HomeMy WebLinkAbout; Trenchless Technology Aptos Transmission Line; Trenchless Technology Aptos Transmission Line Project; 2008-09-02Frac-Out Contingency Plan for Horizontal Directional Drilling for
the Aptos Transmission Line Project
Aptos, Santa Cruz County, Califomia
Prepared for:
Harris and Associates
EDAW AECOM
Prepared for:
Harris and Associates
120 Mason Circle
Concord, CA 94520
(925) 827-4900
Prepared by:
EDAW
2099 Mt. Diablo Blvd., Suite 204
Walnut Creek, CA 94596
(925) 279-0580
September 2, 2008
Frac-Out Contingency Plan for Horizontal
Directional Drilling for the Aptos
Transmission Line Project, Santa Cruz
County, CA
The information provided in this document is intended solely for the use and benefit of
Harris & Associates^ Inc.
No other person or entity shall be entitled to rely on the services^ opinions,
recommendations, plans or specifications provided herein, without the express written
consent of EDAW, 2099 Mt Diablo Blvd., Suite 204, Walnut Creek, CA 94596.
O D
TABLE OF CONTENTS
1.0 INTRODUCTION AND PROJECT DESCRIPTION 1
1.1 OVERVIEW AND PURPOSE 1
1.2 PROJECT DESCRIPTION 1
1.3 SITE DESCRIPTION AND EXISTING CONDITIONS 5
2.0 HDD TECHNIQUE 5
2.1 PILOT HOLE INSTALLATION PROCESS • 6
2.2 REAMING AND SWABBING PROCESSES 6
2.3 FULLBACK PROCESS 6
3.0 POTENTIAL MODES OF HDD FAILURE 7
3.1 FRAC-OUT DURING HDD OPERATIONS 7
3.2 OTHER MODES OF FAILURE DURING PILOT HOLE INSTALLATION PROCESS 7
3.3 OTHER MODES OF FAILURE DURING REAMING AND SWABBING PROCESSES 7
3.4 OTHER MODES OF FAILURE DURING FULLBACK PROCESS 7
4.0 HDD FAILURE PREVENTION AND MITIGATION 7
4.1 MITIGATION DURING PILOT HOLE INSTALLATION PROCESS 9
4.2 MITIGATION DURING REAMING AND SWABBING PROCESSES 9
4.3 MITIGATION DURING FULLBACK PROCESS • 10
5.0 FRAC-OUT FAILURE AND MITIGATION 10
5.1 FRAC-OUT PREVENTION 10
5.7.7 Design
5.1.2 Construction -
5.2 MONITORING FOR FRAC-OUTS 10
5.2.1 Pump Pressure
5.2.2 Circulation Rate
5.2.3 Ground Surface Inspection ^ ^
5.2.4 Surface Water Inspection
5.2.5 Special Safety Considerations
5.3 RESPONSE TO A FRAC-OUT 11
5.4 UNCONTROLLABLE FRAC-OUTS 13
6.0 HDD FAILURE AND ABANDONMENT CRITERIA , 13
7.0 REFERENCES 14
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LIST OF FIGURES
Figure 1. Project Location •, ^
Figure 2. Segments to be Installed Using HDD 4
Figure 3. Frac-out Prevention and Mitigation • 8
LIST OF TABLES
Table 1. Prevention and Mitigation for HDD Failure 9
Table 2. Frac-out Response Equipment •. 11
Table 3. Frac-out Notations 1^
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1.0 INTRODUCTION AND PROJECT DESCRIPTION
1.1 Overview and Purpose
The Santa Cruz County Sanitation District (District) Aptos Transmission Line delivers
sewer flows from several gravity subsystems to the East Cliff Pump Station. Since its
construction in 1979, the Aptos Transmission Line has experienced structural failures in
multiple segments. To alleviate problems caused by the structural failures, approximately
3.5 miles of sewer lines are scheduled by the District to be replaced along with
improvements to existing pump stations, replacement of two existing pump stations, and
construction of two new pump stations. Existing sewer lines that are circumvented will
either be removed or abandoned, and an existing pump station and associated restroom
facility, will be demolished. The project will be completed in two phases. While much of
the project will use the open trench method of pipe laying, one segment will be installed
using the jack and bore method, and two segments of the line will be installed using
Horizontal Directional Drilling (HDD).
