EPA-600/2-76-134
June 1976
Environmental Protection Technology Series
WASTEWATER RECLAMATION PROJECT,
ST. CROIX, U.S. VIRGIN ISLANDS
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-76-134
June 1976
WASTEWATER RECLAMATION PROJECT,
ST. CROIX, U.S. VIRGIN ISLANDS
by
Oscar KM sen Buros
Black, Crow and Eidsness, Inc.
Gainesville, Florida 32602
Project No. GAK 11010
Project Officer
Robert Mason
Research and Development Branch
U.S. Environmental Protection Agency
Region II
New York, New York 10007
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Research and Development
Branch and the Municipal Environmental Research Laboratory, U.S. Environ-
mental Protection Agency, and approved for publication. Approval does
not signify that the contents necessarily reflect the views and policies
of the U.S. Environmental Protection Agency, nor does mention of trade
names or commercial products constitute endorsement or recommendation
for use.
ii
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FOREWORD
The Environmental Protection Agency was created because of
increasing public and government concern about the dangers of pollution
to the health and welfare of the American people. Noxious air, foul
water, and spoiled land are tragic testimony to the deterioration of
our natural environment. The complexity of that environment and the
interplay between its components require a concentrated and integrated
attack on the problem.
Research and development is that necessary first step in problem
solution and it involves defining the problem, measuring its impact, and
searching for solutions. The Municipal Environmental Research Laboratory
develops new and improved technology and systems for the prevention,
treatment, and management of wastewater and solid and hazardous waste
pollutant discharges from municipal and community sources, for the
preservation and treatment of public drinking water supplies, and to
minimize the adverse economic, social, health, and aesthetic effects of
pollution. This publication is one of the products of that research; a
most vital communications link between the researcher and the user
community.
The study described here was undertaken to demonstrate the reuse
of municipal wastewater as a means of conserving valuable water resources
in a water-short semi-arid area by recharging groundwater supplies with
treated effluents.
Francis T. Mayo
Director
Municipal Environmental
Research Laboratory
ill
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PREFACE
With a burgeoning population and a concomitant insufficiency of
potable water, the United States Virgin Islands is continually faced with
the necessity of constructing additional desalinization plants. The
freshwater supply is a combination of rainwater collected in cisterns, a
rather meager amount of groundwater, and a rather large proportion of
desalinated water. To conserve potable water, saltwater flushing is
resorted to in some areas. Since the rainfall is unpredictable and highly
nonuniform during the year, with either substantial rain or none at all
for months at a time, the aquifers are generally either full or empty.
Because of the tremendous importance of the water problem, with its
social and economic implications, it is obvious that any reasonable
alternative to a once-through-use-and-discharge-to-the-ocean must be
investigated. In the present work, recharge of suitably treated wastewater
is addressed experimentally. The selection and preparation of a recharge
site, study of the nature of the aquifer, and techniques of recharge are
all discussed against the background of a semiarid, subtropical island
environment.
As a comprehensive geologic and sanitary engineering study of St. Croix
from the standpoint of groundwater recharge, this report will serve as a •
foundation for the development of a water management master plan for the
island, as well as the model for studies of other similar islands and
selected coastal areas.
Robert W. Mason, Ph.D.
Research and Development
Representative, Region II
iv
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TABLE OF CONTENTS
Page
FOREWORD <11
PREFACE 1v
LIST OF FIGURES vii
LIST OF TABLES x
ABBREVIATIONS AND SYMBOLS xi
SECTION
I INTRODUCTION 1
Description of St. Croix 1
Outline of the Wastewater Reclamation Project 8
II SUMMARY 14
III CONCLUSIONS 16
IV RECOMMENDATIONS 17
V PRELIMINARY INVESTIGATIONS OF THE RECHARGE AND
STUDY AREA 28
Selection of the Recharge and Study Area 28
Description of the Study Area 39
Golden Grove Recharge Area 45
Negro Bay Recharge Area 49
Hydrological Developments in the Study Area 51
Water and Wastewater Systems on the Island 53
VI DESCRIPTION OF THE PROJECT FACILITIES 59
Advanced Wastewater Treatment Plant (AWWTP) 59
Recharge Areas 76
VII MONITORING ACTIVITIES DURING THE PROJECT 87
Water Quality 87
Groundwater Quantity and Movement 90
Rainfall Data 91
Advanced Wastewater Treatment Plant 91
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TABLE OF CONTENTS (CONTINUED).
SECTION Page
VIII RESULTS AND DISCUSSION 95
Water Quantity Changes Due to Recharging 95
Water Quality Changes Due to Recharging 113
Water Quality in Future Operations 119
AWWTP Operations 119
Cost Factors 120
IX MAJOR PROBLEM AREAS ENCOUNTERED IN THE PROJECT 122
Conceptual 122
Coordinated Planning 123
Changing Conditions 123
Project Location 124
Delays 124
Equipment Outages 125
Natural Disasters 125
Summary 125
X OTHER ACTIVITIES ASSOCIATED WITH THE WASTEWATER
RECLAMATION PROJECT 126
Irrigation 126
Clam Culture 127
Pisciculture 127
Interrelationship 128
REFERENCES 130
APPENDIX 133
PART A LOGS OF PROJECT WELLS 135
PART B PRIMARY WELLS-ANALYTICAL DATA 144
PART C SECONDARY WELLS—ANALYTICAL DATA 178
PART D STREAM SAMPLES-ANALYTICAL DATA 200
PART E AWWTP OPERATIONAL DATA 206
PART F SOIL BORING INFORMATION 208
PART G WATER LEVELS IN PROJECT WELLS 210
PART H ENGLISH-TO-METRIC CONVERSION 244
vi
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LIST OF FIGURES
Number Page
1 Location of St. Croix, U.S. Virgin Islands 2
2 St. Croix, U.S. Virgin Islands 3
3 Rainfall and groundwater potentiometric levels
in central St. Croix 5
4 The cost of desalinized water purchased during
the period 1972 to 1975 7
5 The project study area in central St. Croix 10
6 The Golden Grove and Negro Bay area in central
St. Croix 11
7 Schedule of the phases of the wastewater
reclamation project 12
8 Future well field development in the Golden
Grove recharge area 22
9 Future expansion of the spreading basins in
the Golden Grove recharge area 24
10 Proposed horizontal well 26
11 Public-owned lands in central St. Croix 30
12 Soil limitations for septic tanks in central
St. Croix 31
13 Geological conditions in central St. Croix 32
14 Results of percolation tests made at recharge
sites under investigation 34
15 Surface geological features in the Golden
Grove area 38
16 Well locations in the study area 40
vii
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LIST OF FIGURES (CONTINUED).
