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Home My WebLink AboutRESOLUTION 1980-90 ~., ... CITY OF KENAI RESOLUTION NO. 80-9(3 A RESOLUTION OF THE COUNCIL OF THE CI1'Y OF KEhAI, ALASKA, FOR P.CCEPTING THE AMENDAiENT TO THE KENAI IYASTE{t'ATER FACII.ITIES PLAN APRIL 1y80. 19HEREAS, ~the Kenai iYastewater Facilities Plan, published in September 197$~ recommen e a route alorig t~ie Spur Hignway for the Central Kenai Bypass Interceptor, and iVHEREAS, a change was approved by the City of Kenai revising the original route of the Central Kenai Bypass Interceptor to a route designated as the Mission-Cook Route, and titHEREAS, a Public Hearing for rhis amendment was held on April 16, 19~0, and WHEREAS, no comments have been received hy the May 12, 1980 date for clasing of Public Hearirzg. NOi9, THEREFORE, BE IT RESOLVED by the Council of the City of xenai, Alaska, that the City of Kenai acc~pt the "AMENDMENT KENAI ~9ASTEjYATER FACILITIES PI:AN APRIL 1980", which is attached and made part of this resolution. PASSED BY THE COUNCIL OF THE CITY OF KENAI, A KA, this 21st day of May 1980. ~""' RE ATTES?' ar e an, ity er ~ , ... ~ ('[] A-.~EfJl~tti:.. i '' L1[,~ KEt~T+i !;'ASTi=1'.`A"TLR f=ACli_iTlf:S PI t,N Ar RIL 1980 INTRODUCTIOIV The t:enai 1:'aste+vater Facitities Plan, published in September 1978, recor~mended that a Central Kenai (nterce~-~tor bP constructed to alleviate overloading in the existing sewer system. The City of ~:enai received a Step 2 grant t~ desian the interceptor and CN2F~ HII.L was authorized to i;egin final ddsian in Aprii 5979. The facilities plan recommended that the interceptor be constructed in t~~o phases. The first phase woutd relieve existing sewer over(oading an~l the secoc~d phase ~voutd relieve overloading estimated to occur in 19E5 to 1990. During the ~nal ciesian of the interceptor, revisions to the originai facilities plan route a(ignment were necessary because of construction costs and easement acquisiiion difficutties. Also, it was concluded durtng ~na{ design thai an all-c~ravity interceptor wauld be too costly and that an alterRative gravity and pump station-pressure iin~ inter- ceptor would be the more cost-effective solution. The Alaska ~epartment of Environmental Conservation on h!arch 10, 1980, requested an amendment to the facilities plan be prepared for the route modification, another public fiearing be held, and that a negative declaration be issued by EPA. BACKCROUND tNFORrJtATION I Facilities Plan Central Kenai Bypass Interceptor :_, The faci(ities plan recommended, as shown on Figure i, Yr~at the Centra! - Kenai Bypass Interceptor be constructed to alteviate overioading in the ~ existing Central Kenai sewer system and reiieve dependency on the erod- ing bluff sewer. The existin~ system was estimated tc be near capacity . abaut the year 1980. To accomplish this, 1t was recoms*~en~ed that the existing 16-inch-diameter gravlty Fast Kenai tnterceptor be extended 2,400 feet westward aiong Kenai Spur Road anc~ then connected by a 14-inch-~diameter, 2,300-foot-tong gravity pressure fine to the existing interceptor at South Spruce Street and Kenai 8each Road. The 16-inch-diameter ara:•ity sewer was recom- mended to be laid at minimum slope to provide sufficient efevation (static head} for the 14~inch-diameter gravity pressure tine. ! ,•w It ~+as also recomrnended that a 