 01810 The grading plan indicates the possible location of a house on each of the lots , as well as the location of the subsurface disposal system which would service each individual house . The finish grading associated with the construction of each septic system and house , as well as the roadway, has been shown on this grading plan . Since the site is primarily pasture , minimal tree cutting will occur if this proposal is implemented. Some regrading of the site will occur to accomodate the finish grades required to meet the roadway and septic system standards previously referred to. Each of the houses within the development would be serviced with Town water which will be extended within the roadway from the existing water main on Salem Street . Fire protection would exist from hydrants to be installed on the roadway . Again , this information is shown in total on the subdivision plan and profile sheet, as well as the grading sheet. The roadway would be constructed in accordance with the Town of North Andover subdivision control requirements , as well as the requirements of other applicable departments within the community . In order to achieve conformance with these requirements , and to meet the alignment regulations of the subdivision control law, a small parcel of land , labeled "X " on the plan , will be created. It is the intention of the developer to convey this small portion of land to the Town as part of the right-of-way grant. The houses proposed to be constructed on each lot have been located so that they are at least fifty feet ( 501 ) from the edge of the existing wetland on the adjacent site . in addition , the site has been designed so that there is no encroachment or grading within twenty- five feet (25 ' ) of the wetland area. This 25 ' no-cut zone and 50 ' no-build zone have been delineated on the plan . The septic systems have been laid out to be constructed at least one hundred feet (100 ' ) away from the wetlands and other drainage areas . The septic systems have been laid out in accordance with the Town of North . Andover Board of Health requirements . The storm drainage system to be constructed within the roadway has been designed and laid out in complete conformance with the Town of North Andover subdivision requirements . This system consists of a pair of catchbasins at the end of the roadway , which will collect the surface storm water runoff, and being equipped with sumps , will collect sediment that runs off from the roadway on the site into the drainage system. The storm drainage will be discharged into a small detention area which will be located at the end of the cul -de- sac and contained within an easement. - 3 - MERRIMACK ENGINEERING SERVICES, INC. • 66 PARK STREET * ANDOVER, MASSACHUSETTS 01810 This detention area will mitigate the impacts of development of the site , as it relates to the peak flow of surface water generated for a 100 year storm. This storm drainage is then discharged from the detention area into the existing wetland and the watershed which it currently discharges into. The outlet from the detention area is located twenty- five feet (25 ' ) from the wetlands and adjacent to a small swale which currently exists on the site , and currently carries storm water into the wetlands . Other portions of the site will be sloped and graded so that the discharge , again , is to the existing wetlands via overland flow. This is the current cap of runoff, and again , the ultimate discharge of the runoff from the site . The storm water from the site does not access any sensitive receptors such as water supplies , etc . As noted in the drainage calculations for the subdivision , a zero percent (0%) increase in the runoff rate will be provided through the construction of this subdivision . Because there is an existing house on the site , the net potential impact of the subdivision is three (3 ) single family lots . As a result, it is estimated that the construction of 3 single family homes on the property will result in the generation of approximately eighteen (18 ) trips per day on the roadway and on Salem Street. Given the moderate traffic volumes currently existing on Salem Street , this represents a relatively small increase in the traffic on the roadway. Assuming that two (2 ) children per house reside in the subdivision , this development has the potential to generate an additional six (b ) children in the North Andover school system if the buyers of the houses are located not in North Andover , but from the outside area . Again , the net increase in school -age children as a result of this development cannot be accurately estimated as the buyers for each of the homes to be constructed are not known at this time . The Town of North Andover, as a result of the construction of this development, will be required to provide normal administrative services as well as normal solid waste collection and disposal , and normal maintenance of the roadways . The Department of Public Works will not need to provide sanitary sewer service to these lots as they will be serviced by septic systems ; however they will supply water from the existing municipal system through the installation of the water main within the roadway. SCHEDULE f OR CONSTRUCTION It is anticipated that this subdivision will be constructed in one total