Number Page
17 Geological cross section of the coastal plain 43
18 Geological cross section of the Golden Grove
area at right angles to the streambed 44
19 Geological map of the coastal plain 46
20 Geological cross section of the Golden Grove
area along the plane of the streambed 47
21 Geological cross section of the Negro Bay area 50
22 The source of wastewater flows in June, 1974 56
23 The source of wastewater flows in September,
1975 57
24 Chloride content of the incoming wastewater to
the AWWTP in 1974 58
25 Flow diagram of the AWWTP 62
26 Aerial view of the AWWTP 63
27 AWWTP production utilized for artificial
groundwater recharging 72
28 The Golden Grove recharge area 78
29 Aerial view of the Golden Grove recharge area 80
30 The Negro Bay recharge area 85
31 A typical page from the AWWTP operator's log
showing the effluent flow chart 93
32 A typical page from the AWWTP operator's log
showing flow data and electric power consumed 94
33 Infiltration rates in the recharge basins 96
34 Hypothesized flow of groundwater in the upper
aquifer in Golden Grove 101
35 Comparison of wells GG-3 and GG-5, 1973-1974 103
viii
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LIST OF FIGURES (CONTINUED).
Number Page
36 Comparison of wells A-18, GG-3, GG-13, and
PW-8, 1974 104
37 Comparison of wells GG-3 and PW-6, 1974-1975 106
38 Comparison of wells GG-3, PW-8, and PW-9, 1974 107
39 Potentiometric groundwater levels in Estate
Golden Grove, 1972-1974 109
40 Potentiometric groundwater levels in Estate
Golden Grove, 1974-1975 110
41 Water balance in Golden Grove with and without
artificial recharging 111
42 Chloride content of monitor wells in the study
area 114
43 Proposed interrelationships between water use
and reuse activities on St. Croix 129
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LIST OF TABLES
Number Page
1 SOIL CLASSIFICATIONS IN THE PROJECT AREA 36
2 MAJOR WATER SOURCES ON ST. CROIX 55
3 EQUIPMENT USED IN THE ADVANCED WASTEWATER
TREATMENT PLANT 64
4 DESIGN AND ACTUAL PARAMETERS FOR THE
BIOLOGICAL SECTION OF THE AWWTP 65
5 OPERATING DATA FOR THE AWWTP 68
6 WATER AND WASTEWATER QUALITY MONITORING
SCHEDULE 89
7 PROJECTED COSTS FOR THE PRODUCTION AND
RECOVERY OF RECLAIMED WASTEWATER BY
GROUNDWATER RECHARGE 121
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ABBREVIATIONS AND SYMBOLS
Standard Abbreviations
AWWTP Advanced wastewater treatment plant
BOD Five-day biochemical oxygen demand
C Centigrade
cm Centimeters
cu Cubic
E Estate Envy
EPA Environmental Protection Agency
FCR Free chlorine residual
ft Feet
FTU Formazin turbidity units
gal Gallons
gpcd Gallons per capita per day
gpd Gallons per day
gpm Gallons per minute
ha Hectares
in. Inches
kg Kilograms
km Kilometers
1 Liters
Ib Pounds
m Meters
mgd Million gallons per day
mg Mi 11i grams
xl
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mil gal Million gallons
MLSS Mixed liquor suspended solids
PVC Polyvinyl chloride
PWD Public Works Department
SAR Sodium absorption ratio
sec Seconds
sq Square
Std Dev Standard deviation
SVI Sludge volume index
IDS Total dissolved solids
USDA U.S. Department of Agriculture
USGS U.S. Geological Survey
V.I. Virgin Islands
WAPA Water and Power Authority
wk Weeks
Well Abbreviations and Symbols
A Adventure
BMW Bethlehem Middle Works
E Envy
F Fountain
FP Fair Plains
GG Golden Grove
GP Grove Place
LL Lower Love
MB Manning Bay
xii
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Rain gage
Public well—pumped
Public well—not pumped
Private well--pumped
Private well—not pumped
Sampling station on a stream
xiti
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SECTION I
INTRODUCTION
DESCRIPTION OF ST. CROIX
St. Croix is the largest of the more than 50 islands and cays
which comprise the Territory of the U.S. Virgin Islands. The Virgin
Islands are located 1,100 miles (1,770 km) southeast of Miami, Florida,
and have been a possession of the United States since 1917 when they
were purchased from Denmark (see Figure 1).
St. Croix is 84 sq miles (217 sq km) in area. It is about
20 miles (32.2 km) long and 6 miles (9.6 km) wide at its broadest
point (see Figure 2). A range of low mountains forms a spine along
its longer east-west axis. The Northside Range at the western half of
the island hugs the northern shore and a flat coastal plain has been
formed from the foothills of the range to the south shore. It is on
this coastal plain between the two major towns of Frederiksted and
Christiansted that the majority of the people of the island live. The
island has about 40,000 inhabitants and the major sources of employment
are in alumina processing, petroleum refining, watch assembling,
tourist-related services, or government agencies. Agriculture, which
used to be the largest source of income on the island, has dwindled
considerably in the last decade. The growing of sugarcane has been
phased out, leaving beef cattle and dairy products as the major
agricultural enterprises.
