nmwdoc 2014 conference flood control dams on basalt foundations – two case studies dan aguirre, pe...

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NMWDOC 2014 Conference Flood Control Dams on Basalt Foundations – Two Case Studies Dan Aguirre, PE - Wilson & Company Craig Hoover, PE - Bohannan Huston Inc. May 7, 2014

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NMWDOC2014 Conference

Flood Control Dams on Basalt Foundations – Two

Case Studies

Dan Aguirre, PE - Wilson & CompanyCraig Hoover, PE - Bohannan Huston Inc.

May 7, 2014

Contents/Agenda

▲Las Ventanas Dam – Craig Hoover▲Boca Negra Dam – Dan Aguirre

Las Ventanas Dam

Las Ventanas Dam

Las Ventanas Dam

Las Ventanas Dam

Las Ventanas Dam

▲Site Geology– West mesa formed by up faulted blocks– Followed by sedimentation– Followed by volcanic eruptions– Olivine basalt flows characterize the site– Basalt is exposed at the surface in many places– Covered with up to 12’ of sand in other areas

Las Ventanas Dam

▲Site Geology/Field Investigation– GeoTest Inc.– Core drilling indicated the depth of basalt was

typically 30 feet thick– At least one core found the basalt to be more

than 50 feet thick– Material beneath the basalt – calcareously

cemented sand and gravel of the Santa Fe Formation

Las Ventanas Dam

▲Site Geology– Basalt – gray to black to black-red– Vesicular to varying degrees– Areas where highly vesicular the vesicles

(cavities) were large and appear interconnected– Singular joints and fractured zones were

observed in the basalt cores

Las Ventanas Dam

▲Site Geology– Joints either bare or coated with carbonate

deposits– Fracture zones 1 to 2 feet thick– During coring water was lost in most corings-

attributed to interconnected vesicles– Air found blowing from one boring after

completion of drilling and varied with the atmospheric wind indicating fractures connected to the surface

Las Ventanas Dam

▲Foundation for a Dam? – Highly variable surface and depth to rock– Highly vesicular areas– Apparent high permeability– Water lost during coring indicating

interconnectedness of vesicles– Fractures connected to the surface

Las Ventanas Dam

▲Foundation Treatment and Cutoff

Las Ventanas Dam

▲Foundation Treatment and Cutoff

Las Ventanas Dam

▲Foundation Treatment and Cutoff

Las Ventanas Dam

▲Foundation Treatment and Cutoff

Las Ventanas Dam

▲Cutoff Trench and Cement Treated Slurry

Las Ventanas Dam

▲Cutoff Trench and Cement Treated Slurry– Flowable mixture of Portland cement,

aggregates, admixtures (water reducing and air entrainment) and water

– 28 day compressive strength 500 psi to 1,000 psi

– Placed to full depth of trench

Las Ventanas Dam

▲Foundation Treatment Cement Treated Soil

Las Ventanas Dam

▲Foundation Treatment Cement Treated Soil– Scarify soil to full depth– Dampen soil– Add cement per mix design– Mix and add water to optimum moisture content

minus 1% to plus 2%– Compact to 96% maximum density

Las Ventanas Dam

▲Foundation Treatment Cement Treated Soil

QUESTIONS?