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HomeMy WebLinkAbout0214.095TO: ATTENTION: FROM: DATE.: SUBJECT: BEOUEST ". --:;. . _. "-_.-, .. -. ". @ 2 City of Palo Alto City Manager's Report HONORABLE CITY COUNCIL Policy aad Servku Com mitt •• CITY MANAGER April 19. 1995 DEPARTME! .. '1": p"blic Work> CMR:114:9S Approval or CODs.lba' Scope of Work for Arastrade .... C ..... k EMoa Improvement Project, CIp" 7708 aDd App..,'''' Dr Coasoltaat Scope "fWork!or Arastradero Lake Dam ODd Spillway. CIp 19111 This report requests tlUI1 the Polky and ~ Committee approve the attached proposed scopes ofwurl< fOr the Arastradero Creek Erosioo Improvement and Arastradero IAe Dam and Spillway Improv=ent projects. RECOMMENDATIONS Staffrecommends that the Policy and Services Committee: J. Approve tbl: atIlICbed proposed ~ of work for tho AIastradero Cteek Eros;"" Improvement Project, CIP 477il8. 2. App<<JVe \he attached scope of wort for the Arastradero IAe Dam and Spillway Project. C1l'19102. POI.ICY IMPLICATIONS Awoval of Ibis ~oda1ioo is c<JIl5istelll with the Hazard Reduction Program of the Seismic Safety subsection and the P ..... and Environmental Resource sections of the existing Comprehensive Plan. EXECUTIVE ~l!MMARY 00 1uiy 19. 1994. the Polky and Services Comminee requested thai staff submit the scope <>f work foe the Arastradero Creek Erosion Improveme:!l Pr<>ject for r",iew and approval Staff is also including. revised Dam and Spillway Improvement Project scope of work for revi<:w. because Ibis project is interrelated and has similar envirorunental issues as the creek. Staff inletlds 10 modi!) an existing agreement with Geomatrix C<>nSultants. Inc, to ~>te Ibe revised scope of work fOr the dam and spillway and to enter into I sepanrte agreement w;tIt Ge..'<I1alrix COOsultants. Inc 1 which wool<l include the new scope of work foe the creek. Pagel 01) '.:'1> .. "-.", :-. ,.- ~. -. - :-',' -" .. , "- .'.~ ... -' o Oeomatri" Consultanls, Inc., was previously chosen woogh the coosultanl selection process for !he dam and !las ably a.<;sisted staff in identiJ)ing !he envirorunenW i."""",. Retaining their oerviccs will provide for bO!h efficie~ and c<>ntinuily duri.~g the design phase. A!. a result, staffhas not prepared a draft r"'l"est for proposal. but iru;tead has developed draft scopes <>f wed: 10 be include<l in agreemcnts with Geomatrix Coosulta.'1ts, In.:. Staff held four meetings over the last year with coo<:erned members 0( the community, enviroomentali31s aud the Planning Department 10 obtain input 00 bO!h pr(}je<:l.. Based on coounenls zeceived from the community, staff developed a "'--ope for the Creek Elosion lmprovement Project and Dam aM Spillway Project, as indicated in Atta<:bments A and B. Following is a summary o(the majo< is""" d"lSCUSSed in L'Ie community meetingS that ore addIessc<Iin the scope< of wed:; Creek ErosXm Improvement Project t perform • bydrologi<: study 10 analyze rainfall runoff causing =k erosion lltllizing riparian habitat restoraOOll and bio!ecJu,Jcal bank S1Ji!>ilization exper-.ise t evaluate replacing existing culvert1l with pedestrianlbiC}cle bridges 10 red"". futon erosion potential t improve se1ec1ed paths adjacent 10 the creel: 10 ~ er03ion and moo during winter months t consider usc ofweirs as an erosion and fJQw cootrol regulator t provide res!ocative landscaping within riparian habitat t protect existing utility easemeDl • atJ1ize expertise in riparian habitat resklration and biOlechotical bonk stabili,.lltioo. Ieclmiq .... 