ER 1110-2- 1807DRILLING IN EARTH EMBANKMENT DAMS AND LEVEES

Jeff Schaefer, Phd, P.E., P.G. Lead Civil EngineerUSACE Risk Management Center8 December 2020

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Prevent damage to embankments and their foundations from: • Hydraulic fracturing• Erosion• Filter/drain contamination• Heave or other mechanisms

During activities like: • Drilling operations• Sampling• in-situ testing• Grouting• instrumentation installation• borehole completion• borehole abandonment.

PURPOSE

3APPLICABILITY

Any drilling or investigation into or near a structure with Federal Interest including Dams, Locks, and Levees (Includes those in PL84-99)

If the investigation is being instituted by an outside group it requires a 408 Permit

Section 408 – Authorized in Section 14 of the Rivers and Harbors Appropriations Act of 1899 (33 USC 408): Provides that the Secretary of the Army may, on recommendation of the Chief of Engineers, grant permission for the alteration of a public work as long as that alteration is not injurious to the public interest and will not impair the usefulness of the work.

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BACKGROUND

The use of water, drilling mud, compressed air, and various drilling fluids have resulted fracturing of the embankments or foundations as evidenced by loss of circulation, connections to other borings, and blowouts on embankment slopes.

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BACKGROUND

Conversely there are cases where heave, borehole collapse and significant disturbance have occurred. while drilling in granular materials below the groundwater level.

Caused by not using a proper drilling fluid to balance the water pressures in the soil or using high energy systems that induce heave in order to evacuate the cuttings.

Delicate balance between too much induced fluid pressure that will cause hydraulic fracture and not enough fluid pressure that will result in borehole instability, heave, or significant sample disturbance.

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INCIDENTS ON USACE DAMS

East Branch Dam – Grout loss during PZ installation in Impervious section. -Complete water loss during drilling in impervious section.

Whittier Narrows- Complete water loss during drilling in impervious section. Littleville Dam- Water loss and pz communication during drilling.Abique Dam- Drill fluid loss when drilling in core. Hartwell Dam- Drill fluid loss and rod drops when drilling next to conduitThomaston Dam- Drill fluid loss and rod drops when drilling next to conduitAddicks and Barker Dams- Grout leaks and hydrofracture of embankment around conduit groutingWolf Creek Dam – Grout leaks through work platform, crest crackingCenter Hill Dam- Grout leaks and work platform deformation.Patoka Saddle Dam- Grout hydrofractures found embankmentKentucky Lock- Grout hydrofractures found in embankment.Red Rock Dam- Grout hydrofracture during remedial grouting. Mosul Dam – Numerous hydrofracture signatures in grout data. Tappan Dam- Initiated internal erosion when drilling through a confining layer at the toe of the dam

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INCIDENTSSherard, J.L., “Embankment Dam Cracking,” Embankment Dam Engineering, S. Poulos and R. Hirschfeld, Eds., John Wiley and Sons, New York, N.Y., 1973,pp. 272-353.

Wister Dam (Oklahoma) - Crest Cracks from groutingEl Isiro Dam (Venezuela)- Core Cracked from Foundation Rock GroutingShek Pik Dam (Hong Kong)- Numerous borings experienced fluid loss during the drilling. Graminha Dam (Brazil)- Complete Drill Fluid loss during PZ installations. Djatiluhur Dam (Indonesia)- In borings drilled from the crest to evaluate the integrity of the core sudden water loss occurred in almost all the borings. Matahina Dam (New Zealand) – Excavation of embankment revealed grout fractures. Yards Creek Upper Reservoir Dam (New Jersey) –A large number of borings were drilled through the core and in nearly all of these water was lost in the lower half of the core. Garrison Dam (Missouri River) – Holes were drilled through the partially constructed embankment or the purpose of grouting the underlying foundation. A high percentage of the holes exhibited a major loss of drill water within the embankment. Lovewell Dam (Nebraska)- 26 borings lost drill fluid in impervious embankment.La Villita Dam (Mexico)- A boring accomplished with rotary drilling with heavy bentonite abruptly lost fluid at 40 ft. At the same time an instrument 100 ft away along the crest reacted to the fluid loss. Livingston Dam (Texas)- Water losses during drilling for PZ installation experienced in more than half the borings. Hartford Dam (Georgia)- A boring was made through the crest over an abutment where the dam was approximately 100 ft tall. All the drill water was lost at a depth of 20 ft and then continuously between 20 and 55 ft.Ilha Soteira Dam (Brazil)- A boring was drilled to install a piezometer into the clay embankment. At a depth of 11 meters water loss occurred.