phase, It is anticipated that a Notice of Intent will be filed with the North Andover Conservation Commission in April of 1989 , and definitive plans will be filed with the Planning Board at approximately the same time . - 4 - MERRIMAdK ENGINEERING SERVICES,INC. • 66 PARK STREET • ANDOVER,MASSACHUSETTS 01810 An Order of Conditions for the development would be anticipated for issuance in May or June of 1989 , and subsequently , approvals by the Planning Board issued in June or July of 1989 . Construction could begin , at the earliest, by late summer or early fall of '1989 and be completed in approximately three (3 ) months . Of course , this will be a function of economic conditions , which vary , and as such , portions of, or the entire development, may not be completed until 1990 or later. Houses will be constructed at the time of roadway construction , or the entire roadway , storm drainage system and ancillary filling will be undertaken by the developer , and houses constructed sometime thereafter. The developer must obtain individual subsurface disposal system permits for each of the houses to be constructed on the lots , as well as individual building permits for each of those houses . It is anticipated that those permits will be sought after Planning Board approval of the subdivision and receipt of an Order of Conditions by the Conservation Commission to construct the development. MERRIMACK ENGINEERING SERVICES, INC. • 66 PARK STREET • ANDOVER, MASSACHUSETTS 01810 TEST P ITS/PERCOLATION TEST DATA ENGLISH CIRCLE NORTH ANDOVER, MASSACHUSETTS ( D. O.H . = DEEP OBSERVATION HOLE) LOT 1 D. O. H. 1 - 1 0" - 06 " topsoil 5/14/87 06 " - 102 " sandy till water @ 78 " D. O. H . 2- 2 0" - 06 " topsoil 5/14/87 06 " - 102 " sandy till _ '.. water @ 96 " PERCOLATION TEST 1 - Percolation Rate 12 min/in @ 48 " 12/14/88 PERCOLATION TEST 2 - Percolation Rate 4 min/in @ 48 " 12/14/88 LOT 2 D. O. H. 2-1 0" - 12 " top & subsoil 5/14/87 12 " - 42 " fine clay sandy gravel water @ 12 " D. O. H. 2-2 O" - 12 " top & subsoil 5/14/87 12 " - 30" clay layer 30" - 60" gravel water @ 12 " D. O. H. 2-3 0" - 12 " top & subsoil 5/14/87 12 " - 3011 clay layer 30" - 60 " gravel water @ 12 " D. O. H. A 0" - 24 " top & subsoil 12/14/88 24" - 84 " sandy boney till 84" - 102 " sand no water D. O. H. 2 0" - 18" top & subsoil 2/4/87 1811 - 90" compact gravel till w/cobbles water @ 24" MERRIMACK ENGINEERING SERVICES, INC. + 66 PARK STREET • ANDOVER, MASSACHUSETTS OISIO 2 - D . O.H . 3 0" - 18" top & subsoil 2/4/87 18" - 72 " sandy silty till 72" - 108 " compact sandy silty till no water PERCOLATION TEST 1 - Percolation Rate 6 min/in @ 48 " 12/14/88 PERCOLATION TEST 2 - Percolation Rate 2 min/in @ 36 " 12/14/88 LOT 3 D. D. H. 1 0" - 18" top & subsoil 2/4/87 18" - 108 " coarse sandy till water and mottle line @ 36 " D. O. H . 3-1 0" - 24" top & subsoil 5/14/87 24 " - 72 " gravel water @ 24" D. Q. H. 3-2 0" - 30" top & subsoil 5/14/87 30" - 72 " clay layer 72" - 132 " gravel water @ 24" PERCOLATION! TEST 1 - Percolation Rate 2 min/in @ 38" 12/14/88 PERCOLATION TEST 2 - Percolation Rate 2 min/in @ 42 12/14/88 MERRIMACK ENGINEERING SERVICES, INC. • 66 PARK STREET • ANDOVER. MASSACHUSETTS 01810 Form 3 ''A OEOE File No. r, Commonwealth (To bA p►ov3ded by�EQE} — ;f , of Massachusetts � City/Town NORTH AND-OVER E I f Appikcent GENE Notice of intent Under the Massachusetts Wetlands Protection Act, G.L. c. 131, §40 and Application for a Department of the Army Permit Under the T wn of North Andover Bylaw, Chapter 3 Section 3.5 A&B rt I:General Information Location: Street Address SALEM STREET NORTH ANDOVER Lot Number 1.2 3-,. ROAM Project:Type BUFFER Description CONSTRUCTION OF A ROADWAY HOUSES & APPURTENANCES WITHIN 100' OF A RESOURCE AREA. Registry: County ESS "NORTH Current Book. 1327 _&Page 711 Certificate(lf Registered Land) i, Applicant GENE L. ENGLISH Tel. (617) 935-2251 Address 1 S REST EXTENSION WOB N 8 1 >. Property Owner GENE ENGLISH Tel. (617) 935-2251 Address 14 HARVARD STREET EXTENSION , WOBURN, MA 01801 B. Representative MERRIMACK ENGINEERING SERVICES Tel.(508) 475-3555 Address 66 PARK STREET, ANDOVER, MA 01810 T. Have the Conservation Commission and the DEOE Regional Office each been sent,by certified mail or hand delivery, 2 copies of completed Notice of Intent,with supporting plans and documents? Yes a No C] 31 rMlnrNrn 11 /i/fib , 8. Have all obtainable permits,variances and approvals required by local bylaw been obtained? Yes © No X$ Obtained; Applied For; Not Applied For: PRELIMINARY SUBDIVISION DEFINITIVE SUBDIVISION APPROVAL APPROVAL BOARD OF HEALTH SEPTIC SYSTEM PLANS 9, Is any portion of the site subject to a Wetlands Restriction Order pursuant to G.L.c. 131, §40A or G.L. c. 130, §105? Yes 0 No 10. Ust all plans and supporting documents submitted with this Notice of Intent. Identifying Number/Letter Title,Date A SUBDIVISION PLAN ENGLISH CIRCLE IN NORTH ANDOVER MASS DRAWN FOR GENE L. ENGLISH, APRIL 1989 MERRIMACK ENGINEERING SERVICES, 5 SHEETS B DRAINAGE CALCULATIONS BY MERRIMACK ENGINEERING SERVICES DATED APRIL 1989, 23 SHEETS C ENVI RONMEIdTAL' REPORT ENGLISH CIRr.I i=, BY MERRIMACK ENGINEERING SERVICES APRIL 1989, ,. 