HDD operations have a potential to release drilling fluids into the surface environment
through fractured bedrock, into surrounding soils and eventually to the surface, referred to
as frac-outs. Drilling fluids consist mainly of a bentonite clay-water mixture, and are not
classified as toxic or hazardous substances, however it can potentially have an adverse
impact on species and habitat if released into sensitive environments such as creeks,
wetlands, or other waterways. This Frac-Out Contingency Flan (FCP), has been prepared
in compliance with the permitting requirements laid out by the Califomia Department of
Fish and Game (DFG) and National Marine Fisheries Service (NMFS), and establishes
operational procedures and responsibilities for prevention, containment, and clean-up of
frac-outs associated with the proposed HDD segments of the Aptos Transmission Line
Project, Santa Cmz County, Califomia. All personnel responsible for the work must adhere
to this plan during the directional drilling process. The objectives of this plan are to
minimize the potential for frac-outs, provide timely detection, response and notification in
the case of frac-out occurrence, and avoid impacts to environmentally sensitive resources.
1.2 Project Description
The Aptos Transmission Line extends from the Rio Del Mar Pump Station in the
southeastern portion of the District, to the East Cliff Pump Station in the northwest, with a
series of pumping stations placed along the alignment, and follows roadways and skirts
beach areas (Figure 1). The project area includes an existing 24-inch force main, running
from Rio Esplanade (Aptos Esplanade) Pump Station westward to the town of Capitola.
Phase one of the project will consist of the constmction of a new 20-inch force main, a
new 18-inch force main, new pump stations at Tannery Gulch and Potbelly Beach, and
new facilities at New Brighton Beach State Park, including two pump stations and two
force mains. The 20-inch force main will start on Park Avenue and connect into the pre-
existing system that continues into Capitola. This main will be approximately 12,350 linear
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feet and will be installed in an open trench. The 18-inch force main will be installed
simultaneously in a shared trench with the 20-inch force main, and will be approximately
10,340 linear feet in length. At New Brighton Beach State Park, a stretch of 4-inch force
main will be installed from the campground to the day-use parking area using HDD.
Phase two of the project will consist of the constmction of a new 18-inch and 20-inch force
main, an 18-inch slip-lined force main, conversion of an existing pump station to a
manhole, installation of a new pump station, and improvements to an existing pump
station. The 18-inch and 20-inch mains, and a 3-inch electrical conduit, will be installed
beneath Aptos Creek using HDD. The two mains may be installed at the same HDD
crossing location if feasible.
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Figure 1. Project Location
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Figure 2. Segments to be Installed Using HDD
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1.3 Site Description and Existing Conditions
The Aptos Transmission Line Project site is located within the Tannery Gulch, Borregas Creek,
and Aptos Creek watersheds, and has topography varying fi*om gentle to steep slopes ranging in
elevation between sea level and 160 feet above sea level. The landscape is comprised of coastal
strand, coastal bluff, steep drainages, and graded residential subdivisions. Two separate segments
of the project site will be constmcted using HDD; the New Brighton Beach State Park during
Phase I, and Aptos Creek during Phase II. Soils located within the areas constmcted using HDD
consist primarily of Tierra-Watsonville complex 15 to 30 percent slopes (USDA 2007) at the
New Brighton Beach State Park, and Elder sandy loam 0 to 9 percent slopes, with, some Beaches
and Elkhom sandy loam 2 to 9 percent slopes at Aptos Creek.
Within the two portions of the project area that will involve the HDD, several vegetation types
are present, including Central Coast riparian scmb community, northern coastal bluff scmb, and
eucalyptus woodlands. Aptos Creek is a concrete-lined channel, with a sandy bottom within the
HDD project area, and lacks riparian or aquatic vegetation, backwater, pool, cobble, or riffle
habitat immediately upstream. Special-status plants are not expected to occur within the study
area (EDAW 2008). Special-status wildlife species that have a potential to occur within the
project boundaries include the monarch butterfly {Danaus plexippus), Califomia brackishwater
snail (Tryonia imitator). Tidewater goby (Eucyclogobius newberryi). Central Califomia Coast
ESU steelhead {Oncorhynchus mykiss irideus), western pond turtle (Actinemys (^Clemmys)
marmorata), nesting birds, and roosting bats. Several avoidance measures are being employed to
protect these species during constmction including pre-constmction surveys for special-status
species, and the mitigation and monitoring measures outlined in this FCP as part of the
permitting requirements laid out by CDFG and NMFS.