In the latter part of the eighteenth century when agriculture
was the only industry, the entire island was divided up into plots of
about 150 to 300 acres (61 to 122 ha). Each plot was called an estate
and given a name. This system of estate division remains today and
forms an important function in the location of any point on the
island. These names, such as Golden Grove, Adventure, and Negro Bay,
are used throughout this report to aid in the location of areas for
those familiar with the island.
Water Supply
Along with this shift from a rural agricultural economy
towards industrial growth and tourism, there has been a rapid increase
in population and a rise in the standard of living. With these
changes has come a massive increase in total water consumption.
Unfortunately the low topography of the island does not promote the
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cc
0 100 200 300
MILES
0 ~50 100 150
VENEZUELA
Figure 1. Location of St. Croix, U.S. Virgin Islands.
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Cd
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Study Area GROVE PLANT
Boundary
MMCHMBB
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GREAT
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Figure 2. St. Croix, U.S. Virgin Islands.
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formation of rain clouds as reliably as on the larger, higher islands in
the Caribbean. The average rainfall is only 40 to 45 in. (102 to 114 cm)
per year. This combined with the extremely high evapotranspiration rate
restricts the amount of surface and groundwater on the island available
for water supply usage.
Although each dwelling is still required by law to be
constructed so as to catch and store the rainwater from its roof as a
basic source of water, it has been necessary for the government to
augment this supply through a water distribution system. This
additional water was originally derived from wells located in the
central part of St. Croix, and is now supplemented by large seawater
desalinization plants located in Christiansted and mid-island at the
Martin Marietta Alumina Company.
The combination of rainwater catchments and groundwater could
go a long way in satisfying the demand for water on the island, but
they are very much dependent on the pattern of weather in the area.
In the past few years this pattern has tended to minimize the benefits
to be derived, directly or indirectly, from the rainfall. Figure 3
compares rainfall and the water levels in two wells in central St.
Croix over the past 4 years. Although the average rainfall over this
short period approaches the norm expected, the distribution of
rainfall throughout the individual years has made it difficult for
efficient cistern storage and has detrimentally affected the efficient
natural recharge of the groundwater.
The combination of reduced rainfall, a diminished groundwater
supply, and increased individual consumption has caused the demand to
exceed the production of water from these traditional sources.
Although only about 70 percent of the populace is connected to the
public distribution system, it has been necessary to use increasing
amounts of desalinized water in the system until presently the
groundwater contribution to the total water supply picture is only
about 30 percent. This is discussed in further detail in Section V
under the topic, Water and Wastewater Systems on the Island.
The desalinized water for the potable system is produced by
two distillation plants, one operated by the Virgin Islands Water and
Power Authority (WAPA) and the other by the Martin Marietta Alumina
Company. Each provides about 0.65 mgd (2,460 cu m/day) to the system.
The average amount of water being distributed in the public system
during the spring of 1975 was about 1.8 mgd (6,813 cu m/day)f
This amount represents the supply and not the demand, as the
demand for water exceeds this figure by possibly as much as 30 percent
for just the existing hookups. Additionally, in the past year or so
at least 14 miles (22.5 km) of water mains have been added to the
system. Connections to these new mains have been almost nil as there
is insufficient water in the system to properly service any new
consumers. It has been quite normal to wait 2 to 3 years for
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Figure 3. Rainfall and groundwater potentiometric levels in central St. Croix.
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individual homes to obtain permission to hook up to the potable
distribution system and even after the connection is made there is no
assurance that a steady supply of water will be available.
Hater Costs
As the price of petroleum has increased so has the cost of
producing desalinized water, which requires oil-fired boilers to
produce the steam used in the distillation process. Since almost two-
thirds of the water in the public potable system is derived from
distillation plants the aggregate cost has increased drastically. The
changing cost to the public system for this water over the past three
years is shown in Figure 4. This shows the cost to the government
from both the WAPA and the Martin Marietta plants. In June, 1975, the
cost of water from these plants was $5,16/thousand gal ($1.36/cu m)
and $6.86/thousand gal ($1.81 cu m) respectively, for an average of
0.75 mgd (2,839 cu m/day). This is compared to the estimated cost of
$0.30/thousand gal ($0.08/cu m) for groundwater produced on the
island.
Although water is sold to the general public for $4.00/
thousand gal ($1.05/cu m), which is about ten times the cost in the
mainland United States, the government is still losing money in
distributing it due to the high proportion of expensive desalinized
water used.
At present the WAPA is increasing its water supply capacity by
the construction of a new 2.25 mgd (8,516 cu m/day) desalting plant
which should be on line sometime in the latter part of 1975. Although
this could possibly give the island a surplus of water, it is realized
that the Martin Marietta Alumina Company will soon be phasing out its
sales of water to the government and that in the past the consumer
demand has always risen to match the amount of water that the
government has been able to distribute.
Water Reuse
With the water supply system based mainly on desalted water,
the water is converted from seawater to fresh water at great expense,
used once, and then returned to the ocean as wastewater. Not only is
it expensive, but also the expansion of the desalination facilities
creates a situation where there is a greater dependency upon water
from a single source instead of the more versatile multiple-source
concept which the island still possesses. If this desalted water
could be used once, processed for reuse, and utilized again before
being completely degraded by discharge back into the ocean, the cost
of the processing between uses should be significantly below the
expense currently required to recover fresh water from the ocean by
distillation.
6
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NOTE: 1. COST BASED ON SELLING PRICE FOR
AN AVERAGE PRODUCTION OF 0.75 mgd.
2. DESALINIZATION BY MULTISTAGE FLASH
EVAPORATORS USING A SEAWATER FEED.
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Figure 4. The cost of desalinized water purchased during the period 1972 to 1975.
