Sinkholes: Plan of Action-1983

BOILING SPRING LAKES, N.C.
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A Coastal Area Demonstration Project by:
PLANNING & DESIGNASSOCIATES, P.A.
3515 Glenwood Avenue Raleigh, North Carolina 27612 Telephone[phone]

TABLE OF CONTENTS
Page #
CHAPTER I PURPOSE, OVERVIEW, AND SUMMARY 1
CHAPTER Ti A REVIEW OF THE PROBLEtK 5
CHAPTER III SCENARIO DEVELOPMENT 16
CHAPTER IV ALTERNATIVE COURSES OF ACTION AND RESPECTIVE COSTS AND
BENEFITS 22
CHAPTER V RECOMMENDED COURSES OF ACTION 29
CHAPTER VI DMIONSTRATION VALUE FOR OTHER COASTAL COMMUNITIES 36
APPENDIX
A.
VICINITY MAP
44
B.
BOILING SPRING LASES MAP
45
C.
BIBLIOGRAPHY
48
D.
U.S. ABtlY SINKHOLE STUDY
50
E.
IMPERVIOUS LAB EXHIBITS
55
F.
SELECTION ANALYSIS EXHIBITS
58

a
City of Boiling Spring Lakes
NORTH CAROLINA
20461
BOARD OF COMMISSIONERS
Alfred R. Toney, Mayor
Richard W. Buckbee
Florence B. Anderson
Thurston Cumbee
James J. Jeffries
MAYOR'S COMMITTEE FOR BOILING SPRING LAKES HAZARD REDUCTION PLAN
Ed Stanley, Chairman
Walt Anhalt
John Dozier
Cliff Alley
Ernie Wise
Albert Mayberry
TECHNICAL ADVISORY COMMITTEE
Ed Stanley, Chairman - Mayor's Committee
Ralph D. Cantral - NRCD
Michael DeSberbinin -'Resources Development Commission, Brunswick County
John Harvey - Brunswick County Planning Department
Colonel William A. Heizmann, III - U.S. Army
Jerry Kraynack - NRCD, Wilmington, NC
Cecil Logan - Brunswick County Emergency Management
Steve McEnvoy, P.E. - NRCD, Raleigh, NC
Maynard Owens - Soil Conservation Service, Brunswick County
Rick Shiver - NRCD, Wilmington, NC
WITH TECHNICAL ASSISTANCE FROM:
Planning and Design Associates, P.A.
3515 Glenwood Avenue
Raleigh, NC 27612 [phone]
Terry W. Alford, President
Consultants: Michael V. Butts, MUP, Project Manager; Rex H. Todd, AICP;
James Wang, P.E., Wang Engineering; Debbie Tant and Janet Roberts, Word
Processing
The preparation of this plan was financed in part through a grant provided
by the North Carolina Coastal Management Program, through funds provided by
the Coastal Zone Management Act of 1972, as amended, which is administered
by the Office of Coastal Zone Management, National Oceanic and Atmospheric
Administration. The Town of Boiling Spring Lakes contributed cash and
in -kind services.
May 24, 1983

PURPOSE AND OVERVIEW
The development of sinkholes in the Boiling Spring Lakes area continues to be
a source of annoyance and expense. The sinkholes, which develop as a result
of the solution and breakdown of the limestone substructure, make the area
unsuitable for both a railroad and a dam (and the associated residential
development). Given, however, that substantial investments have been made,
the need exists to prepare for actions which will reduce potential hazards
and stabilize the situation (i.e., sinkhole development) to the extent
feasible and practical.
The sinkhole problem in Boiling Spring Lakes (BSL) has received considerable
study by various groups to include the U.S. Army, Army Corps of Engineers,
Reeves Telecom Corporation (BSL Developer) and the State Department of
Natural Resources and Community Development'(NRCD). While much has been
learned about the character of sinkholes in BSL, the Town itself has not been
provided a means by which to consider the alternative courses of action it
may take given the range of possible disasters which could occur from
sinkhole development. In an effort to develop an action plan for the Town,
Mayor Toney appointed a Mayor's Committee for the Boiling Spring Lakes Hazard
Reduction Plan, chaired by Ed Stanley. Following this appointment, the
committee made application for, and received funds through the N.C. Coastal
Area Management Act (CAMA) for development of this Sinkhole Hazard Reduction
Plan for Boiling Spring Lakes.
{Ij: 06 `1'
The purpose of this plan is two —fold. First, this plan is to serve as a
guide to decisions relative to the short term and long term courses of action
taken in response to sinkhole activity. Second, through its methodologies,
this plan is to serve as a demonstration to other coastal communities plagued
with a similar set of scientific, political, and economic circumstances.
Regarding the first of these purposes, the overall goal of the Boiling Spring
Lakes Sinkhole Hazard Reduction Plan established by the Mayor's Committee is:
To maintain the stability of the main lake at Boiling Spring Lakes,
to continue to operate the railroad safely, and to provide
emergency access to the east side of the tracks, all in a manner
which: 1) improves the long—term mutual compatibility of the lake
and the railroad, 2) serves the interests of community pride, and
3) is consistent with the adopted Land Use Plan.
1

OVEaV32V
The Mayor's Committee considered several types of
a selection. Those considered may be grouped into
categories:
1. Prevention.
action plans before making
the following three
A prevention plan is one which identifies hazards or causes of hazards
before they occur and prioritizes the magnitude and severity of each, and
then sets forth a strategy for eliminating the causes or reducing the impact
of the hazard over time. This is the kind of plan that one undertakes when
he realizes that toys on the staircase causes home accidents, and then sets
about the house to clear the stairway of toys and other items.
2. Reaction.
A reaction plan catalogues disaster situations in great detail and
articulates, step by step, which party will react in which situation and in
which way, organized by level of situation. Emergency Management Plans and
Military reaction plans are set forth in this format.
3. Policy Strategy.
A policy plan and strategy plan which assumes a particular level of
catastrophe, sets out mutually agreeable objectives among the parties
involved, and identifies and analyzes suitable technical solutions. This
plan would provide a basis for coordinated and effective action toward
collective objectives in the event of an incident within a narrow range of
solutions, rather than dwelling upon the details of each isolated incident
and a multitude of solutions.
The latter category, Policy Strategy, was the planning framework adopted for
the Boiling Spring Lakes effort.
Within the Policy Strategy framework a number of planning methodologies were
utilized based upon the need to address both technical and political concerns
and stimulate new ways of thinking about a situation which has existed for
years. The following is an overview of the methods used with the details of
their application (and respective results) presented in each subsequent
chapter.
In order to establish a representative base of the community, Mayor Toney
appointed the Mayor's Committee for the Boiling Spring Lakes Hazard Reduction
Plan. This group provided invaluable information regarding the history of
the problem, previous efforts to study it, relationships between parties
involved and contacts for interviews and data collection.
2

In order to gain as much technical information and expertise into the product'
as possible, the Chairman of the Mayor's Committee appointed a Technical
Adivsory Committee (TAC) comprised of representatives of the governmental and
scientific community (see credits page in the front of this document). After
having studied the technical background papers related to the project (see
bibliography, Appendix C), the consultant interviewed members of the TAC
individually to collect their perceptions and references for collection of
additional technical material. These findings were placed into a working
paper which became the foundation for the problem identification phase of the
project (See Chapter III).
In addition to the Mayor's Committee and TAC, the U.S. Army became an
important component to the planning effort. Invitation to participate on the
TAC was extended to Colonel Heizman at Sunny Point, who due to legal
constraints, was only able to participate through written correspondence and
selected interviews. The information provided by the U.S. Army was essential
and the method of contact provided the necessary "methodological link"
between the TAC and the Army.
The Corps of Engineers declined the invitation to participate on the TAC,
primarily due to the fact that they are a representative of the U.S. Army.
The Brunswick County Planning Department opted not to attend the TAC meeting,
but rather respond in writing. The Resources Development Commission did send
a representative.
Over the course of the project, the Mayor's Committee and the TAC met
alternately, allowing the consultant to structure working papers and
assignments accordingly. It was through this design that the technical and
political aspects of the problem were kept in proper balance.
Following the establishment of the TAC, creative analysis of the technical
material was undertaken through group work sessions which focused on scenario
writing (see Chapter III). This exposed many of the ways in which the major
parties would react to future sinkbole-related problems.
Subsequent work sessions, regarding the interview and research material,
produced alternative (technical) courses of action (see Chapter IV).
Later, cost -benefit analyses were performed and other selection criteria were
developed upon which action choices were made (see Chapter V).
This process has produced this document which is organized under six chapter
headings, the first five of which outline the problem solving method, from a
definition of the problem through creative solution identification exercises,
development of alternative courses of action and finally, recommended courses
of action. Chapters II through V are organized under four subheadings to
include: Introduction, Methodology, Findings and Conclusions. Readers from
other communities interested in the plan's application to their respective
jurisdictions are encouraged to focus their review on the "Methodology"
sections and Chapters I and VI.
3

Chapter VI, "Demonstration Value for other Coastal Communities" is a critique
of the methodologies used in this planning effort and their demonstration
application to other communities.
SUHMY OF CONCLUSIONS AND RECO2�DATIOHS
This research and planning process confirmed the ultimately complex nature of
the sinkhole problem. Several conclusions from this work are presented
below.
1. Sinkholes existed long before the development of the U.S. Army Railroad
or Boiling Spring Lakes Dam (see Appendix B1).
2. Sinkholes in the Boiling Spring Lakes area are caused by a dissolving and
eroding limestone substructure. The impact of other compounding factors is
yet unknown.
3. To date, methods have not been established by which to predict if and
when the next sinkhole will develop.
4. The residential and recreational development of Boiling Spring Lakes and
the U.S. Army Railroad are both viable and well established land uses in the
Boiling Spring Lake's area. The parties involved, therefore, must seek a
solution which foster a mutual co -existence.
5. Recommended short-term action.call for the development of an emergency
access plan (across the railroad), conduct a vibration study of the train
traffic and undertaking a deliberate fund-raising strategy to enlarge the
Lake Maintenance Fund.
6. Recommended long-term actions call for a "wait and see" posture, making
minor repairs as needed utilizing the single grant curtain method, and
shifting to consideration of alternative measures should major repairs be
needed.
4

CHAPTER II
♦ REVIEW OF THE PROBLEM
II;P 076 1 j-*5#;j
The breakdown of the limestone substructure and resulting sinkhole
development has caused considerable havoc to the Boiling Spring Lakes area.
The desire to identify short-term and long-term solutions to stabilize the
U.S. Army railroad and Boiling Spring Lake's dam has resulted in a
substantial amount of study over the last twenty years. Many theories,
views and opinions have been aired from the various perspectives, and at
times, tumultuous encounters have ensued.
Prior to consideration of alternative solutions (i.e., courses of action),
a clear definition of the problem must be presented and generally agreed
upon. The following is a statement of the problem, enumerated as major
findings and conclusions which have been gleaned from selected reports,
studies, hearing records and interviews with key people (see Appendix C,
Bibliography). This summary attempts to present a balanced perspective of
the problem.
2 DDOLOGY
The Boiling Spring Lake's sinkhole problem has been couched by many as
"studied to death." The aim of this planning effort is not to add to the
"study" library, but rather focus on the "solution" phase of the planning
cycle. To avoid an unnecessary rewriting of the history of the BSL
sinkhole problem, the consultant extracted findings and conclusions from
the various studies and interview summaries, and organized them under the
following topic headings for better understanding.
The Mayor's Committee and Technical Advisory Committee has concurred with
the following set of findings and conclusions.
FINDINGS
General
Boiling Spring Lakes is located in Brunswick County along Highway 87 (see
maps in appendices,A and B2). Boiling Spring Lakes was originally designed
as a "planned retirement community" in the late 19501s.
From 1970 to 1980, Boiling Spring Lakes had the highest population growth
rate in Brunswick County.
The community contains approximately 17,000 acres within its municipal
boundary — one of the largest in the area in the state.

