Final Report Centralized Water Feasibility Study for Knotts Island & Gibbs Woods-1997

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FINAL REPORT
CENTRALIZED WATER FEASIBILITY STUDY
FOR
KNOTTS ISLAND & GIBBS WOODS
DCM COPY DCM COPY
lease do not remove!!!!!
Division of Coastal Management
Bissell Professional Group
Kitty Hawk, North Carolina
in association with
Edwin Andrews & Associates
Raleigh, North Carolina
Devised February, 1997

FINAL REPORT
CENTRALIZED WATER FEASIBILITY STUDY
FOR
KNOTTS ISLAND & GIBBS WOODS
Prepared By
Bissell Professional Group
Kitty Hawk, North Carolina
in association with
Edwin Andrews & Associates
Raleigh, North Carolina
Revised February, 1997
I
"The preparation of this report (map, document, etc.) 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 Ocean and
Coastal Resources Management, National Oceanic and
Atmospheric Administration."
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KNOTTS ISLAND & CIBBS WOODS CENTRALIZED WATER
FEASIBILITY STUDY REPORT
TABLE OF CONTENTS
SECTION I: Introduction
SECTIONII: Population & Water Demand Projections
SECTIONIII: Water Survey Results
SECTIONIV.• Source Analysis
SECTION V: Basis of Design and Cost Estimates
SECTION VI: Implementation Plan

List of Figures
Follows Page
Figure 1: Study Area Vicinity Map 3
Figure 2: Knotts Island Conceptual Water System Layout 28
Figure 3: Gibbs Woods Conceptual Water System Layout 28
List of Tables
Page
Table #1:
Residential Building Permits Issued
4
from 1985 to 1995
Table #1A:
Rate of Growth
5
Table #2:
Population, Housing & Water Demand Projections
5
Table #3:
Survey Responses
I I
Table #4:
Knotts Island Groundwater Survey Results
21
Table 95:
Gibbs Woods Groundwater Survey Results
22
Table #6:
Wells & Well Sites Required for Central Systems
23
Table 47:
Knotts Island with Fire Protection
27
Preliminary Estimate of Probable Project Cost
Table #8:
Knotts Island without Fire Protection
27
Preliminary Estimate of Probable Project Cost
Table #9:
Gibbs Woods with Fire Protection
28
Preliminary Estimate of Probable Project Cost
Table 910:
Gibbs Woods without Fire Protection
28
Preliminary Estimate of Probably Project Cost
Table #11:
Summary of Projected Cost Per Connection
29

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SECTION I: INTRODUCTION
The 1990 Currituck County Land Use Plan recommended as one of its goals that a plan be
prepared addressing the feasibility of providing centralized water supply systems for the
Knotts Island and Gibbs Woods areas of Currituck County. The purpose of this study is to
fulfill the goal of providing a water system feasibility study for those two areas. The report
addresses an evaluation of water sources that could be utilized as a basis for the water
systems and the populations to be served and resulting water demands to be provided. A
preliminary basis of design is then presented in order to determine the estimated costs, and
then to look at funding sources that may be available and implementation strategies that
should be considered for providing a centralized water system for each of these communities.
As work began on this study, it became apparent that a question which needed to be
addressed early on was whether or not the public perceived a need for centralized water
systems in these communities. In order to solicit as much input as possible from the public
within the time available, a survey was mailed to all of the property owners of record located
within these two communities. The survey also advertised two public meetings - the first
which was held at the Gibbs Woods Civic Center, and the second at Knotts Island Elementary
School, both on Monday,
September 30, 1996 to discuss the results of the survey and the need for centralized water in
both areas. The results of the surveys and public meetings were extremely valuable to the
study process, and will be discussed later in this report.

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SECTION II: POPULATION & WATER DEMAND
Knotts Island is located in the northeast section of Currituck County, situated between Knotts
Island Channel to the east and Northwest River to the west. No direct transportation is
available from the remainder of the Currituck mainland, except for the ferry which runs from
the Currituck County Courthouse area to Knotts Island. A highway access is via Highway
615 from Virginia Beach. The majority of the western portion of the island is composed of
wetlands which comprise the Mackey Island National Wildlife Refuge.
While some developable areas exist in the northwest corner of Knotts Island, the east side of
the island contains the majority of the soils which are suitable for development using
conventional on -site wastewater disposal systems.
Knotts Island contains zoning districts including: Residential -Mixed Use (RA), Agricultural
(A), General Business (GB), and Residential/Recreational (RR). The majority of the land
with good development potential is zoned RA, which permits development with a minimum
lot size of 40,000 square feet.
Gibbs Woods is located in Moyock Township, west of Knotts Island and south of the
Virginia/North Carolina State line, and is accessible by S.R. 1248, S.R. 1250, and
S.R. 1351 through Virginia Beach. Zoning within the Gibbs Woods study area is primarily
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agricultural (A), with small areas of general business (GB) and residential (R). Developable
soils within the Gibbs Woods area are primarily located within the agricultural zoning district,
which requires a minimum 3-acre lot size for new development. The study area vicinity map
is shown on the following page (Figure 1).
Population and water demand projects were made for both areas based on current zoning
district regulations, an analysis of the development potential of the soil types present within
these zoning districts, and information obtained from the Currituck County Department of
Planning & Inspections, including a 10-year history of building permits issued, average
occupancy rates, and the average number of people per dwelling unit in each study area.