10-inch-diameter line he constructed paraltel to tE~e inter~eptor aionq henai 3each !?oad from ~outh Spruce Street io the treaiment plant. The Central f<enai f3ypass Interceptor order-of-magnitude consiruction cost v~as estirnated in the facilities plan to be $370,000 based on January 1978 doliars. The a:osts fdr gravity pipelines inciuded e•<cavation to a depth of 8 feet anc~ compacted backfill. The pipe was assumed to be asbestos concrete. No trench dearatering or difficult excavation condi- tions were anticipated. Pipeline cosis were increased by 10 percent to cover difficult traffc control and pipe-Iaying canditions for the Central Kenai Interceptor. Casts of taying the pipe down the bluff were assumed to be ~ve times the costs of Iaying the pipe in flat ground. Surface restoration c:osts were included where a~propriate. Gravity lines were assumed to ha~~e ~rianhoies at a maximum spacing of ~+00 feet. Central Kenai Rerouting To relieve overloading of the existirsg Central Kenai lnterceptor in Old Kenai, estimated to occur in 1985, the v~astewater facilities plan atso recommended that a new pump station be cens:ructed at Cook and I~~ain Streets to intercept flow in tiie existing interceptor and pump it Lhrough a n2w 10-inch-diameter, 1,C00-foot gravity line running a(ong F1ain Street to the Centrai Ker.ai Bypass Interceptor. i2ero~ting the existing s2wac~e flovrs into the newr pump station woutd require constructior of 1,400 feet of 8-inct:-diam.eter gravity sewer. ~ ~ ~ The Centrat Kenai rerouting order-of-magnitu~e cost was estimated to be $380,000 based on January 1978 costs. This cost ~vas developed ~n ~ the same criteria as the Centrai henai Bypass Interceptor. . - - ~ Destgn j . Predesign Report ~ The preliminary design of the interceptor indicated that the facilities ~ ` ~ plan r~commended interceptor route along the Kenai Spur P.oad would ;.; ~' require substantiai~y higher construction cosis because of poor soits ~ ~, ~ i conditions along the ravine bottom and deep excavation depths along the ~', ' Kenai Spur Roa d. A lso, acquis t tion o f proper ty r ig h t-o f-way easemen ts -~ ~ for the Kenai Spur Road route were started. The location where the pipetine drops from central Kenai to the creek ravine bottom crosses ~ private property. Pipeline right-of-way easements were denied by the ~ ;, . ; . owner because the route travels near a private cemetery. ,~ . ' ~ ~ Thus, an alter*~ative route as shown on Flgure 1(Mission-Cook route) ~',~ was investigated as an alternative with fewer easement conflicts. ~ r ~ "' . ,6 . ~ .- = ~ 2 1 . !~I . ?'he f?ission-Cook route tivas an a1! gravity route. It vras recur~mended because it f~ad the lo~vest iotal present worth cost, no annual operation and maintenance costs for pump station o~eration, eliminated tiie need for pump station 2, and required no phased construction for future growth in the old Central f:enai tovrn area. The route consisfed of 4,I50 feet of tb-inch-diameter gravity sewers, 300 feet of 8-inch- diar~eter gravity sewer, and 2,000 feet of t4-inch-diameter pressure line. The estirnated i;unstruction cost was $835,000 based on estimated July 1980 dol(ars. The predesir~r~ of the t.dission-Cook route was based on ground-level topographic survey and limited sofls investis3ation. The costs for gravity pipelines ~+ere based on trench excavations of 18 to 20 feet