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The potential source of this reusable water, public wastewater
flows, receives only primary or no treatment at all before being
discharged into the ocean. However, in accordance with the current
implementation of federal environmental legislation, it may soon be
necessary to provide secondary treatment to all wastes discharged from
the island. All of these steps require progressively higher quality
effluent, and very little extra processing is required to adapt these
effluents to various water reuse programs on the island. Among these
programs would be reuse for agricultural irrigation, pisciculture,
groundwater augmentation, fire control, prevention of saltwater
intrusion, and various industrial purposes.
The idea of wastewater reclamation is not new, the inadvertent
reuse of wastewater being rather widespread throughout the United
States and the rest of the world. It is a major factor necessitating
the treatment of water before distribution to the public. Koenig
(1966) in a study of 155 communities in the United States served by
surface water found that, including industrial wastewaters, the median
reuse factor was about 50 percent. Throughout the world there are
areas where deliberate reuse of wastewater is being practiced. These
are predominantly in the arid regions where the cost of procuring new
water exceeds that of processing wastewater for reuse. Localities in
California, Texas, Israel, and South Africa are utilizing wastewater
reclamation plants for various purposes.
OUTLINE OF THE WASTEWATER RECLAMATION PROJECT
Project Description
The concept of wastewater reclamation and its subsequent reuse
for groundwater recharge on St. Croix has been studied and suggested
by the U.S. Geological Survey (Robison, 1972; Jordan, 1973) and
engineering consultants (Engineering-Science Inc., 1968). This report
covers a study entitled "Wastewater Reclamation Project on St. Croix,
U.S. Virgin Islands," which was sponsored by the U.S. Environmental
Protection Agency (EPA) and the Virgin Islands Government, Division of
Natural Resources Management. In this project-a portion of the flow
normally discharged to the sea from the island's new primary treatment
plant at Bethlehem Middle Works was used for reclamation purposes.
The flow was diverted and processed in an advanced wastewater
treatment plant (AWWTP) adjacent to the primary plant. Processing was
by biological and physiochemical means and produced a treated
wastewater which was-conveyed by a force main to recharge areas
located about 1-1/4 miles (2 km) away. Here it was stored in a
holding tank and introduced into the groundwater aquifers by various
methods. This was for the purpose of improving the yield of wells in
the area and assisting in preventing further seawater intrusion which
threatens Fair Plains, one of the government's major we'll fields on
the island.
8
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The project was handled for the government by the consulting
engineering firm of Black, Crow and Eidsness, Inc., of Gainesville,
Florida. Project personnel worked on the island continuously from
April, 1971, to October, 1975, studying the problem, supervising the
construction, operating all of the facilities involved, and evaluating
the results. Early in the project the recharge sites were located and
a study area of about 8 square miles (23 km) was defined, which
included the drainage basins where the recharge activities would take
place. Wells and surface water throughout this study area were
monitored for 2-1/2 years in order to clarify the hydrological
characteristics of the region and to establish baseline data for the
project before recharging began. The study area is outlined in
Figures 2 and 5. The most important portion of the region is shown in
detail in Figure 6.
Project Objective
The overall objective of this project was to determine the
feasibility of increasing the freshwater reserves on St. Croix by the
use of wastewater reclamation. This consisted of the artificial '
recharge of the groundwater on the island using tertiary-treated
wastewater effluent. The project entailed not only the operation of
the treatment and recharge facilities but the study of the wastewater
collection system; the geohydrological character of the recharge area
and the subsequent water distribution; evaluation of the effects on
the groundwater regime; and the costs associated with the production
of fresh water in this manner.
Project Phases
The project was divided into four phases: initiation,
investigation, operation, and evaluation. A diagrammatical outline of
these phases and their scheduling during the project is shown in
Figure 7.
Phase 1 - Initiation. This included the discussions and
efforts made in formulating a proposal that outlined the steps of the
investigation and proposed a budget to match these plans. During this
time the grant application and approval were obtained and a
contractual agreement between the parties involved was defined and
finalized. This phase ended in March, 1971, with the assignment of a
full-time engineer to the project who began field work on St. Croix
the following month.
Phase 2 - Investigation, Design, and Construction. This phase
covered the investigation of the conditions that affect the recharging
operation and included the selection of the sites for recharging and
the area to be monitored during the project. Studies were made of the
hydrology, geology, soils, land use, groundwater, and surface water,
in the study area. A monitoring program was begun to establish
baseline data on water quality and quantity. An advanced wastewater
9
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STUDY AREA
BOUNDARY
Figure 5. The project study area in central St. Croix,
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PUBLIC SAFETY
HEADQUARTERS
CHECK DAMS
GUT
FISH
PONDS
60 GG-5
GOLDEN GROVE
RECHARGE AREA
I \
SPUR LINE ^
SPREADING BASINS
(TYPICAL)
NEGRO BAY
RAIN GAGE
SPREADING BASINS
FAIR PLAINS
WELL FIELD
NEGRO BAY
RECHARGE AREA
SURGE TANK
SPRAY \\ ^rz
1000
MAIN TO CONVEY
RENOVATED WASTEWATER
TO RECHARGE AREA
Scale Feet
0 500
0 100 200 300
Scale in Meters
PRIMARY WASTEWATER^X
TREATMENT PLANT \\
Figure 6. The Golden Grove and Negro Bay area in central St. Croix.
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INVESTIGATION DESIGN
I INITIATION i AND CONSTRUCTION I OPERATION
1
INITIAL MEETINGS
OF EPA, TERRITO-
RIAL. AND
ENGINEERING
OFFICIALS
V
1 1
ENGINEER
ASSIGNED FULL
TIME ON
PROJECT
(MARCH, 1971)
x
SALINE WASTE-
WATER AND
FLOODS HALT
RECHARGING
OPERATIONS
EVALU-
ATION
EVALUATION
AND FINAL
REPORT
NOTE: SHADING INDICATES THE ASSUMPTION OF CONTROL
BY THE VIRGIN ISLANDS GOVERNMENT
to
PROJECT INITIATION.