Utilizing soils map overlays furnished by the Planning Department, the acreage of soils which
are either suitable for development or marginally suitable for development were determined
for each area as a basis for determining an estimate of the number of dwelling units likely to
exist at buildout. Soil types which were considered to be generally suitable for development
include: Altavista, Bojac, Conetoe, Dragston, Munden, and Newhan. Soils which are
moderately to marginally suitable for development include: Augusta, Nimmo, Osier,
Portsmouth, and Tomotley. The Roanoke soils, while generally not considered wetland soils
in these areas, are generally considered to have low development potential due to the presence
of massive clays.
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LEGEND:
A: RNOTTS ISLAND AREA
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B: GIBBS WOODS AREA
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FIGURE 1
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OARE
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The historic data available on residential building permits from the Currituck County
Department of Planning & Inspections from 1985 to 1995 were used to determine the rate
of growth toward this ultimate build -out figure. Since the growth rate accelerated during the
most recent five years of the historic data, the more rapid development rate was utilized in
the projections.
The following tables summarize the data utilized to develop population and water demand
projections. As shown in Table 2, the number of dwellings at Knotts Island is expected to
grow from the current estimate of approximately 583 to an ultimate build -out number of
approximately 2,842. At Gibbs Woods, it is projected that the existing dwellings which
number approximately 166 will increase to approximately 362 at buildout of the developable
areas. Water demand is based on the North Carolina Division of Environmental Health
standard of 400 gallons per day per dwelling unit.
RESIDENTIAL BUILDING PERMITS ISSUED FROM 1985 TO 1995
TABLE #1
Yr.
Location
'85
'86
'87
'88
'89
'90
'91
'92
'93
'94
'95
Totals
Gibbs Woods
4
3
3
0
0
3
4
4
.2
5
9
37
Knotts Island
1 5
1 10
1 13
1 8
1 13
1 8
1 19
1 21
1 18
1 25
1 16
1 156
IF- I

RATE OF GROWTH
TABLEAA
LOCATION
1985 THRU 1995
1991 THRU 1995*
Gibbs Woods
3.4 D.U./Year
4.8 D.U./Year
Knotts Island
14.2 D.U./Year
19.8/D.U./Year
*Utilized in Projections
POPULATION, HOUSING & WATER DEMAND PROJECTIONS
TABLE #2
1985
1995
2005
2015
Ultimate*
Projected
427
583
781
979
2,842
Dwellings
KNOTTS
ISLAND
Projected
Population
943
1,288
1,725
2,163
6,279
Expected
Water
N/A
0.233
0.312
0.392
1.14
Demand
(MGD)
Projected
129
166
214
262
362
Dwelling
Projected
Population
347
447
576
706
974
GIBBS
WOODS
Expected
Water
N/A
0.066
0.086
0.105
0.145
Demand
(MGD)
*Based on development potential using soils and zoning as constraints, and
' using the following occupancy rates and persons per dwelling:
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IF--
OCCUPANCY RATE
PERSONS/DWELLING
KNOTTS ISLAND
0.8529
2.59
GIBBS WOODS
0.9311
2.89
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Based on the water demand projects presented in Table 2 above, it is suggested that, if central water supplies are
developed for Knotts Island and Gibbs Woods, the following capacities be used as a basis of design
Initial Capacity
Ultimate Capacity
Knotts Island
0.40 MGD
1.0 MGD
Gibbs Woods
0.010 MGD
0.015 MGD
' In the development of these estimates, it was assumed that the advent of a centralized water system
would not of itself be growth inducing and would not result in any changes of zoning. The trend in
' Currituck County over the past several years has been to maintain or reduce allowable density rather
than increasing it, and this trend is not expected to change in the foreseeable future.
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' SECTION III: WATER SURVEY RESULTS
As mentioned previously, a water study survey was mailed to all property owners of record
on Knotts Island and Gibbs Woods. The purposes for conducting the survey were threefold.
' The surveys were used to gather information about water quality and quantity for use in
completing the source analysis. They were also utilized to determine general public opinion
' and perception regarding the need for centralized water supplies on Knotts Island and Gibbs
' Woods, and to take various opinion and concerns into consideration in the preparation of the
report. Finally, the survey was used to advertise public meetings which were held at Knotts
Island and at Gibbs Woods to discuss the results of the survey and to receive additional public
input concerning the need for central water systems in these areas.
A total of 1,028 survey forms were mailed to property owners during the week of September
9, 1996. Of the surveys mailed, 471 responses were received, which is approximately a 46
percent return rate. (Responses were received through the end of October , 1996, in part due
to additional public interest generated through airing a tape of the public meeting held at
Knotts Island on the public information channel for a week after the public meeting.)
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Approximately 54 percent of the respondents from Knotts Island were opposed to the
development of a centralized water supply for that area, with approximately 36 percent in
favor, and approximately 10 percent undecided. At Gibbs Woods, approximately 47.5
percent of the responses were in favor of a centralized water supply, approximately 45
percent opposed, and approximately 7.5 percent undecided. The results of the surveys are
tabulated on the following page.
Development of the questionnaire was the joint effort between the consultants and the
Currituck County Planning staff, and is presented on the pages following the response
tabulation. Groundwater quality and quantity issues are discussed and related to the aquifers
in Section 4. Due to the voluminous nature of the questionnaire responses, they are only
summarized in this report, but a complete copy of all responses received is on file in the
Currituck County Planning Department.
