Cost over­runs, rains hit wa­ter­shed dam re­make

Times Colonist - - Front Page - BILL CLEV­ER­LEY

A $2.58-mil­lion Cap­i­tal Regional Dis­trict project to re­place a 115-year-old dam is fac­ing con­struc­tion cost over­runs, and its com­ple­tion is be­ing chal­lenged by re­cent heavy rains.

The dam re­place­ment project is on Lubbe Lake — one of three reser­voirs in the Gold­stream wa­ter­shed that serves as a backup wa­ter sup­ply for Greater Vic­to­ria.

The CRD started low­er­ing the lake level in June and work started in July to re­move and re­place the 45-me­tre earthen dam known as Lubbe Lake Dam No. 4.

But staff say that de­spite pre-de­sign and pre-con­struc­tion site investigation, once the old dam was re­moved “un­ex­pected ge­o­log­i­cal con­di­tions” were dis­cov­ered, in­clud­ing the pres­ence of a large rock knob with chan­nels on either side and un­du­lat­ing and highly frac­tured bedrock.

Those con­di­tions have ne­ces­si­tated sub­stan­tial ad­di­tional grout­ing and foun­da­tion work, push­ing the an­tic­i­pated project cost to $3.16 mil­lion — al­most 25 per cent over the orig­i­nal bud­get.

“The record draw­ings and record in­for­ma­tion from the orig­i­nal dam, given the orig­i­nal con­struc­tion date, ob­vi­ously was lim­ited,” said Ted Rob­bins, CRD se­nior man­ager of wa­ter ser­vices.

“We had to re­move the old dam and then un­der­take some re­vised de­sign work, which re­sulted in some ad­di­tional con­crete be­ing re­quired to form the base of the dam be­fore we started re­con­struct­ing the dam with clay,” he said.

“Given the need for that work, the sched­ule has been pushed and the ad­di­tional con­crete work, it’s go­ing to re­quire a bud­get in­crease.”

The orig­i­nal $2.58-mil­lion bud­get in­cludes a project con­tin­gency of $230,000, which will be eaten up to fin­ish the project. CRD staff are seek­ing an­other $581,000.

Ad­di­tional un­ex­pected con­struc­tion costs in­clude: $200,000 for foun­da­tion de­sign and con­struc­tion mon­i­tor­ing; $368,000 for foun­da­tion and abut­ment prepa­ra­tion; $440,000 for en­gi­neered con­crete foun­da­tion; and $170,000 for weather de­lays, says a re­port go­ing to the Regional Wa­ter Sup­ply Com­mis­sion on Wed­nes­day.

Re­place­ment of the dam was sup­posed to start in July, but be­cause of the ad­di­tional foun­da­tion work, that didn’t be­gin un­til De­cem­ber.

Mean­while, it has been a chal­lenge dur­ing the re­cent heavy rains to main­tain the lower wa­ter lev­els needed to do the work. Pumps have been work­ing over­time and be­cause there’s no nearby power source, the diesel needed to fuel them has been flow­ing as fast as the wa­ter they’re pump­ing away.

“Es­sen­tially, we’ve had to drain the lakes, Lubbe Lake and the reser­voir, to un­der­take the orig­i­nal dam de­com­mis­sion­ing and then the re­build. So in the win­ter­time here, we’ve had to main­tain a lower level in the lake be­low the foun­da­tion work, which has also been added to some of the costs,” Rob­bins said.

“With the rains we were hav­ing last week, we were running 24-7. As long as we’re not hav­ing the heavy pre­cip­i­ta­tion, we don’t need to run the pumps so it’s just on a day-by-day ba­sis,” he said.

Ac­cord­ing to the re­port go­ing to the com­mis­sion, pump­ing will likely be re­quired un­til the dam com­plete or rains sub­side.

All costs as­so­ci­ated with pump­ing are be­ing al­lo­cated to the 2018 and 2019 op­er­at­ing bud­gets, the re­port says.

The work was orig­i­nally to be com­pleted by the end of Septem­ber 2018. The hope now is that it can be fin­ished by late March.

As part of the backup sys­tem for Greater Vic­to­ria, the dam work poses no threat to this sum­mer’s drink­ing­wa­ter sup­ply.

How­ever, the Gold­stream sys­tem is used to as­sist the Gold­stream River fish­ery with wa­ter re­leases in the fall. Rob­bins said it’s too early to say how that could be af­fected.

“We do rely on it in the event of an emer­gency. We do also pro­vide some fish­ery re­leases for the Gold­stream River,” he said. “We are an­tic­i­pat­ing the Lubbe dam work to be com­plete hope­fully by March of this year and depend­ing how much rain we get be­tween March and the sum­mer, we’ll ac­cu­mu­late some stor­age there.”

The dam was built be­tween 1895 and 1903. Pre-de­sign, de­tailed de­sign and con­tract ad­min­is­tra­tion was done by Stan­tec Con­sult­ing Ltd. The con­tract for re­place­ment was awarded to Stone Pa­cific Con­tract­ing.

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