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TECHNOLOGY Tuesday 27 June 2017

Engineers use replica to pinpoint California dam repairs

By BRADY McCOMBS the velocity of the water,
Associated Press track how much air is be-
Eds: Clarifies the replica is ing absorbed in the water
of the spillway; links video; and document what they
updates summary. With AP see in weekly reports to
Photos. AP Video. California authorities.
LOGAN, Utah (AP) — Inside To help with the design, the
a cavernous northern Utah separate team investigat-
warehouse, hydraulic en- ing the spillway failure sent
gineers send water rushing California water officials
down a replica of a sec- and Utah hydrologists a list
tion of a dam built out of of factors they’ve found
wood, concrete and steel that could have contrib-
— trying to pinpoint what uted to the failure — many
repairs will work best at the focusing on the condition
tallest dam in the U.S. for of the spillway’s concrete,
a spillway torn apart dur- slab joints and foundation.
ing heavy winter rains that But no one factor has been
triggered the evacuation discovered yet to deter-
of 200,000 people living mine how the failure hap-
downstream. pened, said John France,
The sound of rushing water a dam engineering consul-
is deafening as Utah State In this Friday, June 16, 2017, photo, hydraulic engineering professor Michael Johnson looks at tant leading the California
University hydraulics engi- the water flow on a replica of the Oroville Dam spillway at Utah State University’s Water Research investigation.
neering professor Michael Laboratory, in Logan, Utah. Dam experts say one of
Johnson kneels in front of a Associated Press the most unsettling aspects
replica of an Oroville Dam going down the spillway tion process,” Craddock foot (30-meter) long rep- of the events is that it oc-
spillway the size of a small would ease pressure on said. “Water behaves very lica that took 40 days to curred without warning
house to examine one of the spillway, the Utah test- similar at a smaller scale as build begins when a crew after decades of mainte-
two channels that run the ing has determined that a larger scale.” member slowly opens a nance and inspection re-
width of the spillway to al- an adjustment to a curve Physical models to test large steering wheel like ports showing no clues of
low air into the water to about halfway down the proposed dams and dam valve that sends water the pending collapse.
prevent bubble formations spillway would only slightly repairs are necessary be- screaming down a chute California state officials
that can damage the con- improve its effectiveness. cause “the flow of water modeled after the spillway have pointed to the tor-
crete spillway of the real The idea was to make the is very complex and mo- and crashing into blocks rents of runoff pouring into
dam. curve more gradual near mentum is transferred at that disperse it and send it the dam at the time of
The new channels, called a steep part of the spillway the molecular level,” John- in waves to a replica of the the crisis. But the amount
aerators, are one of the where it caved in and left son said. “We haven’t got river. Johnson almost has to of water streaming down
key features in the pro- a gaping hole the size of enough computer power shout for his team to hear the two flood-release spill-
posed $300 million spillway a football field in the con- to model that many mol- him above the noise of the ways when they began
reconstruction set to be crete chute. ecules at once,” he said. water mimicking a flood. to collapse was relatively
completed by November Though computer model- Each simulation of the 100- The hydrologists calculate small.q
— when winter rains and ing is being used exten-
snow will once again in- sively to plan the spillway Avis teams up with Waymo
crease the flow of water repairs, California officials
into the lake above the and the hydrologists say
dam. high tech testing is no re- on self-driving car program
While a separate team of placement for dam replica
dam experts tries to solve research. Johnson’s team
the mystery of why the spill- has a $277,000 contract for PARSIPPANY, N.J. (AP) — provide fleet support and at its locations. Waymo,
way crumbled last Febru- the work and will issue its fi- Avis is teaming up with maintenance services for owned by Google parent
ary, the hydrologists who nal report in the early fall. Waymo on a self-driving Waymo’s program at its company Alphabet Inc.,
built the replica are using it Water flow patterns, pool- car program. The partner- Avis and Budget car rental will continue to own and
to guide California authori- ing and waves can be ship aims to support Way- locations. Under the multi- run its self-driving cars and
ties on how they should different than computer mo’s fleet and its early year deal, Waymo’s cars will continue with its exist-
build a new spillway so models predict, said Ted rider program, which has will receive automotive ing partnerships.
that it can withstand rush- Craddock of California’s a public trial in Phoenix. services such as cleanings Shares of Avis Budget
ing waters. Department of Water Re- Avis Budget Group Inc. and oil changes from Avis jumped more than 9 per-
Besides confirming that the sources. said Monday that it will and be allowed to park cent in morning trading.q
channels to aerate water “This is an important valida-