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ABALONE COVE LANDSLIDE ABATEMENT DISTRICT (ACLAD). Board of Directors Sharon Nolan Mary Sheridan Neil Siegel Emily Vaughan Robert Douglas, Chairman Mgr. Well Operations Daphne Clark Secretary Sandy Marshall. ABALONE LANDSLIDE ABATEMENT DISTRICT (ACLAD). - PowerPoint PPT Presentation
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ABALONE COVE LANDSLIDE
ABATEMENT DISTRICT(ACLAD)
Board of Directors Sharon Nolan Mary Sheridan Neil Siegel Emily Vaughan Robert Douglas, ChairmanMgr. Well Operations Daphne ClarkSecretary Sandy Marshall
• Geological Hazard Abatement (GHAD) District– created by the Beverly Act (SB1195) of l979;
ACLAD was the first district formed (1981)• Governed by a Board of Directors (5 persons)
elected from property owners in the District– Assisted by a Secretary and Manager of Well
Operations • ACLAD assesses property owners in the
district to pay for construction and maintenance of abatement measures– Example: Dewatering wells
• GHADs are a means by which homeowners can “help themselves”
ABALONE LANDSLIDE ABATEMENT DISTRICT
(ACLAD)
Abalone Cove Landslide
Altamira ShaleBasalt
SLIDE SURFACE (IMPERMEABLE LAYER)
Rain
GROUNDWATER BUILDUPS WITHIN LANDSLIDE
FRACTURES/FISSURES - CONDUITS FOR INFLITRATING WATER
RESULT:•INCREASE WEIGHT•INCREASE PORE PRESSURE•MOVEMENT
GROUNDWATER AND LANDSLIDES
?
Toe
Head
TRAPPED WATER
Wells added after l985
ACLADDewatering
Wells2006
1980 wells
WW6WW1WW14
WW12WW13
WW11WW8
WW16
WW15
WW17
Abalone CoveLandslide
WW18
WW19
WW9
WW20
WW5
WW2 WW4
WW7
WW10WW3
(Aver. daily production forFebruary and September)
Well Production 1980-2006Aver. Production approx.150,000 gals/day
First wells drilled
Upslope wells added
WW1
WW14
WW12
WW13
WW15
WW16
WW8
WW11
WW17
WW6
WW7
WW3
WW2
WW4WW
9
WW5
WW19
WW18
Abalone Cove Landslide >6,000 gal/day
1-6,000 gal/day
<1,000 gal/day
>20,000 gal/day
ACLADOriginal set of wells
1980-81
Abalone Covelandslide
WW2
WW3
WW5 REDRILL
Major Maintenance
Project
Proposed
Completed
WW1
WW6
Aver=15 in/yr
RAINFALL ANDWELL PRODUCTION
WELL PRODUCTION
RAINFALL
WET YEARS
DRY YEARS
RAINFALL THRESHOLD21-23 in/yr
RAINFALL AND MOVEMENT IN THEABALONE COVE LANDSLIDE
WET YEARS
DRY YEARS
CREEP (mm/yr rate)
ENSO cycles (5-8 yrs)
Highly Developed
Sparsely Developed
INCREASERAINFALL
WITH ELEVATION
40% increase
SUMMARY
• ACLAD Dewatering wells currently pumping ~ 200,000 gals/day; nearly 300 acre-feet water annually
• Since l980, water table elevations have dropped:– 25-60+ feet in Abalone Cove Landslide wells– 8-10 feet in upslope well
• Creep (mm/yr rate) in Abalone Cove Landslide occurs when rainfall totals >~22 inches/year
• Need to rehab older wells and drill new wells in upslope areas
(wet years)
ABALONE COVE LANDSLIDE ABATEMENT DISTRICT
(ACLAD)
1980-2006: TWENTY-SIX YEARS OF
PROGRESS AND SERVICE
• DEWATERING WELLS• GPS MEASUREMENTS
ACLADProduction
Wells2006
>6,000 gal/day
1-6,000 gal/day
<1,000 gal/day
WW1
WW14
WW12
WW13
WW15
WW16
WW8
WW11
WW17
WW6
WW7
WW3
WW2 WW4WW9
WW5WW19
WW18
Abalone Cove Landslide
>20,000 gal/day