GRANT PROPOSALS,
AND CONTRACT
FINALIZATION
DESIGN AND
CONSTRUCTION OF
RECHARGE FACILITIES
INVESTIGATION OF THE SOILS, GEOLOGY.
HYDROLOGY, WATER, AND WASTEWATER ON
ST. CROIX INCLUDING WATER QUALITY
MONITORING
OPERATION
OF
RECHARGE
FACILITIES
REPAIR.
UPKEEP
RE-
CHARGE
FACIL-
ITIES
CONTINUED MONI-
TORING OF WATER
QUALITY AND
QUANTITY
DESIGN
OF
AWWTP
CONSTRUCTION
OF THE AWWTP
OPERATION OF S
THE AWWTP S
1969
1970
1971
1972
1973
1974
1975
Figure 7. Schedule of the phases of the wastewater reclamation project.
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treatment plant (AWWTP), force main, holding tank, and recharge
facilities were designed and constructed. All facilities were tested
for operation. This phase was completed in January, 1974.
Phase 3 - Operation. Phase 3 began in February, 1974, and
consisted of operating the plant and recharge facilities.
Improvements and modifications were made to the AWWTP and recharge
facilities as required during the operational phase. Recharging
operations continued until October, 1974, when they were curtailed due
to the high total dissolved solids (TDS) in the incoming wastewater.
The high TDS was caused by the saltwater flushing system employed in the
town of Frederiksted which was connected to the central wastewater
interceptor system during that month. In November, 1974, the primary
plant and wastewater collection network were rendered inoperative by
heavy rains and flooding. Also damaged were the recharge facilities in
Estate Golden Grove. Repairs to all facilities were completed by May,
1975. However, further recharge operations were restricted by the high
TDS in the collected wastewater due to the use of salt water for
flushing in the town of Frederiksted. The operational phase of the
project ended in May, 1975, with the complete transfer of the project
facilities to the Virgin Islands Government, Division of Natural
Resources Management.
Phase 4 *• Evaluation. The data gathered throughout the
project were evaluated to determine the actual feasibility of the
project, both on a technical and economical basis. This final report
contains the results of the evaluation and contains recommendations
for further development of the wastewater reclamation project. Phase
4 was completed in November, 1975, with the completion of this report.
13
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SECTION II
SUMMARY
The wastewater reclamation project on St. Croix has
demonstrated that it is possible to economically augment the island's
freshwater reserves through the use of reclaimed wastewater for the
artificial recharge of groundwater. The most successful method of
recharge has been with the use of spreading basins in Estate Golden
Grove.
The project has spanned close to 5-1/2 years from its
initiation to the publication of this final report. It has resulted
in the construction and operation of an advanced wastewater treatment
plant and recharge facilities which can process up to 0.5 mgd (1,892
cu m/day). Investigation of the geology, hydrology, and groundwater
movement in the area and the compilation of considerable data on
treatment plant operations, recharge activity, well water quality, and
groundwater quantity has been completed.
After numerous delays in the construction of the treatment
plant, recharging operations began in February, 1974. During the
subsequent 8 months various minor problems in the system were resolved
and plant production steadily increased until in October, 1974, it was
possible to recharge an average of 1 mil gal/wk (3,785 cu m/wk). The
restriction at that point was caused by a lack of treated wastewater
effluent, rather than the capacity of the recharge areas.
Of the two recharge sites utilized it was possible to
eliminate one and focus all attention on the most feasible site at
Estate Golden Grove. At the recharge rate used in Golden Grove, no -
significant adverse effects were observed among the parameters examined
in the groundwater extracted downstream of the project. There was,
however, evidence of a notable increase in available groundwater in the
vicinity of the recharge activities.
The major problems experienced during the project's
operational phase were:
The lack of sufficient wastewater for treatment and
subsequent recharge.
The mechanical failure of equipment associated with the
treatment process.
14
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The transfer, to the central treatment plant, of
wastewater containing a high percentage of seawater.
This last problem, followed immediately by a record flood on
the island, caused the premature termination of the recharge
activities in October, 1974. Although the flood damage nas been repaired,
it is not expected that the saltwater problem will be resolved until the
latter part of 1975. At that time it will be possible to resume the
artificial recharge activities.
Using the present facilities for treatment and recharging it is
estimated that recoverable groundwater could be increased by at least
0.35 mgd (1,351 cu m/day) at the recovered water cost of about $2.15/
thousand gal ($0.56/cu m).
Although this is considerably higher than the $0.30/thousand gal
($0.08/cu m) estimated for recovering the limited amount of groundwater,
it is much cheaper than the cost of $5.16/thousand gal ($1.36/cu m) for
water produced by the government's desalinization plant on the island
and additionally it will provide a dependable source of fresh water for
St. Croix.
In addition to the work on artificial recharge, the project
personnel worked with other public and private entities on the island to
foster the use of reclaimed wastewater for other purposes. This proved
to be successful and broadened community support and participation in
the idea of water reuse. Among the other reuse projects that are being
carried out on St. Croix are agricultural irrigation, pisciculture, and
the raising of freshwater clams.
Continuing research on the project will be carried out by the
territory's Water Resources Research Center located at the College of
the Virgin Islands in St. Thomas.
15
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SECTION III
CONCLUSIONS
It is economically feasible to use reclaimed wastewater to
artificially recharge the groundwater on St. Croix. However, it can
only be accomplished successfully at carefully selected areas on the
island. A site in the alluvial valley at Estate Golden Grove was
demonstrated to be highly suitable for recharge by the use of
spreading basins.