2.0 HDD TECHNIQUE
HDD is a method of pipeline installation which limits surface disturbance to the pipeline right of
way (ROW) to the entrance and exit points of the HDD. Because the extent of direct disturbance
is limited, this method is preferable to the traditional open trench method in areas .where the
disturbance to the ROW would be particularly problematic, including areas that contain sensitive
biological resources such as creeks, wetlands, or habitat for special-status plants and animals, or
areas where open trenches would be prohibitively disturbing or destmctive to existing
infrastmcture.
The process of installing a pipeline using HDD involves several pieces of specialized equipment:
a drill rig fitted with connectable drill-stems usually measuring in 20-foot lengths and a mud
shaker or mixing tank. The mud shaker prepares and recycles the drilling mud, or drilling fluid,
which is made up primarily of a combination of water and bentonite, a non-toxic clay derived
from the alteration of volcanic ash. The drilling fluid acts to lubricate the drill, coat the borehole,
and carry cuttings back to the surface.
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Installation of a pipeline using HDD consists of three distinct processes, or steps; installation of
the pilot hole; incremental reaming of the pilot hole followed by swabbing the borehole; and pipe
pullback. Each of these steps is discussed in detail below.
2.1 Pilot Hole Installation Process
The first step to installation of a pipeline using HDD is the drilling of a pilot hole. The pilot hole
is drilled along a predetermined alignment, with entry and exit points that have been determined
using traditional survey methods. The drill head is usually tracked using an electronic system
that includes a package contained within the pilot drill string near the cutting head, which can be
monitored using an above ground hand held detector. One system that is often used is the Tensor
Tm-Tracker®. As the head of the drill is tracked, adjustments can be made to the drill pathway.
The drill rig and shaker will be set up and an entry pit measuring approximately 10 feet square
will be dug for the entry point. This pit will allow for circulation of drilling mud and cuttings to
flow from the borehole to the shaker for recycling into the drill stem. The pilot hole, usually a 9-
7/8-inch diameter bore, is installed below the proposed crossing, using a rotary cutting head,
lubricated with drilling fluid which is pumped into the pilot hole via the annulus of the drill stem.
This fluid also acts to suspend and carry the drilled cuttings to the surface and forms a cmst on
the walls of the borehole, providing additional stability and integrity. The installation of the pilot
hole is closely monitored for information regarding the penetration rate and confirmation of
geotechnical strata, so that the reaming and swabbing process can be fine-timed.
2.2 Reaming and Swabbing Processes
Reaming of the pilot hole begins at the exit point where a reamer head is attached to the end of
the drill stem. The drill stem is then pulled back through the pilot hole from the exit point
towards the entry point. The reaming tip enlarges the hole as it passes through. This is often done
several times with incrementally larger reamers being passed back and forth through the
borehole.
Following the reaming process the borehole is swabbed to clean out the remaining soil cuttings
and prepare the borehole for the pipe. When reaming and swabbing is complete, the swab is
removed from the drill stem at the exit hole, so that the pipe may be attached to it.
2.3 Pullback Process
Once the borehole is at the desired diameter to accommodate the pipe, a reinforced pullhead is
attached to the end of the pipe, and the pipe is pulled into the borehole using the drilling rig. The
pipe is usually filled with enough water to compensate for the potential of the pipe floating in the
drilling fluid.
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3.0 POTENTIAL MODES OF HDD FAILURE
3.1 Frac-out During HDD Operations
A frac-out, hydraulic fracturing of the geologic substrate resulting in a release of drilling fluid,
can occur when there is pressurization of the drill hole beyond the containment capabilities of the
soil material. Loss of drilling fluid can also occur via fissures in the ground that allow drilling
fluid to easily seep, or escape, outside of the confines of the borehole. Frac-outs are most likely
to occur as the drill head passes. This can be indicated by a drop in the pressure of the drilling
fluids or a decrease in fluid and cutting retums at the entry point. This drop in pressure can be
observed prior to the actual release of drilling fluid at the surface, and if acfion is immediately
taken, the frac-out can be prevented.
3.2 Other Modes of Failure During Pilot Hole Installation Process
Several factors can influence failure of the pilot hole installafion process. Improperiy maintained
equipment can lead to mechanical failure. Loss of borehole integrity can cause the walls of the
borehole to collapse onto the drill stem, resulting in increased friction and potentially leading to
mechanical failure. The drill head may diverge from its intended path due to interference with
the tracking equipment caused by magnetic interference or an inability to properly place the
surface tracking equipment.