10 assure that impacts 011 the natural riparian habitat are adC<jualely assessed Dam And Spillwll!mproyemgpl Proiect t maintain sigt'.ificant oak trees on downstream embankment althe dam • provide • spillway wlticb is cwvilinear and con.<;Iruc"'oed 0( gabions • maintain riparian habitat on upstrellDl embanl.:ment of \he dam t provide rest",ati\'e lands<;oping consistenl .. ith Ibe creek rip&ian habitat • replace every removed Ire'! v.i!h three new trees t prevent f.Jttber erosion from undermlnlng utilities adjacent 10 spillway t provide for lUlQual safety inspections of the dam'. dov.llS!ream embanl<mem t grade dam downstream embanlunalt 10 blend •• turaDy into \he existing hillside t u1>1I2. expenise in riparian habitat re>toratioo and biOledmkal bank stabilization techniques lo assure Iha: impacts 011 the natura! riparian habitat are adequately "",esse<!. Staff proposes 10 coocurrentJy JlCOC<S' 00th peGject. through \he Site and Design Review. final deslgo. and coostructioo pIlases. This W1l1lnclude completing an environmental assessment before contract coostructioo is undertaken. It will pro>ide the opporturiity for • more .-----.~---;"---. -"; , comprebensivc ovC1"iew by the community and in<:rea.<e the potential for more competitive COIlSIructioo bid< c!'JC 10 I larger volume of .. ark. After Ihe scopes for bct.h projects are approved by Ihe Policy and Services Committee, ,1aff will mum 1<> Council for approval of. new agreement "itll Geomalrix Coosultanl<, Inc, for Ihe c-I< Project and !he ~ agreement Mth Geomatrix C.oosultants, Inc. for Ihe Dam and Spillway Project • fISCAl, IMPACI Fuods for bo(h projects are included in the Aram-adero Lruce Dam CIF 19102, CoIiection Sy:;Iem Improvemenls CIP 47102 and the Arastradero Creek Erosion Repairs CIP 47708. UiURQNMEI'UAL ASSESSMENT AI! environmental ossessmeaI will be perfOl'llled as part of Ihese projects befure or during Ihe design of the proje<o!s and before the actual construction of L."provemellts. AlTACRMENTS A -Arastradero en:et t.rosion Improvements, CIP 41108, Scope ofWodi; B· Arastradera ld.Dam and Spillway Project. CIF 19102, Scope of Work PRFJ'ARED BY, George Bagdon. Assistant Director of Public Wo<ks' DEPARTMENIHEADREVlEW: g~ ~ ____ _ GLENN S. ROBERTS DirecI<Jr of Public Works CITYM.t,NAGERAI'PROYAL: .. ~ 1\\.~Aw _____ _ BERNARDM.~;yt ce: Lynn all.pen. Ellen Christia.'lSeD Linda Elkind CMR:ZI':lIS Assistant City Manager \ • " _' .'.-'c-; ":' ',':::' ,,' • _r :-' SllMlllAll'l'- AlI.ASTRADERO CREEK EROSION IMPROVEMENTS CIP 417il8, SCOPE OF WORK -_ .... Remove existing a:Jvens and replace with pcdeslri.nlbi<.ycle bridges :0 reduce IU!ure ~ion poIeQtiaI wherever bydrau!ically possible. Ocsiga two bridgcs 1)< culven trail <ro!Sing. 10 suSIain fire access vehicle loading. Ropm erosion in culvert site areas and 90 IkgrtC creek be'" using biolecllnical bank SIabilization 1eCbniques. If bydrauLUJ1, ina~. tbeJl use gabion, ~ mattress II:<:hniqI>;:s bIe1>.1ina Ihom into Illc natunl env'.romnent. CoIWder using 110 ... COO!roI fea!ures. SlY'..l! as weirs. between trail crossing ,itos 10 prevent floodiIlr ami c .... te wetland areall. ImpCove Illc trail between sne. I and 2 to prevens saturation during Illc Wltcr mooIhs. ~ <:reck riparian habitlt using MIlve vegetatioo ~ing in toofonnance with !be draft vi&ion stlltemem developed by Parks and Opea Space staff. Rmin sigrrificarl oak and/or 0Iber I!