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INCIDENTSIndependent panel to review cause of Teton Dam failure, 1976, Failure of Teton Dam: Report to the U.S. Department of Interior and State of Idaho.

Field hydraulic fracturing tests were performed in the remaining embankment section. The following excerpt from the report clearly shows the issues with improper drilling techniques inducing damage to an embankment dam.

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GROUT LEAKS

WOLF CREEK DAM

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GROUT LEAKS

Addicks Dam Grout Leaks

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HYDRAULIC FRACTURE

Barker Dam TX

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KENTUCKY LOCK

HYDRAULIC FRACTURE

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Mayersville Setback Levee

HYDRAULIC FRACTURE

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LOCATIONS WITH HIGHER RISK OF HYDRAULIC FRACTURE

Areas in the embankment or foundation where arching of the soil stresses can occur are more susceptible to hydraulic fracturing.

• Near and over steep abutments• Near abutments where abrupt changes in slopes occur. • Adjacent to rock overhangs • Adjacent to buried structures or abrupt foundation geometry change

that create a differential settlement condition• Adjacent to conduits• Narrow zones of soil backfill were placed between the structure and

rock face. • Thin cores that have experienced more settlement than the adjacent

shells. • Dams in very narrow valleys. • In areas where the embankment is subject to differential settlement

perpendicular to the axis due to large changes in thickness of compressible foundation or embankment soils.

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EROSION

Introduction of drilling fluids into existing cracks under high pressure can potentially cause erosion and widening of the crack walls

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FILTER/DRAIN CONTAMINATION

The use of drilling mud, grout, or bentonite backfill materials can clog filters or drainage features.

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HEAVE AND SAMPLE DISTURBANCE

• Failure to prevent stress relief (especially below the groundwater table) can cause heave or severe sample disturbance.

• Invalid test results• Invalid interpretation of subsurface conditions

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POLICY• Drilling Program Plan• Restrictions on the use of Drilling Fluids• Drilling Procedures• Borehole Completion• Drilling Personnel• Approval Requirements• Reporting• Exemptions

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DRILLING PROGRAM PLAN CONTENTS

• Objective and Justification• Exploration Team• Existing Information Review• Essential Geologic and

Engineering Drawings• Drilling Scope and Methodology• Risk Evaluation• DSO/LSO Certification

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DRILLING PROGRAM PLAN (DETAILS IN APPENDIX B)

Objective and Justification• Clear summary of the objective.• What is the purpose of the testing, sampling,

instrumentation, etc• Minimize invasive drilling.• Purpose should be based obtaining information

related to potential failure modes. • If an approved PFMA or risk assessment has not

been performed, the exploration team must perform a thorough evaluation similar to the PFMA process.

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DRILLING PROGRAM PLAN Exploration TeamList members of the exploration team• Name• Organization• Title• Registration• Years of Experience

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DRILLING PROGRAM PLAN Existing Information ReviewCompile, review and summarized all relevant information.• Geologic mapping, boring logs, driller’s notes, and reports portraying information from previous

investigations and construction.• Geotechnical files and reports including Site Characterization Reports • Foundation Completion Reports • Embankment Construction Reports• Periodic Inspection or Periodic Assessment Reports• As-built drawings• Archived records • Other construction reports• Construction photos for both original embankment construction and any subsequent construction• Instrumentation plans, data, and reports• Project records available in district and project offices.

