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FAFARD ENVI IMPACT REPORT HIGHLAND ACRES Form 5 DEOE File No. 64-92 (To be provided by DEOE) c Commonwealth CitylTown SALEM of Massachusetts Applicant FAFARD COMPANIES --� � Order of Conditions Massachusetts Wetlands Protection Act G.L. c. 131, §40 From Department of Environmental Quality Engineering To tor . Gregg Marren The Fafard Comnanies (Name of Applicant) (Name of property owner) 290 Eliot St. 290 Eliot St. Address Ashland, MA 01721 Address Ashland, MA 01721 This Order is issued and delivered as follows: ® by hand delivery to applicant or representative on Or ohPr d , 1 g ae (date) by certified mail, return receipt requested on (date) This project is located at Highland Avenue, Salem, MA The property is recorded at the Registry of Essex Book 5292; 6172 Page 734 ; 73 Certificate (if registered) The Notice of Intent for this project was filed on Harch 25 , 1983 (date) The public hearing was closed on January 12, 1984 (date) FindIT8partment of Environmental The Quality Engineerinq has reviewed the above-referenced Notice o intent and plans and has held a public hearing on the project. Based on the information available to the DEOE at this time, the DEQE has determined that the area on which the proposed work is to be done is significant to the following interests in accordance with the Presumptions of Significance set forth in the regulations for each Area Subject to Protection Under the Act(check as appropriate): ® Public water supply (3 Storm damage prevention O Private water supply ® Prevention of pollution ® Groundwater supply O land containing sheiBish ® Flood control O Fisheries 5.1 nests checl<ed above. Th? DF,QF. orders that all work shE!I be pe.forned in accordance with said conditions and with the Novice of Intent re!ererced above. To the extent that the fol- lowing conditions mo,ify or differ frcnl the p:Ens• Spccifi:,ation5 or Cthcr proposcJs 5L:miltcd vrith the NCffce of Intent, the conditions shell cor!:cl. GEr.aral Ccr.::i;io- ; `L, '!ti --n .n, s'C1n_1 hereat, a";��with£�l rel:ted sialutes End Cts rcgulCtci` nE_s- 1 . a!IuretGco�-, , v;l: ., cc:,;.d. ns y ures, sh be d_eme•: taus- to revoke or modify t::n'.s Crder. 2. This Order does not grant any property rights Gr any exclusive privileges; it does not authorze any injury to private property Cr in',eC!on of prP:ate rights. 3. This Order does not relic•:e the permit"ee or any other person of the necessity of comp!ying with all other applicable federal, Salt;; or focal statutes, ordlnarises, by-!avis or rag2ations. 4. The work authorized haraun der shall be completed within threa years from the date of this Order unless either of the fdllo':✓ing apply: (a) the work is a maintenance dredging project as prcvided for in the Act; or (b) the time for comp!eficn has been extended to a spec'.fied date more thawthree years, but less than five years, from the date Cf Issuance and both that date and the special C!rcumst2nce5 vtarrant!ng the extended tins period are Set fcrth in tiiis Order. 5. This Order nay be eY.,Ended by the issuing autf:cry fcr one or more periods of op to three Tears each up on app5ca tion to the :°suing Guth ori ty at!east 30 Cays ,,cr to tha exp iraticn do e Cf line Order. 6. Any fill used in connection with this pro Ect 'St- be clean fill, ccntainir,g no trash, refuse, rubbish nr de• bris, including but not limited to lumber, tricks, plaster,vire, late, paper, oar dbGerd, pipe, tires, ashes, refrigerators, motor vehicles or parts of any of the foregoing. 7. No work she!!be undertaken until all admen:S'rative apceal periods from this Order have Elapsed cr, if such an appea! has been filed, until all proceedings tefcre the Department have been completed. 8. No wcrk shall to undertaken ur.t:l the Final Order has been recorded in the Registry of Deeds or the Land Court for the district in which the land is located, within the Chain of titre of the affected property. In the case of recorded lend, the Final Order shay also be noted in the Registry's Grantor Index under the name of the owner of the land upon which the prcposed wcrk is to be done. In the case of regstered land, the Final Order shall also be noted on the Ltd Court Certificate of Title of the owner of the land upon which the proposed wor!<is to be done. The recordirg information shall be submitted to the DEOE on the form at the end of this Crder prior to commencement of the work. 9. A sign shall be disp,ay ed at the site rot!ess than Mo square feet or more than three square feet in size bearing the vicrds, "t.!assacin;aa-s Cepartnent cf Environmental Quality Engineering, File Nur ter 64-92 10. Where tna De^ c. zf c TCn C , , c ee ! ^ i c d de�ar: _ .. ^i. r.._..:a, i.a`t., _r�.r._ r ny IS rEgLE�to b m4..e a ci Tlnc::Cn an.. J 10 SSu2 a°LperSc_.^� C. __�, ..E C:.fs ,.^. Com.m ISSGn shall to a pang to a!I a!'enCy , 'CC2EdiC-< e.rJ f.EEG'.;s C a L_.'_r 11 . Upon CC 7 Ct t-- /,crk dESC,,CEd FE:E:-I, th E appi!Can' S a!I I c h'./ e^' Q ha! a i,h r uE t in :veiling t Cert t.cEfe of Comp:;E..ce oe zsued sta!!rg that t,^e work has been satis`ac:orily completed. 12. The work sha'I confcr n to the fcllcwing plans and special conditions: 5-2 Plans: S j Detail=5ca`l�e 1"=44 ' pat preearedd and tfo=e Hi Mand Realty File with: t 1/�3dlJss as P 9 y ..an of Land in Salam, revised Trust by Essex Survey DEQE MA - Showin_g—Bordering 7/30/ SeLvice and revised 84 Vegetated Wetlands by by Farfard Companies HMM Assocs. 5J34/84 7/30/84 2. Supplemental Drainage Study . 7/17/34 - HP.PI Associates DEQE Highland Acres pre- Concord, MA pared for Farfard Compa ' Special Conditions(use additional paper it necessary) 1. All wetlands to be filler as a result of this project shall be compensated for on a one for one, square foot for square foot basis . These replacement areas shall have surface and ground- water elevations approximately equal to the wetland areas to be filled. Their overall location and horizontal configuration, with respect to the banks of the watercourses they border, shall be similar to that of the filled wetlands, and they shall have an unrestricted hydraulic connection to the same water body as the wetland system adjacent to which they are being con- structed. A step-by-step plan for the wetland replacement shall be prepared by the Applicant. 2. All replacement areas to be constructed shall be lined on their surface with topsoil excavated from the wetlands to be .filled as a result of the project. Arrangements shall be made for storage and protection of the topsoil after removal and before replacement. 3 . A report shall be presented to the DEQE and the Salem Conservation Commission at the end of two growing seasons subsequent to the implementation of this project indicating the amount of wetlands that has actually been replicated/created by the construction of the replacement areas and any associated construction or plantings. Any proposed compensatory wetland area which does not revegetate with characteristic bordering vegetated wet- land species over 75% of its surface area within two growing seasons shall be planted with characteristic species. A plant- ing plan for such purposes shall be presented to and approved by the DEQE prior to its implementation. (continued) .................................................................................................................................................................. (Leave Space Blank) 538 ' Special Conditions (continued) SALEM (Fafard Companies) Wetlands File 064-92 4 . At least 75% of the surface of the replacement areas shall be reestablished with indigenous wetlands plant species within two growing seasons , and prior to said veaetative reestablish- ment, any exposed soil in the replacement area shall be temporarily stabilized to prevent erosion. 5. The large pit near the intersection of First Street and Swampscott Road with a storage volume of 86 , 000 cubic feet, as referred to on pages 12, 13 and 16 of the referenced "Supplemental Drainaae Study" , shall be increased in size to accommodate theinflowfrom "Catchment S-1" associated with the one hundred year design storm. 6 . So that the proposed construction will net exacerbate ex_ .sting local flooding problems, the "discharge at the low point of Catchment S-4" , as described in the referenced drainage study and shown on the plan titled: "Highland Acres, Prelimi- nary Plan of Land in Salem, MA" and dated February 4 , 1982 and revised May 5 , 1983 by Robert E. Maschi, P.E . and R.L.S. , shall not be increased beyond its present level, 110 cubic feet per second. 7 . Prior to any construction within one hundred feet of the wet- lands as shown on the above referenced plan, an erosion control barrier shall be installed between the construction site and any downgradient wetlands. 8 . The Fafard Companies, Inc. shall be responsible for ensuring that maintenance of all drainage inlets and outlets become a condition of all leasing or ovmership of those properties for sale or lease within Highland Acres which will have drainage easements on them and will forward copies of all such mainten- ance agreements to the Salem Conservation Commission and the DEQE. 9 . The City of Salem and the Fafard Companies, Inc. shall enter into an agreement which guarantees maintenance of the proposed control structure, and forward such agreement to the Salem Conservation Commission and the DEQE. 10. Construction and locus plans for any proposed above-ground or underground storage facilities for chemicals and/or fuel, to- gether with engineering construction plans, shall be submitted to the Conservation Commission and the DEQE prior to their construction. 