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Currituck County
_� Ik•Ixtrtnunt of I'lannin�, atxl Itulmclitxu
r. lint Office Iktx 70
It,7o.- Curtum(k, N„tth Carohij., 27929
919.111 1055 / 919.232.3378
KNOTTS ISLAND/GIBIIS WOODS WATER STUDY FAX [phone]
1 Currituck County is now in the process of determining the need for centralized water on Knolls Island and Gibbs
Woods. Similar studies have been completed for the Mainland and Outer Batiks areas.
Your input for this study is extremely important. Therefore, we respectfully request that you take a couple of
minutes to reply to the following questions and return immediately in the pre -addressed, stamped envelope
included.
' I. What best describes your situation:
❑ 1 live at Knolls Island
❑ I own property at Knotts Island, but do not live there
2. Your street name or address (optional):
3. Do you have a well on your property?
❑ Yes ❑ No (If no, skip to question ll7)
4. Depth of well (if known): feet.
1 S, Well driller (if known):
6. Water Quality Issues:
' a. Does your water cause brown/orange stains?
❑ Yes ❑ No
b. Does your water cause green staining?
' ❑ Yes ❑ No
C. Does your water have odor problems?
❑ Yes ❑ No
' d. Do you have a water softener?
❑ Yes ❑ No
e. Does your well produce enough water?
❑ Yes ❑ No
f. Other problems:
7. Would you support a central water supply system on Knolls Island?
❑ Yes ❑ No
8. Any other comments:
Should you have any questions about this survey, please call Shelby Lusk at 232-3378 ext. 260.
A public meeting will be held at Knolls Island Elementary School on Monday, September 30, 1996 from
8:00 p.m. - 9:30 p.m. to discuss the results oj'this survey and the need for central water.
Your attendance is encouraged.
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Currituck County
Ik•ltunnt•w of I'lannutl; :111(1 I11s1)cctioru
.rY
I'4Mt (Vice N)x 70
167�, Ctirnnak, Noxtl) Carolina 27929
919-2 Q 1055 / 919.232.3378
FAX [phone]
KNOTTS ISLAND/GIBBS WOODS WATER STUDY
Currituck County is now in the process of determining the need for centralized water on Knotts Island and Gibbs
Woods. Similar studies have been completed for the Mainland and Outer Banks areas.
Your input for this study is extremely important. 7berefore, we respectfully request that you take a couple of
minutes to reply to the following questions and return immediately in the pre -addressed, stamped envelope
included.
I. What best describes your situation:
i ❑ I live at Gibbs Woods
❑ I own property at Gibbs Woods, but do not live there
2. Your street name or address (optional):
' 3. Do ro you have a well on your property?
Ely Yes ElNo (If no, skip to question ll7)
i4. Depth of well (if known): feet.
S. Well driller (if known):
t6. Water Quality Issues:
a. Does your water cause brown/orange stains?
1 ❑ Yes ❑ No
b. Does your water cause green staining?
❑ Yes ❑ No
C. Does your water have odor problems?
❑ Yes ❑ No
' d. Do you have a water softener?
❑ Yes ❑ No
e.. Does your well produce enough water?
1 ❑ Yes ❑ No
f. Other problems:
7. Would you support a central water supply system at Gibbs Woods?
❑ Yes ❑ No
8. Ar{y other cornnrents:______--__—_—_-----_---__—___—_`_ —_—_
Should you have any questions about this survey, please call Shelby Lusk at 232-3378 ext. 260.
' A public meeting will be held at Gibbs Woods Civic Center on Monday, September 30, 1996 from
6:00 p.m. to 7: 30 p.m. to discuss the results of this survey and the need for central water.
Your attendance is encouraged.
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GIBBS WOOD OTTS ISLAND WATER STUDY
SURVEY RESPONSES
(TABLE #3)
Total Number of Surveys Mailed:
KNOTTS ISLAND
Generally in Favor of Central Water
Generally Opposed to Central Water
Undecided or Needs Cost Information
Total:
GIBBS WOODS
Generally in Favor of Central Water
Generally Opposed to Central Water
Undecided or Needs Cost Information
Total:
Total Number of Surveys Returned:
(Unopened)
Total Respondants:
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19028
12
127 (36%)
189 (54%)
37 (10%)
353
56 (47%)
53 (45%)
9 (8%)
118
471
(46%)

Many comments were received which were noteworthy in terms of presenting different
opinions regarding the need for centralized water supply in these areas. Several of these
comments are repeated below:
A. Gibbs Woods Responses:
Excerpts from Positive Responses:
1. The majority of respondents utilize a water softener.
2. Nearly all of the respondents indicated that their wells produce a sufficient
quantity of water.
3. Several respondents felt that central water would be good for the entire area
and that the sooner provided the better off everyone would be.
4. Concern was expressed about the shallowness of the wells with potential of
contamination.
5. One respondent indicated that North Carolina should work with Virginia
Beach to bring water supply to these areas from Lake Gaston.
6. One respondent was in favor of a desalinization system.
7. At least one respondent was in favor of centralized sewage as well as central
water.
8. At least one respondent was concerned about water loss due to power
outages.
Excerpts from Negative Responses
1. Several respondents were adamant that they would not hook up to a
centralized water system under any conditions.
2. Several respondents were more concerned about garbage disposal and paved
roads than water supply.
3. Concern was raised about limiting development.
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4. Several respondents were concerned about the potential cost of connecting
to a central system.
5. At least one respondent felt that the individual should be responsible for water
and not the taxpayers as a whole.
Undecided Responses
1. Several of those undecided appeared not to have made a decision due to
uncertainty about cost.