Boiling Spring Lakes does not contain any AECs as defined in the "State
Guidelines for Areas of Environmental Concern" (15 NCAC 7H).
Boiling Spring Lakes has other fragile areas: recharge area for regional
groundwater aquifer, pocosins, scenic freshwater lakes and pine forest, and
habitat for endangered plants and wildife.
The community is not participating in the National Flood Insurance Program,
yet there are areas thought to be subject to flooding.
Boiling Spring Lakes is without the benefit of a water supply system or a
wastewater disposal system. These systems may not be economically
feasible. Every precautionary measure must be taken to insure that present
and future development does not adversely affect the community.
The community has sufficient land area to accommodate anticipated and
unanticipated growth, even with fragile areas, soils with severe
limitations and the absence of major facilities.
Nearly all lake front lots are sold with approximately 75-80 percent of all
interior lots sold.
Soil and Hydrology Characteristics
Boiling Spring Lakes is cited as a "very sensitive area" in the Land Use
Plan, referring to the fact that this area is a major recharge area for the
Castle Hayne Acquifer.
Lot sizes are generally one half acres or more in Boiling Spring Lakes.
Given the unsuitability of the soil for acceptance of septic tank and field
absorption systems, and the importance of this area as a recharge area, the
half acre lot size may be too small.
The existence of sinkholes is common throughout the world where the bedrock
is composed of limestone. Areas near Los Angeles, Houston, Mexico City,
Tokoyo, Johannesburg, South Africa and Florida are areas characterized by
sinkholes with limestone bases.
Sinkhole activity may increase with a manipulation of the water level,
either a drawing down through heavy pumping or loading the water table
through impoundment. This change acts as the final triggering device for a
set of pre-existing physical circumstances.
The Boiling Spring Lake area is characterized as being environmentally
sensitive.
The sinkhole problems at the Boiling Spring Lakes site are directly related
to the solution activity in the top portion of the Castle Hayne limestone
formation. The problem is related directly to the highly permeable
6

condition due to the solution activity in the top 10 feet of the formation
and not the problems associated with the,large cavities or large openings
in the Castle Hayne formation. The large opening evidenced at the ground
surface has developed in a "funnel" shape from a much smaller shape in the
limestone rock.
The impoundment of the water at Boiling Spring Lakes established a higher
recharge area, thus creating a steeper hydraulic gradient between the
recharge and the discharge area. This gradient change causes the water to
move faster through the limestone and agitate the overlying soil which
bridge the cavities, causing accelerated sinkhole development.
The "Allen" stream bed is five to fifteen feet above the top of the
limestone. This upper level of soils and cavernous limestone allows water
to easily percolate, while the limestone below this level is not as
permeable, thus forming a recharge area.
Discharge is to Allen Creek and to a lesser extent Orton Creek, with a
concentrated discharge area downstream (about 200 to 2,000 feet downstream
of the railroad).
Sand cavities located between five to twenty-five feet below the surface of
the land have been present for tens of hundreds of years.
As these cavities enlarge, the overlying soil bridges until the cavities
become so large that the soil collapses forming a sinkhole.
There exists no method, as yet, for locating these cavities nor for
determining when these cavities will collapse.
Many of the sinkholes are old, having been formed naturally hundreds of
years ago. Some are more recent since the construction of the Boiling
Spring Lakes Dam in 1962. The present circulation of the water, both past
and present, can account for the solution of the limestone.
The nature of the soils and limestone are not prone to produce large,
sudden drop -outs, but rather develop over a period of time. This will
permit the problem to be identified and warnings issued to stop rail
travel.
Boiling Spring Lakes Dam
The Boiling Spring Lakes Dam was designed by Henry Von Oesen, Engineer, and
constructed in 1961. It is an earth dam, 32.5 feet high and 1,560 feet
long with 6,137 acre/feet storage capacity. The 250 acre lake was built on
Allen Creek, 200 feet upstream of the U.S. Army railroad.
The Town of Boiling Spring Lakes took over ownership of the dam from Lake
Owners Corporation, on March 2, 1981.
7

Sinkholes appeared adjacent to the U.S. Army Railroad in 1962.
The U.S. Army constructed a bridge across the most active sinkhole area
after a 1964 investigation.
Reeves Telecom Corporation was required to make repairs (grouting) to the
dam in 1964 and again in 1969.
In 1976, a sinkhole developed on the upstream slope of the dam, partially
draining the lake. The Reeves Plan for Boiling Spring Lakes Dam repairs
was approved in 1977 by the State which called for the drainage of the lake
and one line of grout along the dam. The plan was approved conditioned
upon placement of piezometers at intervals below the dam and several beyond
the right abutment for 2,000 feet (should the lake be refilled). The
piezometers were to be closely monitored and results furnished to the
Military Ocean Terminal at Sunny Point. Repairs to the dam were made
during 1978 to 1979. The lake was refilled in the Spring of 1979.
As a result of the lake being drained for repairs (1977-1979), the
Brunswick County assessor reduced the valuation assessment of water front
properties (land only) by about 50 percent.
The U.S. Army Corps of Engineers requires a permit be issued for dams where
the stream flow exceeds five cubic feet per second. Since Allen Creek does
not meet this threshold, a Corps of Engineers permit to fill or refill the
Lake is not required.
The Army proposed a three line grout curtain along the Dam with costs
estimated at approximately $750,000. The Reeves Telecom Corp., however,
proposed a one line of grout along the dam with costs aproximated at
$40,000. Since the Army failed to prove that the three line grout curtain
was clearly superior to the one line grout curtain, the one line curtain
was judged adequate.
Since construction of the dam, boils have developed downstream of the dam
(generally 600, to 2,000 feet south of the dam).
Boils were identified downstream in 1963 and following dam repairs, again
in the same location in 1976.
The dam safety program of 1979 - 1981 requires all dams with high hazards
classification to be inspected. North Carolina used the Federal 1964 list
which identified 297 dams of this high hazard class, with Boiling Spring
Lakes being one of them. From this list, North Carolina set up a priority
inspection program.
The dam repairs of 1978-1979 were completed just prior to the Corps of
Engineers inspection.
8

There are no habitable dwellings downstream from the dam and therefore loss
of life due to any breach in the dam is unlikely. The high hazard
classification of the dam results from the fact that the Army railroad is
the only railroad access to Sunny Point Military Ocean Terminal, which
crosses below the dam.
Analysis indicates an inadequate spillway and hence an overtopping of the
dam will occur resulting from.a 0.5 pmf (Probable Maximum Flood). This
inadequacy, however, does not meet the Corps of Engineers "seriously
inadequate spillway" criteria.
Overtopping will only occur during weather conditions that would be so
severe that the rail traffic would be stopped.
According to the Corps of Engineers Savannah District Representative, Mr.
Earl Titcom, there is no evidence of water flowing from the old boil areas
between the railroad embankment and the dam and no evidence of new boils
have been seen at the downstream toe of the present railroad embankment.
There is a natural tendency for the discharge points to migrate downstream
of the major recharge area. Hence, with the dam in place, it is
anticipated that springs will develop downstream from the dam. These new
discharge points will become progressively larger, ultimately draining the
lake (this is evidenced by two new springs which were located on each side
of the railroad below the dam when the dam was drained on December 1,
1976).
If new spring developments took place at the base of the dam, such
upwelling of water could cause a failure_of the dam. A dam failure would
likely damage the rail system directly or indirectly.
Given the natural migration of the discharge point downstream, the Boiling
Spring Lakes reservoir is not permanent, with a life expectancy predicted
to last between a few weeks and several tens of years.
The sinkhole problems at the Boiling Spring Lakes site are directly related
to the limestone solution erosion activity in the top portion of the Castle
Rayne limestone formation. The problem is related directly to the highly
permeable condition problems associated with the large cavities or large
openings in the Castle Rayne formation. The large opening evidenced at the
ground surface has developed in a "funnel" shape from a much smaller shape
in the limestone rock.
The Town of Boiling Spring Lakes has a Lake Fund (i.e., dam
maintenance/repair fund) in the amount of $13,500 (January, 1983).
E

U.S. Army Railroad through Boiling Spring Lakes
The U.S. Army Railroad began operation in its present location through
Boiling Spring Lakes in 1955.
The railroad provides train access to the Sunny Point Military Ocean
Terminal, the Carolina Power and Light Brunswick Nuclear Power Plant and
Pfizer Industries. The train traffic averages about one per day, with a
maximum of three per day. The following is a summary of train traffic over
the last three years:
(1)Army
Trains
(2)CP&L
Trains
(3)Pfizer
Industries Trains
FY80
- 2872 Cars
FY80
- 14 Cars
FY80 -
528 Cars
FY81
- 1878 Cars
FY81
- 78 Cars
FY81 -
709 Cars
FY82
- 1325 Cars
FY82
- 17 Cars
FY82 -
651 Cars
There is an average of 8 to 10 cars per train with a maximum of about 55
cars. Based upon a car length of 60 feet, the average train length is 480
to 600 feet with a maximum length of 3300 feet.
There are various types of cargo being transported along the U.S. Army rail
line. Cargos for the Army include: Class A, B, & C Explosives, ammunition
components, POL Products and Lumber. Chlorine and an occasional car of
spent fuel are transported for CP&L, and for Pfizer Industries, lime,
starch and perlite are needed.
As noted earlier, a sinkhole developed adjacent to the U.S. Army Railroad
in 1962. Subsequent investigations in 1962, '63, and_164 resulted in_tbe
construction of a bridge across the active area.
In 1976, sinkholes again began to appear along the U.S. Army rail line.
Following the 1976 sinkhole development, Sunny Point adopted a special
operating and inspection procedure for the section of track downstream from
the dam.
Speed Indicators have been installed on the Locomotives that are used to
cross the Boiling Spring Lakes area. Locomotive Engineers have been
instructed to travel at 5 MPH or less when in this area. Slow Boards have
been erected at both ends of Boiling Spring Lakes which set the train speed
at 5 MPH. The Rail Maintenance Crew inspects the roadway bed each day,
Monday through Friday.
Between 1978-1979, a 1360 foot section of the railroad bed was widened to
permit cars to derail and fall over on their sides without sliding down the
slope, and thus reducing the risk of explosion due to derailment.
The United States of America (U.S. Army) filed suit against Reeves Telecom,
Inc. on July 29, 1981, claiming damages in the amount of $688,318.28. The
claim was based upon repair costs to establish the U.S. Army railroad after
sinkholes developed subsequent to the construction of the BSL dam. The
10

jury found in favor of the USA but due to statutes of limitation, the U.S.
Army was only awarded $91,500.
The most critical area of Sunny Point access railroad downstream of the dam
is the timber trestle. Derailment on the trestle or a failure of the
trestle would allow cars to fall 35 plus/minus feet to the stream bed.
A failure of the dam would likely cause the railroad trestle to be
destroyed and substantial damage would occur to the railroad embankment.
Vibrations from rail traffic may cause some breakdown of the limestone and
sand bridges (i.e., accelerate the rate of sinkhole development). It is
unlikely that harmful levels of vibration are transmitted through the
existing railroad bed (which is over 30 feet in depth to the natural
grade). It is possible, however, that harmful levels of vibration are
transmitted through the pilings and caissons which support the trestle and
railroad bridge.
Only one company proposed a coal terminal in the Southport Area which would
have required use of the Army rail line through Boiling Spring Lakes.
Williams Terminals proposed to develop a 400 acre tract just north of
Southport on the Cape Fear River. The initial capacity -was estimated at 10
million tons per year with an ultimate capacity at twice that amount. It
was concluded that the Army rail system through Boiling Spring Lakes "will
probably need upgrading."
An Environmental Impact Assessment would likely be required either by the
federal or state governments, before the various permits could be issued
for development of a major coal terminal.
While the possibility for locating a coal terminal at/or near Southport
(necessitating the need to traverse Boiling Spring Lakes) is extremely
unlikely, the results from coal train impact studies are applicable to the
U.S. Army railroad/Boiling Spring Lakes dam situation. Study findings
include:
Medical, fire and police emergency responses can be delayed at grade
crossings by passing trains. Also delayed are volunteers on their
trip to the station to pick up emergency vehicles.
Boiling Spring Lakes traffic delay and related impacts and grade
crossing accidents were rated as higb•priority. The solution called
for improved grade crossing protection. These improvements,
including flashing lights, have been installed at Fifty Lakes Drive
and East Boiling Spring Lakes Road.
Boiling Spring Lakes has an average annual medical call and fire
call rate of 78 and 28, respectively. The potential delays due to
current or future road traffic is identified as negligible.
11