11. Any other changes proposed for the project as shown on the plans referenced above shall be submitted to DEQE and the Conservation Commission prior to implementation. At that time a determination will be made on whether said changes will re- quire additional conditions or the filing of a new Notice of Intent. Issued by the Department of EnvironmenliaLLyality Engineen . Signature • On this_4th day of October 1984 before me personally appeared Thnma a P MrT neigh 1 i n Ar i nq rnmm tome known to be the person described in and who executed the foregoing instrument and acknowledged that he/she executed the same as his/her free act and deed. Public My commission expires The applicant,the owner,any person aggrieved by this Superseding Order,any owner of land abutting the land upon which the pro• posed work is to be done or any ten persons pursuant to G.L.c.30A,§t OA,are hereby notified of their right to request an adjudicatory hearing pursuant to G.L.30A, §10.providing the request is made by certified mail or hand delivery to the Department within ten days from the date of issuance of the Superseding Order,and is addressed to: Docket Clerk.Office of General Counsel,Department of Environmental Quality Engineering,One Winter Street.Boston,MA 02108.A copy of the request shall at the same time be sent by certified mail or hand delivery to the conservation commission,the applicant,and any other party. A Notice of Claim for an Adjudicatory Hearing shall comply with the Department's Rules for Adjudicatory Proceedings,310 CMR 1.01(6).and shall contain the following information: . (a) the DEOE Wetlands Fite Number,name of the applicant End address of the project; (b) the complete name,address and telephone number of thea party filing the request,and,if represented by counsel,the name and address of the attorney; (c) the names and addresses of all other parties,if known; (d) a clear and concise statement of(1)the facts which are grounds for the proceeding,(2)the objections to this Superseding Order, including specifically the manner in which it is ai'eged to be inconsistent with the Department's Wetlands Regulations(310 CMR 10.00)and does not contribute to the protectic .of the interests identified In the Act,and(3)the relief sought through the adju- dicatory hearing,including specifically the char. as desired in the Superseding Order; ( (e) a statement that a copy of the request has been ant to the applicant,the conservation commission and each Other party or rep- resentative of such party,it known. Failure to submit all necessary information may result ir.a dismissal by the Department of the Notice of Claim for an Adjudicatory Hearing. Detach on dotted line and submit to the prim to commencement of work. ........_.................................._...._...................................._.............................................................................»...................»............... To Issuing Authority Please be advised that the Order of Conditions for the project at File Number has been recorded at the Registry of and has been noted in the chain of title of the affected property in accordance with General Condition B on , 19_ It recorded land, the instrument number which identifies this transaction is V registered land, the document number which identifies this transaction la Signature Applicant C 5-4B n W FINAL ENVIRONMENTAL IMPACT REPORT HIGHLAND ACRES i , HMM Document No. 83-532 August , 1981 Prepared for: THE FAFARD COMPANIES 290 Eliot Street Ashland, MA Prepared by : HMM ASSOCIATES 336 Baker Avenue Concord , Massachusetts 01742 t TABLE OF CONTENTS 1 . INTRODUCTION 2. COMMENTS ,RECEIVED ON DRAFT EIR 3. RESPONSES TO COMMENTS 4. DRAINAGE STUDY -ii- INTRODUCTION This document is the Final EIR for the proposed HighlaVd Acres development in Salem , Massachusetts. The site is roughly bounded by Swampscott Road , Highland Avenue, the Salem High School , the Highland Park Golf Course and Thompson' s Meadow. The project includes 700 condominium units in quadraplex buildings. The number of condominium units has decreased since the Draft EIR, which reported about 750 units. This change is the result of meetings with Salem planners, park commissioners and the conservation commission during which concerns were raised about project density. Following these meetings, the density was reduced from 8 units per acre to 7 units per acre. This change , in association with changes in total acreage devoted to residential development , has reduced the number of units from 800 (originally ) to 750 (reported in the Draft) to the current 700 units . In addition there will be approximately 45,000 square feet of commercial space and 305,000 square feet of light industrial space. These uses are consistent with existing zoning. Access to the commercial and industrial areas of the project will be mainly from Highland Avenue. , Access to the residential portion of the project will be from Swampscott Road and through Highland Park to Willson Road. A more detailed description of the project and its potential environmental impacts , is presented in the Highland Acres Draft Environmental Impact Report filed with the EOEA on April 15, 1983. The Final EIR has been prepared pursuant to the MEPA regulations , 301 CMR 10.07. This Final EIR contains all comments received on the Draft EIR. Responses to these comments have been drafted by the project proponent and are attached. Since no significant project changes have occurred, the Draft EIR is not being recirculated as part of the Final EIR. Subsequent sections of this Final EIR are as follows: n Section 2 contains the comments received on the Draft EIR. -1- i 1 Comments were received from the Secretary of the Executive Office of Environmental Affairs, the Department of Environmental Quality Engineering (DEQE) and the Metropolitan Area Planning Council (MAPC) . No comments were received -from the public , or local agencies. In the margin of the comment letters the proponent has placed circled numbers which correspond to the responses to comments. Section 3 includes responses to each comment received on the Draft EIR . Section 4 contains additional information regarding the drainage issues associated with the project . This work was carried out in response to comments received by the Secretary of the EDEA, DEQE and MAPC. 1 i i -2- n ^y .x. 2. COMMENTS ON THE DRAFT ETR n �f e 7�a�z�nanuaea�i o��Gatilacf ccGc�/.� &euz4i'v 011emn1 U'nui,on2m1en&1—V11ains 700 TOamG�irl�e JCxeel � ' go.4 on, Awad(6,16 NOV.? MICHAEL S. DUKAKG GOVERNOR JAMES CERTIFICATE OF THE SECRETARY OF ENVIRONMENTAL AFFAIRS SECREETARYRY ON DRAFT ENVIRONMENTAL IMPACT REPORT PROJECT NAME: Highland Acres PROJECT LOCATION: Salem EOEA NUMBER: 4573 PROJECT PROPONENT: Fafard Company DATE NOTICED IN MONITOR: April 25, 1983 The Secretary of Environmental Affairs herein issues a statement that the Draft Environmental Impact Report submitted on the above referenced project does adequately and properly comply.with Massachusetts General -Laws, Chapter 30, Section. 62-62H inclusive, and the regulations implementing MEPA. I find that although I have questions about some of the underlying assumptions in the drainage study and some concerns about the amount of wetland to be altered, the DEIR has addressed the issues identified in the Scope. I, therefore, declare the DEIR adequate with the expectation that the following questions will be answered adequately in the FEIR. The FEIR shall contain a copy of this Certificate with my comments, the comments received on the DEIR, and responses to the comments. My specific comments are as follows: Traffic The DEIR shows a significant degradation in capacity at the Swampscott Road/ Highland Avenue and Marlborough Road/Highland Avenue intersections that is 1O attributable to the proposed development. Modifications and signalization are identified as means of minimizing these problems. The FEIR should identify what improvements should occur and who should be responsible for their implementation. FORM D #4573 Page 2 Wetlands The letter of comment from DEQE implies that this project will be'it ubject to the revised Wetland Regulations. If this is the case, the project, as presented, cannot receive permits. Under the old Regulations, the project might receive Opermits, but issuance of such permits would be clearly opposed to the intent of the Act. I feel that the proponent should develop an alternative scheme, perhaps by reducing density, that would significantly reduce the impacts on wetlands and present such a scheme in the FEIR. Drainage The drainage study presented in the DEIR raises some fundamental questions that must be addressed in detail in the FEIR. The runoff coefficients (c) used in the drainage study are surprisingly low for such a site. The site is one with frequent rock outcrops, shallow till soils and steep slopes yet the c values range from 0.2 to 0.5 with nearly 240 Ac of the 5004-' Ac site given a value of only 0.2. This appears to be a significant under- estimation of the runoff coefficient and should be justified in detail or revised for the FEIR. The drainage study should be supported by detailed calculations for before and after development showing' (1) detention area capacities and requirements for each drainage area tributary to a detention basin, (2) computation of time of concentration and subsequent rainfall intensity, (3) routing from one ponding area to another to the ultimate discharge point. The plans used in these calculations should represent the latest iteration of the development proposal. Miscellaneous ® The FEIR should reconcile the discrepency identified by MAPC between the site layout plan and the drainage plan. June 1, 1983 DATE G JAtjE S. fl0YC1 . ,6 CRETARY 1 �/� 4191Ile0/116YW l2 , e/11 J1acllrJclt ^� =_- _ .,S 1l oiler to/��(�nrrionmrnlu��iia/.y Ony/inrr�/ii? o `.