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Home My WebLink About0282.093- ~. . , . . , -, '~' " , ;" May 6 1 1993 THE HONORABLE CIT~ COUNCIL Palo Alto~ CA Arastrad~rQ Creek Acc,ss Road ImprQV9ments Project -St~ Report Members ot the Co~ncil: Rgport ip Brief This is an informational report ~nd no council action is required. The purpose of this report is to respond to Council's request for s~Gii to review alternatives ot roao wi~~h and access methods to ~intain utility facilities. Background At the August 10, 1992 meetin9, Council continued the matter of repairing the Arastraderc Creek Access Road and directed staff to return with a b:"d for a dirt or gravel road no wider tnan the equipment that ~ould be needed. Prior to that action, council also requested staff to investigate other methods and equip:me.nt that could be adopted to gain access to the facilities that require maint~nance. There are three utility systems that follolll the road for its entire lenqth--an electric pole line, and water main and wastewater colleotion pipe. Aiso l a gas main follows the read from Arastra Lake to the Palo Alto Hills SUbdivision. Access to maintain and replace t. ...... ese facilities during t.he infrastructure programs are via this road. Minimal repair and maintenance has been required d1.lring the last ten years. This has been primarili~ due to the age of the systems and the good w~ather (lack of storms). Th~ electric pole line has reached the end o~ its useful life and inspections indicate the poles must be replaced now. The water and wastewater systems are t~enty-nine years old. The ~ater system to date has required some maintenance for leaks and cathodic p~otection. The main is reaching an age where increaoing amounts of maintenance can be expected. 'l'he wastewater collection system has required mo~e maintenance than the ~ater line. The wastewater main had two blockages in the laDt two years that caused sewage to flow from manholes onto the adjacent ground. The wastewater main has been crushed by tree root intrusion. This main is broken in two areas and needs to be repaired no~. CHR:2&2::'3 L - 1 - Mainta~ninq the fo~thills electric system requires a l~rge, e)(pens.l·...-e ($3000-$5000 per day) helicopter or a class 8 size vehicle (crane/auger/bucket truck{s) ,3-aAle. gross vehicle ~eight {GVW) 53,000 pounds, 29 feet long and 8.5 feet ~id~). The total length of a cl~ss S rnainten~nce vehicle approaches 90 feet ~hile pulling a trailer '!Jith 45-60 foot poles. The electric \.!tility requires this vehicle to maintain the foothill pole linoas. The foothills pols line is 28-30 years old. Tha poles range from 45 to 60 feet in heiqht and support electric conductor3 ~hich trans~it poyer at a voltage of 12,000 volts. A pole: survey in 1992 identified twenty-six out ot "fifty poles 'Which are d..;!teriorated and/or danqerou~. State Law, General Order 95, mar.dates that these poles be replaced. These old and deteriorated poles represent a fire hazard and a liability to the City. Helicopters are more dangerous, require schE"duling time, good weather, and are not an option for emergency access at all times ana weath€lr conditions~ Helicopters are ::langerou$ to use in hilly, windy tree-covered areas 'With live electric lines. Poles and equipment 'Would have to be lifted on long cables and would S'ilia:t from side to side while being transported. Usinq a helicopter to put a 12-18 inch diameter pole in an augured hele would put the workers on the ground in a high-risk position. City maintenance costs would increase, because of higher insurance premiums paid by contractors using a helicopter for this type ot ..... ork. Finally, statf believes that loud, overheaa helicopter noise would distress the wildlife in this ar£a to a muc.h gre.ater extent than ground construction it/crkers using a gravel access road. Walking in equipment to make repairs to these foothill utilities is not a practical solution for ul...ility ::>perations. The size and types of equiptTlent the City curre.ntly owns end h,as trained emplcyees to safely use to perform repairs can only be driven to the ~ork sites. The access road is not just for planned activities but, more i~portantly, !or q~ick emergency access to make unforeseen repairs. The Water Division requires a class 8 (3-axle, GVW 32,000 pour.ds, 24 feet long and 8.5 feet ... ide) size vehicle. The smallest required vehicle is a te!"