7 SHEETS ., 11,Check those resource areas within which work is proposed; (a)( Buffer Zone (b)Inland; Bank' Land Subject to Flooding, 0 Bordering Vegetated Wettand• 0 Bordering 0 Land Under Water Body a Waterway* © Isolated (c)Coastal; 0 Land Under the Ocean•' El Designated Port Area' 0 Coastal Beach* C] Coastal Dune 0 Barrier Beach 0 Coastal Bank • Rocky Intertidal Shore* 0 Salt Marsh" 0 Land Under Salt Pond* 0 Land Containing Shellfish• 0 Fish Run" •Likely to involve U.S. Army Corps of Engineers concurrent jurisdiction.See General Instructions for Completing Notice of Intent, 3.2 12. Is the wetland ,resource area to be altered by the proposed work located on the most recent Estimated Habitat Map (if any)of rare, "state-listed"vertebrate and invertebrate animal species occurrences provided to the conservation commission by the Natural Heritage and Endangered Species Program? YES [ ] NO [ X} Date printed on the Estimated Habitat Map Issued NO MAP AVAILABLE [ } (it any) JANUA_Y 1989 If yes, have you completed an Appendix A and a Notice of Intent and filed them, along with supporting documentation with the Natural Heritage and Endangered Species Program by certified mail or hand delivery,so that the Program shall have received Appendix A prior to the filing of this Notice of Intent? YES [ } NO [ } 3.3 Part It:Site Description Indicate which of the following information has been provided (on a plan, In narrative description or calcula- bons)to clearly,completely and accurately,describe existing site conditions. Identifying Number/Letter (of plan,narrative or calculations) Natural Features: A,B,C Solis A,B,C Vegetation A,U,C Topography A B Open water bodies(Including ponds and lakes) A,B - Flowing water bodies(including streams and rivers) A,B - Public and private surface water and ground water supplies on or within 100 feet of site A B - Maximum annual ground water elevations with dates and location of test A,B,C Boundaries of resource areas checked under Part I, item 11 above Other Man-made Features; Structures(such as buildings,piers, towers and headwalls) A,B, - Drainage and flood control facilities at the site and immediately off the site, including culverts and open channels (with Inverts),dams and dikes A%B'C' Subsurface sewage disposal systems A,B, "- Underground utilities Roadways and parking areas A B - Property boundaries, easements and rights-of-way Other Part III.Work Description Indicate which of the following information has been provided(on a plan. In narrative description or calcula- tions)to clearly,completely and accurately describe work proposed within each of the resource areas checked in Bart I,item 11 above. Identifying Number/Letter (of plan, narrative or calculations) Planview and Cross Section of: A B Structures(such as buildings,piers,towers and headwalls) A B - Drainage and flood control facilities,including culverts and open channels(with inverts), dams and dikes ABC Subsurface sewage disposal systems&underground utilities A,B - , Filling,dredging and excavating,Indicating volume and composition of material Compensatory storage areas,where required in accordance with Part ill,Section 10:57 (4)of the regulations "^ Wildlife habitat restoration or replication areas -- Other Point Source Discharge Description of characteristics of discharge from point source(both closed and open channel),when point of discharge falls within resource area checked under Part 1,Item 11 above,as supported by standard engineering calculations,data and plans,including but not limited to the following; a•4 1. Delineation of the drainage area contributing to the point of discharge; 2. Pre-and post-development peak run-oft from the drainage area,at the point of discharge,for at least the 10-year and 100-year frequency stcrrn; 3. Pre-and post-development rate of infiltration contributing to the resource area checked under Part I,item 11 above; 4. Estimated water quality characteristics of pre-and post-development run-off at the point of discharge. Part IV:Mitigating Measures 1. Clearly,completely and accurately describe,with reference to supporting plans and calculations where necessary: (a) All measures and designs proposed to meet the performance standards set forth under each re- source area specified in Part 11 or Part III of the regulations;or (b) why the presumptions set forth under each resource area specified in Part 11 or Part III of the regula- lions do not apply. 0 Coastal Resource Area Type: Identifying number or totter © Inland of support documents © Coastal Resource Area Type: Identifying number or letter ❑ Inland of support documents 3-5 C Coastal Resource Area Type; Identifying number or fetter .� Inland of support documents 2. Clearly,completely and accurately describe,with reference to supporting plans and calculations where necessary: (a) all measures and designs to regulate work within the Buffer Zone so as to ensure that said work does not alter an area specified In Part I,Section 10.02(1) (a) of these regulations; or (b) if work in the Buffer Zone will alter such an area,all measures and designs proposed to meet the performance standards established for the adjacent resource area specified in Part II or Part HI of these regulations. r Coastal Resource Area Type Bordered By i 00•Foot Discretionary Zone; Identifying number or letter rZ Inland BORDERING VEGETATED WETLAND of suppoM documents WORK INVOLVES CONSTRUCTION OF HOUSES 50' FROM THE A B BORDERING VEGETATED WETLAND; GRADING 25' FROM THE BORDERING VEGETATED WETLAND; CONSTRUCTION OF APPURTENANCES TO THE HOUSES & ROAD WITHIN 100' OF THE BORDERING VEGETATED WETLANDS. A 0% INCREASE IN RUNOFF IS TO BE PROVIDED; EROSION CONTROL DURING CONSTRUCTION IS PROPOSED. ALL NON-PAVED AREAS ARE TO BE LOAMED AND SEEDED. 