� ill/li�ollan Jlcslon i III 1¢1/ -l FI/ n 3 +' ANTHONY D. CORTESE, Sc.D. /�f•!1</c �i�/on. •J(/u!, /IOI'u//, :///^�C/•P// Cemmi„ien,r 7275191 MEMORANDUM TO: James Hoyte, Secretary, Executive Office of Environmental Affairs- A MEPA Unit �/Y�}, FROM: William J. St. Hilaire, P.E. 1.0 Regional Environmental Engineer-Northeast Region SUBJECT: Highland Acres , Salem, EOEA #4573 - DEIR The DEIR submitted indicates that 26 acres of wetlands are to be altered for the industrial , residential and commercial develop- ment of the site and that an additional 13 acres of wetland are to be altered for the golf course portion of the site. These quantities are far in excess of those allowed by the Wetlands Protection Act Regulations 310 CMR 10.00 et. al. 310 CMR 10.55 defines and sets forth presumptions of significance for Bordering Vegetated Wetlands, which comprise the majority, if not all , of the wetlands on the site. General performance standards for Bordering Vegetated Wetlands are also set forth in 310 CMR 10.55. They stipulate that°the issuingauthority (either the Salem Conservation Commission or the D,E.Q.E. ) may issue an Order of Conditions permitting work which results in the loss of up to (a maximum of) 5000 square feet of Bordering Vegetated Wetlands when such area is replaced in accordance with the following general conditions and any additional conditions the issuing authority deems necessary". The regulations require that the surface area of the replacement area to be created shall be equal to that which will be lost. The ground water and surface elevation and the overall horizon- tal configuration and location with respect to the bank of the replacement area must be the same as that of "the lost area. The re- placement area must have an unrestricted hydraulic connection to the same water body associated with the lost area and shall be located within the same general area or reach of the waterbody or waterway as the lost area, and at least 75 percent of the surface of the replacement area shall be reestablished with indiginous wetlands vegetation. The regulations also stipulate that the maximum allowable amount Memorandum y Page 2 April 26, 1983 of Bordering Vegetated Wetland that may be lost as a result of work done by the applicant without compensation is 500 square feet. As presently planned, Highland Acres is not a permittable site under the Wetlands Protection Act. It should also be noted that the proponents of the project have•not yet applied to the Salem Conservation Commission for work to be done on the site and that the submission of an ENf, DEIR or final EIR in no way precludes them from doing so.' PD/jb metropolitan Area Planning Council 110 Tremont Street Boston, Massachusetts 02108 (617).451.2770 Serving 101 Cities & Towns in Mel+opolitan Boston A May 20, ft8 CEIVED The Honorable James S. Hoyte, Secretary MAY Z 5 V1 Executive office of Environmental Affairs 100 Cambridge Street Boston, Massachusetts 02202 CFFICf OF TNF S NItT', t' L' N, a«rl.I1t5 Attention: MEPA Unit RE: Highland Acres Development, Salem (MAPC #EIR-83-16, Received April 20, 1983) EOEA #4573 Dear Secretary Hoyte: In accordance with the provisions of Chapter 30, Section 62 of the Massachusetts General Laws, the Metropolitan Area Planning Council has reviewed the above-referenced draft environmental impact report. The Council regrets that it cannot comment on this draft report since it is quite unclear just what is to be commented on and what its relationship to the analysis. The document presented contains numerous contradictions and deficiencies. These include: e the number of residential units to be developed - the project description states 750 but the accompanying drainage plan enumerates 840. e the site plan itself - the site plan presented in the project description is not reconcilable with that presented in the drainage plan. They show entirely different road configurations and one locates housing units on drainage retention ponds specified in the other. e overall layout - a use plan presented in the appendix shows the swapped parcels dedicated to "golf" while the drainage plan specifies residential construction. Beyond the contradictions there are addi.tionai .deficiencies that appear to require some attention, although it is difficult to be sure because of uncertainties in the project: 1. traffic -. the simple assertion that 'the access road through the golf course will be the "primary (residential) access" (section 6.1.3) Q is inadequate, especially in light of the traffic assignment on p. 6-26, although the effect of this on the analysis is not entirely clear. El,zabeth A aransi,eld. President IN ilkan,C.Sayer. V,ce-Ptes�dent hank E. Baxter.Secretary Patricia A.Brady.Treasurer E.ecuhre Duecror:Alexander V.Zaleski Secretary James S. Hoyte - 2 - May 20, 1983 2. drainage - while the drainage plan in general appears adequate there is no discussion of possible erosion due to high velocities accgmpanying O increased runoff. Also the storage elevation of drainage pond at area #12 set at elevation 113 (p. 6-63) is � foot below the pond elevation (spot elevation = 113.5) on the drainage plan. O 3. archeologic - before any final determination can be finalized, the archeologic study should be completed. The Council feels that to adequately comment on any aspect of this proposal it must have an accurate, uncontradictory description of it including a real site plan. Since siting is so crucial to a project of this magnitude, this is all the more important. We hope these questions can be cleared up in either a redraft of the DEIR or in a supplementary DEIR so that we may comment before a final is drafted. Aey' n G. Truslow Executive Director/ Director of Planning JGT/MFO/lab cc: Mr. W. Gregory Senko MAPC Representative, Salem Ms. Margaret B. Briggs HMM Associates Mr. Michael F. Oman MAPC Staff .y 3. RESPONSES TO COMMENTS Response No. I A detailed traffic study was undertaken as part of the: Draft EIR. As noted in that report, major design improvements will be required at the intersection of Highland Avenue and Marlborough Road to properly interface the proposed Marlborough Road Extension. As noted in the DEIR, the recommended design option at this location ( referred to as the Build 1 Alternative in the DEIR) would incorporate a left turn lane along the Highland Avenue southbound approach for vehicles turning left into the proposed project development . . Marlborough Road Extension would include four lanes , two in and two out of the project site. The improvements at the Highland Avenue/Marlborough Road intersection would require new signal hardware, conduits and revised signal timing. Minor geometric improvements would also be necessitated at the Marlborough Road eastbound approach at this location. In addition, a right-turn deceleration lane for vehicles travelling northbound along Highland Avenue to Marlborough Road Extension should also be included in the design option. Massachusetts State funds have been earmarked, ,under the Massachusetts Public Works Economic Development Grant Program, for improvements to the Highland Avenue/Marlborough Road intersection, the extension of First Street from Highland Avenue to Swampscott Road, and Marlborough Road Extension from Highland Avenue to First Street. A total of $500,000.00 has been allocated for these roadway improvements. The Massachusetts 'Public Works Economic Development Grant Program was instituted to assist and promote industrial and commercial development in the Commonwealth. The Grant Award can be used for design and construction of roadway improvements. To insure completion of the roadway improvements identified under the Grant Award, the project proponent has committed to provide assistance for improvements which may required within the proposed project site, such as for completion of the First Street or Marlborough Road Extension -4- k roadways. The extent of this assistance cannot be determined until that time at which bids are accepted for the roadway improvement project. # Although the project proponent does not plan at this time .. to be responsible for recommended future improvements at the Highland Avenue/Swampscott Road intersection, the proponent will commit to working with the State and local public works departments in the development of acceptable design options at this location, aimed at improving progressive movements through the area and reducing potential safety hazards. The recommended design options for the latter location are identified in the DEIR, and include traffic signalization and minor widening and geometric improvements. Response No . 