Dam problem getting costly

When it rains, it pours.

The economy is souring and tax revenues are slumping, but the cost of infrastructure is soaring.

A planned dam touted as the solution to the region’s water-supply problems for the next 50 years will cost nearly twice its expected price, according to the engineering firm assigned to the job.

Another firm, solicited for a second opinion, agrees that the costs will higher than expected — but not as steeply higher.

Predictably, opponents of the dam took advantage of the news to argue that the plans should be abandoned altogether and that dredging, rather than raising an existing dam, be pursued.

Before any such decision — however remote the possibility — is even considered, the Rivanna Water and Sewer Authority must determine which of the two updated cost estimates is accurate.

To do that will require more money — to pay a panel of three experts to review the competing estimates.

The company currently in charge of the dam project says that costs will jump from $37 million to $70 million in order to deal with the fractured and weathered rock that’s been discovered at the site. The second company puts the costs of coping with the rock problem at around $56.5 million.

How much it will cost to pay the review panel is as yet unknown.

Meanwhile, a group that has always opposed the dam-building say cost increases reinforce their claim that dredging is the way to go.

Citizens for a Sustainable Water Supply Plan says that local officials overestimated the cost of dredging and underestimated the cost of damming to reach their preferred plan of expanding the Ragged Mountain Reservoir. The group says that dredging the South Fork Rivanna Reservoir is a better option.

Officials counter that they studied the various options for water supply (including piping water from the James River) for two years, and that the Ragged Mountain project is the best option.

If costs keep rising, might Ragged Mountain become too expensive even for its advocates?

We don’t know where that break point is. But creating a permanently enlarged water supply is overall a better option than repetitive dredging.

Dredging, if done, should be regarded as a maintenance cost. Its purpose would be to restore the capacity of the Rivanna Reservoir. But that reservoir is subject to rapid siltation, so dredging would have to occur with relative frequency. And frequent dredging also would be expensive. Frequent disruption of the aquatic habitat also would impose certain environmental costs.

Damming also exacts environmental costs. But Ragged Mountain is less susceptible to siltation and once the dam extension was completed, habitat could re-establish itself and remain in equilibrium for a longer period of time.

It’s not time to abandon the dam plan — not by a long shot.

But area residents better batten down the hatches and get ready for a fiscal battering. No matter what option is chosen, it’s likely to only get more expensive.