3.6 Part V:Additional Information for a Department of the Army Permit 1, COS Application No. 2 (to be provided by COE) (Name of waterway) 3. Names and addresses of property owners adjoining your property: 4. Document other project alternatives(i.e.,other locations and/or construction methods, particularly those that would eliminate the discharge of dredged or fill material into waters or wetlands). 5. 81/2" x 11" drawings in planview and cross-section, showing the resource area and the proposed activ- ity within the resource area. Drawings must be to scale and should be clear enough for photocopying. Certification is required from the Division of Water Pollution Control before the Federal permit can be Issued.Certification may be obtained by contacting the Division of Water Pollution Control,I Winter Street, Boston, Massachusetts 02108. Where the activity will take place within the area under the Massachusetts approved Coastal Zone Management Program,the applicant certifies that his proposed activity complies with and will be conducted In a manner that is consistent with the approved program. Information provided will be used in evaluating the application for a permit and is made a matter of public record through issuance of a public notice.Disclosure of this Information is voluntary,however,if necessary Information is not provided,the application cannot be processed nor can a permit be issued. I hereby certify under the pains and penalties of perjury that the foregoing Notice of Intent and accompanying plans,docu ants and supporting data are true and complete, to the best of my knowledge. �K- &::,� - I ApgJL 12 1989 Signat re of Applicant GENE L. NGi_I Date ilk ARRTI 19_ 1989 Signature of Applicant's RepresentativeX.4 US SKI ©ate FORM "Z%Ceplloa to ENO Form 4346 approved by HgvaACL. I May 1032 MEo 100 (TEST) 1 MAY 8Z This dorrmrnt Contains. a taint Department Cr the Army and State of Masssrhusatts app11ea1ton for a permit to obtain perminion to perform activities in United Stotts wafers The Office' of hlonslemsnt and audpet IOM6l has approved those questions required by the US Armr Corps of LaplM1ena. OMS Nosaber 0102•003a and sapiralion dale of 30 September 1403 applies" This alaleo Oat will be get Is • point type 3.7 En} Zvi fCicle �» gene Z Znglish JA*ed •:St�t6m Geologicil. ,survey " South Gro'veland Quadrangle Site jbocu 't .2083 .and 1.13 .25,'000) b lOQO' 2000 4000 1 •"> \ 1 �.,f 1 a,i,, .o•a •per (', ��_ .,.1�++ •�•;:. . .``\� r "'r��'�' Rom• .•• ._/ :%rl\i`_'�)� � 1. `% . %r'�^��� �♦ . �� � •�- o � �C�� �•.�7��fir, \ � ,% .<`�.. \\.� \ ! JI ' \ f s - vw ,Y •ti • + 1 ' 9 Merrimack Engin�eri�g i Sezv�ces , Znc. : •Engineers Surveyors •� flan a 'e Lr F a < ' dark Street ;* Andover, <Massacl�us'etts Q18ZD * : :Tel {5d8) :+475 3555 r f BRA 14 GE. ANALYSIS for 'I ENGLISH CIRCLE '.on ISALEM STREET ! :NORTH ANDOVER, MASS. I GENE:. L: ENGLISH. 'I 4 %1R A Cr STREET, �►P:Rl�. '1�89� $ CyG qi vlarolt 1. C)LINT0195 1 WALL A MERRIMACK ENGINEERING SERVICES, Inc. : 66 Park Street Andover, Massachusetts 01810 planners '• engineers 0 surveyors English Circle - Gene L. English Sheet No . 1 of 23 Calculated by J. Soucy date 4-5-89 Checked by V. Cantone date +j(/'rfj Table of Contents 2 Site Locus 3 Street Drainage Design 11. Pre and post Development; Data 14 Pre Development Analysis 18 Post Development Analysis 22 Detention Pond Description 23 Summary Merrimack..Engineering Services , Inc . * Engineers - Surveyors - Planners 66 Park Street * Andover, . Massachusetts 01810 „* Tel (508) 475-.3555 English Circle -- Gene L. English Sheet No. 2 of 23 Calculated by J. Soucy date 9--5-89 Checked by V. Cantone date United States Geological Survey - South Groveland Quadrangle Site Locus at 1" = 2083 and 1/3 ft (1 25 , 000) 0 1000 2000 4000 is ,`1rn r /'l�r. �a�Jtl '/• \ °' / •I Cr f 1 % � ``` its . `'•`,i ^,�•; \ �,pr^\�! ..y. Ar, ��t , . 1, '\; `• cl \ l, :rJiiu 'J 1E. •• :•, •�• � .� :\.,ram � � � J },�-: r ` - �' -�'�,-.ram t,;. ' r -f� �. , f�... -.. 1 �• �k � � 1'�//�� Merrimack Engineering .Services , Inc . * Engineers -. Surveyors - Planners 66 Park Street * Andover , , Massachu'setts 01810 * Tel . . (`5O8) '475-3555 English Circle - Gene L. English Sheet No. 3 of 23 Calculated by J. Soucy date 4--5- 89 Checked by V. Cantone date Street Drainage Design Merrimack Engineering Services , Inc . * Engineers -- Surveyors -- Planners 66 Park Street * Andover, Massac.husetts 01810 * Tel , ('508) 475-3555 English Circle Gene L. English Sheet No. 4 of 23 Calculated by J . Soucy date 4-5--89 Checked by V. Cantone date Plan of Street Drainage Contributory Areas scale 1" = 80 ` 0 40 80 160 ti •/A !t�rZ fRQN WeG,k4N,03 `�RM%7TEt))GR40P �* 4tE-� [rrNQ5 IH �B �� r SLAT d' pipR ) Qp� Cp40 IV 14, i ! 4 r.� f .�•4� i T 'JCE C rn WE B .41, nF s ' 4 � `• �f'\a'`� R4b/NG PERMIT C[E4RING d .a .: 4•,v t uvta7�a er rEP 4� A 2 ,No Ic- 1y N.9 f � •5 M � r ,� '.. 40 It's r ty.�p r �. t Iay Old•—r-,,,q R/CNARD ,� �' r , j , /-,ZA/v W/NN/NG i `n,Y jt ♦r`�lee '1 i5 344EM ST,NO A42�DYt'R ��� •0 \ , � r A4ASS' / H! �' A� . ! / i FM for 1•�\ .,�1.0 0� � '. A/ r<D. 1` 11 •. �J G4Wi4EAK'E✓.