2 The Notice of Intent for this project was filed with the Salem Conservation Commission in March, 1983 (File $64-92) . A public hearing was held on June 9, 1983 by the Salem Conservation Commission. At that time, a sub-committee of 3 Conservation Commission Members was established to work on the details of the project with the developer. The Fafard Companies agreed to waive the time limit for issuance of the Order of Conditions in order to work with the sub-committee. ,At this point , the developer is still working with this group. Input received during the MEPA process will be available to the Conservation Commission for use during deliberation on this project . Since the inception of this project, several measures have been agreed to by the developer which mitigate impacts to wetlands . At the beginning of project planning, the Conservation Commission indicated interest in three parcels of land for conservation purposes. These parcels are to be traded to the City in return for land abutting the Golf Course in which the Conservation Commission has no interest. This land swap is described in the Draft EIR. -5- A second concern about the project raised by local authorities was the density. The original density of the project was 8 units per acre. In response to the local concern over this density , it was reduced to the current 7 units per acre. This represents a total reduction of the project by 100 units . Thus, the developer has already reduced the density of the project , a measure suggested by the EOEA. The current plan does result in the alteration of wetland areas. However, the purpose of the alteration is to reduce an existing flooding problem at Swampscott Road, and mitigate project related drainage impacts. Modifications to wetland areas involve mainly excavating ponding areas and adding control structures to enhance the flood storage capacity of the ponds . Construction of housing units will infringe on the outer boundaries of the wetland. However, the limited negative impacts this infringement may have on certain statutory interests are offset by the significant positive impacts to the flood control and storm damage prevention actions of the wetlands. Response No . 3 See Part 4 of this Final EIR. Response No. 4 The site layout plan represented in Figure 3. 3. 1 of the Draft EIR is a preliminary layout plotted to show the density of the development . This plan has been changed as the project has been refined. The land swap with the Golf Course , additional study on the drainage system, and a change in the internal roadway system resulted in the site plan shown on the large scale plan attached to the Draft EIR. Siting of individual units within the residential area will depend upon terrain and other land features. -6- " i 5d in response number 2, a Notice of Intent was ,he Salem Conservation Commission in March of 1483. t understands that the MEPA process does not requirement for an Order of Conditions from the onseCommission. Response No .._. 6 See response Number 4. The siting process for a project such as this one depends on many factors, including terrain and wetlands. The site plan shown as Figure 3. 3-1 in the Draft EIR was a preliminary plan designed to show the proposed density of the residential development. As project planning has progressed , land swap arrangement , wetland and drainage factors , and traffic and .access impacts have altered the project layout. The project site-layout as it has evolved as a result of these factors , and as efforts to mitigate impacts identified in the Draft EIR have been incorporated into the plan. The attached site drainage plan shows the current layout. There will be approximately 700 housing units. This plan is not expected to change significantly. Response No. 7 As noted in the DEIR, general access to the proposed residential development will be provided via (1) the proposed Road "A" , to First Street , to Swampscott Road, and (2) along the new roadway through the Highland Park Municipal Golf Course, to Willson Street . It is expected that this latter route will be the primary access , particularly for non-work based trips . It is projected that during peak hour periods, approximately 57 percent of the work-based trips to and from the residential development would use the access road through the golf course , due to travel time considerations. However, '. since this route offers a much more attractive entrance to the residential development, a larger portion of trips duringthe , off-peak hours are expected to use this access, versus the � alternative access to Swampscott Road. Response No . 8 See Part '4 of this Final EIR. Response No. 9 The archaeologic study has been completed. No archaeologic resources were found in the project area , although several sites were located outside the project boundary. Some potential historic sites were noted on the property. A copy of the Phase II study has been forwarded to the Massachusetts Historical Commission and the EDEA. t 4. DRAINAGE STUDY 4 .1 Purpose . This hydrologic analysis was performed in order to assess the potential impacts of the Highland Acres development project on storm drainage. This analysis is independent of the analysis presented in the Draft EIR and is in response to the written comments on the Draft EIR. Based on discussions with city engineers there are three primary locations where the potential .for flooding currently exists and may be increased due to development of the Highland Acres site. These three locations are along Swampscott Road south of the site , at the box culvert beneath the Boston and Maine railroad tracks east of the golf course , and at a set of three 48" culverts which convey drainage beneath Jefferson Avenue. This analysis focuses on the present and future peak discharges at these three design points which are associated with the 10, 50, and 100 year design storms. In addition, by routing the 100 year design storm from one ponding area to another and eventually to each design point, the adequacy of the storage capacity of existing and proposed ponding areas is assessed. 4 . 2 Methodology The methods used in determining peak discharges from catchments within the study area are based on procedures presented in Technical Release Number 55 (TR-55), Urban Hydrology for Small watersheds, prepared by the Engineering Division of the Soil Conservation Service (SCS) of the U.S. Department of Agriculture (Reference 1) . This method is designed for small urbanized watersheds. It is based on procedures outlined in the SCS National Engineering Handbook , Section 4, Hydrology (NEH-4) and largely parallels the SCS Modified Soil Cover Complex Method which adapts NEH-4 to small watersheds (Reference 2) . -9- Basically , the TR-55 method utilizes curve numbers ( CN) that describe watershed cover conditions to determine the' 'total amount of runoff associated with 24-hour design storms whidb follow a rainfall pattern typical of eastern United States (a type II rainfall distribution) . . The peak discharge is then determined as a function of slope , watershed shape , the amount of impervious area , the extent of hydraulic modifications, and the location and amount of ponding and swampy areas within the watershed . It should be noted that the use of curve numbers in the TR-55 method replaces the use of "c" coefficients in the rational method . Both values are measures of the . imperviousness of a watershed' s cover, however, the "c" coefficient also incorporates other factors such as slope and rainfall intensity . These two values are not directly comparable . For this analysis, watersheds contributary to the selected design points are subdivided into catchments for peak discharge determinations. Based on peak discharges and times of concentration for each catchment , triangular hydrographs are plotted with the excess runoff from the 24-hour storm included in the "tail" of each hydrograph. As appropriate , inflow hydro„raphs are added together to determine the total inflow hydrograph for design points and for existing or proposed retention areas. Using these inflow hydrographs , the Puls Method is used to calculate reservoir storage , maximum water level , and outflow hydrographs foz retention areas. Using these procedures, . this , complete inflow-outflow analysis incorporates detention area capacities, times of concentration within the individual catchments of each watershed , and the preliminary sizing of proposed control structures in order to . route runoff associated with design storms through the study area. Additional descriptions of methods and input parameters are included in Appendix A. -10- 4 . 3 Existing Conditions Runoff from the Highland Acres development site currently. drains towards three locations. For the purposes of this study , the land areas contributing runoff to each of these locations are considered three watersheds comprising the total study area . These three watersheds are identified and described below. s Highland Park Watershed : Runoff from this watershed flows from north of Highland Avenue through a portion of the development site and golf course to the existing box culvert beneath the Boston and Maine Railroad tracks. From this point , runoff flows to a ponding area south of Jefferson Avenue , beneath Jefferson Avenue in a set of three 48" culverts, and into a swampy area north of Jefferson Avenue which drains to Salem Harbor. Possible diversion of surface runoff to the Highland Park Watershed from an adjacent watershed to the north is controlled by the Salem 'Engineering Department . Based on conversations with that department , this diversion has not been included in this analysis . All other areas which may contribute runoff to the triple culverts beneath Jefferson Street are included in the Highland Park Watershed. , This watershed is presently about 640 i acres. Thompsons Meadow Watershed : A portion of the site currently drains directly to Thompsons Meadow without entering the Swampscott Road drainage system. This portion of the development site , as well as the offsite drainage area between this portion and Thompsons Meadow, is considered the Thompsons Meadow Watershed. Surface drainage -11- enters Thompsons Meadow in three distinct channels south of the site . From Thompsons Meadow surface' water drains to Salem Harbor via Forest River. fit should be noted that this 54 acre watershed does not include all offsite runoff to Thompsons Meadow. s Swampscott Road Watershed : This watershed includes all areas which contribute runoff to the Swampscott Road drainage system at the point where this drainage system leaves the site towards Thompsons Meadow . The critical point of this drainage system is the 36" culvert which conveys drainage beneath Swampscott Road from the southwest to the northeast near the tennis club and the southern boundary of the Highland Acres site. Hereafter, this control point will be referred to as the culvert beneath Swampscott Road . The Swampscott Road Watershed includes portions of the Highland Acres site northeast of Swampscott Road as well as a more extensive offsite area to the southwest of Swampscott Road which extends north beyond Highland Avenue. After leaving the Highland Acres site, runoff from the Swampscott Road Watershed travels to Thompsons Meadow. Within the study area there are three primary control points where the potential for flooding presently exists and may be exacerbated with development within the study area. The first two control points are the box culvert beneath the B & M railroad tracks and the triple culvert beneath Jefferson Avenue. Both of these are within the Highland Park Watershed. The third control point is the culvert beneath Swampscott Road. The three major watersheds have been subdivided into smaller catchments to improve the accuracy of drainage calculations. These catchments are identified on the map in Figure 4-1 . Key input parameters used in modeling storm runoff in each catchment are summarized in Table 4-1 . Methods . -12- c I IIt Y�i, (� 6 / lpM6 0 I 'l f � o IE'X� TEL ij I! ' E BJ5 gg �1 //r��,t��l.r'�.1� � s� � .. �Yst 1P' u� { �` 'f �✓.a 1 ? u I ., a js' ' � :C c ,�L Olt 660A ➢�}� l., � �� 70i� ��1 �� fl. -41w� {ant��5`F,j aT i�,u.