<eS within tbe riparian CO<ridoc and pIarJt three new trees Jar every cree removed. S'bedu!e wnotruction Jar late summer 10 avoid nesting birds (betweeD July and October 1996)_ . • lJtilize cxpcrlise in' riparian habitat restoration and biofeclmlcal bon!< stabilization Iechniques in developing Illc bydrological analysis and designing !be e_ repair ooIotions. TASK PHASING: Prepare ltydrologlcal ..,.lysis and preliminaly desip. Asoess possible adverse impacts H and downsueam 0( site areas. Prepare an enviroomen<al as..<eSSlDO!II and Site and Design R<:view pacbge. Utilize expertise in riparian habitat reoIOration and biot«:hnicaJ bank stabilization Icclmiques 10 _ !bat impacts on tb< oarural riparian habitat are adequately ass<ssed. Prepare finaJ design (plans, specifications and constructioo cost _te). Provide comttuction monitoring and leS!iog. '.,:',\:'_:: 'I~" ','/", . ">,,~ i, "'in .,,: ',' ,- , . ,: ":::F1~",!b~,t;~'i~~0,*~l}!",.~(~ '. i' ~'.--ii·.(.: " .... ~ .. , \'! ·s_ ;.j.",~ ';:-~t;.~-~:~i'I~~l.<);l ,.< ,~. ." , ,', ' . .' '\ , " " " , " ... , . " .... ), , , ! .~ :'~~!i~~ " " SITE'3 ... 'FORMER BRESSLER......., + PROPERTY , + ± ' + ARASTRADERO \nn-iE=t~ St-l(r.T :J ", 20 FEET PU\BLlC :ft~.:=-:rr::::-:::-;' + UTILITY ,;ASEMENT+ , , ,', I ' ;'; ., o 1.-__ .... '"'. '",CT • + t ·s,,. ~ N I I , .:t.. lO ARASTRADERO LAKE DAM .:t.. ' ARASTRADEROCREEK ," " " .. .'.', ",,".- ., ,,' ,. , 'I. '.. ~J-' ",-: " ,'\ . " , , "..-:~./ .. • 1 • • • • .' SUMMARY ARASTRADERO LAKE DA.'f AND SPILLWAY, CIP 19102 REVISED SCOPE OF WORK '­ ; Clear ~irablc growth on downstream 5lope 0{ clam 10 allow Fx annual safety mooltoring inspectioos. Fill gullies and boics created by erosion "lid tree removal. CoIlIour doWDSlream dam slope 10 blend nacuranJ into existing hillside. Investigate !he need " possible construc:tioo 0{ a d.<IDlage trench on the downstreom slope 0{ !he dam in areas experiencing seepage. Modify dam spillWliY 10 be curved. widened, cleepelled and lined with gabioos and reno mattress rock filled wire Nskets. Inoorporate ballIes or CO!rreIeIgabion featun:s in critic2! mas if nocessary to adequately =modale stonn flo .... and preveot further erosion from undermlnin& ad"JacenI utilities. • InstaIl I "",ion or concreteJgabion features at Ill< bose of Ill< spillway to prevent <reel: boUom erosion. • PIa<e Ioproil on dQwnstream slopes of <lam and apply hydrooeed!ttS!Ontive land"'.ping to the dam. spillWlY and ali areas impacted by COI!SUUction to mainWn riparian habita:. • Retam significaDI oak and/or oIher IreeS on dQ",1IS!ream slope and pIaDI: three new IreeS for every 1m: removed. ScIIedule amstruction to .void adjaceDt wildlife nestiDe (betweeD July and 0cI0ber 1996). TASK PHASING, Prepare deWIed preliminary design. • Prepare I revised env'.romneotaI .sses"¥« and Site and DesigR Re1i jew package. Utilize expertise in riporian habital restonlion and b~1micaI bonk stabilization IeClmiques 10 assure Ihal impacts on !be natural riparian habitat are adequately ass<ssed. Prepare fin&] desiga, (plAns, specifi<:>tions and construcIioo cost estimate). • Provide CODSIru<tion monitoring and testing. , I I I I I ~ © w w ex: u \ ------ ~ ..... , 0/">­ LV ~ /2 ~." ..... 0 0.. -I .... « o = a: 0 a: Q.. 0 a: 0.. CI) .. -" """ -- " .. .;.: -~7' ".