The yearly accident rate for the three railroad crossings at Boiling
Spring Lakes is .04 for the current status and .14 for the future
status.
Anticipated land use effects from coal train movements are
esthetics, noise, vibration, effects on historic structures, and
conflicts with land use.
Due to the heavy cars, accelerated wear of the rail structure is
anticipated, making derailment more likely.
Noise levels have not been qualified for locomotives, warning
whistles, or rolling track. Facility studies suggest that any
noise from this type of operation must be judged relative to the
other noise generators of the area. Welded rails, locomotive
mufflers and modified engine casings are suggested as ameliorating
measures.
The rail system within Boiling Spring Lakes was not determined as a
"significant land use compatability problem" in the Boiling Spring Lakes
Land Use Plan, but is cited as a "problem and implication from unplaned
developed growth."
The Boiling Spring Lakes Land Use Plan cites the U.S. Department of the
Army's rail spur in Boiling Spring Lakes as a man—made hazard. It notes
that Sunny Point is the largest ammunition terminal on the east coast and
serves all branches of the military. The train and its cargo both present
potential hazards. The Land Use Plan for Boiling Spring Lakes proposes the
adoption of the following policies relative to the railroad, dam, and
sinkhole problems:
Policy Statement Al. The Town of Boiling Spring Lakes recognizes
the value of waterfront property. The Town also recognizes the
potential adverse impact upon the quality of the lakes and limiting
of access with continued development. Consequently, the Town shall
seek to minimize all adverse impacts and to insure reasonable access
to the lakes.
Policy Statement A. The Town of Boiling Spring Lakes is aware of
the potential threat of life and property associated with the
ammunition terminal railroad, and the nuclear power plant. The Town
is also aware of some of the mitigating measures each of the
facilities has employed. The Town shall continue to seek information
regarding those measures in order to inform its citizens and to
cooperate with the facility management and appropriate regulatory
agencies to minimize the risk.
Policy Statement C7. Considering all the needs of Boiling Spring
Lakes, the limited resources available and the long term impact,
wastewater control has to be a top priority for funding. Other
12

programs can be initiated which are not capital intensive and can be
implemented with the policies in the Boiling Spring Lakes Land Use
Plan related to federal and state assistance, (Flood Insurance,
Wastewater Control and Public Access).
Policy Statement C9. The Town is aware of the critical importance
of the railroad to the region, state and nation. Due to the concern
of the community, the Town shall require all development to provide
a buffer along the right-of-way. In return, the Town expects the
U.S. Army to assure appropriate maintenance and install the
necessary safety measures which the railroad warrants.
In November, 1981, the U.S. Army Engineer Division, Savannah, Corps of
Engineers completed a "Study of the Access Railroad Sinkhole Problem" for
the Military Ocean Terminal at Sunny Point, North Carolina. This study
proposed five alternative courses of action the U.S. Army could take to
deal with the occurance of sinkholes along the access railroad bed (i.e.,
need for relocating the existing railroad). Alternative I was the
recommended strategy, namely: operate as is with a contingency plan to
relocate the railroad along the Boiling Spring Lakes dam as the emergency
arises. (See Appendix D).
The only viable solution available which would assure full immobilization
capability for the U.S. Army Terminal would be the construction of a land
bridge (i.e., Alternative IV, estimated cost $7.4 million).
The Corps of Engineers, 1981 study called for the following engineering
considerations (i.e., need for further study).
a. Confirm extent of problem (i.e., local or widespread).
b. Confirm sequence of potential failure and probability of a
catastrophic failure.
c. Confirm factors influencing development of sinkholes along the
MOTSU ARR.
d. Confirm technology for and probability of detecting sinkholes.
e. Confirm the effects of a failure on operations.
f. Determine feasibility and effect of only partially lowering/
emptying the lake.
g. Determine feasibility:
1. Raising/lowering the lake to compact the sinkholes.
2. Vibratory compaction of the sinkholes.
3. Reinforced earthfill.
4. Pile support of ARR.
13

5. Floating or mat foundation.
6. Incremental bridging.
h. Develop repair plan.
Conclusions from the Corps of Engineers 1981 study include:
a. There is no effect on MOTSU throughput as a result of the
current slow order. The slow order does add 10-15 minutes to the
transit time for a train.
b. The possibility of a catastrophic failure is extremely remote
under current procedures and the possibility of a derailment is
minimal.
c. The sinkholes along the Allen Creek reach of the MOTSU ARR are
directly related to the impoundment of Boiling Spring Lakes.
d. Legal and community impacts are integral parts of the sinkhole
problem.
e. Funding requirements for other MOTSU work dictate that we seek
the most economical solution to the problem.
CONCLUSIONS
Due to the limestone substructure and sinkhole development, the Boiling
Spring Lakes area is not a good place to build either a railroad or a dam.
While the impoundment of water (Boiling Spring Lakes dam) and the subsur-
face flow of water has presumably accelerated the solution and erosion of
the limestone resulting in sinkhole development, the rate of increase
beyond that of the natural rate cannot be determined (given the state of
the art and costs).
The nature of the soils and limestone are not prone to produce large,
sudden drop -outs, but rather to produce sinkholes which develop over a
period of time. This will permit the problem to be identified and warnings
issued to stop rail travel.
The U.S. Army's only viable solution to assure long-term stability of the
railroad would be the construction of a continuous land bridge. This
solution, however, would result in the placement of 42" caissons into the
bed of the limestone creating an avenue for the transmission of vibration
which may, in turn, accelerate the breakdown rate of the limestone and sand
bridges (i.e., the solution becomes part of the problem).
14

Given the need for national security and the expense of relocation, the
possibility of closing down Sunny Point and/or relocating the railroad
outside of the BSL area (i.e., the railroad will go away) is extremely
unlikely.
Given the investment of the property owners and Town of Boiling Spring
Lakes in development of the dam, it is extremely unlikely that "the dam
will go-away". However, given the natural migration of the discharge
points downstream, the reservoir is considered temporary with an unpre—
dictable life expectancy.
Thus, the issues recognized above are complicated by the desire of both the
Army and the Town to coexist in Boiling Spring Lakes. It is within this
context that Chapter III presents various scenarios of how coexistence may
best be achieved.
15

INTBODUCTION
As indicated in Chapter II, the problems in the Boiling Spring Lakes area
are caused by the dissolving and crumbling of limestone beneath intense
lands uses including the U. S. Army Railroad and the BSL dam. This
situation is extremely complex because it has a long and intense history,
it involves many parties with diverse interests and viewpoints, it has been
analyzed from a number of technical disciplines and it has the potential to
last as long as geologic time itself.
Initial interviews with selected experts and an examination of the
technical material has indicated that any work toward a "solution" must
cover several fronts simultaneously. These fronts include the political
(i.e., need to identify interest and weave an acceptable level of
understanding or at least mutual tolerance among them), the technical
(i.e., need to identify the chemical and physical nature of the limestone
problem and prescribe scientific/engineering steps to retard the rate of
increase of the problem), and the strategic (i.e., need to identify
alternative ways to provide emergency access in the case of significant
blockage of roads due to sinkhole activity or train derailment).
In order to operate on these fronts simultaneously, a scenario writing
approach was undertaken with the Technical Advisory Committee. The
following briefly defines and describes scenarios, and presents the results
of the developmental scenario writing/work session.
As Mr. Hirschhorn indicates in his article titled "Scenario Writing: A
Developmental Approach," scenario writing is a generic term encompassing
a broad range of approaches, assumptions and techniques. All, however,
share in common an attempt to describe or write a "history of the future."
Scenarios can be written from several perspectives and categorized in three
separate ways:
1. state vs. process scenarios
2. end state vs. beginning state scenario
3. prediction vs. planning and decision making scenario
Larry Hirschhorn, Scenario Writing: A Developmental Approach, Journal
of the American Planning Association, April 1980, Vol. 46, Number 2, page
175.
16

First, state scenarios simply posit what the world or relevant context
will be like a number of years from the present, without describing at the
same time bow the world "gets to be that way." Process scenarios, in
contrast, specify the sequence or chain of events that lead up to a
particular future state.
Second, in end state scenarios, some conception of a future state
determines how the scenario is written. They are goal oriented. . .how you
get there depends largely on where you said you wanted to go. However, in
the beginning state scenario, the beginning, not the end, functions as
the starting point or benchmark for the scenario and the scenario specifies
how or why future states emerge. The occurrence of events along the way
determines the destination.
Third, scenarios can be used for either the purpose of prediction or for
planning and decision making. In the former, the scenario writer looks
primarily for accuracy, validity and, where meaningful, statistical tests
of plausibility. In the latter, the scenario writer looks primarily for
usefulness, surprise, richness and the power of the scenario to provoke
unexpected ideas for plans.
These types of scenarios can be brought together into several parings. For
example, a process scenario may be end state driven to be used for
prediction, and so on.
Because the Boiling Spring Lakes situation has such an unpredictable end
state and because of its planning needs, a rp ocess--beginning state —
planning scenario was selected. This choice used a methodology known as
a "developmental scenario" put into the context of the Boiling Spring Lakes
situation:
"A development scenario begins with an initial state (our current
understanding or "mind set" of today's problem in Boiling Spring
Lakes) and describes a process through which a particular social
system (the Town Board and residents, the Army, the Developer, the
State and others) can arrive at one or a series of end states
(action strategies) that are not specified prior to the construction
of the scenario itself." (Hirschhorn, p. 175).
This involved constructing "linear developmental chains" composed of cause
and response events: environmental circumstance, problematic or driving
forces, institutional action or response, failure or success modes (which
blocks or enhances success), and a set of alternative or new responses
(which lead to a new chain).
To create such chains, the Boiling Spring Lakes Technical Advisory
Committee (TAC) and its consultant used a "working —wall chart" method of
recording and a structured brainstorming method of generating ideas. The
consultants prepared a list of "problematic or driving forces" in terms of
17