� Pitt V�NIX Le { so•�^.,E�J.' �r . ..rj'mUhe o i �.?O.' /"7, .��. 'a''.-. 'Aa2Bes •�..� ----- CATCHMENT BOUNDARY WATERSHED BOUNDARY SCALE 1:25 000 7 0 1 MILE i00_0 0 1000 1000 3000 4030 5000 6000 7000 FEET 1^ .5 0 1 MILOMETER CONTOUR INTERVAL 10 FEET SALEM, MASS. - NATIONAL GEODETIC VERTICAL DATUM OF 1929 MASE DEPTH CURVES AND SOUNDINGS IN FEET—DATUM IS MEAN LOW WATER N4230—W7052.5/7.5 THE RELA70NSKIP BETWEEN THE TWO DATUMS IS VARIABLE SHORELINE SHOWN REPRESENTS THE APPROXIMATE LIME DE MEAN HIGH WATER 1970 U d THE MGN RANGE OE TIDE IS APPROXIMATELY 9 FEET PHOTOREViSED 1979 QUADRANGLE LOCATION AMS 6869111 SW—SERIES V814 FIGURE 4-1 PRE-DEVELOPMENT WATERSHED AND CATCHMENT BOUNDARIES -13- i TABLE 4-1 SUMMARY OF IN'UT PARAMETERS - PRESENT WATERSHEDS Time of Area Average Average Concentration Watershed/Catchment (Aries) CN Slope (Minutes) HIGH AN) PARK WATERSHED HP-1* 93.0 78 Steep: 14% 22 a HP-2* 123.9 83 Steep: 11% 35 HP-3 154.9 79 Moderate: 7% 30 HP-4 142.7 77 Steep: 11% 49 HP-5 62.0 81 Steep: 9% 23 HP-6 43.3 80 Steep: 8% 22 Area Subtotal 619.8 SWAMPSCOTT ROAD WATERSHED S-1* 27.4 79 Steep: 14% 22 S-2* 29.7 77 Steep: 17% 14 S-3 150.7 80 Steep: 8% 46 S-4* 20.1 77 Steep: 16% 13 Area Subtotal 227.9 THOMPSONS MEADOW WATERSHED T-1* 12.6 77 Steep: 8% 8 T-2* 18.1 77 Steep: 16% 7 T-3* 20.0 77 Steep: lO% 11 Area Subtotal 50.7 TOTAL AREA OF STUDY AREA 898.4 " Totally or partially within development site. -14- described in TR-55 were used in determining these parameters, and background information and assumptions are provided in, Appendix A. Peak discharges at the design point of each catchment are presented in Table 4-2 for the 10 year, 50 year, and 100 year design storms. In interpreting the peak discharges it is important to realize that these peak discharges occur at different times and at different locations. Therefore, peak discharges are not necessarily additive. Since travel times (times of concentration) for the catchments vary from 7 minutes to 49 minutes, peaks from smaller catchments occur considerably sooner than peaks from larger, or more remote catchments. The result is illustrated in the hydrographs in Figure 4-2. These hydrographs represent the discharges associated with the 50 and 100 year storms which enter the retention area adjacent the railroad tracks ( retention area A) as a function of time starting from the beginning of each design storm. These hydrographs are plotted by summing the contributory hydrographs from catchments HP-1, HP-'2., HP-3, HP-4, and HP-5. Hydrographs from catchments HP-2 and HP-3 are displaced to appropriately account for travel time to the retention area. As indicated in Figure 4-2, for the 100 year design storm the predevelopment peak inflow to the retention area adjacent to the railroad tracks is about 1500 cubic feet per second (cfs) , and this peak a occurs approximately 40 minutes after the beginning of the storm (T = 40) . Of the 1500 cfs , 560 cfs is contributed by catchment HP-2 and 430 ,by HP-3. Smaller discharges are contributed by catchments HP-1 and HP-5 which peak prior to T = 40 and by HP-4 which peaks after T = 40. A similar hydrograph analysis indicates the pre-devel- opment peak discharges at the culvert beneath Swampscott Road are 390 cfs :at T = 60 and 330 at T = 60 for the 100 and 50 year design storms , respectively . Based on the limited storage capacity in the channel upstream of this culvert and the flow restriction created by the culvert , it appears that substantial street flooding on Swampscott Road occurs during storms of this -15- TABLE 4-2 PRE-DEVELOPMENT PEAK DISCHARGES BY CATCHMENT FOR 10, 50, AND 100 YEAR DESIGN STORMS Peak Discharge (cfs) Watershed/Catchment 1. 0-year 50-year 100-year HIGHLAND PARK WATERSHED HP-1 115 200 241 HP-2 285 472 557 HP-3 218 373 446 HP-4 157 273 327 HP-5 92 157 190 HP-6 83 134 157 SWAMPSCOTT ROAD WATERSHED S-1 61 105 125 S-2 63 108 130 S-3 160 270 ' 322 S-4 67 105 121 THOMPSONS MEADOW WATERSHED T-1 32 51 59 T-2 38 63 75 T-3 38 64 76 -16- 1500 1400 1300 - 1200 1100 1000 100 YEAR 0 m 900 - Soo 00 600 a m ^ 700 50 YEAR 600 600 400 300 200 l 100 O O 10 20 30 40 50 60 70 80 00 100 110 120 130 TIME {Minutaol t FIGURE 4-2 Pre-Development inflow Hydrographs for Retention Basin Adjacent to Railroad Tracks (Basin A): 100 and 50 Year Design Storms intensity . For the Thompsons Meadow Watershed the 100 and 50 • year storm peaks are 210 cfs and 178 cfs, respectively . Thi potential flooding effects of this runoff are dampened as peak discharges enter the large storage area of Thompsons Meadow. Runoff represented in the inflow hydrograph in Figure 4-2 is restricted by the box culvert beneath the railroad tracks. An inflow-outflow analysis based on this inflow hydrograph and the design of the box culvert indicates that the water level in the ponding area adjacent to the railroad tracks rises to elevations of 22 . 2 feet and 21. 5 feet for the 100 and 50 year design storms , respectively. For comparison , the railroad bed above the culvert is at about 26 feet . The retention basin between the railroad tracks and Jefferson Avenue receives storm water runoff discharged from the box culvert as well as from a small catchment identified as HP-6. An inflow-outflow analysis of the partially blocked triple culvert beneath Jefferson Avenue indicates that runoff associated with the 50 and 100 year design storms are contained within this retention basin without spilling over Jefferson Avenue . Maximum water levels are 14. 9 and 14. 4 feet for the 100 and 50 year storms , respectively. The elevation of Jef- ferson Avenue above the triple culvert is approximately 17 feet . In conclusion , the present drainage pattern in the study area presents the serious potential for flooding in the Swampscott Road Watershed . The 390 cfs peak discharge associated with the 100 year storm exceeds the capacity of the culvert beneath Swampscott Road, and flooding along the roadway can be expected during . severe storms events. In the Highland Park Watershed , a considerable amount of natural and manmade detention area dampens peak discharges to downstream control structures . The most significant of these are the basins adjacent to the railroad tracks and adjacent to Jefferson Avenue . Ponding levels in these basins rise significantly during design storms but do not breach the railroad tracks or Jefferson Avenue during the 100 year design storm. Peak discharges into these basins for the 100 year design storm are 1500 cfs and 270 cfs , respectively . -18_ . 4 . 4 Future Conditions Assessment of post-development drainage impacts are baled. on Highland Acres development plans prepared by Fafard Company dated 4 February 1982, revised 5 May 1983 (114-1001 ) and on roadway profiles prepared by Fafard Company dated 11 April 1983. Salient features of the drainage plans are the construction of several retention/detention ponds with associated control structures, the diversion of runoff away from the Swampscott Road Watershed , and the continued use of the existing detention area adjacent to the railroad tracks. While development plans generally conform closely with the natural topography , excavation and grading activities will create some important modifications in catchment boundaries. These changes are reflected in the post-development watershed and catchment boundaries deliniated in Figure 4-3 and in the watershed areas presented in Table 4-3. Drainage from 20.5 acres of the Swampscott Road Watershed is diverted to the Highland Park Watershed. Likewise, drainage from an additional 3. 