With the AWWTP operating at design capacity of 0.5 mgd (1,892
cu m/day) and allowing for down time and losses in groundwater
recovery, it will be possible to recover groundwater for a cost of
about $2.15/thousand gal ($0.57/cu m). With expansion of the existing
plant and recharge areas to a capacity of 1 mgd (3,785 cu m/day) the
cost can be reduced to about $1.64/thousand gal ($0.43/cu m).
It is not economical to artificially recharge and recover any
of the subsequent groundwater from the marl formation in the recharge
area in Estate Negro Bay on St. Croix. Infiltration and percolation
rates were too low and eyapotranspiration rates were too high to
warrant further efforts in this type of soil structure.
With the existing AWWTP it is possible to treat the incoming
wastewater, as it was constituted during the 8 months of recharge
activity, so that with normal operation the effluent will have a
turbidity of less than 3 Formazin turbidity units (FTUs) and a free
chlorine residual of over 3 mg/1, after a 30-minute contact time (see
Section VIII).
The use of an effluent low in organics and turbidity with a free
chlorine residual for artificial recharge in the recharge basins in
Estate Golden Grove will permit the operation of-the basins with a
minimum of odor or algae problems and a high rate of infiltration into
the soil. The average sustained rate of infiltration experienced in the
Golden Grove basins was about 14 gpd/sq ft (0.57 cu m/day/sq m) on a wet
cycle basis.
The recharging activities which took place in Golden Grove and
Negro Bay, during the 8-month period of project operations in 1974, did
not significantly affect the water quality of any pumped well in the
area on the basis of the parameters examined (see Section VII).
The use of seawater for flushing purposes must be terminated in
areas where the wastewater is to be processed for reuse.
16
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SECTION IV
RECOMMENDATIONS
Continue the Project
The reclamation of wastewater for artificial groundwater
recharge should be continued on St. Croix. It has proved to be an
economically feasible enterprise and should be a benefit to the island
not only for groundwater augmentation but other uses as well.
Strengthen the Organization
The entire reclamation project is of sufficient importance and
complexity that it requires careful organization and staffing to
ensure its future success. If the operation continues within the.
Division of Natural Resources Management, it should be organized with
one person having the responsibility for operations, monitoring,
distribution, and coordination with other agencies. This person
should be an engineer with experience and/or training in both the
fields of water supply and wastewater treatment. He should probably
hold the title of Assistant Director. There should continue to be a
separate superintendent for the AWWTP since this, in itself, is a
full-time job.
The AWWTP and recharge facility must be adequately manned. It
presently is understaffed and will not be able to sustain full
production for very long without additional staff.
Coordination with other departments and individuals concerned
with the reuse of water is vital to the efficient utilization of this
resource. The program of expansion and promotion of water reuse for
beneficial purposes must continue to stress the multiuse concept of
the project.
Coordinate Future Planning
The concept of the reuse of water must be incorporated into
all aspects of planning for water supply and wastewater collection on
St. Croix. Although it may not be advantageous to recycle all of the
water on the island, all new water and wastewater installations and
changes, both public and private, must be reviewed as to their effect
on the reclamation project. A master plan for water management on St.
Croix, which will be published about March, 1976, will aid in this
evaluation process.
17
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Control Saltwater Usage
The use of seawater as a source of fire and flushing water
must be carefully evaluated since its use is not compatible with the
reclamation of wastewater at a reasonable cost. It must be
remembered, though, that salt water is a very inexpensive source of
water. The complexity and expense of attempting to eliminate all
saltwater discharges to the wastewater collection system on the island
may not be commensurate with the benefits derived from a 100 percent
reuse capability.
At the present time, it is recommended that the saltwater
usage in Frederiksted be eliminated by the direct use of fresh water
in the saltwater system. This will require about 0.08 mgd (300 cu
m/day) of fresh water. This will permit the use in the AWWTP of at
least 0.5 mgd (1,892 cu m/day) of low chloride wastewater for
reclamation purposes. The additional fresh water produced through
artificial recharge and recovery can be returned to the system to make
up the flushing water. This will permit the reclamation project to
operate until about June, 1977, when the wastewater interceptor system
is completed to Christiansted and the wastewater containing salt water
from Christiansted will be delivered to the central treatment plant on
the south shore. Christiansted uses an estimated 0.6 mgd (2,271 cu m/day)
of seawater for flushing purposes, which is over 7 times the amount used
in Frederiksted and hence difficult to replace with fresh water.
If, by approximately June, 1976, plans for the elimination of
all the salt water in the Christiansted area have not been finalized
and agreed to in plan and principle by the Public Works Department,
V.I. Housing Authority, and the owners of the major hotels,
condominiums, and restaurants using salt water, then it is doubtful
that the wastewater coming from the area can be used for reclamation
purposes and without further modifications the project would probably
be shut down again in 1977. The unilateral prohibition of saltwater usage
in the area without an immediately available, cheap alternative would
probably create an extremely negative reaction against the concept of
water reuse.
Split the Wastewater Flow at the Primary Plant
If the salt water cannot be eliminated from the Christiansted
area, then it is recommended that a new pumping station be built
adjacent to the collection structure at the primary treatment plant.
This pumping station would pick up a percentage of the wastewater
entering the structure from the central and western portions of the
island before it is contaminated by the salty wastewater from
Christiansted. The pumping station would then transfer the wastewater
directly to the AWWTP with provisions for screening and degritting
enroute or via one of the primary settling tanks. In the latter case,
the primary facility would need to be altered to permit the splitting
18
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of flows within the plant so that the high and low IDS wastewaters
could be treated separately.
With this plan, reclamation efforts could be continued and
expanded to the capacity of the influent available. If successful
extended operation at that level indicated that the usage could be
expanded to efficiently utilize most of the wastewater from
Christiansted; then careful, coordinated plans could be made and
carried out to initiate the needed changes to smoothly incorporate
this additional supply into the water reuse system.