� /•5T/ W i E•� 1 1 f I SA[fM 37,NO ANd�/ qM All •s�' � �• I3EEP[AN+•KX9 4.NARQ)f fit! •� �� , ��` .'r / ti / Alf. Y ,• , SAL � --�,!��/��-�'S.L�'1 ,/ �•STREF 1 -J14utrLDa �°��M N`� N/'lr ` LEONARO M. ,� PETER 4. d �ITR/CE M C4RPENT,�R WANME s N fLE/L/ STD NO ANO(JYER,MAa6 LEM sr, V �� Merrimack Engineering Services, Inc, * Engineers Surveyors - Planners. 66 Park Street * Andover, Massachusetts 01810 * Tel ('508) :475.-3555 English Circle _ Gene L. English Sheet No. 5 of 23 Calculated by J . S6ucy date 4-5-89 Checked by V. Cantone date Techniques and parameters ; Peak flows were calculated using the Rational Method (Q=CIA) . All street drainage was designed for a 10 year storm frequency. The selected cover type coefficients are; C = 0. 90 for any impervious area . C = 0 . 30 for any area to be foamed and reseeded (disturbed) . C = 0 . 20 for any area to remain in a natural state (undisturbed) . All street drainage pipe to be reinforced concrete with a minimum diameter of 12 inches . Manning' s equation will be used to determine the qualities of pipe flow, the coefficient of friction for all pipe assumed equal to 0 . 015 The minimum pipe slope is 0 . 5% . .The minimum velocity is 2 . 0 feet per second . The maximum velocity is 10 .0 feet per second. The minimum cover over all pipes is 2 . 5 feet except for class V RCP for which the minimum cover is 2 feet . Catch basins are to be located on both sides of the roadway on continuous grades at intervals of not more than 350 feet. Catch basins shall be located at all sags iri the roadway, and near the upstream corners of intersecting roadways unless the intersection is at the top of a vertical curve. Street chart description; „from" the structure at the begining of the pipe being designed . CB - Catch Basin DMH -- brain Manhole HW - Headwall "at station" the roadway station of the above structure. "to" the structure at the end of the pipe being designed . "at station" the roadway station of the above structure. "area name" the name of the contributory area for whose runoff the pipe is being designed. . "area" the area in acres of ' the contributory area. Merrimack .Engineering Services , Inc. * Engineers - Surveyors Planners 66 Park Street * Andover, MassAchUsctts 01810 * Tel . ('508) 475-3555 English Circle - Gene L. English Sheet No. 6 of 23 Calculated by J. Soucy date 4-5--89 Checked by V. Cantone date "impervious" the amount of the contributory area which is impervious in percent. "disturbed" the amount of the contributory area which is disturbed in percent . "undisturbed" the amount of the contributory area which is, undisturbed in percent. "weighted C" this is the composite cover coefficient of the contributory area. "sum of CAs" for pipes which carry more than one contributory area this is the running sum of the weighted C multiplied by the area of all contributory areas previous to the one being calculated in that column for that pipe . "hyd . length" the hydraulic length of the contributory area in feet . "avg. slope" the average slope of the contributory area in percent . "Tc" the time of concentration of the contributory area in percent. "intensity" the design storm rainfall intensity in inches per hour. "Q = CIA" peak runoff through the pipe in .cubic feet per second. "pipe size" size of the designed pipe in inches . "pipe slope" slope of the designed pipe in percent. "velocity" velocity of flow through the pipe in feet per second . "depth" depth of flow through the pipe in inches . Merrimack Engineering Services ,, Inc . * Engineers -- Surveyors - Planners, 66 Park Street * Andover; Massachusetts 0181.0 * Tel . ('508) 475-3555 nglish Circle - Gene L. English Sheet No. 7 of 23 alculated by J. Soucy date 4-5-89 pecked by V. Cantone date or 2 year storm event; rom I CB 1 { CB 2 DMH 1 t station 1 3+35,RT ( 3+47 ,LT 1 3+54 ,LT 0 1 DMH 1 I DMH 1 I FES 1 t station 1 3+54 , LT 1 3+54 , LT 1 --- rea name I A l I A 2 1 -- rea 1 0 . 213 1 0 . 294 I -- mpervious 1 56 . 9 1 74 . 9 1 --- isturbed I 43. 1 1 25. 1 1 ,ndisturbed I -- I -- I -_ ,eighted C 1 0.64 1 0.75 1 -- ,um of CAs 1 -- I -- 1 0 . 36 iyd. length I 340 1 340 1 -- ;vg. slope 1 1.0 ( 1 . 0 I - - 'c 1 12 1 15 1 15 .ntensity 1 2. 5 1 2 . 2 1 2. 2 1 = CIA I 0 .3 I 0 . 5 1 0 . 8 >ipe size 1 12 1 12 1 12 >ipe slope 1 2 .0 1 2 . 0 1 2 . 0 relocity 1 3.3 1 3 .7 1 4 . 3 lepth 1 2.0 1 2 .9 1 3 . 5 :or 10 year storm event; :rom 1 CB 1 i CB 2 1 DMH 1 it station 1 3+35 ,RT 13+47 ,LT 13+54 ,LT ,o 1 DMH 1 i DMH 1 1 FES 1 it station. 1 3+54 ,LT 13+54, LT I -- €rea name { A l 1 A 2 1 -- €rea 1 0 . 213 1 0. 294 1 -- Lmpervious ( 56.9 1 74 .9 1 -- 9isturbed 1 43. 1 1 25. 1 1 -- sndisturbed I -- 1 --- 1 veighted C 1 0.64 1 0.75 1 -- �um of CAs 1 -- 1 -- 1 0. 36 iyd. length 1 340 1 340 I -- ivg. slope 1 1 .0 1 1 . 0 1 --- `c 1 12 1 15 1 15 intensity 1 3. 8 1 3. 5 1 3. 5 CIA I 0. 5 1 0. 8 1 1 .2 pipe size 712 1 12 1 12 pipe slope 1 2.0 1 2.0 1 2..0 velocity 1 3.8 1 4 . 3 1 4 . 8 3epth I 2. 8 1 3 . 4 I 4 . 2 4errimack Engineering Services; Inc.. *. Engineers - Surveyors - Planners . 56 Park Street * Andover, Massachusetts 01810 * Tel . (508) 475-3555 ^. . - . . . - ■■■■E r1■f■■E■■■► �■11■r1fE�t•■■Ian■M■as WE asw+f■■an'MM ■■Mf■INNER■E■047fIMMNfMNMM■MAD■■■ENI■■r1N■■fEI.