3.3 Other Modes of Failure During Reaming and Swabbing Processes
During reaming and swabbing failure can be caused by a loss of integrity of the borehole,
resulting in collapse. During the reaming process, injection of large volumes of drilling fluid can
result in unintended caverns being carved out, leading to instability of the borehole walls. Should
collapse occur, friction on the drill stem could increase to the point of mechanical failure.
3.4 Other Modes of Failure during Pullback Process
During the pullback process failure could occur if the pipe does not successfully pull through the
hole due to insufficient space in the bore hole, high friction, or wall failure.
4.0 HDD FAILURE PREVENTION AND MITIGATION
Methods for preventing or mitigating for failure, prior to complete HDD failure are discussed
below, and ouflined in the following flow chart (Figure 3).
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Figure 3. Frac-out Prevention and Mitigation
Begin HDD
Monitor drilling
Fluid Circulation
and Drill Pathway
Monitor drilling
Fluid Circulation
and Drill Pathway
Data Taken:
- Drilling Fluid Pressure
- Cutting Returns
- FracHDut on Land
- Turbidity Plume/
Frac-out in Water
Drop in Fluid
Pressure?
Or
Drop in
Circulation of
Ruid and
Cuttings Return?
Make \
Adjustments \
to Drilling /
Fluids /
Make
Adjustments
to Drilling
Fluids
Frac-out \
stopped? y
Yes
Biological
Monitor says
drilling can
resume?
No
Make
Requested
Changes
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Table 1. Prevention and Mitigation for HDD Failure
Pilot Hole Installation Reaming and Swabbing Pipe Pullback
• Geological testing: • Monitor pump • Ensure drilling rig
soil samples will be pressure to has adequate power
taken and a frac-out maintain circulation to pull weight of
potential of drilling fluid and pipe and drill stem.
determined. cuttings.
• Drilling fluid and • In case of wall • Maintain neutral
cutting circulations collapse, remove buoyancy of pipe
will be monitored. reamer and re-during pullback.
• Deviations will be attach drill bit to re-• Deviations will be drill hole.
immediately
drill hole.
corrected via
pullback and re-
direction of drill
bit.
4.1 Mitigation During Pilot Hole Installation Process
Prior to implementation of the HDD pilot hole installation, several steps can be taken to prevent
failure. Soil samples will be taken along the crossing path to identify any geological weaknesses
that may exist subsurface. The information gleaned from these samples will be used in planning
the specifics of the HDD. Commercially available HDD design software can bc used to model
the potential for frac-out given the geology, anticipated borehole diameter and drilling fluid
consistency.
Characteristics of the drilling fluid and cuttings will be monitored for signs of circulation failure.
or inadequate caking on the borehole walls. If a loss of circulation is identified, the HDD
operator can make adjustments lo the fluid consistency or drilling rate lo facilitate caking and
maintain adequate lubricafion on the drill stem. Additionally, the HDD operator can partially pull
back in the borehole, to ream out the pilot hole and flush collected cuttings before they create a
barrier in the borehole.
Should the pilot hole deviate from the intended pathway, the HDD operator can pull back and
correct the deviation. If the deviafion is significant, the abandoned section of the pilot hole can
be grouted with bentonite, and the path can bc redrilled.
4.2 Mitigation During Reaming and Swabbing Processes
As the HDD operator reams the bore hole, the pump pressure can be adjusted to maximize the
opportunity for cuttings to circulate while maintaining the integrity of the borehole walls. Should
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the borehole suffer a wall collapse, the HDD operator can remove the reamer and re-attach the
drill bit head to re-drill the hole.
4.3 Mitigation During Pullback Process
Ensure that the drilling rig used for pull back has sufficient power to pull the weight of the drill
stem and the pipeline through the borehole. It is also critical that the HDD operator knows the
density of the drilling fluids, weight of the pipe, and the volume of water needed to maintain
neutral buoyancy.
5.0 FRAC-OUT FAILURE AND MITIGATION
Procedures for preventing, monitoring and responding to frac-outs are outlined in the following
sections.
