Rocky prob­lem causes ‘speed bump’ for dam

Nelson Mail - - Front Page - Cherie Sivi­gnon cherie.sivi­[email protected]

Rock may be im­ported for part of the em­bank­ment of the Waimea Com­mu­nity Dam, which is un­der con­struc­tion in the Lee Val­ley, near Wake­field.

Un­der the orig­i­nal plan, ex­ca­vated rock from the build site was to be used for the rock fill dam, a $104.4 mil­lion project be­ing man­aged by Waimea Wa­ter Ltd.

How­ever, Waimea Wa­ter chief ex­ec­u­tive Mike Scott said some of that rock was caus­ing con­cern.

The con­cern re­lated to ‘‘the be­hav­iour of the rock in the drainage zones’’, which in­cluded the up­stream face and the bot­tom of the em­bank­ment, he said.

Much of the rock had met ex­pec­ta­tions, but ‘‘other ar­eas where rock is to be used in the em­bank­ment be­came a con­cern’’ af­ter ini­tial test­ing in Jan­uary. Fur­ther test­ing and tri­alling was un­der way.

‘‘It was a sur­prise,’’ Scott said. ‘‘I’m not feel­ing par­tic­u­larly stressed. It feels like a speed bump rather than we’ve hit the wall.’’

The is­sue was ‘‘fairly solv­able’’, he said, and the dam’s de­sign and con­struc­tion would be ad­justed to suit.

Scott agreed that the com­pany might have to buy some rock, but said it was too early to say whether this would be the case and, if so, what ef­fect it could have on the over­all cost of the project.

‘‘This is re­ally fresh. We’ve got to do the lab anal­y­sis and test­ing first.’’

Waimea Wa­ter Ltd is re­spon­si­ble for manag­ing the con­struc­tion, op­er­a­tion and main­te­nance of the dam. It is a joint-ven­ture part­ner­ship be­tween the Tas­man District Council and Waimea Ir­ri­ga­tors Ltd. The ge­ol­ogy at the site has long been tagged as one of the ma­jor risks for the project.

Scott’s com­ments come af­ter Waimea Wa­ter chair­man David Wright spoke to Tas­man District coun­cil­lors via video con­fer­ence on Thurs­day dur­ing an open council meet­ing.

Wright con­firmed that bedrock had been found at the site.

‘‘It has re­quired a bit more ex­ca­va­tion than what we might have wished. How­ever, we have found bedrock,’’ Wright said. ‘‘We can an­chor the dam, so there are no is­sues around that as­pect going for­ward.’’

He also said there had been ‘‘some is­sues’’ with the type of rock fill needed for the em­bank­ment. The team was work­ing through the op­tions, which could in­clude im­port­ing some rock.

More de­tail would be pro­vided for a full council meet­ing, sched­uled for late March.

‘‘We will be brief­ing share­hold­ers on that cer­tainly by the 26 March council meet­ing or ear­lier, if known,’’ Wright said.

Coun­cil­lor Anne Tur­ley said she found it em­bar­rass­ing to be asked at com­mu­nity as­so­ci­a­tion meet­ings about difficulti­es at the dam site and to not know about them.

‘‘I would ask that if there are is­sues, that we do get . . . early dis­clo­sure rather than hear­ing it in the com­mu­nity,’’ Tur­ley said. ‘‘It’s not a good look.’’

Wright said it was fair comment, and spoke about a ‘‘trade­off’’ be­tween hav­ing time to make a de­ci­sion and brief­ing the share­hold­ers.

‘‘We have got to be able to come to a con­sid­ered po­si­tion be­fore we’re able to come to you and other share­hold­ers with a view on what that might mean to tim­ing/cost to com­plete,’’ he said. ‘‘We’re do­ing that as ex­pe­di­tiously as we can, but we are equally aware what that does is po­ten­tially al­low for spec­u­la­tion in the com­mu­nity.’’


Waimea Wa­ter chief ex­ec­u­tive Mike Scott says an is­sue with some of the rock to be used for the em­bank­ment of the Waimea Com­mu­nity Dam is ‘‘fairly solv­able’’.

An artist’s im­pres­sion of how the fin­ished dam will look. The con­cerns about the rock re­late to the drainage zones, which in­clude the up­stream face and the bot­tom of the em­bank­ment.

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