level of sinkhole activity, etc. upon which the group stated likely
responses from their personal perspectives or from the perspectives of
their agency. The focus of the effort was to learn, in a creative setting,
what reactions would likely be, and where opportunities for coordinated
response and potential conflicts in response were.
FINDINGS
With the Technical Advisory Committee (TAC) as participants, the scenario
writing worksession began with the following set of circumstances and
categories for action:
Issues: There are three major factors around which all "issues in the
Boiling Spring Lakes problem revolve: (1) Railroad Operation; (2) Secur-
ing the Lake; and (3) Emergency Access across the Railroad.
Actors: The Town, the U. S. Army and the State of North Carolina.
These are the parties with stakes in the process and with concern for
positions in the forthcoming action plan.
Environmental Circumstances: These are broad classes of incidents which
may stimulate action on the part of the community of Boiling Spring Lakes,
the U. S. Army, the State of North Carolina or any combination of these (in
a coordinated manner). So far there are four such classes:
(1) Recurrence of sinkholes that result in drainage of.the lake or in
damage to the railroad, or both —these may be of major or minor magnitude
and severity; (2) Railroad derailment unrelated to sinkholes (again, of
major or minor magnitude and severity); (3) Periods of limited access for
emergency vehicles to cross the railroad (short periods and long periods);
and (4) Renewed sinkhole activity of no immediate impact to the lake or to
the Railroad (major or minor activity levels).
Problematic driving forces: These are the actual incidences (in varying
degrees or levels of magnitude or severity) which actually cause action by
one of the parties. They are the "precipitating incidents" to action which
can be either uncoordinated and impulsive, or well -planned and coordinated.
Array of Actions: These range from actions which are highly predictable
and possible to a dream list of what's really desired regardless of its
feasibility. They range from solutions which are feared or avoided at all
costs to those which are the most likely.
Scenario or event -chain construction: These are cause -and -effect
linkages between actors and the actions of other actors. In other words,
what response will the Town have to a certain action by the Army who is
acting in response to one of the instances (problematic driving forces).
How do these responses fit together? Do they expose overlaps or conflicts
which are better dealt with now and planned for, than left unsaid? What
are the plausible develomental sequences?
18

Factors of Success or Barriers to Success: See Chapter II
Alternative Actions: See Chapters IV and V
Commentary: See Chapter VI
At the worksession, emphasis was placed on identifying the position of the
two major actors, the Army and the Town, and crystallizing their
opportunities to:
go separate ways, or
cooperate but end up in about the same place, or
cooperate and push for fulfillment of mutually acceptable
objectives, particularly in the face of a catastrophe with
relation to the limestone substructure.
Within that context, the TAC produced the following scenarios to six
hypothetical "environmental circumstances:"
1. Minor sinkholes along the sides of the dam and the railroad
itself.
In this case, the Town would contact the County Commissioners and call
their attorney and begin to study the relationship between_tbe Army and the
Town. They would report the incident to the State (NRCD).
The State would report it to the Corps of Engineers and encourage the Town
to hire Henry Von Oesen or some other engineering consultant to study the
condition of the dam.
The Army might stop traffic, add inspectors to inspect the tracks, notify
the State in Raleigh or in Wilmington, and follow up the report with an
immediate response for their contingency plan. The County, through Cecil
Logan, the new Emergency Management Officer, would inspect the site and
review the situation along with the State in order to assure the
preparedness of alert or emergency responses.
2. 100-foot sinkhole in the railroad bed but no damage to the dam.
In this case, the Town would contact the Army and the State.
The State would notify the Army and then notify the Town, and start
immediately to drain the lake to make it safe. The State and Corps of
Engineers people would come in and study the situation. They would notify
the owners of the dam (the Town). Boiling Spring Lakes would not need to
do a study if the Army makes repairs and the State okays the repairs. Then
the lake could be refilled.
19

Since this is federal property, the Army would want to make repairs first.
Everybody else would be in a responsive mode.
The County would take no responsibility.
Industries would put pressure on the County to help get the railroad
moving.
3. A major sinkhole develops along the dam (the third such incident
in three years, with costs averaging $90,000 each time); water
spills through a breach in the dam causing significant damage to
the railroad bed and trestle. Train traffic is stopped indefi-
nitely.
In this case,, the Town would call an attorney, open the valves to drain the
lake, and would look to the Community Development Block Grant Program for
emergency funding.
The State would do the same as before, and so would the County.
The Army would declare it a disaster area and move on its contingency plan.
4. Derailment which blocks and limits access. The access
are on 50 Lakes Drive_ Boiling Snrings Road and North
In this case, the Town would call the Army and Highway Patrol (the lead
agency) which would in turn contact the Department of Transportation (DOT).
The State would check to see that there is no damage done to the dam and
contact DOT.
The County would contact its emergency management coordinator, highway
department or the Sheriff, with the local coordinator in the lead.
The Army would assist the emergency management coordinator and the National
Guard could airlift in or shuttle in help (Coast Guard).
5. Explosion which would be large enough to burn out part of the
Town.
In this case, the Army would determine whose responsibility it was rather
than act.
The State would lower the reservoir or maybe not lower it, since the water
would be needed to help put the fire out.
The Town would resist lowering the lake until the fire was out.
The Forest Service would conduct water air drops.
20

The county coordinator would initiate action plans. The evacuation
situation may similarly cause the Town Rescue Squad and Civil Defense
people to react. (CPQ did a scenario of emergency situations at their
power plant from which the Town can learn).
6. The Town's response to the Army's action, regardless of level of
nature (sinkhole) catastrophe.
While scenarios 1 through 5 above were predicated upon responses to natural
phenomena, the committee also realized that the Town is primarily in a
responsive position with respect to the actions of the Army. Thus, the
group discussed the Army's preparation of its own emergency plan which
poses solutions as follows:
First, the Army has its own emergency contingency plan in which
it may do one of several things. First, during an emergency the
Army may want to construct a 4,000 foot bridge to replace the
existing bridge and leave the existing dam intact. The first TAC
work session revealed that in this situation, the Town would want to
be assured that the vibrations would not cause damage to the dam.
It would want assurance that this is, in fact, an improvement to the
existing situation. It would want to prepare a statement of concern
for the Army to consider during and after construction, and it might.
want to undertake parallel studies on vibration to the substructure
or to the steel pilings. They may want to give the dam to the Corps
of Engineers.
Second, during an emergency the Army may put the railroad on top of
the existing dam. In this case, the Army would do considerable work;
the Town would go immediately to court or perhaps hesitate to study
the pros and cons of the issue; the Town could use the old railroad
as a road in a swap. The Town could share the cost of repair through
a grant. The State would take no responsibility. In this case, the
Town would no longer be responsible for maintaining the water level.
CONCLUSIONS
Major tbemes exposed in the work session's six scenarios include the need
to study the condition of the dam and the railroad regardless of the extent
of catastrophe; concern for financing of repairs; concern for public safety
and property values (rail property and individual resident property); legal
responsibility; and interaction of parties in a timely and deliberate
(planned) manner.
It is upon these scenarios and themes that Chapter IV (Alternative Courses
of Action and Respective Costs and Benefits) is based.
21

CHAPTER IV
ALTERNATIVE COURSES OF ACTION
AND RESPECTIVE COSTS AND BENEFITS
IRrBODUCTION
The solutions (i.e., alternative courses of action) to stabilize the
Boiling Spring Lakes dam and railroad, and reduce the hazards associated
with sinkhole development, were identified through a review of existing
studies and the scenario writing exercise. Once the alternative solutions
were identified, engineering studies were initiated to determine the costs
and benefits of each solution. The Technical Advisory Committee (TAC) also
participated in the costs and benefits analysis phase.
METHODOLOGY
The alternatives list, which follows, was sent to the TAC, accompanied with
the engineer's costs and benefits analysis report. The task of the TAC was
to review the material and conduct their own assessments based upon the
following instructions:
1) Given your area of expertise, please complete the selection grid
(Exhibit A, See Appendix F) for each of the nine alternatives. Please
rate each alternative as "high," "medium," or "low" on each selection
criteria by placing an "H," "M," or "L" in each cell.
2) Having done #1 above, what are the particular advantages and
disadvantages of,each alternative? What is your most preferred and
least preferred alternative? (Please complete on Exhibit B, See Appendix
F).
3) Related to the array of alternatives, which lend themselves to
short—term strategies for the Mayor's Committee and which for long—term?
Given that the Mayor's'Committee and the Army are both in a "wait and see"
posture, what short—term and long—term steps do you see as advisable for
the Town to undertake to place them (and the Army for that matter) in an
appropriate state of readiness for renewed sinkhole activity of significant
consequence? (Please list three short—term and three long—term steps in
the space provided below).
In undertaking the three aforementioned steps, the TAC was reminded that in
a very real sense, the situation before the Mayor's Committee is two
pronged: 1) how to be best prepared and best respond to renewed sinkhole
activity; and 2) how to be best prepared and best respond to the Army's
action to repair the railroad.
The results of this process are presented in Chapter VI, Recommended
Courses of Action.
22

FINDINGS
The following alternative courses of action were selected for a costs and
benefits analysis (Note: not in priority order):
1. Lower the mean water level of the lake by one foot.
2. Construct a dam downstream of the existing dam.
3. Construct a set of terrace dams, either one or two in the middle
of the lake.
4. Relocate the railroad onto the existing dam.
5. Construct a single grout curtain the entire length of the dam.
6. Construct a triple grout curtain along the existing curtain
line for the entire length of the dam.
7. Install a non -porous membrance of considerable size on the bottom
of the lake near the existing dam.
8. Establish alternative emergency access routes so that train de-
railment would not inhibit public egress from and access for
emergency vehicles to the east side of the tracks.
9. Conduct a study of the vibration which the railroad contributes
to the substructure through its trestle system.
The following is a technical review of the costs and benefits of the above
alternative courses of action:
(1) Lowering the Water Level
At the present water elevation (30.3 ft. AMSL) in the 14ke the water
seepage through the dam was calculated to be 1.26 x 10 cubic feet per
second (See Figure 1, Appendix E). To reduce this seepage, the water
elevation in the lake could be lowered to reduce the hydraulic gradient.
Low�ring the water level one foot would reduce the seepage rate to 1.16 x
10 cubic feet per second or 8.1%, and lowering_5be water level 5 feet
would reduce the seepage rate by 41% to 7.5 x 10 cubic feet per second.
Although lowering the water level will reduce the water seepage, it is not
know to what extent this would reduce the solution of the limestone and
formation of sinkholes. In order to determine the exact result from this
alternative, extensive geologic and engineerng analysis would be necessary.
The loss of property value for the water front lots around the lake is
expected if this alternative is adopted.
23