!;-wheel dump truck. A backhoe is also required to dig and load at the. repair site~ The foothills concrete cylinder water main ranges from 14 inches to 18 inches in diameter and is installed at an average depth of 5 feet. Valves, pipe sections and fittings used in repa.iring concrete cyli.nder pipe of tr-.. is diameter are very t'.ea"''')t and need to be delivered to the wor-k site and 1 i f't.ea iI'.to place by a bacy,.hoe. Preparing a safe and properly shored repair pit for ¥ater, ~~stewatp-r and gas workers requires removing sufficient pipe cover and surrounding soft \Jet backfill to set shoring against £table trench walls. The material CJlR:282:U L ! ,~ I I I" ! , I i , I , I , - %'iaJnoved fTom these .... ork pits must be hauled. 3'Wa), from the sites. suitable ~ackfil1 materials must be importEd to the repair $ite~ W3.ste'Wi!ter requires a class 8 Hydro Flushing (J-axle, GVW 38,01J0 pounds plus water lorfeight I .2 9 feet long and So teet '-"ide) vehicle to cleer main blockages. The smallest vehicle r.equireti tor digging to ma~e main repairs is the same as required by the Water Division~ A backhoe is also mandatory for making wastewater main repairs. <:eneral1y, 'Waste\lo?ater mains are buried deeper tha.n 'Water lines (State Depa~ment of Health SerY"ices requirement), to avoid health related problems during repairs. The foothill vitrified clay wastewater collection li~e varies in size from 2-10 inches4 The depth of the ~astewater line in the foothills ranges from 5 feet to 15 fee~ at 35 ~anholes. The average depth is g feet. The gas utility r~quires a ten-~heel dump truck, service truck and a backtJoe to make gas main repairs. The size of the vehicles use~ to make qas main repairs is the samE as vehicles used by the Water Division. The foothill gas main is an 8 inch steel line buried to ~n average depth of 36 inches. The Fire Department has notified utility staff of their need for ten foot minimum width access along the proposed access road alignment. The Fire Department needs to provide access for the mcst basic class 2 large fcur .. h~el drive pickup siz.e vehicles t'or emergency fire response to utility lines~ Palo Al to Hills, 1..os Altos Hills, Pale Alto Country club and Hewlett Subdivision. Fire staff also requested the installation of fire hydrants on the existing water main, so that class 8 pumper enginos (2-axle, GVW 35,000 pounds, 27.5 feet long and 8.5 teet wide) may also respond to any futUre fires via thjs access road. Gravel/pirt/Width Acces~ ROJlQ Staff research found that rural gravel roads are generally designed to be 11 f.aet~ al thOl,lgh 10 foot or eve:-.. 9 foot lanes are-use-d. for gravel roads -vith low traffic voluu;.es and fev trucks. Common design p-cdcticE.. includes a minim'J.,m 'i.""ight shoulder 'Width of 2 feet for local roads, with an average daily traffic (ADT) volulIIe of fifty vehicles or less per day. staff also resea,rcned gravel road durability. The expected gravel loss per year fox gravel roads ranged from 0.18 inch for a lightly traveled. gravel road to 2.24 inches for a high traffic volume gravel ["oad. The gravel losses are due to weather influences, grade conditions and machinir.g, regardless of traffic volume. The City should expect to lose approximately an inch of gravel per year to 'Weather~ traffic and base soil conditions. The proposed 6 inch aggregate surface .. ill provide a safe surface~ An annual progra~ of maintenance grading and spot additions of aggregate on ClU<: 282: 93 . ~---'--' ---~." -L .. .. , ..... __ .J .. - ~~,~~ . '--.,:.-- " -. an as n!!eded basis can also be expected. Problems may occu!:" on tl:",e stepper sections 0-: the proposed access read and more maintenance may occur in thase areas. The s!ippel-ine.ss of unpaved roads in both .... et and dry states is important fro!!: the safety aspect. especially in dO*7mill curves ~here skidding and sliding are dangerous. A gravel Eourface 'Will reduce slipperiness and maintenance of the utility a=cess road. staft recommends a gravel road to feet wide. foot width is consistent with accepted lo~ ADT road desig:n~ using a minirr.um a foot lane width shoulder. Discussion ~he recommended 10 yolume rural gravel with a 2 foot right The cost of constr~ctinq the proposed gravel access road at a 10 foot minimum width will be approximately $150,000. The incraased cost, as compared to last year 1 s bid prices l are for additional surveyir'9 and removal of additional vegetation grovth from within the proposed project ali1nment. Staff believes that a 10 foot wide gravel road is the minimum safe access road that can b':! recommended. The saf"ety of the City employees driving 8 foot 'Wide vehicles in the worst weather conditions llIust be considered when determining tha ndn1rnum safe vidth and surface type fer an access road. Staff ~i11 return to Council ~ith a mitigated negative declaration and a project bid to consider in June 1993. ie ct~tted. er CWiak E i.7;::;t' WGW Ed~a~· J. Mrlzek I\ie~im D~r o~ Utilities F emil! - . ty Manaq1i~ Related CMRS; 246~, 31B:91~ 373:.92 CKR:282:U r~ I