■■ E■■■f IMONN NNEWi.SMME AN■fI■■rA■ArA■l11■NH■■■MEN■EMMIN M■■EE IMBUE NNNW :Mt■■■■N■1■M'1■AI■OD■■MIN■II■■■MIME■ M■ESE[Nl■H■ ■!■■■■1'1■E■ ■SEE;■;SEE;oE.ti EEl+E Full0 ME I'lf I r,on ME FA,ON Nr on ME "a an rI■■NEON rME EE ■■■■■[■■■■■■I<NyMII■ ■■rll■11■■'1■f■■i■■■�1■■!■II■■■■ EMEEE[■■■■NW.aff A A■IA■■0M!■'M EVES ANRYANMY■SEISE SEEMS ROSEN[■■■■KNOWN.1[i■MT i■IEM■Ilf/,■HIE■■►I ME■■Il SEES .�eH■■E■[■E■■INN*t]fa■,tr0■kJAr 71■■flEfl■I.MEEIS■E■ESEEME■ N■E■M OWNER■■QXMFORMER 11116fEfa I107:A,l/MEI/E■E■1/■■E■■■ ENDED E■■■■M11T■■rlarl■■M■AAMf,A r,1L•J■'T,1AE■lI,S■■NNE■ N■N■■[INS■■■•.1INM'EfIANE ■M/IM■E■ENE BE■■■BEN■MV_aWNIMBR■r►E■'/■ERVANIN11 VANNO."MINI■■■E■■ E■■■■[EI■EEE;.SHN■1,■MIAED?■■r1EF1■E■`9.INM'VANISH MOONS ■■■MIN■■f■E s;,aEW,SIAMEM■r1■■IE1,■■II■■F1■■W LB■■■■■■■■ ONE Basso;AJ■EIIMARVI■■pilows+1■■'I■FAMEL41S7■INS■ENEME EB■ME A■■■■INE■B'A MMMrIM■ENr1N■■Ii■i1■■■r,MOVIES WOMEN O■■■f■■■■NMENEM rI■MtIlm Il■Irf/rl EnE■I.men■%B■■■■■■■■! .� E■E!EA■■■■SHOWS r1N■■■'■■EMFA■V1NNIA■ESri■N■N1■EN■NEE:• NBM■■A■■■■■E■rl■REFINE■■►Ai■ESEVIN E■EE■SENSE S■■■■ ■aIN■■IMENE■E■PAN MEWING■EEIr/■//■E►/M■■►IM■N■■■■■■MM■ ■M■HB RAISES NE■Mri BORROW SIIE'1■M■►EEOSERIES SEEMS INN■E2 ■ENE■N■■■EEEri■I/E11■■',E■11I,■II WOMEN■i■NNN■■■ SOMMIN INS■■■�EIEEEEEI/ES■►l EI/E■■1 EI■/tEEEi/IEEEE E!■!E■i%E■ ■Off■A■f■■EfEwIf woman►AVAEI/■i.■■■I•:■E■■■■E■■E/.E■Ntlr ESESS NNSE■ERN11!/A■!aE/S'1[!%■i■MOMME■E■■■■■LMEMI•/ ■■■■■N■■E■■CHAD'1■F/■///+■►ANW,11E■KINSOM■■BROOKS■!I.!■ � ■■■■E BEE■■END■D ME'MiM%EM■I/■■/'/■ROOM IN MINIMUM BURNS ■ ■E■■■E■■■EEEr1E►i■IAS►1/.■/Il/■!S%■■NER-1■21E■1%t■■IPA E ■ENEM BENN■■BWE A■Mww/REMAIN M/IM■■MI!4ka V pN■r.■EMOM■� ■■■M■■■NE■"DOME IIEII/1N Mauna F.■E■■NIL%UOFT\i■■■■i./■M ■ DBl0■■■MM■'MUN/M'MNM-I■rri■■EM■fEW.KOLIT+J%ESN*MOMS !■son son Oro 1 For,■►///■N7 pan ouonE■■ 7,1L[1/1■■■.! INNER■■HINrAFiffimowI./.M►IE 7EEVAN NEESELSE✓[:1SiiPN■!iM■ an was NONE'A'Ass n■'/AI.■EEErM■MEN■L or,S■■War.0111$raOEM E■NNN E■■►/r�N'�Irwiw��►■NwM■■■■�■M�M■��Na�/M■iMM�� NONE■N■D/Mr■'AIM►/uI/■E/E■■■PI'dM■MEN•son r•idRF!IIIn MEN � ■SEEN I,/IEIIri%Ir;/■ME■■lI.IELM GS■i,■■■a.M■El`i�f■■E ■N■■E/.■/./.I/.%i■R%M■■■I,M/.SEiNEiM■■■ESSS■o�0LEEr\■■ M ES■■Ii Mri.",MIN!%■OMEN r a P■►%■i%Now EE■■■ MEW 141F"/.%ii YENEN/A/.t/I■iEMMENEM CUSPS■Nlw:21■ErE■ !N'7r',i/-UE■■■MEN I MMMIN►.%MSG N■■GO■INN■■MAHM■2 L• WIN � �ilr■MESSES■/./.%rSrSE�':%Sir;'i1 SE■E�irES■■■SSMG M'a1111EE■ a� ■■MIN■MOOSE■'I►�/%I.M■►f EG■■ENMal SEE■■�kamo M■On■ ■■■N■■M■■■%•II,/ ■r."�■*■■■MGr■■■■■��i■■!N■D',i' AN ■■MO■■NNN 0%51GM1:ANm/D■ew■■■■NEZ soon■BEHIND LO/1LOZ BROWN NL4�.�1R%r!%Dlpla■■Moprlinom■■■■M01R iM■MEN■M1*R'+;s N■■EI,;;11105 a !:il■■NM!SNN■■■RSEME1■■ENE■ ■E■ ■NMr:GS/-2■::N■iR �rM�!��rIE■fINH■■Mf■f■■M■■■fMM■ INN' =70!._NFO■■E■■IN■■EEBBB Osman Mumma INNONE r' �:iiFisl INNER■■i■izongs0155020511■■1111 2 /■ + r r - , • r - rr gamma=��ummmwiimnaw==M� lllll§MMMMllllllMI MR ZZAA III I ISO rMOMWAfaa%M1110m IIIII■��/�lli�i��%�� . I IN WAA�,r/MFA9, INNER ■MOWN M II'rNr.-MM..3 v 111MMI�I!�W/i►I/ lll■■ loth /X,!►/ llll0r,lJFAVbM 111VAFV74- 1 sir AV . 11 - - - - - - . . English Circle - Gene L. English Sheet No. 10 of 23 Calculated by J. Soucy date 4-5--89 Checked by V. Cantone date .. o CHART 35 N I Ct 0s OG h ao PAiL h \\ 4oh Qo n x \ o Dw \ 0 00 Oh q W � Q { ! i • p a 0 `s IN V 'a ! Do v 0 IA' ! � a o Aa c �eepppp p Q 000 O COOO q4 00000 - � V10 r U Sdd - A - AJ1007YA a►o"u o QD ►, 46 o ►, m h v M f a0'10U o vo r. w a a M PIPE FLOW. CHART I2-INCH DIAMETER Merrimack Engineering Services , Inc. * Engineers - Surveyors - Planners 66 Park Street * Andover, Massachusetts 01810 * Tel . (508) .475-3555 English Circle - Gene L. English Sheet No. 11 of 23 Calculated by J. Soucy date 4-5--89 Checked by V. Cantone date Pre and Post Development Data Merrimack Engineering Services, Inc. * Engineers -- Surveyors Planners 66 Park Street * Andover, Massachusetts 01810 * Tel . ('508) 4 -3555 English Circle - Gene L. English Sheet No. 12 of 23 Calculated by J. Soucy date 4-5--89 Checked by V. Cantone date Technique; The Pre and. Post Development anslyses. were performed for a 100 year storm event using the methods outlined in the [United States Soil Conservation Service ' s Technical Release 55 . Soil types ; The site and its contributory areas are composed of one soil group, listed below, as defined by the Soil Conservation Service in its report titled "Soil Survey of Essex County, Massachusetts Northern Part" and distributed as shown on the following soils map. CbB, CbC - Canton, hydrologic group B. Curve Number (CN) selection; Three land use descriptions were chosen for the site . These descriptions and their respective CNs are taken directly from the Soil Conservation Service ' s "Guidelines for Soil & Water Conservation" , Table B-1 page B7 . Hydrologic Soil Group A B C D Streets : paved with curbs and storm sewers . 98 98 98 98 Referred to as "impervious" . Also included under this description are all building and driveway areas . Lawns , parks , golf courses , cemeteries , etc . good 1/ 39 61 74 80 Referred to as "disturbed" . Meadow or idle-good condition 30 58 71 78 Referred to as "meadow" . All areas within the Pre and Post Development Analyses fall under one of these descriptions , which when cross-referenced with the correct Hydrologic Group gives the correct base CN. For each subarea the base CNs are combined by percentage to create a composite subarea CN. Merrimack Engineering Services , , Inc. * Engineers ..