The other alternative to this solution would be to use a plastic liner on
the upstream slope of the dam. This liner is totally impermeable and will
not allow any water seepage along the blanket. Although this will provide
a totally impermeable blanket, it does not have the ability to seal itself
if it is ruptured. If the blanket is ruptured, it would be necessary to
lower the lake level below the fracture to repair it. The cost of this
material is $1.05 per square foot including installation. (The price was
quoted from Schlegel Lining Technology, Inc.). For a 50 foot plastic
blanket the total cost would be $77,000 and the cost of the 100 foot
blanket would be $145,000.
Before the placement of either the clay or the plastic layer, the area to
be covered must be cleared and graded to remove the topsoil and to smooth
out the area. Since the lake is not drained, the soil behind the dam would
be very wet making grading of this area difficult. If the area is left
alone to dry naturally, it would take quite some time before normal grading
could start. The cost of efforts to grade the wet area could be expensive
and could raise the construction cost of placing an impervious layer by
50%.
(8), Establish Alternative Emergency Access Route(s) Across the Railroad
The present access roads which cross the U. S. Army railroad are Fifty
Lakes Drive, N. Apache Road and Boiling Springs Road. The railroad
traverses the Town Limits for a distance of approximately 23,000 linear
feet. The roads identified above cross the railroad right—of—way
(beginning at the southern most point of the Town and heading north) at
about 5,000 feet, 11,000 feet and 14,000 feet respectively. This means
that 9,000 feet separate South Lakes Drive and Boiling Springs Road. As
noted in the findings of this document, the average train length is about
480 to 600 feet with a maximum length of about 3,300 feet. While a train
derailment which blocked all three access roads is unlikely, associated
hazards (e.g., fire, ammunition or nuclear waste spill, etc.) may render
all present access routes impassable. Further, just the delays at grade
crossings by passing trains may necessitate medical, fire and police
emergency responses to seek alternative routes. The alternate routes have
been selected (see Appendix G). The costs are considered minimal —just the
cost of maintaining equipment and soil to develop the roadway at the time
of the emergency or develop it now with access limited to emergency
vehicles.
(9) Conduct a Train Vibration Study Along the Trestle and Bridge Area
The anticipated "scope of work" for a vibration study of the trains
traveling through Boiling Spring Lakes includes:
a. Conduct on —site vibration readings (before and during train
travel) at the following locationsf
(1) Train trestle
(2) Train bridge
(3) Train bed base (between railroad bed and BSL dam)
27

silty soil based on soil 5borings in a previous report. The permeability
factor (k) of 3.28 x 10 cubic feet per second was therefore assumed.
This permeability factor was obtained from An Introduction to Geotechnical
Engineering by Robert Holtz and William Kovacs (Figure 7.6, page 210).
The flow net for the existing dam was developed and is shown in Figure 1
(see Appendix E). From analysis and calculations it was determined that
the present rate of water seepage through the dam is 1.26 x 10 cubic
feet per second per linear foot at the center of the creek. Appendix E,
Figure 2 shows the flow net for the case when a 50 foot impervious layer is
placed on the upstream slope of the dam. This layer causes the flow under
the dam to start farther from the base of the dam, and the hydraulic
gradient of the flow is reduced and consequently slower flow under Pe dam
will be observed. The seepage rate was calculated to be 7.69 x 10
cubic feet per second. This is a reduction of 23% from the existing
seepage rate.
The flow net with the 100 foot impervious layer is shown in Figure 3,
Appendix E. It is conceivable that the flow must start even farther from
the base of the dam. The hydraulic gradient of the water is decreased by
the impervious layer causing the water to have less velocity and to erode
less through the limestone_5 The seepage rate with the impervious layer was
calculated to be 5.9 x 10 cubic feet per second, which is a reduction
of 53% from the existing rate.
Two types of impervious layers, clay or plastic, are considered to be the
best materials for this alternative. Each type of layer will be discussed
on the pro's and con's and also estimates are given.
The use of a clay layer on the upstream slope of the dam would consist of a
1 foot deep layer of clay covered with the topsoil that had existed at the
dam and a layer of type D Rip -Rap. The cover layer of top soil and Rip -Rap
are added to protect the clay,from drying, cracking, and wave protection.
The advantage of clay material is that if the layer was cracked, the clay
would have the ability to seal itself. The disadvantage of clay is that no
soil material is total impermeable, thus some seepage through it can be
expected although the amount of seepage is,expected to be minimal. The
cost of the clay material is estimated to be $9.50/cubic yard. This
includes the cost of the clay, transportation of the clay for 5 miles,
removal of the top -soil, and the placement and compaction of the clay. The
cost of the Rip -Rap is estimated to be $15/square yard if the material is
available nearby. The Rip -Rap should be placed 50 feet wide along the
entire length of the dam to protect the clay against the lowering of the
water level during the dry season.
For a 50 foot clay layer section the total cost of the clay is estimated to
be $26,000 and the cost of the Rip -Rap would be $1161600. The total cost
for this alternative would be $142,600. The cost of the 100 foot clay
layer section would be $49,000 for the clay and $232,000 for the Rip -Rap
for a total cost of $281,000.
26

b. Analyze in terms of extent to which the vibration, identified
above, accelerates the breakdown of limestone and overstory
(i.e., sinkhole development). The detail of this analysis should
be comparable to that of Harry La Grande's Hydrology Study(see
bibliography, Appendix C).
c. A written report shall be the product of this study to include:
(1) vibration study findings
(2) analysis
(3) conclusions (relative to sinkhole development).
The cost of the vibration study is estimated to be $5,000.
Although the least expensive short term solution to sinkhole development
along and within the dam has been the single line grouting, the long term
cumulative affect of this alternative is more than twice as expensive as
developing an impervious layer on the upstream side of the dam ($416,000
for a single line grout curtain the entire length of dam versus $1659000
for a 50 foot clay layer or $145,000 for a 50 foot plastic blanket).
In Chapter V, these alternative courses of action were assessed against
other criteria as a basis for prioritization and finally selection toward
the expressed goal of mutual coexistence in Boiling Spring Lakes.
28

RECO14KKNED COURSES OF ACTION
INTRODUCTION
This plan identifies nine (9) alternative courses of action which could be
taken to stabilize the Boiling Spring Lakes dam (and in turn, help
stabilize the U. S. Army railroad) and provide emergency access to the east
side of the railroad. These alternatives have been developed through a
review of various studies and interviews, a scenario writing work session
and a cost/benefit analysis work session. The alternatives have been
analyzed through a technical cost/benefit study.
The evolution and ranking of these alternatives was based upon a set of
criteria listed below. From this prioritization, contingency actions have
been established.
To establish a basis for evaluating the nine alternatives prior to the
meeting of the TAC, members were asked fill—in the selection grids
presented in Appendix F, Exhibits A and B, which featured the following
criteria:
Positive Impact on the Problem
Durability Over Time
Unit Cost
Total Cost
Availability of Financing
Adverse Environmental Impacts
Complexity and cost of Maintenance and Management
Required Time for Completion
At the beginning of the Technical Advisory Committee (TAC) work session,
the chairman, representing the Mayor's Committee, requested that alterna—
tive four (4) be amended to read, "Relocation of the Railroad," rather than
"Relocation of the railroad onto the existing dam." Since relocating on
the existing dam is a stated option of the Army, the group decided to add
"Relocation of the Railroad" to the list (as option 10), while maintaining
the original wording for option 4.
Next, discussion was held which (1) raised issues which participants had
discovered during their homework; (2) the method of completing the form
collectively; (3) determining mutually acceptable definitions for each
criteria; (4) agreeing upon the rating scale; and (5) understanding that
all criteria were assumed to be of equal importance (weight).
29

Regarding the latter, "total cost" was measured by estimated dollars for
construction. "Unit cost" was determined incomparable across alterna-
tives, and was deleted from the exercise. All other criteria were assigned
ranges of "low," "medium," or "high" and rated nominally with "H," "M," or
"L." No ratings were applied until each person had acknowledged that he
understood the definition of the criteria and the limits of the rating
ranges.
By collecting the ratings of each alternative on one criteria at a time,
with discussion permitted for clarification only, a "concensus" method was
used to record ratings.
As the group shifted to discussion of advantages and disadvantages of each
alternative, the consultant assigned numbers to the ratings (H-7; M-5; L-3)
and averaged scores within each cell of Exhibits 3 and 4 (Appendix F) to
determine the "group score." These scores on each criteria were sumed to
determine the total score for each of the 10 options, which were then
ranked. Rankings were reported to the group during this work session to
provide feedback and information for the remainder of the session.
FINDINGS
Based upon the aforementioned method, the alternatives were prioritized as
follows:
Rank Alternative
#1 Relocate the railroad upstream of the lake.
#2 Construct a triple grout curtain along the entire length
of the dam.
#3 and #4 Construct a dam downstream of the existing dam, and
(tied) install a non -porous membrane or layer.
#5 Relocate the dam downstream (.5-1 mile) of the lake.
#6 and #7 Construct a single grout curtain the entire length of the
(tied) dam, and construction of a dam (or set of terraced dams)
upstream from the existing dam.
#8 and #9 Lower water level (one foot) of the lake.
(tied) Relocate railroad onto existing dam.
30

The discussion on advantages and disadvantages of each alternative produced
the following:
Alternative Advantages
Lower water reduce hydraulic pressure
New dam downstream add more lake frontage,
transfer active sinkholes
below RR
New dam upstream reduce hydraulic pressure
Relocate railroad
on existing dam change ownership
downstream safer -move RR from active area
upstream safer -dam failure not damage RR
Single grout curtain reduces some seepage
Triple grout curtain reduces seepage
Impervious layer reduces seepage, easy to
install
Emergency access N/A
routes
Vibration study N/A
CONCLUSIONS
Disadvantages
poor esthetics
displaces problem,
expensive
lower water -esthetics
and use reduced.
creates a narrow road,
could drain lake,
vibration could
damage dam.
dam failure still could
cause damage,
expensive.
expensive
relatively inex-
pensive.
expensive.
N/A
N/A
There are a number of conclusions which can be drawn from the above
exercise and findings. These include the following:
1) Many of the top priority options are beyond the control of the Mayor's
Committee in terms of ownership and total costs.
2) There is still lack of agreement about whether the problem of crumbling
limestone in Boiling Spring Lakes is primarily a chemical problem (the im-
poundment of water increases water -limestone contact causing the limestone
to dissolve) or a physical problem (water circulating through the caverns
within the subsurface, thereby eroding the limestone). Both in fact are
operating.
3) Though the interaction between the Town and the Army has been coopera-
tive at the information sharing level, there is still a clear delineation
of legal and financial responsibility dividing the two. This part of the
situation is not likely to change and should be considered in the design of
any coordinated action.
31

4) Since the Town is limited in its control and budget, any strategy
toward working down the priority list must consider short-range and long-
range actions. Several fronts should be undertaken simultaneously, so as
to prepare as best as the Town can for eventual recurrence of sinkholes.
On the latter point, the following set of actions is recommended as the
course of action to be pursued by the Mayor's Committee.
Short -Term Actions
1. Develop and adopt an emergency access plan for implementation
should derailment take place which restricts access to the east
side of the U. S. Army railroad. This plan should be considered a
contingency plan, to be initiated only when access is restricted.
Alternative access routes, fill material, equipment needed,
equipment operator and construction time should be identified.
2. Conduct a vibration study of the railroad trestle and land bridge
areas. If the findings of this study reveals that significant
levels of vibration are being transmitted to the limestone
substructure (and hence,•a possible contributor to the
acceleration rate of the limestone breakdown and resulting
sinkhole development), the Town of Boiling Spring Lakes will be
placed on.a more equal (legal) footing with the U. S. Army, should
any future sinkholes develop.
3. Enlarge the BSL Lake Management Fund. While a number of fund
raising activities should be undertaken, any action (e.g., tax
increase, issuing of general obligation bonds, application for
state and federal grants, etc.) will require the support of the
community. To identify funding preferences, a Town -wide survey
should be conducted. (Note: Town -wide survey costs are esti-
mated at about $1,500).
Long -Term Actions
1. Do nothing - This approach is based upon the old adage, "If it
isn't broken, don't fix it." (Additionally, time will judge the
effectiveness of the existing grout curtain).
2. Undertake a single grout curtain method for repairs, up to a
specified amount or percentage of cost before another alternative
is selected.
3. Install a non -porous membrane or layer when the costs of a single
line grout curtain repairs exceed a percentage specified of the
non -porous membrane alternative.
32