deep with a tre~ich box and a maximum trench width of 30 feet. It was assumed that the native soils could stand ai side sfopes of 1:1. The ~ackfill was to be compacted and the pipe was assumed to be ductile iron. No trench dewaterir.g was anticipated. Costs of laying the pipeline in the creek ravine were based on open-cu; t: ench excavation to a depth of 10 feet and unrestricted trench widths. The back~Il was ctmpacted and the pipe was ductile iron. Ground water was assumed to occur in tfie bottom 2 feet of trench. Surface restoration costs were included where appropriate. Gravity tines v+ere assumed to have manhole spac- ings of 400 feet. Final Design The final design was based on the N;ission-Cook route recommended in the predesign report. The interceptor consisted of 4,500 feet cf 16-inch- diameter gravity sewer, 350 feet of 8-inch gravity sewer, 2,150 feet of 14-inch-diameter pressure tine, and a~~ndonment of pump Station 2. The 16-inch-diameter gravity sewer and 350 feet of 8-inch-diameter grav- ity se~ver would be constructed with an average trench depth of 20 to 22 feet and maximum trench width of 20 feet. The 2,158 feet of 14-inch- diameter pressure line would have an average trench depth of 8 to 10 feet and unrestricted trench widihs. ~`~~ The ~nal design proceeded based on the assumption that the gravity 1 sewer could be construcied ~ith a trench box and cutting the side ~ ~ stopes back. However, as the final design progressed, it was deter- ~I . mined that thp native sandy soil for the gravity sewer wil! not stand at ~ s . stsep side slopes and that the trenches will require bracing (sheeting :k ` anti shoring). The deep trench excavaiion depths may also cause a f potentia! settiem~ni of adjacent utitities. ~' Gravity sewer construction costs were based on sheeting and shoring for all trench 8epths greater than 10 feet. The back~ill was compacted ;~ ~. and no trench dewatering was anticipated. A 20-foot trench width -~ ~ restrictia;i was assumed. Costs of laying the pipe down the ravine were .r ' based on open-cut trer~ch exca~ation to a ciepth of 10 feet and unrestricted trench ~vidth. The backftl -vac uncompacted and trench detilatering was assusned to be requ:red. Surface restoration cosis were included where appropriate. Graviiy lines ~r~re assumed to have manho(e spacings of 340 feet. The estimated order-of-snagnitude construction cost is #4.2 r.-illion, based on January 19~0 dottars. AL7ERNRTIVES Because of the anticipated high consir;~.c,tion costs resutting from the deep construction required for a gravity system in dif~cuft soil condi- tions, alternative :nethods of achieving the City's goal of relieving dependency on the bluff sewer were explored. 7hese ~iternatives inciuded various route variations incorporating pump stations and shallower pressure tines as +vell as breaking the project into two separate schedules for bidding, Separate schedules would atiow the possibility of the City awarding a contract for only a portion of the project (to relieve the bluff sewer~ if bids for the entire project are beyond the City's present fnanciat capabilities. The most feasibJe altersiative io tt~e alt-gravity sevier (atternative 1~ is . a combined gravity se~ver and pumped pressure line (aiternative 2j. This a{ternative wouid fullow the same route as the f~ission-Cook gravity interceptor but would incorpvraie