6 acres of the Swampscott Road Watershed is diverted to the Thompsons Meadow Watershed. Other changes in catchment configurations reflect the collection of runoff into ponding areas E , D, C, and B. The input parameters used in modeling drainage from each catchment are summarized in Table 4-3. As in Table 4-1 , methods described in TR-55 were used in determining these parameters, and background information is provided in Appendix A . For those catchments which are totally or partially within the Highlands Acres development site, a comparison between Table 4-1 and Table 4-3 reveals three general observations. First , there is typically an increase in curve number in the post-development catchments. Curve number is a function of land use and soil type . In areas of residential, commercial or industrial development , higher curve numbers reflect an increase in impervious surface , which in turn create higher -19- i TABLE 4-3 SUMMARY OF INPUT PARAMETERS - FUTURE WATERSHEDS Time of Area Average Average Concentration Watershed/Catchment (Acres) ON Slope (Minutes) HID-LAND PARK WATERSHED HP-1 93.0 77 Steep: 10% 22 Hp-3 154.9 79 Moderate: 7% 30 HP-5 62.0 81 Steep: 8% 23 HPC, 43.4 80 Steep: 9% 22 HP-C* 111.2 91 Moderate: 5% 9 HP-D* 11.4 85 Moderate: 6% 1 HP-E* 11.6 82 Moderate: 6% 2 Hp_7* 2.3� 78 Moderate: 6% 10 .3 HP-8 50.8 80 Steep: 11% 19 HP-9 69.8 75 Steep: 11% 13 Ali Area Subtotal 640.4 SWAMPSCOTT ROAD WATERSHED S-3 150.7 80 Steep: 8% 46 S-5* 18.4 90 Steep: 8% 5 S-6* 18.1 83 Steep: 10% 5 S-7* 16.5 83 Steep: 10% 4 Area Subtotal 203.7 THOMPSONS MEADOW WATERSHED T-2 18.1 80 Steep: 14% 5 T_3 19.6 78 Steep: 10% 5 T-4 16.6 80 Steep: 8% 2 Area Subtotal 54.3 { TOTAL AREA OF STUDY AREA 898.4 * Totally or partially wittdn development site. -21- 7 ' � �W",a'' �. �• p _-y� �� I �11ti 1. IL Itt I .m i 1 a y6 a Wv M•U \ T,. . L ��•i 1wIPII i' l, PJ7 .•/ .'-, v .,, } \� !/I) .t {.t r :� "'S I� , ' 15ab%TR 1-`•*�. v ^.. _ �r � r R Ir. '4� J� t _ /�ti�(�`+.1a54�lYI� � t� � � ll ll 5 � • 0 i \ 3` 14 �o`I l 'v„ •`3 1 y r"''� �, fir{ � c� _ _ f)�.`\ .`pry �� \' ;`� '. ^� c,.� .r r••. �C;• p (-_ �' ! oo � ' • r�...�� rr _ .a' -'fid: 1S.,r` •-.t • Imo. (�a " +° ... f .l' �. i 'kJ fta7 --- -- CATCHMENT BOUNDARY WATERSHED BOUNDARY SCALE 1:25 000 MILEI 1 0 1000 0 IOW 2000 3000 4WD BCW 6000 7000 FEET 1 .5 0 1 KILOMETER CONTOUR INTERVAL 10 FEET SALEM MASS.`, !� NATIONAL GEODETIC VERTICAL DATUM OF 2929 N4234-007052.517.5 It MASS DEPTH CURVES AND SOUNDINGS IN FEET—DATUM IS MEAN LOW WATER VV''TT��(( THE RELATIONSHIP BETWEEN THE TWO DATUMS IS VARIABLE 3970 { L^� SHORELINE SHOWN REPRESENTS THE APPROXIMATE LINE OF MEAN HIGH WATER PHOTOREVISEO 1979 f�� THE MEAN RANGE OF TIDE IS APPROXIMATELY 9 FEET QUADRANGLE LOCATION AMS 6869 111 SW—SER}ES VBIF S FIGURE 4-3 POST-DEVELOPMENT WATERSHED AND CATCHMENT BOUNDARIES _20- i TA - TABLE 4 4 POST-DEVELOPMENT PEAK DISCHARGES BY CATCHMENT FOR 102 50, and 100 YEAR DESIGN STORMS 4 Peak Discharge (cfs) Watershed/Catchment 10-year 50-year 100-year HIGHLAND PARK WATERSHED HP-1 120 208 249 HP-3 218 373 446 HP-5 83 134 157 HP-6 83 134 157 HP-C 401 596 681 HP-D 60 89 101 HP-E 47 71 79 HP-7 74 115 132 HP-8 129 207 243 HP-9 97 168 204 SWAMPSCOTT ROAD WATERSHED S-3 160 270 322 S-5 141 201 225 S-6 88 133 151 S-7 92 139 158 THOMPSONS MEADOW WATERSHED T-2 52 85 101 T-3 44 75 90 T-4 67 103 117 -23- approximately 270, 000 cubic feet of available storage between.' the elevations of 110 and 114 feet . Water retained Pond D k during dry periods will be between the 114 feet water level and the pond bottom. Similar preliminary construction specifications for each pond are presented in Table 4-5. These are based on the dry weather pond surface areas delineated in the design plans the storage calculations in Appendix A. These specifications are preliminary and may be adjusted based on field conditions encountered during construction or based on final design of the ponds and control structures. These preliminary plans, however, serve to demonstrate the feasibility of mitigating adverse drainage impacts downstream of the development site with the retention pond concept . Based on an inflow-outflow analysis of the 100 year design storm, Ponds E, D, and C all adequately retain runoff from the post-development site without flooding streets or residential areas within Highland Acres. The maximum water levels in Ponds E, D, and C associated with the 100 year storm are below 117, 112, and 96 feet , respectively , and thus do not approach emergency spillway elevations. In addition, each pond effectively reduces peak discharges associated with the post-developed site. While the 100 year storm peak discharge into Pond E , D, and C is 78, 97, and 683 cfs, respectively , the peak outflow from these ponds is 4, 4, and 19 cfs . In contrast to pre-development discharges, the ponds sustain outflows of similar magnitudes for several hours after rainfall has peaked. Pond B collects runoff from post-development catchments HP-8 and HP-3 of the Highland Park Watershed. Design specifications presented in Table 4-5 indicate that Pond B requires no excavation. During dry periods there will be no change in water elevation in this area, and during wet periods the proposed new road through the golf course will serve as an embankment to temporarily detain water in Pond B. A Post-development inflow-outflow analysis for the 100 year design storm indicates that a 536 cfs peak discharge into Pond -24- peak discharges at the catchment design point . Second, there is typically a decrease in the time of concentration or travel time for each developed catchment . This is associated with increased impervious surface and hydraulic modifications such as subsurface drainage pipes. Third , there typically is a decrease in average catchment slope associated with grading and terracing development lots and roadways. For the 10, 50, and 100 year design storms, peak discharges for each post-development catchment are presented in Table 4-4 . Although changes in catchment boundaries make direct comparisons with pre-development catchments difficult , there is an increase in localized peak discharges in those areas undergoing residential , commercial , or industrial development . As in the pre-development peak discharges presented in Table 4-2 , the post-development peak discharges presented in Table 4-4 are not necessarily additive because of important differences in 'times of concentration, catchment design points and routing. The primary mitigating measure designed to reduce the adverse effects associated with increased peak discharges is the construction of ponding areas to detain stormwater runoff and delay the travel time to downstream control points. Ponds E, D, and C are located in the residential development area of Highland Acres and collect surface runoff from catchments HP-E, HP-D, and HP-C, respectively . Discharge from Ponds E and D is conveyed by sub-surface 24" pipes . to Pond C. Each of these thr@e ponds is located in localized low - areas presently containing wetland vegetation and intermittent streams . Each will be excavated to increase water storage . capacity while maintaining a permanent water level relative to the local groundwater level. For example , Pond D will be excavated to a depth below 110 feet from the present level of about 113. 5. A maximum dry weather water level of 110 feet will be maintained by a control structure with an invert elevation of 110 feet . The maximum pond level , as regulated by an emergency spillway will be 114 feet allowing for -22- 700 - 600 $ 600 a a 400 n m n 7 300 200 100 O O 10 20 50 40 50 BO 70 so 00 100 110 120 190 TIME(Mk%4") - FIGURE 4-4 Post-Development Inflow Hydrograph for Retention Basin Adjacent to Railroad Tracks (Basin A): 100 Year Design Storm z B at T = 40 is dampened to a 56 cfs peak outflow with the maximum water level reaching about 51. 6 feet at T = 90. The proposed road , at an elevation of 52 feet , serves as the IS emergency spillway for Pond B. Due to the retention of runoff in Ponds E, D, C, and B the peak discharge to the detention area adjacent the railroad tracks (Ponding Area A) associated with the post-development 100-year storm is approximately 700 cfs and occurs at T = 20. This is shown in the inflow hydrograph in Figure 4-4. The post-development inflow peak is substantially less than the peak of 1500 cfs associated with existing conditions. The maximum water level in this retention area is similarly reduced from 22. 2 feet to 19. 4 feet in the post-development case. The reason for this dramatic reduction is the presence of Ponds D, E , C, and B. With the inclusion of these ponds , runoff from 340 acres, or 57% of the effective watershed, is routed through at least one detention basin. Of particular importance is Ponding Area B which collects runoff from - 206 acres including the large HP-3 catchment north of Highland Avenue . Of the 100 year storm, post-development peak of 700 cfs which occurs at T = 20, only about 3% is contributed by the' 57% of the drainage area which is routed through detention areas and 97% is contributed by the catchments which are located southeast of the proposed new road through the golf course (HP-1 , HP-9, HP-7, and HP-5) . These observations attest to the beneficial effects of the retention areas in reducing peak discharges. The complementary effect of reducing a peak discharge is prolonging the discharge during the course of the storm event. Discharge to the retention basin adjacent the railroad tracks continues for several hours. For example, after three hours of the 100 year design storm (T = 180) , the post-development inflow to this basin is 120 cfs while the pre-development discharge is only 80 cfs. -26- TABLE 4-5 SIMMARY OF STORAGE POND ELEVATIONS AND CAPACITIES Pond Area at Total Elevations Available Minimum Storage Ponding for Storage (feet) Elevation Capacity Area Minimum Maximum (Acres) (ft3) Outlet Control E 115 120 1.32 450,000 24" pipe culvert ! ' D 110 114 1.21 270,000 24" pipe culvert C 90 100 4.13 2,700,000 18" pipe cluvert B 47 52 4.95 114009000 36" pipe culvert A 16 25 0.77 61600,000 4' x 6' box culvert SCHEMATIC ROUTING IN HIGHLAND PARK WATERSHED , a OO() t The peak discharge to the retention area between the railroad tracks and Jefferson Avenue is also reduced because of the upland retention ponds. The pre-development peak inflA to this area associated with the 100 year storm is 270 cfs and detained water reaches an elevation of 14. 9 feet . In contrast , the post-development peak reaches only 230 cfs and the water level rises to only 13. 