Among the six options listed above, #3 (management fund for the lake)
presents the most immediate and significant way in which the Town can
prepare for the inevitable occurrence of renewed sinkholes.
The essence of this strategy is a fund—raising phased investment approach
toward target thresholds. As funds reach the threshold of either an
investment opportunity (higher interest rate, etc.) or a more long—term
strategy (such as the impervious layer on the bottom of the lake),
decisions are made, investments or purchases undertaken, or the strategy is
renewed. The following describes in detail why it is recommended, and what
funding levels are required.
The Boiling Spring Lakes Management Fund
Although the Town presently has a Lake Management Fund ($13,500), it is not
sufficient to pay for anticipated repair costs, nor is it sufficient to
avail the City to alternative measures which may have more long—term
benefits.
Before the Town can identify what constitutes a "sufficient" Lake
Management Fund (i.e., dollar amount), two questions must be answered: l)
What is the frequency at which sinkholes occur, and 2) What is the likely
costs for dam repairs following sinkhole development. As indicated
earlier, the state of the art and the brief recorded history of sinkhole
development in Boiling Spring Lakes makes a statistically valid answer to
the above questions impossible. Although such precision is lacking, a
"ball park" figure is, nonetheless, needed. With this caveat in mind, the
following analysis is presented.
Based upon dam repair costs of previous years and an interview with Bob
Davis of Henry Von Oesen and Associates, cost estimates were established.
The costs of future repairs could range between $10,000 to $500,000. Minor
repairs (to the dam and lake only) could range between $10,000 and $50,000
with major repairs ranging between $100,000 and $500,000.
Inquiries were made with Planter's National Bank to determine at what
investment thresholds (e.g., $50,000 or $100,000) special interest rates
and terms become available. Currently (February, 1983), all such
investments are paying about the same interest rates (around 8%), with no
predictability in the future. Nevertheless, the larger the base amount,
the better off the Town will be as investment opportunities arise. At any
rate, earnings on large amounts are more than earnings on small ones.
Given the above estimates and assessment of investment opportunities, it is
recommended that the Town of Boiling Spring Lakes establish a "Lake
Management Fund" in the amount of $50,000 (to be adjusted annually by the
inflation rate). This amount should cover the repair cost for any future
minor sinkholes, and provide a base from which to earn interest toward the
cost of any major sinkhole development.
33

As indicated below, the "Lake Management Fund" should be generated at an
annual rate of from $10,000 to $13,000, depending upon the annual
inflation rate and interest rate:
Using the following formula, we find that the future
value of $61,500 at a 4% inflation rate and $76,000 at
an 8% inflation rate is approximately $50,000 (the
present value of the target amount).
P F(1-i)N
where P = present value
F - future value of a sum of money
i expected inflation rate
N = number of years at a given it
Calculations:
at 4% inflation rate:
$50,000 - F(1-.04)5 $61,322 or about $61,500
at 8% Inflation rate:
$50,000 = F(1-.08)5 3 $752863 or about $76,000
To determine the annual end -of -.year payment needed to reach
the targeted $61,500 or $76,000 within five years, the fol-
lowing formula is used:
A = F i
(1 + i) - 1
where A = size of annual payment
F = targeted amount
i - expected interest rate
N a number of years at a given.2
1 6 2"Introduction to Planning Techniques," Keber, Robert,
Pembroke State University, 1981.
34

0
Calculation:
at 8% interest rate:
A = $61,500 .08 $10,483
(1 + .08) - 1=
A = $76,000 .08 5 $12,955
(1 + .08) - 1=
at 10% interest rate:
A - $61,500 (1 +•1010)� - 1= $10,074
A = $76,000 .10 = $12,449
(1 + .10) - 1
at 12% interest rate:
A = $61,500 .12 ` $91681
(1 + .12) - 1=
A = $76,000 (1 +•1212) - 1= $11,963
Once the $50,000 mark is reached (i.e., $61,500 or $76,000 or as adjusted
for inflation), the Town should reassess their situation (as history
establishes a more accurate sinkhole occurrence rate and repair cost rate),
and work down the prioritized list of actions (1 - 10) as the situation
dictates.
In this manner, the Town will have a systematic program of enhancing
security for the future.
W

DB�HSTRATION VALUE FOR OTHER COASTAL COMMUNITIES
This year, the Office of Coastal Management of the Department of Natural
Resources and Community Development funded five coastal demonstration
projects. The Boiling Spring Lakes project is one of them.
This chapter is an epilogue which reflects upon the situation in Boiling
Spring Lakes and the analytical and technical work undertaken to address
that situation. It highlights the strengths which other communities may
wish to replicate, and exposes points upon which other communities may wish
to improve as they apply methods used in Boiling Spring Lakes.
As has already become apparent to the reader, the demonstration value of
the Boiling Spring Lakes project lies within its analysis of the situation,
its selection of planning methods and its techniques for carrying out those
methods.
This chapter examines each preceding chapter primarily from a methodo—
logical standpoint, with assessment of strengths and recommendations for
improvements in subsequent applications. To get the most out of this
chapter, it is best to have read the document itself and to refer to it
while working through this chapter.
ARTICULATION AND ASSESSMENT OF DMIDNSTRATION VALUE
Chapter I --Purpose and Overview
The situation at Boiling Spring Lakes presents a typical coastal area
dilemma in which fragile natural resources and community development needs
confront each other. Other similar cases include pressures for new
development on cherished and even unstable oceanfronts and the development
of intensive waterbased uses in primary.nursery areas.
On the other band, the situation in Boiling Spring Lakes is unique in that
the natural resources are particularly vulnerable (the limestone sub—
structure is incompatible with any form of intense development and
apparently will remain so for all of geological time) and the uses there
are particuarly intense (the City of Boiling Spring Lakes is committed to
being there as a lake —based, predominantly retirement community, and the U.
S. Army is intent on using the railroad for national defense purposes).
36

Before the Mayor's Committee and its consultants began seeking solutions,
they articulated the following questions to help focus their mission and
scope of work.
1. What is the real problem? How do we define the problem when all
options, studies, court cases and scientific studies to date ap-
pear inclined toward one viewpoint or another?
2. Who are the parties involved and what are their strengths and weak-
nesses (i.e., jurisdictions, authorities, financial capacities,
political postures, commitments to their viewpoint, and stakes in
the process)? Who has the power to act and who is merely respon-
sive?
3. How does #2 above compound our understanding of #1 ?
4. How can planning be of meaningful assistance in resolving the
problem as recognized?
5. What type of planning instruments should be developed, what areas
of expertise will be required to help develop them, what commitments
are required, and who will be responsible for funding the proposed
short and long-term actions?
other communities will find such pre -planning essential for clarity of
purpose and vision, even before data collection begins. At Boiling Spring
Lakes, it was important to reflect upon these questions throughout the
development of the project.
Chapter II --A Review of the Problem.
As explained in detail in Chapters II and III respectively, the situation
in Boiling Spring Lakes is complex, from a physical (i.e., engineering) and
political perspective.
Examination of the physical aspects preceded examination of the political
because the problem was initially conceived as a physical one --one which
could be clearly perceived, studied and remedied with engineering
solutions. This conventional wisdom led to a detailed research effort into
the earlier studies, court cases and a collection of any technical pieces
on sinkhole problems elsewhere. Additionally, intensive interviews were
conducted with technical experts and other persons who had previously been
involved with the Boiling Spring Lakes situation. The interviews became
the base upon which candidates for the Technical Advisory Committee (TAC)
were identified. The TAC served to review alternative solutions and the
cost -benefit findings, and set priorities for recommendation to the Mayor's
Committee.
During the process of interviewing the various parties involved (the Army,
the town, county, state and citizens), it became apparent that all
technical solutions would be heavily influenced by the politics of the
situation.
37

Additionally, it was apparent that the viewpoints of the participants were
adverse (the Army seriously wanted to maintain its railroad in Boiling
Spring Lakes and the Town seriously wanted to maintain the Lake and sustain
property values).
Understanding this situation gave the Chairman of the Mayor's Committee a
second reason to establish the Technical Advisory Committee —to get a
well-rounded political perspective on the values at play within and around
the situation at Boiling Spring Lakes.
A third reason for appointing the TAC was that the planning process needed
to be accountable within itself, and the product needed to be viewed as
credible and legitimate. The TAC along with the Mayor's Committee provided
a two -tiered approach to checks and balances, and it spread the working
body to include other than community residents.
Once the TAC was established, the next step was to establish a process
through which the TAC and Mayor's Committee would become involved in the
project. Each group was given a series of working papers throughout the
planning process. The TAC would meet first in a work session format, with
their conclusions and findings recorded and sent to the Mayor's Committee.
Subsequent to the TAC work sessions, the Committee held their own work
session. It was through this process that the broad based technical and
political critique preceeded the Town's critique, and, hence, maximized the
use of the TAC.
Having established the process, the first step was problem definition.
While conscious of the five questions presented above, the Mayor's
Committee and the TAC reflected upon the following guidelines, which are
recommended to other communities at the problem definition stage.
1. Articulate clearly at the outset what aspects of the problem
you are going to focus upon. All analytical methods are laced
with values, usually those held by the examiner, the audience/
client or the technician who developed the method. False ob-
jectivity is often a downfall in problem definition and needs
assessment. Be prepared to recognize these aspects and be prepared
to make adjustments during the study.
2. Take risks in challenging the conventional wisdom related to the
problem. Take nothing for granted and learn to disect viewpoints
according to interest and stakes in a situation.
3. Build in checkpoints along the course of the study, such as the
two -tiered approach at Boiling Spring Lakes, based upon specific
criteria of how balanced or how in-depth your information needs
are.
4. Identify early what your product is. In the Boiling Spring Lakes
case, it was important to not "re -study the already overstudied"
technical aspects of the situation for which thousands of dol-
lars had already been spent. Our product was to be an action
plan —not solely a new understanding of the problem from which
some other group would then develop a plan of action.
38

5. Be prepared for conflicting expert opinion at every level.
Working papers, testimony and work sessions findings will invari-
ably conflict, rendering creative consensus building a requirement.
6. Use a participatory process. While this principle is well
stressed in CAMA projects (such as in its guidelines for land use
planing (15 NCAC 7B)), it stands repeating as an important ele-
ment of projects where intial consensus is not apparent.
7. Expect the unexpected. In the Boiling Spring Lakes case, the
lack of emergency access to the east side of the tracks, while
cited as a reason for concern, emerged as a real problem in its
own right. This led to an unexpected assessment of emergency readi-
ness and cast a different light upon the preoccupations with dam
,stabilization and continuous operation of the railroad.
By addressing these points early, many hidden agendas, misconceptions,
miscommunications and future stumbling -blocks can be eliminated at the
problem definition stage.
Chapter III —Scenario Development
Chapter III demonstrates how the Boiling Spring Lakes project met the seven
guidelines presented immediately above.
The findings from the technical assessment in Chapter II indicated that
creative methods were required to challenge assumptions underlying earlier
findings and to expose aspects of the problem not heretofore recognized or
emphasized.
One of the principal attractions of the scenario writing exercise is its
ability to activate creative processes. Namely, to adjust perspectives and
expose the participants to a wide range of consequences of given actions
through a set of "what if" situations. In Boiling Spring Lakes, the
interests were clearly drawn and the respective opinions of "what the problem
is" and "what should be done about it" were well known. Politically, the
situation seemed stalemated and the entire problem solving process appeared
high -centered. The need existed to "shake-up" the situation, to re -activate
creative problem solving processes. The scenario writing exercise provided
this necessary "shake-up."
Scenario writing (see the particular reference in Chapter III) was chosen as
the main planning method because the Boiling Spring Lakes problem is so
dominated with the passage of time (geologic time). Most appealing in the
context of the Boiling Spring Lakes situation was the beginning -state
scenario rather than the end -state scenario. This allowed the group to look
at the world in terms of "opportunities" rather than "problems," and allowed
the group more latitude to respond to changes in the situation as it
proceeded.
39