a pump station to. redu~e trench depths on part of the rcute. Both this alternatlve and the gravity interceptor ° are shown on Figure 2. The alternative 2 project will be separated into Lwo schedules: Schedule A- tdission and Main Street to the sewage treat- ment ptant Schedute B- Siuff and Front Avenue to r4ission and Main Street ; i``~ t~ Schedute A would allow the City of Kenai to relieve overioadina in the cxisting Central Kenai se»er system. Schedute B would be constructed to relieve future overloading estimated to occur in 1985 to t990. Atternative 2, Schedule A wouid consist of 350 feet of 8-inch-diameter gravlty sewer (20 to 22 feet deep), 2,150 feet of 14-inch-diameter gravity pressure line (8 to 10 feet deep), 1,350 feet of 8-inch-diameter pressure line (8 to iti feet deep), and a new 1,]00 gprrs pump s:ation. Schedule S woutd consist of 1,950 feet of 8-inch-diameter pressure 11ne (8 to 10 feet deep), 1,100 feet of 16-inch-diameter gravity sewer, (14 to 16 feet deep) and a new 930 gpm pump station. 4 ~~'..." -~ ~ - -' , .~ ,~d ~ -- - ~ r:~ - ~ ~ ._ ~, .~_ ~~>, - •,~, ~.... ~~ ' ~ ~ ~ . ~ : , ' F . COST 1_SI'It.1ATE APJD EL'Al_UAT101~ ~F ALT~F?NATIVES I Order-of ~agnitude construction costs were estimated for the gravity ~ intercepior (alternative t) and the c~r•avity sewer pump station-pressure line (alLernative 2) and are sho~vn on Table 1. All cosis are for con- ~ f struction in Kenai in January 1y80 dollars. r ~ i ` ~rorh a cost standpoint alone, atternative 2 has the lowest construction ' cost and totai present worth cost. Aiternat~ve 1 has the lowest annual average op~ration and mainten~nce cost. The advantages of alternative 1 are the elimination of pum~ station 2, ~ elimination of future ph<~sed construction, and no annua! pump ~tation ~ operation and maintenanre costs. Disadvantages inctude its high con- struction cost a-~d interf~erence with existing utilities. ~ `~ The major advantage of alternative 2 is its low construction cosi. A ~ a disadvantage is operating and maintais~ing two pump stations. Afternative 2 is recommended as the cost-effective solutton based on its {ow construction and total present worth costs. , ~, IMPLEMENTATION The foliowing steps are necessary to implement the recommended facilities plan revision~. ~: ~; ' o Conduct a public hearing. o Kenai Clty Council adoption of the changes in the facilities pfan. -, - o Submit this amendment with the adoption reso(ution to the DEC and EPA for approval. o Obtain 3 deciarattan oP nonsignificant impact from the EPA. I , " ~ R ~ . The following project schedule has been developed far construction of ~; the interceptor in the 1980 construction season. p' ~ April t5, 1980 Start destgn modificatlons ~~ ' 4 ~ June 1, 1980 Advertise for bids , - June 24, 1980 Open bids ~. ~ July 14, 1980 Start construrtion ~: , October 1, 1980 Construction coa ,~ieted 5 ~ ~ ! ~ ~ ~ 1 ~% . ~ - - r ' _ _ o..~,~~~~~ _i ~ EtiVIROfJl1ENTAL i+iai:~?~~.1fNT A review of the environmental assessrttent rresented in Appendix E of the facilities plan indicates that ti~ere ars minimal changes in the environ- mentai impacts caused by imp(ementing the recommended interceptor alier- native discussed in tiiis amendment. Z"he Russian Orthodox Church has indica±Qd that the origina! route is not acceptable because it would traverse near an otd cemetery. The 1~lission-Cook alignment near the Church and shrine are acceptabte. An archaeologist will be on site during construction in the areas that have been designated as archaeolooicatly sensitive. Secause aiternative 2 provides for shaitower excavation, cons2ruction disruptions +vilt be less severe, and property and utility damage liability will be reduced. 