Promulgate Regulations Concerning Reuse
As soon as practicable, the proper territorial agency or
agencies should promulgate regulations specifically governing the use
of reclaimed wastewater for groundwater recharge, agricultural
irrigation, and any other activity involving water reuse. These would
provide guidelines for the planners and operators associated with the
facilities. As the EPA has gained additional knowledge and experience
in the field of water reuse since it initiated this project in ]969, it
is advised that the EPA be consulted for guidance and assistance in
reviewing the regulatory and monitoring portions of the project in the
future.
Monitoring Future Operations
Monitoring in the study area should be continued. This should
include chemical and biological analysis and the gaging of water
levels in selected wells. A thorough review of the type of analyses
run should be made and modified where appropriate. It is suggested
that BOD and COD measurements of the wells be suspended and that, at a
minimum, all the tests covered in the proposed new EPA drinking water
standards (Environmental Protection Agency, 1975) be instituted.
Disinfection of Recovered Water
All water extracted from the Golden Grove well field in
association with the recharge operation should be monitored and
thoroughly disinfected, as a safety precaution, before distribution.
The Fair Plains collection tank and pumping station should be the
focal point for monitoring, disinfection, and distribution of this
water. The two direct taps onto the force main connecting the Golden
Grove well field to the Fair Plains tank should be either
disconnected or altered in a way that will assure proper disinfection
of any water used. These two taps feed the adult correctional
facility and the Public Safety Headquarters.
The disinfection operation at Fair Plains must be carefully
monitored to ensure that it is being carried out properly at all
times. Consideration needs to be given to the installation of a gas
chlorinator instead of the current dry chemical chlorinator system.
19
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Prohibit Industrial Wastes
Industrial wastes should not be added to the wastewater
ultimately used for reclamation purposes unless they have been
carefully analyzed and evaluated. This is to ensure that no harmful
exotic substances are introduced into the reuse system.
Monitor Coagulants' Effectiveness
The effectiveness of using aluminum sulfate as a coagulant and
filter aid should be continually monitored as the project continues.
The projected changes in the major water source in the western portion
of the island from groundwater to distilled water may have a
detrimental effect on the alum reaction. Other chemicals, including
polyelectrolytes, may be required in the future. Any chemicals
employed should be approved by the EPA for water treatment usage.
Improve Groundwater Recovery
The existing recharge facilities were not intended to maximize
the recovery of recharged water. Additional groundwater extraction
facilities should be constructed in Estate Golden Grove to facilitate
this.
The emphasis should be on the removal of the groundwater from
the upper aquifer which is the one being artificially recharged.
Figure 8 is a sketch of the Golden Grove recharge area and shows the
sequence of well field development that should take place. Initially,
at least the first six recovery wells should be installed. These wells
are located so as to permit rapid removal of water from under the
scattered recharge basins. The additional wells are planned to coincide
with the expansion of the recharge basins as shown in Figure 9. A
feature of this development should be a horizontal collection system
constructed along the northwest property boundary between wells RW-12,
RW-6, PW-1, RW-1, and PW-4. At this point the upper aquifer is close
enough to the surface to permit excavation and installation of the
necessary collectors. A sketch of this system is shown in Figure 10.
As information is gained through the construction and pumping of the
wells, the proposed locations of the additional wells and basins should
be continually reevaluated.
All extraction facilities, wells, or collectors shown have been
located so as to maintain the minimum 50 ft (15 m) horizontal distance
between the wells and the recharge facilities as required by the V.I.
Division of Natural Resources Management (Stolz, 1975). This placement
affords a high degree of hydraulic efficiency for the removal of
recharged water from below the basins, but these wells should be
carefully monitored to ensure that the desired groundwater quality can
be maintained.
20
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Expand the Recharge Area in Golden Grove
Expansion of the spreading basins should take place as shown
in Figure 9. The area suitable for surface methods of recharging is
rather limited in size and expansion in Estate Golden Grove beyond the
areas shown will probably be uneconomical.
Improve the Performance of the AIMTP
The performance and production of the AWWTP would
significantly improve if a steady flow rate to the plant could be
maintained. This can be accomplished by relocating the influent pumps
from the present wet well to the primary clarifier along with the
installation of a new, larger diameter pipeline. This is described in
detail in the section on project facilities under the subheading Plant
Expansion. The majority of the work can be accomplished by local
government personnel and the materials required would cost less than
$10,000. It is urged that this change be instituted as soon as
possible.
Consider AIMTP Expansion
The present plant and installed equipment have the capability
to permit considerable expansion of plant capacity with a relatively
low amount of capital investment. However expansion should only be
carried out if there is full utilization of the present production and
a reasonable prospect for the use of additional reclaimed water.
Plant expansion is discussed in further detail in the section,
Description of the Project Facilities.
Expand Local Research
Research projects on water reuse as they apply to conditions
within the territory should be encouraged. The newly established
Water Resources Center at the College of the Virgin Islands should
take a leading role in directing and funding this research. Some of
the following are suggested topics for research.
The long- and short-term effects on the various local
soils as the result of using reclaimed wastewater for recharge
and irrigation purposes.
The fate of nutrients, organics, and microorganisms in
reclaimed wastewater as it moves through the various types of
local soils.
Viral studies in the reclaimed wastewater and recovered
groundwater.
21
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*rft
TO NEGRO BAY VM FROM THE NEGRO BAY
WELLFIELI
METER
TO
STORAGE
TANK
DIRT ROAD
BURIED 4" WELL WATER
COLLECTOR LINE
BURIED 6" FORCE MAIN
FOR TERTIARY EFFLUENT
FORCE MAIN
STANDPIPE
AND VALVE
BURIED 6"
WATER LINE
AIR RELEASE
VALVE
CONCRETE FORD
WELL
TO BE
DRILLED
FORCE MAIN
STANDPIPE
AND VALVE
DRILLING
PRIORITY
.BASIN
NO. 5
RW-1 = FIRST
RW-2 = SECOND
ETC.