Knotts Island Responses:
Excerpts from Positive Responses
1. At least one respondent was concerned about fire protection and interested
in the improved protection a central supply would afford.
2. At least one respondent was concerned about wells drying up during drought
conditions.
3. Several respondents indicated problems with sand and sediment buildup in
their wells. The possibility of well contamination was raised due to future
development without central water supply.
4. One respondent mentioned that hooking on should be voluntary for existing
owners but mandatory for new development.
5. Water quality problems were mentioned (brown/orange color not conducive
to drinking.)
6. The cost of operating water softeners and replacing them periodically was a
concern.
7. The level of support would depend upon cost.
8. One resident would like to rely on grants and loans so that no tax increase
would result from a centralized supply.
9. Taste and odor problems were mentioned.
10. Several people mentioned the desire to avoid a tax increase.
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11. At least one respondent indicated that bottled water needed to be purchased
for human consumption.
12. It was mentioned that property values would increase with the installation of
centralized water.
13. At least one respondent would also like a central sewer system.
14. It was mentioned that any assessment should not be paid until the time of
hook-up.
Excerpts from Negative Responses
1. Existing well water is of good quality; central supply is not needed.
2. Sewage disposal and water drainage are bigger concerns.
3. Desire for developers to shoulder the majority of burden of centralized supply.
4. Want to stop development of the island.
5. Concern about cost to the individual.
6. Concern about cost impact on senior citizens.
7. Concern about cost to residents who own large tracts used for farming.
8. More concern about mosquito control.
9. Concern about taxes.
10. Concern about mandatory vs. voluntary connections.
11. Concern about population density. Would like to maintain rural character of
the community.
12. It was noted that Sandy Point Resort already has a state -approved central
water system.
13. Concern about drainage.
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14. Concern that quality of some centralized water systems is low (e.g.
Chesapeake).
Excerpts from Undecided Responses
1. Concern about cost and time frame.
2. Would like more information.
3. Concern about getting enough input from young people and newer residents.
4. Concern about system reliability.
5. Wants to make sure that the State of Virginia has nothing to do with it.
6. Most residents would like more information on cost.
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SECTION IV: SOURCE ANALYSIS
Several potential sources of water to supply centralized systems at Knotts Island and Gibbs
Woods were explored. The initial, and most obvious, source evaluated was the utilization of
the Yorktown aquifers which are presently being utilized by most of the individual well
supplies in these areas. A more in-depth analysis of those aquifers follows.
A second potential source would be the Currituck Sound, which has brackish water. Use
would require a desalinization system with a resultant concentrate waste stream to dispose
of. There is presently no accepted cost-effective solution to this disposal problem in
Currituck County. A sound source would also be be sensitive to the release of salt brine
concentrate from new City of Chesapeake deep wells near the Northwest River. The
treatment of this source would be considerably more expensive than would treatment of the
available groundwater sources due to the need for a filtration plant ahead of a desalinization
system. The water quality of the surface water source is also likely to fluctuate considerably
with changing rainfall, runoff, etc. This source is not explored further in this report.
Alternative sources of water available to the Knotts Island and Gibbs Woods areas include
purchase of water from Virginia Beach (including sources such as Norfolk, Chesapeake,
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Lake Gaston and Potomac Aquifer wells located in the Suffolk area). It is believed that the
long-term costs associated with these alternatives would also be significantly greater than
costs associated with Yorktown wells. It would most likely also be politically much more
difficult to accomplish than would the development of in -state supplies.
Due to the relative cost and availability of groundwater in the study areas, the source analysis
focused on utilization of the Yorktown aquifers for Knotts Island and Gibbs Woods.
Aquifer Description:
An earlier report "Geology and Ground -Water Resources of the Hertford -Elizabeth City
Area, North Carolina," Ground Water Bulletin Number 10, by William R. Harris and H.B.
Wilder, 1966 described two Yorktown Aquifers. The Yorktown Aquifers were described as
the Upper Yorktown and the Lower Yorktown Aquifer. Recent data from Virginia and
North Carolina, reveal three water bearing units in the Yorktown Formation. These units are
labeled the Upper Yorktown, Middle Yorktown and the Lower Yorktown Aquifers (Report
of Hydrogeologic Investigation Groundwater Development Phase, Virginia Beach Fresh
Groundwater Project for the City of Virginia Beach, Virginia by Converse Ward Davis Dixon,
Inc. 1981 Pungo Ridge tests PNG-02 & 03 ). Typically, only one or two of these aquifers
are present at any one location because the geologic formations are discontinuous. In the
Water Study Questionnaire the depth of the well information enabled us to estimate the
percentage of wells completed in each aquifer and to determine if any of the aquifers are
absent.
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The Virginia State Water Control Board (Department of Environmental Quality) established
' a test station in the vicinity of Blackwater. Two water bearing aquifers were tested from 20
1 to 24 feet and 66 to 76 feet below ground surface. The water table and the Upper Yorktown
aquifers were logged and water quality samples were collected. Generally, the Yorktown
' aquifer exhibited hardness with less than 0.5 milligrams per liter of iron and the water table
exhibited softer water with more than 1.2 milligram per liter of iron. Information obtained
from these test wells is included as Appendix A.
I
The Gibbs Woods and the Knotts Island area questionnaire responses indicate that the Upper
and Middle Yorktown aquifers are present in both places and the water table aquifer is used
substantially. The Upper Yorktown aquifer is projected to be between 50 to 70 feet below
land surface and the Middle Yorktown aquifer appears to be present from 80 to 120 feet. It
is estimated that the Lower Yorktown aquifer is probably deeper than 120 feet, if present at
all (In the Virginia beach study wells screened below 120 feet had chloride concentrations
' of more than 500 milligrams per liter).