6 feet . Therefore, the probability of water overflowing Jefferson Avenue and flooding the homes in that area are diminished with the addition of the Highland Areas development and the proposed upland ponding areas. In the Swampscott Road Watershed .the peak discharge to the culvert beneath Swampscott Road is reduced in the post-development case . As previously mentioned , the present peak discharges at this control point are 390 cfs and 330 cfs for the 100 and 50 year design storms, respectively . For the post-development case these peak discharges are reduced to 330 cfs and 250 cfs, respectively . Despite this reduction, the stormwater collection system along Swampscott Road appears to be inadequate to handle any storm of this size without street flooding occurring at certain control points . The reason for the post-development reduction in peak discharges in the Swampscott Road Watershed is the diversion of runoff away from this watershed on the Highland Areas site. Most of this diversion is to Ponds E and C of the Highland Park Watershed . The effect of these diversions is limited because, of the 228 acres presently contributing runoff to the culvert beneath Swampscott Road , only 77 acres are on the Highland Acres site. In the future this 77 acres will be reduced to 53 acres, however the development will have no effect on the other 151 acres (catchment 5-3) of the Swampscott Road Watershed which is located primarily west of Swampscott Road and Highland Avenue . Discharges to the Thompsons Meadow Watershed increase slightly in the post-development case. This is primarily because runoff from a small portion of the Swampscott Road Watershed will be diverted to the Thompsons Meadow Watershed. The increase in peak discharges is also a function of an -28- z increase in impervious surfaces and decrease in travel time in the portion of this watershed which will be developed with .k housing units , driveways and roadways. Compared to the present peak discharges of 210 cfs and 180 cfs associated with the 100 and 50' year design storms , respectively , the future peak discharges are 310 cfs and 260 cfs, respectively . Due to the size and storage capacity of the Thompsons Meadow area no noticeable flooding impact from this increase is anticipated. 4. 5 Erosion Control and Construction Impacts Soil erosion control measures will be established during construction of the Highland Acres development site. Controls will include the placement of straw bales, synthetic fabric, or similar filtering material to serve as a silt fence along the edge of exposed , downward sloping areas. In particular, such sedimentation and erosion control devices will be placed around steeply sloping bare areas that will be unprotected by vegetation for prolonged time periods. As soils are disturbed and/or graded during construction, they will be revegetated as soon as possible to stabilize the finished soil cover. Construction of new earthen embankments and retention pond banks on the site will be designed at a maximum 3:1 slope for stability and erosion control. 4. 6 Conclusions and Response to Comments on Draft EIR As currently planned, the Highland Acres development project will result in a decrease in the potential for flooding and adverse drainage related impacts at critical downstream design points . This conclusion is based on results summarized in Table 4-6. Localized peak discharges within the development site will increase due to modifications of surface cover and hydraulic channels, however the downstream adverse effect of these increases are mitigated through the use of retention/detention ponds and the diversion of runoff away from the Swampscott Road Watershed. -29- As indicated in Table 4-6, there is a significant decrease in the peak discharge associated with the 100 year design 'storm j at the three downstream locations of principal concern. Th$se locations are (1) the box culvert beneath the B & M railroad tracks adjacent to the golf course, (2) the triple culvert beneath Jefferson Avenue, and (3) the 36" culvert running from southwest to northeast beneath Swampscott Road near the southern boundary of Highland Acres. The increased discharge to the fourth area, Thompsons Meadow, is not considered critical. This analysis has been performed based on the most recent development plans for Highland Acres. The analysis demonstrates the feasibility of these plans from the standpoint of controlling storm runoff and avoiding increases in peak discharges to critical downstream areas. Design details may change based on conditions encountered during construction or final calculation of ponding capacities and adequate control structures. The determination of maximum ponding elevations and outflow hydrographs is derived primarily from calculations based on the 100 year design storm. Peak discharges and maximum ponding elevations associated with the 50 and 10 year. design storms are less. Comments on the Draft EIR drainage study made by EOEA and MAPC have been addressed in Sections 4.1 through 4. 5. Specifically , this drainage analysis is based on the latest iteration of the development proposal and incorporates the criteria identified in , the EDEA letter of April 250 1983 (see third paragraph of Drainage comments) . As mentioned in Section 4.2 of this analysis, "c" coefficients used in Rational Method and in the DEIR have not been used in this analysis which uses the U.S. Soil Conservation Service TR-55 method for small urban watersheds . Regarding the MAPC letter of May 20, 1983, the elevations presented in Table 4-4, the discussion of pond construction accompanying this table, and the erosion control measures discussed in Section 4. 5 address specific drainage comments . -30- TABLE 4-6 SUMMARY RESULTS OF DRAINAGE ANALYSIS Peak Discharge Associated with 100-Year Design Storm (cfs) (T=time when peak occurs, minutes) Present Future Conditions Conditions Discharge to retention 1500 700 area adjacent railroad (T=40) (T=20) tracks (box culvert) Y'M Discharge to retention 270 230 area adjacent (T=90) (T=30) Jefferson Avenue (triple culvert) Discharge to Swampscott 390 330 * Road culvert (T=60) (T=60) Discharge to Thompsons 210 310 * Meadow (T=10) (T=10) * Nate: Runoff from both the, Swampscott Road Watershed and the Thompsons Meadow Watershed ultimately enters Thompson Meadow. The increased peak discharge directly to Thompson Meadow is partially due to diverting water directly to Thompsons Meadow rather than through the Swampscott Road drainage system. -31- a 4. 7 References for Section 4 1. U. S. Department of Agriculture , Soil Conservation Service, Engineering Division , Urban Hydrology for Small Watersheds , technical release no. 55 (TR-55) , January 1975. 2. U.S. Department of Agriculture, Soil Conservation Service , "Estimating Runoff" , Chapter 2 in Engineering Field Manual for Conservation Practices (Modified Soil Cover Complex Method) . 3. Hershfied , D. M. , Rainfall Frequency Atlas of the United States for Durations from 30 minutes to 24 Hours and Return Periods from 1 to 100 Years , prepared for Engineering Division, Soil Conservation Service, U.S. Department of Agriculture , May 1961. 4. National Oceanic and Atmospheric Administration, National Weather Service , Five- to 60-Minute Precipitation Frequency for the Eastern and Central United States , NDAA Technical Memorandum NWS HYDRO-35, June 1977. , 5. U. S. Department of Agriculture, Soil Conservation Service, Northern Massachusetts Interim Soil Survey Report , February 1982. 6. U. S. Department of Agriculture, Soil Conservation Service, Guide for the Use of Technical Release No. 55 - Urban Hydrology , Albany , New York, December 1977. 7. Pagan, Alfred R. , "How to Calculate Streamflow Time," Better Roads , June 1972. 8. U.S. Department of the Interior, Bureau of Reclamation, Design of Small Dams, second edition, revised reprint , 1977. -32- APPENDIX A DRAINAGE CALCULATIONS k A-1 Determination of 10, 50, and 100 Year Storm Rainfalls A-2 Determination of TR-55 Input Parameters A-3 Hydrograph Plotting A-4 Stage-Storage-Discharge Relationships A-5 Inflow-Outflow Analysis -33- CALCULATION SHEET h Mm CALCULATION IDENTIFICATION NUMB J.O. OR W.O. NO. DIVISION b GROUP CALCULATION NO. PAGE_ I 2 3 �ierm ti��,'on Of /0) SU u ,o( /00 year S�.r.n Iti+•K�+II: 4 5 6 rG,,�J( o(QPAl 'fnr 11.0- Q '1 -(7c�r SIV e.'"s 6 wifi� r¢�rn fro f cf /0 0 . � 9 � S O� 0'1• too y(w V' wpr+e rP� '� o w�Pa �� vt Fere,c cS 3 �,� d 4 .(- pr Sale^^ Mbss��l��se 1�T. II Iz A Rci•,fn QEr o4 �'Co,rro.U(i,�Cl<Ps 13 14 _ ID 5 16 Sn yr. S �. C) 17 / 1e /DL• 4�r�. c �• � 19 20 21 —rkl 71? -S S /� , �tJQ ✓f;71 ?e'C lt4 T Pe � 'C�Vrt '1 22 pp r (� ,/ / L d�`t�r16 .� ' JH ; ,,(" CT tc-Ikfp Uri T(d � S�AtL �ri23 • r . za 1;'t mart SPvP+r` Or allS�' orfF t• C�vr o'� ru r.j �, ,'� � 25 a ti1o�r o(ec 'gr1 Sforw� . 26 V 27 26 29 30 31 32 33 34 35 36 37 36 39 40 41 42 43 44 45 46 CALCULATION SHEET inmi ' CALCULATION IDENTIFICATION NUMBER J.O. OR'W.O.NO. 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P{P{FnGf Z er{ WC. p�t( C.N,w✓ml,•ar{ i4 Wat c o i c fir e, ItQrr° f f- 0 m d( t*uf re Ca{t.�wR t5 ff S9'�'I�rt Cnlc✓%. 1ow+ S�t! '( + a,ffoc.4f�• 16 17 lupe Qntl\ µytlfnvliC (..r9 h . 19 20 21 1 .1JE�ff.n.v ,'o�n L�p� ,f S�to�C / TDrf 22 co t-'t� w.f✓1{"T .WAS 6RE4 0.. wel�•leO..L PCC.Sr�r"1ie d, 7N 23 rt f �. a.-d 6 Vs,n� a 1 "� ' �fo�r-p6�t 3;4e Alts„n ,{ 24 rCo'fL.�rr c'vt"rf pNO[ P ff^-V.S.6 25 �br of•F-i;tt Ca{�.4t.M e.�i-T. Fe' fj,)rcC lcairkwe^lfr Sl-pr1 26 anc� Vi� pvovi.-c 7f,nq{rr We.r•C PLf N1.1G kbl ^ -(fte" E'xlti , ,c) 27 ,1 �n y�[� hlV j z;k �14J„ns ' nNc7[ '�ra{f tjt.R 4X ��dc.�Q�„e✓t� . 26 29 30 31 32 33 iGe �C�• 55 r�e"fllortOr c4e{er�,wr� P{a1c d�zci�Qv 34 o,��ow5 . u�+✓s1 f.