Additionally, scenario writing lent itself to a participatory process,
providing a structure through which to give participants the permission to
lay out values, opinions and assumptions in front of others. In otherwords,
it provided a sense of "creative security" that set the stage for thoughtful
discussion. This, plus the fact that the TAC was comprised of such different
technical and political persuasions, and equally different professional and
personal opinions, produced a meaningful group exercise.
In fact, it is from the scenario writing session that it became clear that a
consensus model was desired— tbat the Army and the Town both had firm
convictions toward staying in Boiling Spring Lakes and that the task at hand
was one of seeking peaceful co -existence.
One of the learnings from the scenario exercise comes from the technique of
themes -extraction. That is, once the scenarios were developed, the
consultant attempted to extract and analyze themes from the scenarios --
looking for opportunities for natural coordination and compatability, as
well as points of obvious contention.
From these themes came the concept of gestalt— that the whole of the Boiling
Spring Lakes solution may be larger than the sum of its parts. Simply put, in
the event of renewed sinkhole activity, each party could act in a separatist
manner, taking steps to bolster its own position at the expense of the
position of the other. Or, it could take steps toward a commonly held
objective which would better not only its position, but the position of the
other. With all parties doing so simultaneously, presumably a situation of
betterment would be created.
Thus, the concept of gestalt and the scenario writing exercise produced the
goal statement presented in Chapter I, repeated here:
GOAL: To maintain the stability of the main lake at Boiling
Spring Lakes, to continue to operate the railroad safely, and to
provide emergency access to the east side of the tracks, all in
a manner which: 1) improves the long-term mutual compatability of
the lake and the railroad, 2) serves the interests of community
pride, and 3) is consistent with the adopted Land Use Plan.
It was upon this Goal and a recall of the problem definition in Chapter II,
that alternative solutions were designed.
Chapter IV --Alternative Courses of Action and Respective Costs and Benefits
Chapter IV presents an array of nine (which later become ten) alternative
solutions.
First, a description of each alternative was developed and each solution was
assessed for its costs and benefits (See Chapter IV).
40

It was during this stage of the project that the need for additional
technical studies became apparent. Subsequently, engineering studies were
undertaken and more detailed cost estimates established (See Chapter IV).
Additionally, the early request for information from the Army's technical
personnel paid off in a timely fashion for consideration with the
alternatives generated by other members of the TAC.
Thus, two of the learnings for replication to other communities in this
chapter are: 1) anticipate greater technical detail for cost —benefit
studies than may be apparent at the outset, and 2) ask for outside technical
information at the earliest possible time, especially where large
bureaucracies are involved.
The next step was to decide how the TAC could use the technical studies and
cost/benefit findings to set priorities for recommendation to the Mayor's
Committee. Chapter IV (and the referenced Appendix F) presents details of
the selection grid procedure that the consultant and the TAC worked through
to digest and assemble information relative to the alternatives. That
process was undertaken in two distinct steps: 1) a homework step, in which
each member of the TAC was sent the selection grids and the cost benefit
information beforehand and asked for response, and 2) the orr-site group
session in which the group collectively reconciled questions from the
homework step and articulated new assumptions and held discussion.
In retrospect, the homework step was useful only for introductory or
familiarization purposes. There was too much material and too many
definitions and assumptions involved (not to mention that the TAC members
were volunteers) to expect much before coming to the meeting. On the
otherband, the work session was much more useful since the group had had the
material to reflect upon before the session. Another key to the success of
the work session was a strict time allotment to each step in the
grid —completion exercise. Additionally, agreement was obtained from the
group members at the outset about the need to streamline the process, to
fully understand definitions, etc., rapidly complete the grid (permitting
questions for clarity only), and then holding brief discussions as needed to
enrich the record. It also helped to have two facilitators present, one to
drive the exercise and the other to watch the clock and ask probing questions
of the group as needed.
This process worked as well as it did because the group had a wide range of
alternatives to consider. The alternatives were well researched with
detailed design and cost/benefit estimates, and a systematic process for
comparison and contrast was instituted.
Chapter V--Recommended Courses of Action
The results and methodology applied to rank the alternatives developed in
Chapter IV is explained in detail in Chapter V. As mentioned in Chapter V,
the application of nominal scores (High, Medium and Low) and later the
41

application of numerical scores, allowed the ranking to be developed to the
point that it could be massaged by the group.
This latter point is important, in that such methodologies are useful to a
specified degree. Often, such are over -emphasized and relied upon too
heavily, especially in situations which are as politically and finacially
constrained as Boiling Spring Lakes'.
For these reasons, as the scores were being tabulated by one facilitator,
the other led a question -and -answer period on the advantages and
disadvantages of each option, to later be taken into account in selecting
the recommended course of action.
Often in such priority setting work, it is easy to forget that the list of
options is not homogeneous on any aspect. In this case, the list of rankings
separates into short-term and long-term actions, as indicated in Chapter V.
From such disection often comes insight into immediate steps for fund
raising, etc. which, in the Boiling Spring Lakes case, led the consultant to
consider alternative investment strategies to help put the community in a
position to better pay for priority solutions in the event of renewed
sinkhole activity.
CONCLUSION
In a nutshell, the Boiling Spring Lakes project indicates that successful
analysis of complex natural resource and political problems stretches
planning methods beyond their technical limits. Planners and community
members who are prepared to shift gears and re -think assumptions, intentions
and their own values during the course of the study are more likely than
others to be successful.
The Mayor's Committee, the TAC and the consultants will be happy to answer
any questions from other coastal communities about particular aspects of the
Boiling Spring Lakes Coastal Demonstration Project.
42

VICINITY MAP
BOILING SPRING LAKES MAP
BIBLIOGRAPHY
U. S. ARMY SINKHOLE STUDY
IMPERVIOUS LAYER EXHIBITS
SELECTION ANALYSIS EXHIBITS
A
B
C
D
E
F
43

APPENDIX A
BOILING SPRING LAKES VICINITY MAP
44

' `11 \ - _ _._ - '.• _ 1 � it ri ., Prcff!/l i r ,ice/ .
p\Po>ut i APPENDIX 61'
FUTURE SITE OF THE
TOM OF BOILING SPRING LAKcS � /—�
AND THE US ARMY RAILROAD L —
_:".._-use
-
-- N3400—'.v7800/7.5 ll r(,) - -
i943 It
M,tta)ecl by Ulc Army Ma
1) Service —
Published to civil use by the Geological Survey Ab o — -- — xaeJ =
Control by USC&GS
= Topography from aerial photographs by photogrammetric methods -
and :;y planetable surveys 1943. Aerial photographs taken 1942 /� - — —� — zT \
1 %
Aso and
40
��_�
/
/i'
11
xs3
So
\\
��_ -.�► 0
Woods a /i
//
le Creek Bride
`Ponds « u �\Y
K?9
if
-- 1 A - =
45
.r.. .� ==_ °>• / 11 ti° - —= J `, Il (\I !�

46
APPENDIX 81
TOPOGRAPHIC MAP SYMBOLS (continued)
VARIATIONS WILL BE FOUND ON OLDER MAPS
Primary highway, hard surface ..... Boundaries: National ...............................
Secondary highway, hard surface .... . . =
Light -duty road, hard or improved surface .............. —
Unimproved road ................. ................
Road under construction, alinement known .............
Proposed road....................................� — - -
State.........................................._.- - —
County, parish, municipio ........................
Civil township, precinct, town, barrio ...............
Incorporated city, village, town, hamlet .............. ..........
Reservation, National or State ..................... — . _ .
Dual highway, dividing strip 25 feet or less............
Small park, cemetery, airport, etc ................................
Dual highway, dividing strip exceeding 25 feet.........
Land grant .....................................— - --
Trail............................................------------
Township or range line, United States land survey..... .
Township or range line, approximate location ..........----___.
Railroad: single track and multiple track ......... ....
Section line, United States land survey ...............
Railroads in juxtaposition ............ .......... ...
Narrow gage: single track and multiple track.......... .
Railroad in street and carline.. ........... .........'
Bridge: road and railroad ........
—r o
Drawbridge: road and railroad ......................
Footbridge......................................... ----...... <---.
Tunnel: road and railroad ..... .... ..................
I !I I I
Overpass and, underpass ...... ...
Small masonry or concrete dam ....... _
Dam with lock ..................................... �-
Dam with road ...... ............... ..............
-
Canal with lock......... ..
Buildings (dwelling, place of employment, etc.) .......... J a.:
School, church, and cemetery. t t t: ; Cem
Buildings (barn, warehouse, etc.).. . .°o
Power transmission line with located metal tower ... .................
Telephone line, pipeline, etc. (labeled as to type) ........ -------.
Wells other than water (labeled as to type) ............. .G.I.....°Gas
Tanks: oil, water, etc. (labeled only if water)............00 ®Water
Located or landmark object: windmill ................ o.. ..... A
Open pit, mine, or quarry; prospect. . . ................... ........ X
Shaft and tunnel entrance .................... ...... a .......... T
Horizontal and vertical control station:
Tablet, spirit level elevation .... .................. BMG5653
Other recoverable mark, spirit level elevation......... a5455
Horizontal control station: tablet, vertical angle elevation VABMp9sr9
Any recoverable mark,vertical angle or checked elevation 4,3775
Vertical control station: tablet, spirit level elevation..... HMX957
Other recoverable mark, spirit level elevation........ X954
Spot elevation .............. . ................... x1369
Water elevation .............. .................... 67o
Section line, approximate location
Township line, not United States land survey
Section line, not United States land survey ............
Found corner: section and closing ....................-+- -T-
Boundary monument: land grant and other ............ a .......... a
Fence or field line . ................................ .
Index contour ........ ____ Intermediate contour..
Supplementary contour Depression contours . .
Fill ................. Cut.................
Levee ............... •........................... Levee with road......
Mine dump.......... Wash
Tailings............. Tailings pond
Shifting sand or dunes l Intricate surface ......
Sand
'Gravel
area...........
beach.........
Perennial streams ....
Intermittent.streams..
Elevated aqueduct....
. Aqueducttunnel......_
-
Water well and spring- ....... °..- Glacier .............
.
Small rapids..........
Small falls ...........
^-�_-
Large rapids.........
Large falls ...........
Intermittent lake .....
'______- Drylakebed ..........
._-
Foreshore flat.......
.."=v_ Rock or coral reef....
r'r�''-L
Sounding, depth curve. 2-'' Piling or dolphin.....
°
Exposed wreck.......
Sunken wreck........
`
Rock, bare or awash;
dangerous to navigation ...........
`
Marsh (swamp)....... Submerged marsh ....��'
Wooded marsh....... - Mangrove ...........
Woods or brushwood.. Orchard.............
Vineyard............! Scrub ...............
Land subject to
controlled inundation _.._____ Urban area ..........