The next available aquifer is the Beaufort Formation (correlatable to Mattoponi Formation
in Southern Chesapeake). This aquifer is expected at a depth of approximately 600 feet
' below land surface in the Gibbs Woods and Knotts Island area. The aquifer consists of
glauconitic sands with moderate hydraulic conductivity. The chloride content i",bably near
' marine concentrations.
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A study performed for the City of Chesapeake in 1982 (Artesian Aquifer Test Well Program,
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Contract 9A, Chesapeake, Virginia, Edwin E. Andrews I1I, 1982) at the Northwest River
treatment plant and three other sites confirmed that chloride concentrations were related to
' hydraulic conductivity. The underlying Potamac Formation contained more permeable sand,
resulting in lower or similar chloride concentrations than the Mattoponi Formation. There
' is probably a source of high chloride water at a depth of approximately 1000 feet in the Gibbs
Woods and Knotts Island area that is suitable for treatment using desalinization technology.
' New wells and expected heavy pumping by the City of Chesapeake would result in a
continuing increase in the chloride concentrations in the Cretaceous aquifers in the Gibbs
Woods and Knotts Island area.
1
' Current Groundwater Resources:
Groundwater resources for the Gibbs Woods and Knotts Island area are limited to a recharge
' area consistingof the Gibbs Woods area extending into Virginia and the Knotts Island land
g g
' area. The groundwater that is currently pumped is stored in four aquifers (water bearing
' sands and shells). There are two characteristics of these water bearing layers that affect yield
and reliability. The first characteristic is the ability of the sand to transmit water to a pumping
' well. This is called transmissivity. The second characteristic is the ability to store water or
storativity. These relatively shallow aquifers store and transmit an adequate volume of water
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to wells in the region. It is uncertain that these formations will transmit the desired volume
to a central system without the use of "well fields", consisting of many low -yield (estimated
25 to 50 gallons per minute, maximum) wells spread out to utilize the storage potential of the
aquifers.
As discussed, the four aquifers are not continuous throughout the area. The geology changes
from sand to clay at many depths in a manner similar to what we see on the surface. For
example, Knotts Island consists of two dominant surface conditions. A regressive beach ridge
sand deposit exists on the eastern edge running north to south (parallel to the outer banks).
This ridge is probably a remnant of the beach from when sea level was higher than it is today.
The area to the west of this sandy ridge consists of low energy lagoon, swamp and estuarine
deposits. It is expected that the best yielding wells in the water table aquifer are along the
ridge. The Yorktown aquifers are typified by shallow marine clays with shells and sand
lenses up to 20 feet thick deposited by littoral or near shore wave energy during the Miocene
Epoch. Each of the Yorktown Aquifers is defined within the Yorktown Formation based on
relative elevation.
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WATER QUALITY:
Knotts Island•
As shown in Table #4 below, it appears that water quality at Knotts Island is generally good,
even in the water table aquifer and the Middle Yorktown aquifer, although water softeners
are generally used. There is significant interest in a central water supply (approximately 34%)
from houses with water table aquifer wells. Many of these systems could probably obtain
better quality water from the Upper Yorktown aquifer. It is noted that most of the Middle
Yorktown Aquifer wells have softeners, therefore, untreated water quality is expected to be
poorer than that which was reported.
It is probable that the ridge also comprises the suitable soil for drainfields, therefore, much
of the development uses the water table aquifer. As population growth results in new
development, new construction will use less suitable soil. It is probable that water quality
in the water table aquifer will be poorer than the ridge area.
CURRITUCK COUNTY WATER STUDY
KNOTTS ISLAND AREA
TABLE #4, GROUNDWATER SURVEY RESULTS
DEPTH < 40 FT. < 40 FT. 40-70 FT. 40-70 FT. 70-120 FT. 70-120 FT.
Yes No Yes No Yes No
Iron
32
74
22
21
1
6
Copper
11
95
5
38
7
Odor
12
94
11
32
1
6
Softener
18
88
11
32
5
2
Volume
104
2
43
0
7
0
Central
supply
36
61
15
26
1
5
Total
213
414
107
734
14
1482
Percent
34.0
66.0
12.7
87.3
0.9
99.1
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Gibbs Woods:
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From the questionnaire it appears that the poorest quality water exists on Gibbs Woods in the
Middle Yorktown aquifer, where most of the wells have hard water with high iron. It
appears that all of the aquifers in the Gibbs Woods area have iron in locations. Iron, sulfides
and hardness are conditions that are likely to occur with wells constructed into the Upper and
Lower Yorktown aquifers. The water quality results from the questionnaire are summarized
in Table #5 below.
A central system would probably require greensand filters, softening and possibly aeration.
Recommended well construction would be into the Upper Yorktown aquifer with an expected
yield of at least 20 gallons per minute per well. For planning purposes wells should be spaced
200 feet apart. Specific testing should be performed to refine the spacing and determine
maximum safe yield, if a central system is developed.
' CURRITUCK COUNTY WATER STUDY
GIBBS WOODS AREA
TABLE #5, GROUNDWATER SURVEY RESULTS
DEPTH < 40 FT. < 40 FT. 40-70 FT. 40-70 FT. 70-120 FT. 70-120 FT.