- e,^tZ -{ar ��+.frft#�Pd Si,o-�3e, �artcl.r� arphS 35 wi k4 ;n (j t w�1 tSktc{ r . �L ty4 ce } rt� +��n/;u ,i f area ;th+n 36 ee P.. + 0T Mbd •�x rc.1?'rN� '�'p 37 -�/`.t}� t ( ('faNl.G �Pny� c, These �4tPi✓fcs 'fe. 36 �tcRor'm014 /r'-TfQN +k l"-roo` S"k pl-'N 39 Mae a.n�`'� -6c (j Su<'vf, S . Afer� t3(F*(»^ 1NFT�bti3 40 4+,a We ! / /C,0".1^f*- f,7 .Volver.1 NSf0. 1/1 �Pa� �1 YC�ofp,Q 41 r L^ fl • C.AQ (T �'Mi/1 r-�.wnl GJQ. P-Hr,t 41. {2 43 i; 45 46 , •i Table 2-2.--Runoff curve numbers for selected agricultural, suburban, and urban land use. (Antecedent moisture condition II, and Ia = 0.25) HYDROLOGIC SOIL GWUP LAND USE DESCRIPTION A B C D Cultivated land!/: without conservation treatment 72 81 88 91 : with coacervation treatment 62 71 78 81 Pasture or range land: poor condition 68 79 86 89 good condition 39 61 74 80 Meadow: good condition 30 58 71 78 Wood or Forest land: thin stand, poor cover, no mulch 45 66 77 83 good cwer2/ 25 55 70 7T Open Spaces, lawns, parks, golf courses, cemeteries, etc. good condition:. grass ewer on 755 or more of the area 39 61 74 80 fair condition: grass cover on 50f to 75% of the area 49 69 79 84 Commercial and business areas (855. Impervious) 89 92 94 95 Industrial districts (72% impervious). 81 68 91 93 Residential:!/ Average lot size Average % Impervious!/ 1/8 acre or lees 65 77 85 90 92 1/4 acre 38 61 75 83 87 1/3 acre 30 57 T2 81 86 1/2 acre 25 54 70 80 85 1 acre 20 51 68 79 84 Paved parking lots, roofs, drivwgrs, etc.!/ 98 98 98 98 Streets and roads: paved with curbs and storm severe!/ 98 98 98 98 gravel 76 85 89 91 dirt 72 82 87 89 1/ For a more detailed description of agricultural land we curve numbers refer to Rational Engineering Randbook, Section 4, $ydrologf, Chapter 9, Aug. 1972. a/ Good cover Is protected from grazing and litter and brush cover soil. Curve numbers are computed assuming the r o%off from the house and driveway is directed towards the street with a minimum of roof voter directed to louse where additional infiltration could occur. !/ The remaining pervious areas (lawn) are considered to be in good pasture condition for these curve numbers. In name warmer climates of the country a curve number of 95 mar be used. ' � • {ro.., TR'JAS (Ri�er¢..c r 1, } L SCS MODIFIED SOIL COVER COMPLEX METHOD - AVERAGE CN l AW Project Name . - { " 3 S _ Analysis Datei y X Pre-Developmemt, _ CY Post-Development Analyst jt- Land Use Soil Group CN Area Area x CN 'y': .:,;t�c-c•{i� l ('130.10 C fil t( a5�4 r Alb _0 I .Z 12N e Total Area ( L X202_ Total Average CN = to m i CALCULATION SHEET �m CALCULATION IDENTIFICATION NUMBER J.O. OR W.0.N0. DIVISION 6 GROUP I CALCULATION NO. - ;PAGE 5 3?L t4m AA 2 G Qa t.tl , -+ Ave Awe 4I dr.41;c pe(0..+ wt Co,4cb wet GM Grtit St„r- 1.c(.��`ri. Mod:fi,P� Ap�rc}}s. 1rca1.K'1" Inr,r- 5 HP-1 Pd F 93,0 78177 10 OL-7)o 0 11+5 c,, 0 6 HPQ P 013.9 SI t 2too `t 5 c 1.t HP.3 PAF 159.9 l9 1 3000. 1-1 8 C !,Q 10 14P-`t P _14x.7 -77 t1 34 o0 0 b C. I 11 14P-7 P4--F b p .2,0 41 I 3044 20 7 b to 12 N P- 6 PtF 43.3 IVo '? X500 O 13 . C ►4 13 14P-L F II (,1 91 5 3So0 Sg a G -71 14 HP- 1D F 11.4 is toxo 30 o NA 47 t5 NP- E F 11.L ¢i 10 to ra O MA 4'a 16 1-fP--)1 F 3'1.3 74 6 1(riQ Ic, o n1A 1+4 17 t4P- bF y0.g $0 I1 I6a6 O a 16 16 HP--tfs F 69.8 75 I4 19 20 9- 1 P 27.4 -79 I'l 13510 0. 3 D 9 21 22 S- 3 PAF 1501 %c B SVOO T 5 G t6 23 S-cl P 20, 1 '7`1 IG 980 0 6 NA 0 2" 5. I`l.4 9a 8 1470 93 o MA 70 25 s-(o F if6. t '63 10 1120 aj 0 r4 III 26 5- } 4= 5; 3 10 9 k 10 o rJA SO 27 26 7-1 P 11.4 71 Sr 1760 0 0 tj a 29 7_a P4.F 101. 1 77160 16'+10 1260t1Toc 0 +10 / D 0030 30 T-'3 P4F 20.0 71478 10 IQoa9�o;too 0*25 2 D Otto 31 T-'l F ib.b 8o ,Q 144o 11 O NA 079 32 33 34 35 36 P _Prrrezent 36 Pte% 39 40 r� 1 42 L ' 43 1L) u�fj2< CeQtlwl� 44 NR ^ not G1)pl,ia�stC 45 1 46 mil CALCULATION SHEET hm CALCULATION IDENTIFICATION NUMBER J.O. OR W.O. NO. DIVISION & GROUP CALCULATION NO. nn ,PAGE S3-;1- r1Mnn A• 3 /• U/ 2 ' N� dro9r� pl, 4 - 5 / 1 -If� /� / 6 14,01Yuq rop�s �Y (.P ME+^ 1U01c /!/rc. YZIIOW�l 7 J V B 9 10 11 (c 4 s) 12 13 14 O Tp -TY 15 16 Te -rlmF y 17 19 zo f - ,J1 zl �� CAfP Of 22 23 24 Z,•. (O'j V,Ovo�,.t1 s a clef;y ?Omtarc 6.54 0r' 'V,w- 25 S w o'f �, jr;b �e�� �1�fug Ca PIIS acc� ^tn� -(u, �f74�e1 Irwe. 26 U 27 26 ' I, /o� Core .�ry{'oNi ck,d open cA,A. e +r-,r—,o ' +r,r s 29 /P t ?(Ow. Ga.'Ec�M4.�.�f IO �2i�y In QO,Nt2 Gr.2'C CLIC JI O.�^� 10 91E'� of 30 til .� FC.rc�Sc�a+c.�w.eJKf�/! ✓f: I,i c dp K'�'f,.� -}-ramie I R {� 32 Yy-e1 �I0 Mack (..GTv'i^ CC�'S�� CP�.JAWtlfT v'I'1�,1 t�lJl 1••VL 33 OQ,•'V u 4c.34 tNQ O.(- off.% [1ooKe'l -G'OeW.I CJ IG•F-.�k4 S 35 LNErL Ga,IC.�IcJ(t4.� 67 /�nn�l�'S eyv-'+vh 36 37 v _ • �q C 1/j S1/Z 36 39 s v V?�oc 40 h MnNn�1..q'S M t. 62 S = S `�p¢ 43 \/ L� -I 1 _ I i/7 44 •q' S "\u! I�V,N r WQ�. �'%IFN nor �.��Olt ( awLQ 45 46 CALCULATION SHEET hI1�I CALCULATION IDENTIFICATION NUMBER J.O. OR W.O.NO. DIVISION E GROUP I CALCULATION NO. �,} :PAGE 53a HtgfA A -q 2 3 s 6 7 t'Gy�c." p`y J'--'C. t �(A'ilonx ktpt -rU< Yo17e'ti�.rxo'� /q••✓en.'e. all- Shown o kac �nlluw.�,� P4�e.s Aro-A ole (e�,-+,HoY,�. t LJP+'c-. it /l f.f'forro .!D IJ y �a r�w!rG ( utd'ly ' pfN,^4eo. Y.d lh4e" la+�Ep� 12 (c.,Af >.,rc ro, /-#T-,c, l `'� ( v �' A�lo �SPI,�s. plr.n aF' rel li s�ryA. •d,'S[.NOY J✓1CT/,ya� S iPm..! (ooscof or% 14 �'P�P✓ �;?� y ot1''ttC vt c.�' g .. 15 IE 17 . t8 19 20 21 22 23 24 25 26 27 26 29 30 31 32 33 34 35 36 37 36 39 40 41 42 43 44 45 46 i 7 R 11 CALCULATION SHEET inmi CALCULATION IDENTIFICATION NUMBER J.0. OR W.0.NO. DIVISION 6 GROUP CALCULATION N0. ;PAGE Sia HAI 14 2 9,5/1 ROAO Tr<ACK RCTEN7tom AKA } 4 CtF,JAI,Ont —.Sr6pA6 VaLur E (�i�� AJC fi E �PJ,.l,Fe 1r"I a �\ tr tC(vr.l in<rt.n rni.,., 7 B N 10 Ib,�ay f 16,4)`1 '2 i3�3,3'�0 1 l33,3ae 13 17 X32 991 ls �f ,uy 14 3} 51 ?`+6 i Si 5,746 15 t4 398j5or ybst140 16 5;2�, o5Y 1, 05 `I 17 o CL5 6n 1 5 ;?oIOoS t3 004 S 5 07 S,p� 0 G t 191, 37 i Ot`! 394 S� 1 0:2 19 20 21 1 c 70x/ 000 22 a.} a,,k08/ 00 - 23 �-Z _ , k00, 009 24 2-� 4Ii 4001 00 '0 25 7 gJ 400 goo 26 27 ze !`f 29 30 2 31 32 22 53 34 71 35 Sfi Ze 37 38 t4 39 40 1` 4t 42 1 43 44 / 45 46 r 2 3 Y 5 C ) CALCULATION SHEET nm CALCULATION IDENTIFICATION NUMBER J.O. OR W.O.NO. DIVISION 6 GROUP I CALCULATION NO. n PAGE 3 53 NMa1 2 ?FFG£k'S01j AJtNUF '7kiFCc' CULVERT 3 FL�vP srvR�ic F vgwrY £ /y f / Arc 6 �? 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DIVISION & GROUP CALCULATION N0. PAGE S s 3 a HM M £ LfVRT :,tJ/&,JTf=tOw T< , ff, Ad£. 'TRIPLE CQJLVJPl I 2 3 E(k�t-.�t / �i�S,,,M+c Z �.,e.•fi: �o`", �F{t� r.c. arras, _ �S'7a .-� 7t�2 � d,a,hek.r =3.5 4 Oro d 5 6,c ,CV 6 E l c� •H N �D C,t 3 4' f�cs�v..,. B 9 0 / 11 l A, Iz 13 14 It t 0. 2.8 6 '�0 AA 15 79 16 t L Z o s 71 1a 6c. ;Z ` 17 IB 19 Ac T fie? r 20 / lY7 21 \ 22 r5 S 23 24 4 6 1 , 7 I �} 102 30� 25 77 rr 26 17 2T 28 29 30 31 32t7 33 34 —% 35 W 36 -- 3 Iz 7 rl 38 39 too Too 40 41 Q 42 e 43 s 44 45 46 111 CALCULATION SHEET hm CALCULATION IDENTIFICATION NUMBER J.O. OR W.O.NO. DIVISION E GROUP CALCULATION N0. l PAGE 6 53a HAIM 1 ��e7�J LU J` MvERT 2 ELEVATION- nasi £LBV : 3 4 vo,_0 o£ (;f T� T B 4 ,o 115 5 a� 0 it 12 CS y,C?�/D Jr A� sJ7 oo.!;- i3 C- fl IaD 66 ( 0 L195 Loa i 14 15 fi= t Q (cJ5) IT Its O O 16 !! S9, OBo 19 ll � 17�i, 1100 20 I IPS 2A, 7, 140 I.S 2.0.0 21 rr9 3561310 ,o ab.0 22 100 4141f4P0 a..5 30 23 24 POND D 25 EL£vAl Lo GHRPr,rr{ s 26 2T £IPYr.��or p 26 24 ( 1 D .2�7 D O I 30 c,e,l,� ti � '7 31 32 33 34 CIP...�,� ,n )I'n. ram l ` S4P0 I 35 36 11 t! C7 d o It 1 37 36 /!2 13E 3y; I. 0 t3,o 39 71 o4 .�ty !..$ 020. 0 40 f 1 t{ .?-7.f,X646 o'j.0 �..,.0 . 41 42 43 44 45 46 CALCULATION SHEET h"m CALCULATION IDENTIFICATION NUMBER J.O. OR W.O. NO. DIVISION 1, GROUP CALCULATION NO. PAGE 7 sz� H/0 A g .W• z aND fLF vk7,ON -5 TORA6 E - DISCHAk C--£ - 3 4 s ,r k,,.G 6 90 1797 2.$ 7 X67 066 e to ' s /Do � 54,4Dy a�670� 661 10 1 0 e 10 X14 ll°"5"(-(t Iz 13 14 91 a67 06C O. (p S 16 z 9z 524, ,E 2 I, 33 6,0 c 16 IgIZ 2.Oo 17 `I 5`I 106$)264 2 .G7 a,0 16 S `1 S 15 33I 19 3 3.331q.0 G `I6 � , 602, 397 4,00 20.0 20 9 21 1 (, Cl, Nb Zi 4.67 al.D 0i4 �I 13 6,529 5.37 74, o zz 2, tio3,S`1S G ,oO ;Ls,0 23 t0 lOo a 670 6� 1 x,61 24 23 Po ND IS 26 (;-LFvkfION —57-0PA& F--`4�1ISCHARc.E 27 28 VOCuP�£ 29 I/ltrtw-6.,1�..� Cylt`�Iw�uE 30 til als 6�2 31 O 31 2L01124 3 "742 774 50 3ot z2 7 132,7 4 33 332 -S a (. 641 ,16 34 52 35Q, yq9 1, 447, foo 35 36 3 b 37 N elegy , o r 00'.x, (�tT� 3% 37 36 _ = 36 „ 39 0 41 l 0 o O 4 0I 119 <p6 .2 60 9 1 5 ,3 3 41 I 1 5 . I1 CI'I I 7 20 m 42 3 50 77 a1-7-7 4 1, 0 3s 43 y 51 44 r ►, 1t53-71.-33, I S1, � X19 •7 5 z 1 I L147, Soo I. b'I `o � 45 46 CALCULATION SHEET inmi CALCULATION IDENTIFICATION NUMBER J.0. OR W.O. N0. DIVISION 0 GROUP CALCULATION NO. • PAGE Sia km i 2 1r�11�w — Ovtr(o.., ��.l� s1s 4 1 3 6 ISGS� Ov. 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M.4✓�S T23c" o,c{ Gi•E-'�'�c�M1G�'t. 1rG1 nc>tiC� TIOM+ / b i 35 rQy 36 1_ { J 37 38 39 40 41 a 42 43 i 44 45 46 I<{C C VLVf ti 5erC�le.t� ,2 90 y{a� slot~, • mr Pre. d P„zI.PM.., F1m RESERVOIR-STORAGE METHOD Page 2 Time in Inflow I1 + I2 2S Outflow 2S _ 0 water Minutes CFS At + O CFS Lt Level - to lov c�09 ad V / OV 0 C) i C> Y a o a o 3 1 Lt ► s,3 ! o ail 1!291 305 I6.6 a -74`7 10Aq )a% '1 ro0 II63 I-M 3o IDiq 17G � 21) a01 6 7 i� a 60 Li 931 1 65 y G 0-7 119.9 • 50 o 7. o. s 4 60 -793 1547 93-75 204 7955 21. 0 7o 601 13 9 't 01353 al9 89 15 21 .3 ASO 410 101 ( C1cl 9N7.:L x1 .43 X10 a3o hyo 01 � � 230..'}) 965a x1.49 loo 13 -7 3 67 Ib o 19 224 I 9563 pl. q G Ito 9S -2 3 5 97gg y6 � . `iD Ito � 3 16 1 95D-1 2z I 9b65 a1. 3 13 0 59 Iz 917,4 21 ? 1� 7Sa al . a 1,90 9_7 I15 �s�b -I 21 06441 al . l ISO 5 .7 114 555 ao4 $ 139 ai. o 1 1 3 Masa, A04 y'y ao.9 170 5C IIa 1956 'a00 15560 I z o r s It i 7c*7 1q6 7D77 ao. 190 55- 1 1 0 &qR7 a7 200 5 `f 1 0 Cl 110(0 110 'j 20.10 1 f • �' Yu Sf. tICW