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DRILLING PROGRAM PLAN Essential Geologic and Engineering DrawingsPlan, profile and section.• Embankment zones, including added berms, blankets, filters, and drains.• Details of subsurface material classification.• Geologic contacts and continuity interpretations supported by all nearby drilling

and sampling details.• Depth of the top of rock and all other zones of importance.• Piezometer locations showing screened influence zones and recorded

piezometric levels tied to the reservoir water level.• Other instrumentation such as inclinometers, movement monuments, etc.,

shown in the context of the foundation geology contacts and interpretations.• SPT blow counts or other test results defining engineering properties.• Geophysical data, where useful (e.g. cross hole shear wave velocity profiles).• Estimated extent of any zones of interest, including natural and made-made

(grout holes)• Seepage areas tied to geologic units, where possible.• Location of all structures, including seepage control features, outlet works, etc.• Location and types of any distress features (seepage, wet spots, sand boils,

sinkholes, etc.)

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DRILLING PROGRAM PLAN Drilling Scope and Methodology• Number and location of proposed borings.• Utilities, surface and underground obstacles, and

accessibility.• Materials to be drilled, sampled, and tested.• Depth, diameter, and inclination of borings required.• Required sample type (disturbed or undisturbed), size,

location, and reason for sampling.• Proposed laboratory testing.• Drilling, sampling, and testing methods.• Details of the proposed tools and drilling equipment. • Instrumentation and borehole completion requirements

(influence zone, seals, etc.).Drill rig operators: Name and years of experience.

• Field Supervision Personnel: Name, organization, title, registrations, years of experience

• Personnel responsible for logging materials and assuring geologic drawings are updated regularly during the drilling program.

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DRILLING PROGRAM PLAN Risk Evaluation• A detailed description of any drilling fluid used including details

on the circulation system, locations where fluid will contact soil, and circulation pressures that will be used.

• Monitoring needs during drilling, and a contingency plan if loss of drilling fluid or other complications are observed during drilling.

• Measures to minimize the risk of damage to the dam or foundation.

• Measures to prevent the possibility of cross-contamination and leakage from confined and separate ground water aquifers.

• Measures to prevent drill contact with structural features, such as conduits.

• Nearby instruments whose behavior will be monitored during the investigation and the expected response including threshold and limit values, and contingency plans for unexpected response.

• An emergency action plan including a list of emergency equipment and supplies to have onsite (phone/radio, filter materials, grout materials, etc.).

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DRILLING PROGRAM PLANDSO/LSO CertificationProvide a certification page with signature of the appropriate DSO/LSO

The certification must state:

This Drilling Program Plan has been developed and reviewed by experienced professionals and is in compliance with all the requirements of ER 1110-1-1807. The proposed actions are justified and have been developed to minimize the likelihood of damage to the existing structure.

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RESTRICTION ON USE OF DRILLING FLUIDS• Drilling programs in Dams and Levees should be designed to

minimize the need for any pressurized drilling fluid such as air, gas, water, mud, polymers, slurries or any other drilling fluid.

• If drilling fluids must be used DPP shall contain an analysis of the potential to cause damage (hydraulic fracture analysis) and a plan that covers the measures that will be used to minimize the risk.

• All Drilling Program Plans that propose the use of stabilizing or circulating fluids or other media will require additional review and approval as described in paragraph 6f.

• Pressurized air or foam is not permitted.

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DRILLING PROCEDURESGeneral procedures that should be followed when using drilling fluids to limit the risk of damage.

• Tools should be sized and designed to minimize the likelihood of the return flow clogging.

• Fluid discharges from the bit should always be upward• Lower and raise drill tools slowly to avoid pressure changes in the drill hole• Drilling feed rate must be slow enough to avoid crowding the bit• Drilling media properties, pressure, and return should be continuously monitored. • In some conditions, casing can be advanced ahead of the drilling bit to reduce the

risk of hydraulic fracturing by confining the drilling fluids within the casing.• When core drilling rock, the embankment or foundation soil above top of rock must

be protected and isolated from the circulating drilling fluid. Fractures in the bedrock must be considered as potential flow paths in contact with the overlying soil.