Yes No Yes No Yes No
Iron
4
9
10
6
9
Copper
1
11
3
13
1
7
Odor
5
8
4
11
7
2
Softener
4
9
7
9
8
1
-Volume
12
1
16''
1
9
0
Central
supply
6
8
8
9
8
1
Total
32
46
48
49
42
11
Percent
41.0
59.0
49.5
50.5
79.2
20.8
(Note: Tables #4 and #5 were compiled before all responses were received; therefore, the response
rate appears lower than the actual response received to the questionnaire)
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Utilization of Resources:
To develop a centralized water system for either Knotts Island or Gibbs Woods, a number of
well sites must be acquired and developed. Based on the water demand projected int he
previous Section of this report, the following estimated range of wells would be required in
order to accommodate the potential buildout of these areas:
WELLS & WELL SITES REQUIRED FOR CENTRAL SYSTEMS
TABLE, #6
Projected
Water
Demand
Wells
Required
Well Sites
Required
Estimated
Acreage,
Required
Knotts Island
1.14 MGD
32-63
16-32
24-48 Ac.
Gibbs Woods
0.145 MGD
4-8
2-4
3-6 Ac.
The range of well areas tabulated above is based on a range of well yield of 25 to 50 gallons
per minute, and the placement of two wells on each site. The placement of more than two
wells per well site would reduce the acreage requirement, but is subject to hydrogeological
testing and verification.
The impact of such a well system on the aquifers can be minimized by good spacing of the
wells, avoiding localized overpumpage, and by utilizing more than one aquifer.
23

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SECTION V - BASIS OF DESIGN & COST ESTIMATES
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For the purpose of determining the financial feasibility of constructing centralized water
supply systems for the Knotts Island and Gibbs Woods service areas, a preliminary design
scenario f the required infrastructure improvements has been made for both of these
communities. The analysis has taken into consideration the well supply system discussed in
Section IV, which would serve as a basis for design of a water treatment, storage and
distribution system to serve these potential customers.
The design of the water distribution system would change considerably, depending upon
whether or not fire protection is a key consideration in these centralized water systems. If fire
protection is not a criterion, smaller diameter water lines can be used, no elevated storage is
required until the 300th connection is made to the water system, under Division of
Environmental Health guidelines, and looping of distribution lines is less important. Due to
the configuration of the developable areas at both Knotts Island and Gibbs Woods, if no fire
protection is desired, then it may be more cost effective to construct two or more smaller
community -type water supply systems for each study area, with no need to interconnect the
raw water lines to a central wastewater treatment system or to connect the finished water
distribution lines to a centrally -located elevated tank.
During the public meetings at Gibbs Woods and Knotts Island, the question was raised to the
public as to whether or not fire protection was a key concern in these areas. At Gibbs
Woods, fire protection was not viewed, by the persons present at the public meeting, as a high
priority consideration when determining the need for centralized water distribution. At
Knotts Island, however, the majority of those attending the meeting, even though largely
opposed to the centralized water system idea, felt that fire protection was an important
element if a system were to be installed.
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For comparative purposes, preliminary estimates of the probable project costs are shown for
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both alternatives (with and without fire protection capabilities), for both service areas.
Basis of Desien
From the source analysis presented previously, it appears that groundwater is available in
adequate amounts to serve the two population centers. The long-term reliability of water
supply wells will increase as the separation between the supply wells is increased, since they
rely heavily on recharge from rainfall.
As discussed, a water supply source which would need desalinization as available from the
lower Yorktown aquifer; however, it appears to be much more cost effective to utilize the
Upper aquifers with conventional treatment, so the reverse osmosis alternative was not
explored further. Studies of the Currituck Sound as a potential source of water supply has
been explored previously in connection with earlier studies on the Mainland and Currituck's
Outer Banks' water supply potential, and not recommended due to fluctuating water quality
and environmental concerns. Therefore, the water table and Upper and Middle Yorktown
aquifers are assumed to be the preferred sources for these projects for the purpose of
developing appropriate cost estimates.
Information returned with the surveys mailed to the residents in these areas indicated the
probability of iron, and possibly hydrogen sulfide present in the well water, so it is assumed
that the water obtained from these sources will require treatment for iron removal. It may
also need to be softened to remove hardness, depending on the actual aquifers used. Finally
the water will be disinfected. It is likely that greensand filtration with potassium
25

permanganate as an oxidizing agent would be utilized to remove iron and odor from these
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systems. These assumptions are used to develop cost estimates for treatment systems for
these potential projects.
For the alternatives without fire protection, it is assumed that smaller, localized water
treatment systems would be located closer to the well sites in order to reduce the length of
raw water lines. No elevated tanks would be proposed, except where a number of
connections on a particular community system exceeded 300. This would likely only occur
at the main portion of the Knotts Island system. No interconnections would necessarily be
made between the distribution systems, since small diameter water lines would be sized for
domestic flow only.
For a system with fire protection, at least a 24-hour storage volume would be anticipated to
be stored in one or more elevated tanks. Distribution lines would be sized for both domestic
and fire flows in accordance with NFIP and Division of Environmental Health standards.
It is assumed that distribution lines will be run throughout the potential service areas, so that
all platted lots can be served, as well as provisions for future subdivisions, including areas
where easements would need to be acquired in order to run lines outside of existing street
rights -of -way to existing dwellings. [A concern raised at the Knotts Island public meeting
was the ability of a centralized system to serve all potential customers within the identified
service areas, so it is assumed that provisions would be made to extend the distribution lines
to accomplish this objective.]
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1,
1'
1.
1
1
1
1
1,
1'
3.