-. Surveyors - Planners 66 Park Street * , Andover,. Massachusetts 01810 * Tel . . (508). 475-3555 English Circle - Gene L. English Sheet No. 13 of 23 Calculated by J. Soucy date 4-5-89 Checked by V. Cantone date Soil. Conservation Service Soil Survey - Essex County northern part. sheet no. 30, of 42 . Soils map at 1" = 1320 ' (11' - 1/4 mile) I 0 500 1000 2000 I MmD Cr1H 6 tD C bC O C Sts , S B SUB CbC CbD Se PcE Mm6 4e I MD WtC Co \ 4P CbC IPb PbDSe Se dB St A WB 3r P613 WsH RIA PaC n CoC MC S1pb UD b f V SUB Ws ��, RID "is UB 4\ CbiL C h\ P PaH ` /PO�ti... i Wh SUB PbD « S B J 9 CbC � V n �.l'!, \ CoC Wh RIB np� CbB �\ SrB 1 ` COB r / S� Sr V Cbs SUS q t d S 9 $hB CbC : SrA'q S - - s --- Merrimack Engineering Services, Inc. * Engineers - Surveyors - Planners 66 Park Street * Andover, Massachusetts 01810 * Tel . ('508) 475-3555 English Circle - Gene L. English Sheet No . 14 of 23 Calculated by J . Soucy date 4-5-89 Checked by V. Cantone date Pre Development Analysis Merrimack Engineering Services , Inc * Engineers Surveyors -Planners 66 Park Street * Andover, Massachusetts 01810 ' * Tel . ('508) 475-3555 English Circle - Gene L. English Sheet No. 15 of 23 Calculated by J. Soucy date 4--5-89 Chucked by V. Cantone date Pre Development subarea plan. scale 1" = 8011 MINIM- 0 40 80 160 h r1Q�._� 11r—t�n�c aw �D'SE1g ti CCCt,QRI 4ND5 ! . ! ANDS ZAYFQS /Lf A � I ACE- Ste ANT 1 ies a•eP0at �P� ✓�1 fir / /` � P°,,,, •/s ey No AP r�'{ . �.1/ a CE• aw/I PRgNi/�' lb '.. _ /� ♦ •' Cl ARING�'I Q�fI ,NtEDrdY I�Ep .w +' 1 ff0 �a '• ��� ,` '�• ++++ �H q♦tip �6 FflD 10 Sd3 SALEM ,r+.a NO Qy00►254,� Opp em 07341 , /•37Y W I.A. 1 SAC NO NOOYER MAOR 5 ! , M' CJ PLiIN+ _ + EM y �/ �}- asy!_,_.� �I /, •ems' 45/r"'1 LW1! �L/C ) / `Srrrrt�oj+�T•.�~ ; DPEt�'R P.IAHAST,�NO.WWN� � �71PsCE M� 4,AZ Merrimack Engineering Services , Inc. * Engineers -- Surveyors - Planners 66 Park Street * Andover, Massachusetts 01810 * Tel . ('508) 475-3555 ' . English Circle —Gene L. English Sheet No. 16 of 23 Calculated by J . Soucy date 4-5-89 Checked by V. Cantone date Subarea "Pre" conditions Total area =. 4 . 119 acres (planimetered from 40 scale topogaphic survey) Hydrologic I Percent coverage Soil type ' group E of subarea ------------------------------ ------------ ------_-_------- Cb$ ,CbC = Canton B E 100 8 . 2% impervious at a CN of 98 41 . 8% disturbed at a CN of 61 50 . 0% meadow at a CN of 58 Subarea "Pre" CN = 62 . 5 say 63 Route through 300 ft of sheet flow over short grass, n = 0 .15 , s = 0.040 ft/ft Tc = 0 . 303 hr (18 . 2 minutes) to design point 1 . Merrimack Engineering Services , Inc . * Engineers - . Surveyors .- Planners 66 Park Street. * Andover, Massachusetts 01810 * Tel . ()508) 47-5 3555 English Circle - Gene L. English Sheet No. 17 of 23 Calculated by J. Soucy date 4-•5-89 Checked by V. Cantone date Pre Development runoff summary; Subarea Pre Area (acres) 4 . 119 CN 63 Tc (hours) 0 . 303 Time Total 10. 0 0 . 2 0 . 2 10 . 2 0 . 2 0 . 2 10. 4 0 . 2 0 . 2 10 . 6 0 . 3 0 . 3 10. 8 0. 3 0 . 3 11 .0 0 . 3 0 . 3 11 . 2 0 . 4 0 . 4 11 . 4 0 .6 0 . 6 1.1 . 6 1 . 1 1 . 1 11. . 8 5. 2 5. 2 12 . 0 10 . 7 P 10 .7 P 12 . 2 6 . 1 6 .1. 12. 4 3 . 0 3 . 0 3.2 .6 2 . 0 2 . 0 12 . 8 1 . 4 1 . 4 13 . 0 1 . 2 1 . 2 13 . 2 1 . 0 1 . 0 13 . 4 0. 9 0 . 9 13. 6 0. 8 0 . 8 13. 8 0.7 0 .7 , 14 . 0 0 . 7 0 .7 14 . 2 0. 6 0 . 6 14 . 4 0V. 6 0 . 6 14.6 0 . 5 0 . 5 14 . 8 0 . 5 0 . 5 1.5 . 0 0. 5 0 . 5 15. 2 0 . 5 0 . 5 15 . 4 0 . 4 0 . 4 15. 6 0 . 4 0 . 4 15. 8 0 . 4 0 . 4 16 . 0 0. 4 0 . 4 16 . 2 0 . 4 0 . 4 16 . 4 0 .4 0 . 4 16 . 6 0 . 4 0 . 4 16 . 8 0. 4 0 . 4 17 . 0 0 . 4 0 . 4 17 . 2 0. 3 0 . 3 1.7 . 4 0 . 3 0 . 3 17 .6 0. 3 0 . 3 17 . 8 0 . 3 0 .3 18 .0 0. 3 .0. 3 P - Peak flow. Merrimack Engineering Services , Inc . * Engineers - Surveyors - Planners 66 .Park Street * Andover, Massachusetts 01-810 * Tel . (508) 475-3555 English Circle - Gene L. English Sheet No. 18 of 23 Calculated by J. Soucy date 4-5-89 Checked by V. Cantone date Post Development Analysis Merrimack Engineering Services , Inc . *Engineers - Surveyors -- planners 66 Park Street * Andover, Massachusetts 01.810 * Tel . (t08) -475-3555. English Circle - Gene L. English Sheet No. 19 of 23 Calculated by J. Soucy date 4-5-89 Checked by V. Cantone date Post Development subarea plan scale 1" 0 40 80 160 � •so'n+o�vico•SE�a,p�. fRAN We714A'A5 a°o z°avE",r�n , "� y A,Lr.4� ;�, ���S s PQINT 1 •� 1,t ti\r rs �N 0" Ott A+�A �!,`•�,�.` ' ~n+i•M/SM�M••fIP gyp [►�t3`� q`� it "� ti�' ` ♦ ��! fi y •�.'� '., to R _� / YY � I �R. AY�IIi1D fir/ t j r` Q�I �ACK A ry IC£ dwq � RD3 C[E•4R/NGe 1 1 RaI ~ •'`1 \ 4 fN [/ [A>'cOreyNPS to + a•/V�. U REA � I 1/ t-t 40- '• ♦ '�t�° , nor � �1 �,.r 00 RICHARD B. 4' r'r �°o XAN WINNING N �' t4 •S�s MkEmo r.,NO A POP P � AM45• �-1 or AI/F ` " s 1 •/' � LEM NOANOOY�/ /•3T1 WrD I �° (SA7 PLA'V. E.NOROJ / r r 1 J1 air1 r1 arr;.M i W Apo + r' [ , l �� � vp fiFi pd• N rr SAL. ; H=ES.� J,��� ''•STREET AlIr L�ONARD M IW 3 a R M Merrimack Engineering Services , Inc * Engineers - Surveyors - Planners 66 Park Street * Andover , Massachusetts 01.810 * Tel. (508) 475--3555 English Circle - Gene L. English Sheet No. 20 of 23 Calculated by j. Soucy date 4-5-89 • Checked by- V. Cantone date Subarea "Pond" conditions Total area = 0. 