5.1 Frac-out Prevention
5.1.1 Design
As part of a preventative approach to frac-outs when conducting HDD operations, several steps
are recommended. First, geotechnical invesfigations will be undertaken to be used in planning
the flnal bore route and specific equipment to be used. Secondly, the bore will be planned for a
depth that is likely to discourage potential frac-outs from occurring based upon the soils present
along the path of the bore.
5.1.2 Constmction
During the drilling activities, the contractor will have a full-time on-site mud engineer that can
monitor the drilling fluid circulation and retums, and make adjustments to the driUing fluid
properties as needed. Based upon the recommendafions of the drilling mud engineer, a pace for
drill advancement will be set to ensure sufflcient time for cutting and fluid circulation without
unnecessary threat of plugging. Should plugging occur, the rate of advance will be appropriately
increased, decreased, stopped or reversed unfil the plug has been cleared. Drilling pressure will
be kept at the minimum level necessary to maintain circulafion, and if circulafion decreases,
adjustments to fluid properties, drill head advancement rate and reaming diameter will be
attempted before drilling pressure is increased.
5.2 Monitoring for Frac-outs
HDD operafions will be monitored for the occurrence of frac-outs using the following methods.
5.2.1 Pump Pressure
Pump pressure will be monitored by the on-site mud engineer and recorded into a field data log
prior to each joint connection. Any changes or fluctuafions in the pressure will be invesfigated
immediately as they may be indicative of a frac-out.
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5.2.2 Circulation Rate
The on-site mud engineer will confinuously monitor the flow rate of the drilling fluid circulafion
and volume of retums and record the data prior to each joint connecfion or following a change in
retum rate. If the pumping rate differs from the retum rate, a frac-out may have occurred.
5.2.3 Ground Surface Inspecfion
An approved monitor will visually inspect the path of the HDD during drilling operations for
indications of a frac-out. When the path of the HDD crossed beneath upland habitat, the monitor
will follow the drill head as closely as possible, watching for escape of any drilling mud to the
surface.
5.2.4 Surface Water Inspection
An approved monitor will visually inspect the path of the HDD during drilling operations for
indications of a frac-out. When the path of the HDD crosses beneath Aptos Creek, the monitor
will watch for a turbidity plume.
5.2.5 Special Safety Considerafions
HDD activities that could result in frac-out will only be conducted during day-time hours so as to
maximize the potential that any frac-out that may occur is identified and appropriately responded
to in a timely manner. A detailed Health and Safety Plan outlining specific hazards and needed
personal protective equipment will be prepared and made available to all on-site personnel.
5.3 Response to a Frac-out
Prior to the onset of constmction, it is important that all necessary response equipment be located
on site, in an accessible location for quick deployment. The response equipment will include all
of the items listed in the frac-out response chart (Table 2).
Table 2. Frac-out Response Equipment
Straw or hay bales, sandbags,
straw wattles
Shovels
Stakes for securing bales Silt fence
Vacuum-tmck Light towers (for clean-up after
dark if needed)
Water sampling equipment Soils sampling equipment
Boat and appropriate PPE (for
frac-out into Aptos Creek)
Pre-arranged approved drilling
fluid disposal site
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When a drop on drilling pressure, or other frac-out indicator, is idenfified, the following steps
will be taken in a timely manner:
1) Forward progress of the drill will be immediately suspended, however the HDD equipment
will continue to mn to prevent the borehole integrity from being compromised and resulting
in collapse.
2) The area will be immediately surveyed for any sign of a frac-out.
3) If a frac-out is idenfified, it will be immediately contained.
4) If the frac-out occurred in flowing water, the biological monitor will monitor the extent of the
drilling fluid plume and watch for signs of distressed or dying fish.
5) Turbidity monitoring will occur both upstream and downstream from any plume associated
with file inadvertent release of drilling fluid, following federal, state and local guidelines.
Samples will be taken immediately after the frac-out, and at 1 and 2 hours post release.
6) If the frac-out occurs in the upland, the frac-out will be contained by creafing a berm or
barrier aroimd the release to prevent it from spreading.
7) Nofificafions, as oufline below, will occur and the impacts, if any, to sensitive resources or
special-status species will be identified.
8) The frac-out will be thoroughly documented.
9) Once the frac-out has been contained and the on-site biological monitor has given the
approval to resume forward drilling, adjustments to the drilling fluid, or rate will be made,
and drilling will resume in a conservative manner, with special attention paid to any
addifional escape of drilling fluid or new frac-out locations.
10) Should the frac-out resiune, additional adjustments will be made until the frac-out is no
longer occurring.