6 ~~ ~. ~,' I J ~ ~ ~~ ~i~.~r,;,,,,;r;;,;~.+,~, - - ~,~, - - - - ~ ,1 .^ _ ' '__ _ ' _"_~ _ ~ ~ ~ '~ \~'L -CLNiHALKENAt ~~+ ~ ~ ~ ~BYPAS~ INTERCEPTOR M ~~~ ~ ~ ~• ~ ~ Roi1P r~~ -~ •• qtNtJO PV ~ • oVE _~-~--~-t ~ ~1 1 w ('~N~t E - c~ ~rJ ~ 0~. • ~ ~'~(~r~, ~'j: Facilities Plan Route ..' ; ~ ~~~~ ~" \ ~ ~* ~ i ' ; _._. , ' ~ '~ ~ ~ I N \ ~,~/ ~ i ~ J/ ~~ ; ,~ p // '~`'~ ~o ~ ~j~• t\°VERU-N~ AV ~ ~r j ~~f~~ pr _ r ~`!1 ~„~~ E r et~ '~ o ~ I ~~.`7~ .- ~ v~ Av¢. ~~,f ~-~, .~~~~~~~~~ ~ = GI MWLJ- AV[. : ~ , = d' . , .. ~ • d~~~ . _- ! ~• , '• ~~ ~y K VE. - _-_ _ ~ co~~ /rJ ~ ~'''~y ~~ .,~,~. ~~ ~NTER EPTORA' ~ •:•v ': ; ~ ~` • , I~ IY..i " • , i•!~ ~! ~`~~ : ~ ~E '. ` y t. ..a/ •Y ~ M~ - M :I 7 ? • ~ . • ~ y ,~ ~ti. ~ • t.` . by •'Y. '~~ ~,c t~1 ~: i w% ,f~i ~~ ~ ~'~ :~r q'~~ ~ l' ' ~ ,•, vS'-• • . ~~. `'n ~ %~.s i .1 " Predesign and Final Design . (Mission-Cook) Route i ~ - , V ~ .~ GRAVITY SEWER ~ ' ..... PRESSURE ~iNE ~ o~ aoo~ ~ soo~ r;-' . ~ • f'UMP S7'ATION I ~; Figure 1 - CENTtiAL KENAI INTERCEP70R ~ - AI.TERNATIVE ROtJTES ~ .; ~ ~ ~:. , ~: ` ~. L. ~ - a :: , ~, ~- ' ,, ,,. .-_ ~ ~ r ~ i , -- ! . " `~" : .,r . ~; ,t ~ ; i;'~ .~ t {, I .. , ~- ' F - t i =- T_ ~~ , ; I~ ' ~~ ' k . t 'a ~,: . ~' , 1.' h ' " ~a ~ ..,..~.._ - ,..~. ~ - ~.»--_ - - ~ _ .. .~._._~ -ti Table 1 Order of f9ac~n itude Cost~ _ ATtern~t ve 2 Gravity and • Alternative 1 Pump Station Cravity Pressure Line Interce tor Interceetor Capital Costs 1980 Improve:nents $1,880,4Q0 $ 690,OQ0 ( Schesiu I e A ) 1985 lm~rovements 2,320,000 508,000 (Schedule 8) Subtota! $4,200,000 $1,190,000 Annual Average O~M Costs Labor 0 4,~00 Power 0 700 5ubtotal o ~ 5,100 Total Present Worth Cost - 1980 lmprovements ~1,880,000 $ 690,000 1985 Improvements 2,320,000 500,000 Residuai Vatue (690:000) (180,000) Annual OSNi Costs 0 60,000 Total #3,510,000 $t,Q70,000 Relative Cost 3.28 1.00 ~ January 1980 dollars based on Seattle CCt - 3600}. ; ~ ~ ~ ~~_ - - - _ ~ sF N T,9 ly9C ~ ~~ ~r~ F ~ .~ C ~ ~ ~ rrp ~ ~~ /~~F ~ i -- --~ - _ . ~, '~..// ~ ~ \~~~ ~p ~. Existing + `~ T ---+.~ n~ - r Y '"~'~ ~,. ~y „~~ ¢ `.y ~~R. ~ " .T ;! E ~ ~~ a • j~ ;~~ i P~ fa,~`t : ...,.es.;.~s:•.'.::: •n .a~' .,,,,;r ~~N ~ 4 ~4lternative 1 ~ ' G~avity Interceptar . _ _ _ _ _ _ ~ ~/ ' ~ a ~ ~ -'v1i ` ~'_~~ S N . /I ` ~'\ •- ` -~ . ~9 ~F ~ a af~ vR R o Sewer 91 ' ~00 ~~Lp N ~y ~, oveRU~o ave. ~_S ~a i O ,~ Q P~ W ~ ~9y gQ ' ~o Modify o > ; '~ r ~ No Existing Pump ~ a ~'~-R`~c ; yt ~`° ~ ~~~~ ~ 0~`~4` ~~N`~' Station ,~ , ~ ' ~ ~~~~ a ~ ~ Q ; ~ ~~ ~~~~~~~~~ ~~ ~~~~• y~ '~ PENlFjSY{~ ,4v ~ e . 7 1.r, New Pump = ~. • c (~ ~ ~ PEM~NSVIJI /1VE.! . '•• ~ ~y Station t : C~ ~~it'~ ~~O ~~ COOK AVE. • .~' q0 ~t> ' ~~L~ ` SCHEDt1LE A •s~FFr SCHEDULE B :~~ ~~`+ ' ~~ ,~t y,. ... ~~~Y • ~' w~ I~ . y ~ ~ Y ~y~ +'f~ Ze~•~r• ' •'~' .~.i + `y~QL , '~• . t: . ~ a , Alternative 2 Gravity and Pump Statian-Pressure i.ine Q INTERCEPT EXISTING SEWER; ~... GRAVITY SEWER ~ ..... PRESSURE LtNE ( L1 PUMP STATION ». ~~ ~ ~ .~~; ~~P r o aoo' aoo'- ~- Figure 2 . CEIVTRAI KENA! INTERCEPTOR Ai.TERNATlVES