14
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COST ESTIMATES:
Based on the above assumptions and design criteria, estimates of the probable costs to
implement centralized water supply systems within the identified service areas have been
developed. Preliminary configurations of these infrastructure improvements are shown on
Figures 3 and 4 following the tables.
Wells & Raw Waterline
Water Treatment
Storage
Distribution System
Subtotal:
Allowance for Engineering &
Contingencies
Total, Estimated Project Cost
TABLE #7
KNOTTS ISLAND WITH FIRE PROTECTION
Preliminary Estimate of Probable Project Cost
Initial
Future*
Cost
Cost
480,000
710,000
700,000
950,000
1,200,000
800,000
1,964,000
-0-
4,344,000
2,460,000
869,000 492,000
5,213,000 2,952,000
TABLE #8
KNOTTS ISLAND WITHOUT FIRE PROTECTION
Preliminary Estimate of Probable Project Cost
Initial
Future*
Cost
Cost
Wells & Raw Waterline
480,000
710,000
Water Treatment
700,000
950,000
Storage
400,000
800,000
Distribution System
1,352,000
-0-
Subtotal:
2,932,000
2,460,000
Allowance for Engineering &
Contingencies
586,000
492,000
Total, Estimated Project Cost
3,518,000
2,952,000
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Total
Cost
1,190,000
1,650,000
2,000,000
1.964.000
6,804,000
1,361,000
8,165,000
Total
Cost
1,190,000
1,650,000
1,200,000
1.3 52.000
5,392,000
1.078.000
6,470,000

TABLE #9
'
GIBBS WOODS WITH FIRE PROTECTION
Preliminary Estimate of Probable Project Cost
'
Initial Future*
Total
Cost Cost
Cost
' I.
Wells & Raw Waterline
200,000 130,000
330,000
2.
Water Treatment
325,000 150,000
475,000
'
3.
Storage
350,000 100,000
450,000
' 4.
Distribution System
820,000 -0-
820,000
Subtotal:
1,695,000 380,000
2,075,000
'
Allowance for Engineering &
Contingencies
339,000 76,000
415,000
'
Total, Estimated Project Cost
2,034,000 456,000
2,490,000
'
TABLE #10
GIBBS WOODS WITHOUT FIRE PROTECTION
Preliminary Estimate of Probable Project Cost
Initial Future*
Total
'
Cost Cost
Cost
1.
Wells & Raw Waterline
200,000 130,000
330,000
2.
Water
Treatment
325,000 150,000
425,000
' 3.
Storage
100,000 100,000
200,000
4.
Distribution System
522,000 -0-
522,000
'
Subtotal:
1,147,000 380,000
1,527,000
Allowance for Engineering &
229,000 76,000
305,000
'
Contingencies
Total, Estimated Project Cost
1,376,000 456,000
1,832,000
'
*Future costs are in 1996 dollars.
'
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LEGEND
PROPOSED TRUNK uNE
-- CONNECTION BETWEEN MAJOR
POPULATION CENTERS ( FOR
FIRE PROTECTION ONLY )
NOTES:
t) PLAN SHOWS MAJOR WATERUNES ONLY.
SMALLER WATERLINES TO BE PLACED TO
SERVE ALL EXISTING DEVELOPMENT
2) PLAN IS CONCEPTUAL AND SUBJECT
TO MODIFICATION,
GRAPHIC SCALE
r to � ttttttttrt
(scats a mmuTU
t t I as

' Based on the cost estimates outlined above, and assuming that connection of all potential customers is utilized
' in estimating the costs to serve these areas, the following estimates show the per connection costs of
providing centralized water supply systems to these potential service areas, both with and without fire
' protection included:
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1
'
Knotts Island with
Fire Protection
'Knotts
Island without
Fire Protection
Woods with
'Gibbs
Fire Protection
'Gibbs
Woods without
Fire Protection
TABLE #11
SUMMARY OF PROJECTED COST PER CONNECTION
Initial Ultimate
Cost # Conn. Cost/Conn. Cost # Conn.
5,213,000 623
8,368
8,165,000
2,842
3,518,000 623
5,647
6,470,000
2,842
2,034,000 176
11,557
2,490,000
362
1,376,000 176
7,818
1,832,000
362
Cost/Conn.
2,873
2,277
6,878
5,061
The column showing the "Ultimate" number of connections is based on the number of dwellings
' available to be served at buildout from Section II of the report. The cost per connection figures
presented for Knotts Island appear to be fairly typical of costs observed to provide similar public
water supply service in other areas. The Gibbs Woods cost projections are comparatively high due
' to the relatively low density of development existing and projected in that area.
Potential revenue sources and steps suggested for the possible future implementation of these projects are
' discussed in Section VI.
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IMPLEMENTATION PLAN
If Currituck County determines that it desires to pursue the development of public water supply systems for
the Knotts Island and/or Gibbs Woods areas, special attention should be given in an effort to implement these
goals in as smooth a manner as possible. This implemention plan first considers revenue sources which may
be available for water system development, and then examines steps which should be taken, leading ultimately
to construction and operation of these systems. Potential benefits which may be realized from the
implementation of a centralized water supply system plan include the following:
• Improved water reliability (quality & quantity)
• Potential for increased public health as more development occurs and impacts the natural resource.
• Improved fire protection
• Lower insurance rates
Revenue Sources:
Sources of revenue which are typically utilized for implementation of a public water supply system such as
those proposed for Knotts Island and Gibbs Woods include the following:
• User Fees
• Bonds
• Special Assessments
• State & Federal Grant & Loan Programs
• Impact Fees
• Tapping Fees
Each of these sources is discussed briefly below.