577 acres (planimetered from 40 scale topogaphic survey) I Hydrologic Percent coverage Soil type I group I of subarea -------------------------------- I -------------- I ----------------- CbB,CbC " Canton B I 100 59 . 8% impervious at a CN of 98 40 . 296 disturbed at a .CN of 61 Subarea "Pond" CN - 83 . 1 say 83 Route "through 300 ft of sheet flow over pavement , n = 0 .011 , s = 0. 010 ft/ft Tc = 0 . 065 hr (3 .9 minutes) use minimum Tc of 6 minutes . into proposed detention pond 1. Subarea "Rest" conditions Total area = 3 . 542 acres (planimetered from 40 scale topogaphic survey) 1 Hydrologic Percent coverage Soil type E group I of subarea ----------------------------- ------------- I ------------------ CbB ,CbC -- Canton B E 100 10 . 1% impervious at a CN of 98 89 . 9% disturbed at a CN of 61 Subarea "Rest" CN = 64 .7 say 65 Route through 300 ft of sheet flow over short grass, n = 0. 15, s = 0 .027 ft/ft Tc = 0 . 354 hr (21 . 3 minutes) to design point 1 . Merrimack gngineering Serviced, . lnc. * -Engineers -.,Surveyors Planners 66 Park Street * Andover, Massachusetts 01810 * Tel ."`.('508) 475-3555 English Circle - Gene L. English Sheet No. 21 of 23 Calculated by T. Soucy date 4-5-89 Checked by V. Cantone date Post Development runoff summary; Subarea Pond Rest Area (acres) 0 . 577 3 . 542 CN 83 65 Tc (hours) 0 . 100 0. 354 Time Total 10 . 0 0. 2 0 . 0 0 . 2 10 . 2 0 . 2 0 .0 0 . 2 1.0. 4 0 . 2 0.0 0. 2 10 . 6 0 . 2 0 . 0 0 . 2 10 . 8 0. 4 0 . 1 0 . 3 11 . 0 0 . 4 0 . 1 0 . 3 11 . 2 0. 4 0 . 1 0. 3 1.1 . 4 0 . 7 0 . 2 0. 5 11 . 6 1 . 4 0 . 5 0 . 9 11 . 8 8 . 2 4 . 1 P 4 . 1 12 . 0 11 . 1 P 2 . 0 9 . 1 P 12 . 2 6 . 9 0 . 6 6 . 3 1.2. 4 3 . 8 0. 5 3 . 3 12. 6 2 . 3 0 . 3 2 . 0 12 . 8 1 . 8 0. 3 1 . 5 13. 0 1 . 4 0 . 3 1 . 1 13 . 2 1 . 2 0 . 2 1 .0 1.3 . 4 1 . 0 0. 2 0 . 8 13 . 6 0. 9 0. 2 0 . 7 13 . 8 0 . 9 0 . 2 0 . 7 14 . 0 0 . 8 0. 2 0 . 6 14 . 2 0. 8 0 . 2 0 .6 14 . 4 0. 6 0 . 1 0 . 5 14 . 6 0 .6 0.1 0 . 5 14 . 8 0 . 6 0. 1 0. 5 15 .0 0 . 6 0 . 1 0. 5 15. 2 0. 5 0 .1 0 . 4 15. 4 0. 5 0 . 1 0 . 4 15. 6 0. 5 0 . 1 0 . 4 15. 8 0 ..5 0 . 1 0 . 4 16. 0 0 . 5 0 .1 0 . 4 16 . 2 0 . 5 0 . 1 0 . 4 16 . 4 0 . 4 0 . 1 0. 3 16. 6 0 .4 0 . 1 0. 3 16 . 8 0 . 4 0 . 1 0. 3 17 . 0 0. 4 0 . 1 0 . 3 17 . 2 0 . 4 0 . 1 0 . 3 ' 17. 4 0 . 4 0 . 1 0 . 3 17 . 6 0 . 4 0. 1 0 .3 17 . 8 0 . 4 0 . 1 0 . 3 18 . 0 . 0 . 4 0. 1 0. 3 P - Peak flow. Merrimack Engineering Services , Inc. * Engineers - Surveyors -- Planners 66 Park Street *` Andover, Massachusetts 01810 * Tel'. ('508) 475-3555' English Circle -Gene L. English Sheet No. 22 of 23 Calculated by a. Soucy date 4-5-•89 checked by V. Cantone date Proposed detention pond 1 description; Area Level storage Cumulative storage Level Elevation (ft-2) (ac . ft) (ac . ft) 6 199 . 5 2, 400 0 . 055 0 . 268 5 199 . 0 2 , 400 0. 096 0 . 213 4 198 . 0 1 ,760 0 . 065 0 . 117 3 196 . 0 1 , 056 0. Q37 0 . Q52 2 194 . 0 560 0. 015 0 . 015 1 191 .9 72 0 0 Control outlets ; 1 - 4" control outlet inv.out = 191 . 9 2 _ 175 degree "V" notched weir inv.out = 197 . 0 Time Inflow Outflow Surface Storage Outflow (hr) (cfs) (cfs) (ac . ft) . (ac .ft) plot 11 . 0 0 . 1 0. 1 192 . 1 0 . 00 ++ 11 . 2 0. 1 0 . 1 192 . 2 0 . 00 ++ 11 . 4 0. 2 0 . 1 192 . 3 0 .00 ++ 11 . 6 0. 5 0. 2 192 . 6 0 . 01 +++++ 11 . 8 4 . 1 P 0 . 8 194 . 6 0 . 04 +++++++++++++++++++++ 12 . 0 2 . 0 110 P 196 . 3 0 . 07 P +++++++++++++++++++++++++++ 12 . 2 0 .6 1 . 0 196 . 4 P 0 . 06 +++++++++++++++++++++++++++ 12 . 4 0. 5 1 .0 196 . 1 0 . 05 +++++++++++++++++++++++++++ 12 . 6 0. 3 0 .9 195. 8 0 .05 ++++++++++++++++++++++++ 12 . 8 0 . 3 0 . 9 195. 3 0 . 04 ++++++++++++++++++++++++ 13 . 0 0 . 3 0 . 8 194 . 8 0 . 03 +++++++++++++++++++++ 13 . 2 0. 2 0 .7 194 . 3 0 . 02 ++++++++++++++++++ 13 . 4 0 . 2 0. 6 193. 8 0 . 01 ++++++++++++++++ 13 . 6 0. 2 0 . 4 193 . 1 0 . 01 ++++++++++ 13. 8 0.2 0 . 3 192 . 8 0 .01 ++++++++ 14 . 0 0 . 2 0 . 2 192.7 0 .01 +++++ 14 . 2 0 . 2 0 . 2 192 . 6 0 .00 +++++ 14 . 4 0. 1 0. 2 192. 4 0 . 00 +++++ 14 . 6 0. 1 0 . 1 192. 3 0 . 00 ++ 14 . 8 0. 1 0 . 1 192 . 3 0 . 00 ++ 15. 0 0. 1 0. 1 192 . 2 0 . 00 ++ 15. 2 0. 1 0. 1 192 . 2 0. 00 ++ 15. 4 0 . 1 0 . 1 192. 2 0. 00 ++ 15 . 6 0 . 1 0. 1 192 . 2 0 .00 ++ 15. 8 0 . 1 0. 1 192 . 2 0. 00 ++ 16 .0 0 . 1 0 . 1 192. 2 0. 00 ++ 16 . 2 0 . 1 0 . 1 192 .2 0 . 00 ++ 16. 4 0 . 1 0. 1 192 . 2 0. 00 ++ 16 .6 0.1 0. 1 192. 2 0 .00 ++ 16 . 8 0 . 1 0 . 1 192 . 2 0 . 00 ++ 17 . 0 0 . 1 0. 1 192 . 2 0. 00 ++ 17 . 2 0. 1 0. 1 192 . 2 0 . 00 ++ 17 . 4 0 . 1 .0 .1 192. 2 0 .00 ++ 17 . 6 0 . 1 0 . 1 192.2 0 . 00 ++ 17 . 8 0 . 1 0 . 1 192 . 2 ' 0.00 ++ 18.0 0A 0.1 192 . 2 0.00 ++ P - Peak flow. Merrimack Engineering Services, Inc. Engineers - Surveyors -Planners 66 Park Street * Andover, Massachusetts 01810 * Tel . . ('508) 475-3555 • I English Circle W- Gene L. English Calculated by J. Soucy date 4-5-89 Sheet No. 23 of 23 Checked by v. Cantone date Summary; Lasted below are the peak runoff rates from the Pre and Post Development analyses; Peak Pre Development runoff = 1.0 . 7 cfs Peak unmitigated Post Development runoff = 11 . 1 cfs Peak mitigated Post Development runoff = 10 . 1. cfs Through the use of a detention pond all of the increase in runoff caused by •the site development is detained , and a decrease in runoff of 0. 6 cfs for the 100 year storm event is achieved. errimack. Engineering Services, Inc .. 6 Park Street * Engineers — -�Surveyors Planners f11 Andover; Massachusetts 81:0 * Tel. (508) 475--3555