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DRILLING PROCEDURESGeneral procedures that should be followed when using drilling fluids to limit the risk of damage.

In situations where the presence of significant artesian pressure is suspected:– it may be necessary to use weighted drilling muds or raise the drill rig or install surface casing for pressure control along with

the use of drilling mud. – In some cases there may be a high risk of initiating internal erosion by drilling borings or excavating test pits in these areas. – Emergency materials to stop progressive erosion in an excavation, a trench, or a borehole must be on site and readily

available.

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BOREHOLE COMPLETION

• All boreholes and other penetrations shall be sealed after completion

• Backfilling with drill cuttings is not acceptable

• Penetrations in the impervious zones shall be backfilled by tremie placed cement-bentonite grout or bentonite pellets

• Penetrations in the pervious zones shall be backfilled by tremie placed filter and drainage compatible materials

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DRILLING PERSONNEL• Drill rig operators must have a minimum of 5 years

experience drilling with the equipment and procedures described in the drilling program.

• The drill rig operator must be familiar with these guidelines.

• All drilling activities on USACE dams or levees must be conducted in the presence of a geotechnical engineer that is a licensed professional engineer or a licensed professional geologist who will be responsible for maintaining the integrity of the structure

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APPROVAL REQUIREMENTS• Drilling Program Plans must be reviewed and approved by the District

Dam Safety Officer (Dams) or Levee Safety Officer (Levees).

• If any drilling fluid or other stabilizing or circulating media is proposed, a technical review performed by the Geotechnical and Materials Community of Practice (G&M CoP) Standing Committee on Drilling and Instrumentation is required.

• The Standing Committee on Drilling and Instrumentation will be chaired by the GG&M CoP Lead, co-chaired and managed by the Risk Management Center, and staffed with GG&M CoP experts from USACE Districts across the country.

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REPORTINGAll incidents of damage or potential damage related to drilling and associated activities for dams must be reported following procedures outlined in Chapter 13 Reporting Evidence of Distress in Civil Works Structures of ER 1110-2-1156 Safety of Dams- Policy and Procedures.Damage in levees must be reported to the Levee Safety Officers and

Levee Safety Program Managers in the District, MSC, and Headquarters.

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EXEMPTIONS• Drilling required for immediate emergency measures where delays required to

develop the DPP and obtain approvals would result in unacceptable risk of damage or failure, may be exempted from the requirements to prepare a DPP by the District DSO/LSO.

• Emergency drilling should be appropriately expedited but should follow the general guidelines presented in this regulation.

• No other exemptions or deviations from these requirements may be made.

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PROCESS FOR LEVEE SPONSORS• Levee Sponsor reviews and approves plan for alteration that requires drilling. • Levee Sponsor requires designer of alteration and drilling company to develop Drilling

Program Plan (DPP).• Levee Sponsor approves DPP and forwards to LRL along with Section 408 request to alter the

Levee. • LRL POC for submitting DPP and 408 is Bonnie Jennings who can be contacted at (502) 315-

6481 or Bonnie.F.Jennings@usace.army.mil.• LRL Levee Safety Section will review the Section 408 request and the DPP.• Levee Sponsor must address comments and resubmit to LRL. • For DPP’s that require the use of drilling fluids, the DPP will be sent to the Risk Management

Center for review by members USACE drilling experts. • Once comments have be addressed, the District Levee Safety Officer (John Bock) will

approve the DPP. • When the drilling is done in the field, LRL will send personnel to observe the drilling to assure

it is in compliance with the DPP and ER-1807.

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WHERE TO FIND REGULATIONpublications.usace.army.mil

https://www.publications.usace.army.mil/Portals/76/Publications/EngineerRegulations/ER_1110-1-1807.pdf?ver=VGIgFqev2TzKMpcPmIxneA%3d%3d

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QUESTIONS ??