11) The spilled drilling fluid wiU be immediately cleaned up via shovels or a vacuum tmck and
disposed of at a pre-determined location.
12) No drilling fluid will be left on the ground.
13) Following the complefion of HDD activifies, a summary report detailing any frac-outs that
occurred, events leading up to the occurrences, measures taken, impacts from the release,
mitigation for the release, and agency contacts.
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Table 3. Frac-out Notations
In the event of a frac-out the following contact persons will be nofified immediately.
Agency Contact Person Phone Number Permit Number
Biological Consultant
Coimty of Santa Cruz
CDFG
RWQCB
NMFS-NOAA
USFWS
5.4 Uncontrollable Frac-outs
In the event that a frac-out occurs and is not controllable, or containable due to volume or rate,
HDD activities will immediately cease, and depending upon the stage of the drilling at the time
of the frac-out, the HDD operator can either plug the hole near the fracture with a heavyweight
non-toxic material, or back out of the borehole, cap it and start over on a new hole. To plug the
fissure, pump non-toxic sealers into the drill hole, let set for an appropriate amount of time
depending upon the sealer selected, and then resume HDD activities in a conservative manner. If
the fissure or fracture cannot be plugged, back the drill out, and fill the original hole with
bentonite and cuttings under low pressure so as to not create additional releases, then resume
HDD acfivifies in a conservative manner. If the original drill path cannot be reused, plug the
original borehole with bentonite and cuttings under low pressure so as to not create additional
releases, sealing the top 5 feet with grout. Plan a new altemative location, and once approved by
all involved parties, move forward with HDD operations in new location. If HDD attempts fail,
then crossing will need to be constmcted using an altemative method.
6.0 HDD FAILURE AND ABANDONMENT CRITERIA
HDD installation wiU be considered a failure if there are two unsuccessful attempts during pilot
hole drilling, one unsuccessful attempt during reaming, or one unsuccessful attempt during
pullback.
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7.0 REFERENCES
Califomia Department of Fish and Game. 1995. Fish Species of Special Concern in Califorma,
Tidewater Goby, http://www.dfg.ca.gov/habcon/info/fish ssc.pdf
Califomia Department of Fish and Game (CDFG). 2008. Califorma Natural Diversity Data Base
(CNDDB). Database Query for the Soquel and surrounding l-Vi minute Quads. June 29, 2008
update.
EDAW. 2008. Biological Resources Assessment for the Aptos Transmission Main
Relocation Project, Aptos, Santa Cruz County, California. August.
Hagar Environmental Science. 2003. Aptos Creek Fisheries Habitat Assessment. Technical
Memorandum prepared for the Coastal Watershed Council. 60pp. March 3.
Nafional Oceanographic and Atmospheric Administration (NOAA). 2005. Federal Register:
Endangered and Threatened Species; Designation of Critical Habitat for Seven
Evolutionarily Significant Units of Pacific Salmon and Steelhead in California; Final Rule.
Part II. 50 CFR. Part 226. Vol. 70. No. 170: pp. 52488-52626. September 2, 2005.
http://www.nwr.noaa.gov/Publicafions/FR-Nofices/2005/upload/70FR52488.pdf
Storer, Tracy I. 1930. Notes on the Range and Life-History of the Pacific Fresh-Water Turtle,
Clemmys marmorata. University of Califomia Pubiicafions in Zoology. 32(5): pp 429-441.
Sycamore Associates. 2003. Biological Assessment and Preliminary Jurisdictional
Determination for the Aptos Transmission Main Relocation, Santa Cruz County, California.
July.
U.S. Department of Agriculture (USDA). 2008. Web Soil Survey. Nafional Resources
Conservation Service (NRCS). http://websoilsurvev.nrcs.usda.gov/app/WebSoilSurvev.aspx
U.S. Fish and Wildlife Service (USFWS). 2008. Endangered and Threatened Wildlife and
Plants; Revised Designation of Critical Habitat for the Tidewater Goby (Eucyclogobius
mewberryi;,- Final Rule. 50 CFR Part 17. Vol. 73(21): 5919-6006. January 31, 2008.
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EDA W-Frac-Out Contingency Plan for the Horizontal Direction Drilling for the Aptos Transmission Line Project C:\Documents and \ 4
Settings\BobS\Local Settings\Temporary Internet Files\OLKI 77\frac out aptos 08I9081.doc