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User fees are typically designed to primarily offset operational costs, but may also include an amount
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designed to retire debt incurred during initial construction. User fees from other systems in this region
typically range from approximately 12 to 32 dollars per month, depending largely on the size and type of the
system.
Bonds may be issued to be used for design and construction of a water supply system. These would be in
the category of either general obligation bonds, backed by the full faith and credit of the County, or in the
form of revenue bonds, which rely on cash flow from utility system operations to retire the debt. The revenue
bonds do not require approval of the voters, but can be more costly to design and sell.
Special assessments are sometimes made to reduce the amount of capital which must be borrowed to replace
grant funds which may not be available. Assessments can be made based either on footage of waterline, on
a per connection basis, or on some other formula designed to assess potential customers in an equitable
manner. For Knotts Island and Gibbs Woods, the front footage type of assessment would probably not be
equitable, due to the presence of many large tracts of land in these areas.
State and Federal grant and loan programs may be available which include the following:
' • Farmers' Home Administration Grants & Loans. The majority of the funds are normally in the form
' of a low -interest loan repayable over a 40-year period. Grants may be available if needed to reduce
the monthly cost to the users to an acceptable level. This would likely be necessary in the case of
Gibbs Woods, where the cost per connection to implement a water system will be quite high.
' According to the Farmers' Home Administration district office, a pre -application submitted in the near
future would possibly be considered for funding three years from now.
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Community development block grants could be available if the areas were to meet the low to
moderate income requirements which are associated with that program, although the Knotts Island
and Gibbs Woods areas would probably not meet the income threshold.
Governor Hunt is reportedly working on a State infrastructure construction fund which could be
appropriate for this type of project. Since legislation is still pending, the precise terms and conditions
of this proposed funding program, and associated timing, are not known at this time. It is expected
that it would be a revolving grant and loan fund which would be available on a competitive basis.
Impact fees are available only after special legislation is passed in North Carolina. These fees are
designed to offset the cost of providing public services, and are typically charged to developers of
new projects as a condition of project approval. They would probably not be appropriate for the
initial construction of a centralized water supply system.
Finally, tapping fees are typically designed to offset the cost of an actual water service hookup, and
may possibly also supplement operational revenue.
It is suggested if the County wishes to pursue funding of one or both of these projects, that an application
be made to the Rural Economic Development Center for funding by the Farmers' Home Administration grant
and loan program. As part of that process, a user fee schedule will be developed, and a determination made
as to whether a grant may be available which would to reduce the amount of the construction loan required.
If grant monies are not available, special assessments could be used to offset the initial construction costs.
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Organizational Structure:
Several types of organizational structures are available as part of the process of implementing a centralized
water system in North Carolina. These include a County service district, a County water and sewer district,
and a non-profit utility company.
The non-profit utility would be owned and managed by the members of the association (water users). A water
and sewer district could be formed by the County with the County Commissioners serving as the Operating
Board for the district. The Board of Commissioners would also serve as the governing board for a County
service district. With any of these alternatives, a district boundary would be established which would serve
as the service area for each water system.
The County service district affords the County the most power and flexibility in terms of financing
alternatives, including the ability to levy taxes, and the ability to require the connection of new developments
to a water system. A water district would afford the County most of the powers in terms of financing
alternatives available to it, and requires only a vote of the registered voters within the boundaries of the
proposed service district. The County water district would therefore most likely be the appropriate
organization for Knotts Island and Gibbs Woods.
Steps Needed for Implementation:
The first step needed in order to implement a centralized water supply system for either Knotts Island or
Gibbs Woods would be the formation of a district which would govern the creation and operation of the
utility system Once the organizational structure is in place, the board of Commissioners.will be in a position
33 .

to apply for grants and loans to obtain the funds for design and construction. Once funds are in place, the
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process of additional testing can begin, followed by engineering design, issuance of permits, and construction.
The following is an outline of the steps needed to be undertaken to implement these projects:
1. Further explore the desirability of implementing a centralized water system, in terms of the wishes
of the residents of these areas.
2. Establish district (either a County service district or County water district, as appropriate).
3. Apply for Federal grants and loans (also, State funding may become available in the future).
4. Develop a test well program to verify the quantity and quality of groundwater available and to serve
as the basis for finalizing the number and locations of well sites to be acquired.
5. Begin acquiring land for construction of permanent wells.
6. Perform engineering design of water supply, treatment, storage and distribution systems for the
service areas.
7. Apply for construction permits (Division of Environmental Health, Department of Transportation,
possibly the Corps of Engineers' approval for utility crossings will be necessary). This step should
also include the obtaining of easements where necessary to run water distribution lines across private
property where no right-of-way exists.
8. Advertise for bids, obtain construction bids and award contracts for construction of the various
components of the water systems.
9. Perform start-up and testing of the constructed systems; implement a plan of operation.
Based on the mixed responses received from the public through the water survey questionnaire, and the
likewise mixed reactions received at the public meetings held at Knotts Island and Gibbs Woods, it is
suggested that a public information program be continued or expanded as part of the process of determining
the desirability to move forward with the plan outlined above. This expanded program would be designed
to assist the Board of Commissioners in its desire to continue to involve the citizens of the proposed service
areas of Knotts Island and Gibbs Woods in the decision -making process.
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v DCM COPY
Please do not remove from
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Division of Coastal Management. Thank you.