f s;n �y: -rj%" y-•['a';. h^1ti p:
k �.• .tam ,,,_�`sn. • � '•i �. _` � �'v -t' M ► �'-
CURRENT SITE
�'� �s*•r,.T,- y.t` . ■. t'•' .Y+-� _;,c s lay.:• <� •9 � ti,:;��'
- 1F THE
AND THE US ARMY RAILROAD
TOWN OF BOILING SPRING LAKES
,'.� , wti.�' •• :�sr, Wa tr?: •S !� a b,, ..?V� .. a •:. •'--•': �• �.. 't* r ♦t'��t-t" :.
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APPEMT.X C
BIBLIOGRAPHY
"Boiling Spring Lakes Dam Phase I Inspection Report, National Dam Safety
Program," Corps of Engineers, September 1980.
"Brunswick County, North Carolina, N. C. Coastal Area Management Act Land
Use Plan update," March 2, 1981.
"Coal Export in North Carolina: A Review of the Issues," N. C. Dept. of
Resources and Community Development, October, 1981.
"Coastal Energy Transportation Study, Phase III Report, Volume 3," The
University of North Carolina Institute for Transportation Research
and Education, August, 1982.
"Environmental Management Commission Administrative Hearing," April 7, 18,
19, 1978 (recommendation of the hearing officer).
"Grounds - Water Hydrology of the Boiling Spring Lakes Area (as related to
the development of active sinkholes)," LeGrend, Harry E., Consulting
Hydrogeologist, December 1977.
In Introduction to Geotechnical Engineering, Holtz and Kovacs,
Prentice -Hall, Inc., New Jersey. 1981.
"Land Use Plan, Boiling Spring Lakes, North Carolina," First Draft, May,
1982.
"North Carolina Department of Transportation, Cole Train Movements through
the City of New Bern," a preliminary analysis, March, 1981.
"North Carolina Environmental Management Commission, Final Decision,
July 13 and 25, 1979" (approval for Boiling Spring Lakes Dam Repair
Plan by Reeves Telecom Corporation).
"Reeves Proposes City Take-over of property," Newspaper Clipping, by
Ed Harper, Local newspaper, date unknown.
"Reeves Telecom Corporation vs. City of Boiling Spring Lakes," Motion for
Summary Judgement - Transcripts of the June 8, 1977 judgement.
Scenario Writing: A Developmental Approach, Larry Hirschhorn, Journal
of the American Planning Association, April 1980, Vol. 46, Number 2.
"Study of the Access Railroad Sinkhole Problems," U. S. Army Corps of
Engineers, Military Ocean Terminal, Sunny Point, N. C., November,
1981.
48

"Subsurface Investigation, Boiling Spring Lakes Dam," Henry Van Oesen
& Associates.
"U. S. Army Corps of Engineers Permit Program, a Guide for Applications,"
November, 1977.
49

STUDY OF THE
• ACCESS RAILROAD SINKHOLE
PROBLEM
MILITARY OCEAN TERMINAL
SUNNY POINT, NC
APPENDIX D
Prepared by: \�..
U. S. Army Engineer District,
Savannah
Corps of Engineer's
Date: 20 Nov 81
Principal Action Officer:
B. G. Williams
SASEN-MP
912/944-5362
50
r

TABLE OF CONTENTS
,. INTRODUCTION ............. ................................................
I..
EVALUATION......... :................. .................................1-3
REC=4ENDATION.............................................................3
DRA'dINGS: Plates l through-5
APPENDIX:
A. Cost Estimates
B. Memorandum For Record — Environmental .
Inspection — 11 June 1981
C. Background Correspondence
51

INTRODUCTION:
This study presents a recommendation for a solution to deal with the occurrence
of sinkholes in the Sunny Point access railroad bed. The solution selected
should provide the least Risk of Loss of the railroad with the greatest
Confidence of Success for the lowest cost. It is the result of a November 1980
review by MTMC of,a previous report entitled, "Technical Report on the Sinkhole
Development Along the Sunny Point Access Railroad At Boiling Springs, 1918,"
prepared by Savannah District. Funds for this study were provided by MTXC in
March 1981.
Five alternative solutions were considered in the final analysis and will be
discussed below. In addition consideration was given to inducing failure along
the rail line, constructing a floating or mat foundation, and constructing two
additional parallel sets of track through the areas under study. Risk of
liability from potential damage to adjacent properties'was judged too great to
warrant further study of the "induce failure" alternative. The floating or mat
foundation was judged not practical from an engineering standpoint.
Constructing two additional parallel sets of track may reduce the probability
of loss of a line at the same time but is no less vulnerable to failure than
other less costly alternatives.
EVALUATION OF ALTERNATIVES:
In the evaluation of alternatives, the following measures were used: Cost,
Construction Time, Restriction on Operation During Construction, Restriction on
Operation, Environmental Impact, Confidence of Success, and Risk of Loss. No
Restriction on Operation During Construction was a criterion used in selection
of alternatives. Currently, the mission is not adversely affected by :he
physical inspection prior to use of the rail line and the 5 mile per hour slow
order in effect. Confidence of Success was rated good, fair, or ?oor. risk o`_
Loss was rated none, low, moderate, or high. All cost estimates are on the
same basis, November 1981.
None of the alternatives would impact significant amounts of woodlands or areas
used as habitat by threatened or endangered animal species. The alternatives
would not result in significant alteration of the existing environment.
Therefore, a finding of no significant impacts could be prepared for the work
if the final plans are not significantly different from the preliminary plar.s.
A Memorandum For Record dated 11 June 1981 addressing the environmental
inspection is in the appendix.
ALTERNATIVE I. Operate as you are with physical inspection prior to travel and
a 5 mil-e per hour slow order in effect during travel. risk of Loss is low and
Confidence of Success is rood. The following contingency actions are
recommended with this alternative:
1. Maintain a stockpile of rail and ties for a detour in case of the
occurrence of a sinkhole and have a plan for plugging the sinkhole.
a. Cost ...................$78,320.
b. Storage area: North Rai: Holding Yard
52

C. Borrow material from onsite within the existing right-of-way.
d. Time to respond with government forces and equipment .......1 3
weeks
(Stockpiling a prefab bridge, though practical, is estimated to cost about
$231,040 and is not recommended in this alternative.)
2. In the case of a national emergency reroute the railroad over the darn
at the time of mobilization and maintain this as a standby in case of a problem
in the main line.
a. Cost ..................... $25 % 430
b. Storage area for rail and ties......... North Rail Holding Yard.
c. Construction time (government forces) ... Two weeks from obtaining
right -of -entry for construction purposes.
ALTERNATIVE II. Grout Area 1 (Station 805+00 to Station 808+00)ard Area 2
Station 824+00 to Station 825+50). This involves pumping a cement type
mixture underground to strengthen the subsurface. The Risk of Loss is
moderate, and the Confidence of Success is fair.
a. Cost ....... .... 0.......... $19526,600
b. Construction Time ........6 months
In addition the slow order should remain in effect and contingency in case of
the occurrence of a sinkhole should be maintained increasing the cost of this
alternative to $1,604,920.
ALTERNATIVE III. Construct two new bridges, one in area 1 and one in area 2
and replace the wooden trestle over Allen Creek with a bridge. This is
referred to as the "Incremental Bridge" Alternative. The Risk of Loss is low,
and the Confidence of Success is good.
a. Cost ..$1,031,490
b. Construction Time ........18 months
In addition the slow order should remain in effect and contingency in case of
the occurrence of a sinkhole should be maintained increasing the cost of this
alternative to $1,109,810.
ALTERNATIVE IV. Construct a total bridge over the area from Station 792+00 to
Station 832+00, 4,000•feet. The Risk of Loss is none, and the Confidence of
Success is Rood.
a. Cost.....................$7,<<<�0,210
b. Construction Time* ..... ...24 months
53

ALTERNATIVE V. Replace the wood trestle over Allen Creek with a permanent
bridge. The Risk of Loss is low, and Confidence of Success is good.
a. Cost .......................$436,650
b. Construction Time ........... 12 months
In addition the slow order should remain in effect and contingency in case of
the occurrence of a sinkhole should be maintained increasing the cost of this
alternative to $514,970.
RECO.T NDATION:
Alternative I, operate as you are with a contingency plan, is recommended. It
is judged as having low risk, good confidence of success, and a cost of
$78,320.
54

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Figure 1 EXISTING DAM
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231
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Figure 2
DAM WITH 50 Ft. IMPERVIOUS LAYER
:1,
ftfscc fn1l1: 3. ZaZs.o' 5IT lcc ( 12. vix 41a.XIA,, -1. ( I+lu "S �i3/5"
90 J--cilon of Sccpc .jr t•a r•, (xi�il nf� /��. 7—J7)u
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1
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Figure 3 DAM WITH 100 Ft. IMPERVIOUS LAYER
�SP'llw•►/
/ -v
Is•e�•el�: 3.2ti� to -S jsZ.If•+'�;)�It�): s.q-10-Sti'3/5er
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0
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drrp e%o..J PIAOI. It.,er'
1?.Nr�•.;t� «<�tlt 13Y.,�.tra{.fit SI00•►rll
r►� M:1! lur',l�,,,� % 13IilLft•r1.0�' 1951530
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1 ' i'r. t _.�.�:. `r 5:..1ti.:�' Yi.�' .✓.4:r�::» A '•rr�iiv=`^'64 'l�r' 'h► ;L1(;;r.1.Y

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00
EXHIBIT A: SELECTION GRID
POSITIVE COMPLEXITY $
IMPACT ADVERSE COST OF REQUIRED
ON THE DURABILITY UNIT TOTAL AVAILABILITY ENVIRONMENTAL MAINTENANCE TIME FOR
AI.TFRNATTVF rnIIRSRS nR ACTTnN PnnRI PM nurD TTUP rncm rne•r nc et.u{.{It.{r ..n.......
1)Construction of a dam up-
stream from existing dam.
2)Construction of a dam own -
stream from the existing dam.
'
3 Impervious layer
4)Lowering the water level
S)Relocation of the rail-
road onto the existing dam.
6)Construction of single grout
curtain the entire length of
the dam.
7)Construct a triple grout
curtain along the entire
length of the dam.
8)Conduct a train vibration
study along the trestle
and bridge area.
y
9)Establish alternative
emergency access route
across railroad.
H
Please rate each alternative "high", "medium", or "low" by putting fill", "M", or "L" in each cell.
IZI
c

EXIII BIT 4
ALTERNATIVE COURSES OF ACTION ADVANTAGES DISADVANTAGES
1)Construction of a dam up-
stream from existing dam.
2)Construction of a dam down-
stream from the existing dam.
3 Impervious layer
4)Lowering the water level
S)Relocation of the rail-
road onto the existing dam.
6)Construction of single grout
curtain the entire length of
the dam.
7)Construct a triple grout
curtain along the entire
length of the dam.
8)Conduct a train vibration
study along the trestle
and bridge area.
9)Establish alternative
_.
emergency access route
across railroad.
10a) Relocate railroad system.
ro
�d
10b) Relocate railroad down-
r�
stream.
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