Pismo Beach, California - MacLean Dixie...Pismo Medical Center Synopsis • Subject Site Deemed as Potentially Liquefiable during a seismic event • Pile Options Included Rock Piles,

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Pismo Beach Medical BuildingPismo Beach Medical BuildingPismo Beach, California

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Proposed Site Located adjacent to numerous existing structures below and on hilltop

behind

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Proposed Site Located in Previous Marshland Area

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USGS Program Was Utilized to Establish Seismic Design Category of Site

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Site Once Occupied by a Marsh

Site Subject to jLiquefaction

OPTIONS:1. Stone Columns to 35 ft, to continue 15 ft beyond perimeter

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2. Driven Concrete or Steel Piles to 50 ft

3. 8” Diameter Helical Pile

Further Review of Cone Penetration Test (CPT) S di b (CPT) Soundings by Project Geotechnical

Engineers Determine that Stone Columns Should Extend to 45 ft

Li i P i l to Limit Potential Settlement to 2 in or less.

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Foundation Issues to Address

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Boring Logs Indicate Poorly Compacted Clayey Sand, Moist to Saturated in Upper 40 ft

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Competent Bearing Material Classified Material Classified as Dense, Clayey Sand Found at a Depth Below 42 ft.

Boring Terminated at 50 ftat 50 ft

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8” Helical Pile Considered Pending Review of Sieve Analysis

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Theoretical Ultimate Theoretical Ultimate Axial Geotechnical Pile Capacities Were Determined Based Upon Boring Logs Provided

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Estimated Total Installation Torque – Excluding Soil-Pipe Resistance Was Determined for

Installation Equipment Requirements

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Total Theoretical Pile Capacity Determined Using Both Helical Bearing Capacity and Pipe

Friction

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Pile Load Test Was Performed to Verify Theoretical Pile Capacity

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Results of Load Test Indicated That A Ultimate Capacity of 175 KIP Could Be Utilized For Final

Design

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Structural Foundation Plans were Finalized Based Upon Results of Field Load Test

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8” Helical Piles Embeded 8” Minimum into Pile Cap Connected by (4) #5 Dowels Embeded 48”

into Helical Pile at All Columns

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8” Pile Embeded 8” into Pile Cap Connected with (4) #9 Dowels Embeded 60” Minimum into

Helical Pile and 27” Minimum into Grade Beam

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8” Piles Were Delivered to Site Based Upon Revised Criteria Determined from Field Load Test

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One Additional Helical Plate was Added to Pile to Assist in Drawing Pile Down to Proper Depth Thru Extremely Soft Upper Soils

8” Helical Piles Were Installed Utilizing a 25K Pengo Head gMounted to a John Deere 120C Excavator

Soil Was Determined As Noncorrosive so Ungalvanized Piles gWere Utilized To Minimize Cost

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Internal Mandral Tool Utilized to Install the Male/Female Square Ended Piles

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Square Male/Female Connections on .188 Wall Thickness Pipe Allowed for High Installation Torques to be Utilized

Installation Logs Installation Logs were Maintained on All Piles Installed Reflecting Installation Torque in 1ft Increments and Final Pile Depthp

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DP1 Utilized to Monitor Differential Hydraulic Pressure

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Hydraulic Pressure Required to Install Test Pile Was Utilized on All Production Piles

Concrete Batch Plant P id d D i Provided a Design Mix to Eliminate the Necessity to Place the Grout With a Tremie

Further Minimizing Overall Pile CostsOverall Pile Costs

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A Freefall Grout Design Was Provided To Eliminate the Necessity of Tremie

Installation

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Rebar Was Installed Into Grouted Pile

U lUtilizing Centralizers

Engineer Increased Rebar Size as They were Bundled in

Units of 4

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Pile Grout Was Vibrated Lightly Once Steel had Been Installed

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Piles were Installed at Intersections of All Grade Beams and Center of All Columns

Project Completed Utilizing 64 - 8” Diameter Helical Displacement Piles

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Pismo Medical Center Synopsis

• Subject Site Deemed as Potentially Liquefiable during a seismic event• Pile Options Included Rock Piles, Driven Piles, or Helical Piles• Helical Piles were Chosen as Less expensive and Easier to Construct

During the Winter Months• Pile Load Tests Verified Theoretical Pile Capacities and Compression

and Tension• 67 8” Diameter Helical Piles were installed at the site• Deepest Pile at 53 feet with average pile depth of 48 feet across site• Average Pile Installation Time was 43 minutes per pile• All Piles were installed to 25 000 foot/pounds utilizing a Pengo 2 speed

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All Piles were installed to 25,000 foot/pounds utilizing a Pengo 2 speed head and DP1 Pressure Monitor mounted on a John Deere 120C 15 Ton Excavator

• Piles were installed during rainy season with minimal disturbance to site or loss of production

• Piles were Grouted Utilizing a Freefall Mix Design

Design/Construction Team

• Geotechnical Engineer – GeoSolution, Inc.• Structural Engineer – Allshouse Engineering Inc• Structural Engineer – Allshouse Engineering, Inc• Helical Pier Manufacturer – MacLean Dixie HFS• Helical Pier Distributor – Advanced Support

Technology, Inc.• Helical Pier Installation Contractor- J.R. Spencer

Construction• General Contractor – Inland Pacific Builders, Inc.

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