RW= RECOVERY WELL
\ BURIED VALVE
DRAINAGE DITCH
FROM RECLAMATION »' TO FAIR PLAINS
PLANT -»- 1 STORAGE TANK
k
Figure 8. Future well field development in the Golden Grove recharge area.
22
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WESTERN LIMIT
F GOVT. PROPER!
I V V I I ^K ^
POLE* ^MONUMENTS
• •'••• *'-J
• • *-^
FORCE
MAIN
STANDPIPE
AND
VALVE
PAVED PARKING LOT;
"li ^*.
I \
4 !• BASIN NO. 3 I
PUBLIC SAFETY
HEADQUARTERS
BURIED 6"
UUATFR MAIN GRAVIIY
WASTEWATER
INTERCEPTOR
PWR FROM
DRAINAGE DITCH 7^-— POLE GROVE PLACE
I
OUTER FENCE
OF ADULT
CORRECTIONAL
FACILITY
0 50 100
0 10 20 30
Figures. (Extended)
23
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TO NEGRO BAY
METER
TO
STORAGE
TANK
'FROM THE NEGRO BAY
WELLFIEL
DIRT ROAD
BURIED 4" WELL WATER
COLLECTOR LINE
PWR POLE
BU~RIErT6" FORCE MAIN X
FOR TERTIARY EFFLUENT
FORCE MAIM
STANDPIPE
AND VALVE
RECOVERY WELL
TO BE DRILLED
BASINS TO BE
CONSTRUCTED
CONSTRUCTION
PRIORITY
1=FIRST
2=SECOND
BURIED
WATER
FORCE MAIN
STANDPIPE
AND VALVE
4" ALUMINUM
IRRIGATION
BURIED VALVE
FROM RECLAMATION H TO FAIR PLAINS
PLANT -»- I STORAGE TANK
Figure 9. Future expansion of the spreading basins in the Golden Grove recharge area.
24
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PWR/
POLE/
— ^ r
(. BASIN NO.
I NEW BASIN
NO. 5 |
PAVED PARKING L
11- BASIN NO. 3 \
OUTER FENCE
OF ADULT
CORRECTIONAL
FACILITY
xx CORNER OF
PUBLIC SAFETY
HEADQUARTERS
BURIED 6" rRAVITY
WATER MAIN GRAVMY
WASTEWATER
INTERCEPTOR
• PWR FROM
DRAINAGE DITCH / POLE GROVE PLACE
0 50 100
0 10 20 30
Figure 9. (Extended)
-------
'±t.'. :t.y.'.Kj.'.'.VPfrff-
EXISTING •:
WELL Jj
150 ft (46 m)
i
APPROX. 15
(4.6m) .
•xrfftaxfXfWfa*
»vx^««4es^^S5^i»^x«»»SB»^5Mr•^:•«":<•:•»K
HORIZONTAL
EXISTING
UPPER
AQUIFER
UNDISTURBED SOIL
WIDTH OF EXCAVATOR
l« BUCKET »|
>.,..•?..,•: •
•.;.;<»;.-;o.-. CLEAN ',.•.
TWO SHEETS OF HEAVY
TAR PAPER ::;;;
' • •• . »• • « • * •» o *.
• •'•°.'i -„••'*! •* • • » . • .• i
i-«.'vi •">•••.•••.•—»'.y--'
^1^" ,* •rrr^ej. - ._£.» • t > J
8-in. (20 cm) PVC PIPE
'SLOTTED ON TOP EVERY
4-in. (10cm) ,<±m&.
UNDISTURBED SOIL
SECTION A-A
Figure 10. Proposed horizontal well.
26
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The uptake of nutrients, heavy metals, microorganisms,
etc., in local plant materials as a result of the use of
reclaimed wastewater for irrigation purposes.
Quantification of the loss of groundwater by the
transpiration of subtropical vegetation in the territory.
Evaluation and revisions, where necessary, of regulations
and guidelines governing the use of reclaimed wastewater.
A review of the areas of research needed in the field of water
reuse has been made in the paper, "Research required to establish
confidence in the potable reuse of wastewater," (English et al., 1975).
This paper provides additional topics for investigation.
Reduce Costs
The best method to reduce costs would be to combine the staffs
of the adjacent primary treatment plant with that of the AWWTP. The
present arrangement where each plant has a separate staff is an'
inefficient use of manpower and equipment. Combining them under one
government agency with one head would reduce overall labor costs and
permit coordinated operation to the benefit of the wastewater
reclamation project.
27
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SECTION V
PRELIMINARY INVESTIGATIONS OF THE RECHARGE AND STUDY AREA
SELECTION OF THE RECHARGE AND STUDY AREA
The key decision in the project was the selection of the
recharge area. If an unsuitable site had been selected and developed,
then the remainder of the effort on the project would have been
largely wasted. Therefore the preliminary investigations centered
around the selection of a suitable site and the definition of its
hydrogeological features.
In the selection of the areas which were used for recharging,
there were two major constraints involved. The first was financial in
that the budget for the project only provided sufficient funds for up
to 2 miles (3.2 km) of force main. Thus, the maximum distance of the
recharge area from the advanced wastewater treatment plant was
predetermined.
The second major constraint was that the basic decisions as to
the pattern of wastewater interceptors and the location of the central
primary treatment plant were made by others before this project was
begun. Since the influent for the advanced wastewater treatment plant
(AWWTP) would come directly from this primary plant, the location of
that plant determined the site of the advanced wastewater treatment
plant.
The budget for development of the recharge areas was based
upon the understanding that the land utilized must be obtained at
little or no cost. At the time when the original proposal was
outlined in 1969, local officials had indicated that there would be
little problem in using land at Estate Barren Spot in central St.
Croix. This probably seemed natural at the time as the area then
consisted of abandoned fields of sugarcane. The recharge areas were
proposed for a location which was on alluvial soil and in the same
hydrological basin as one of the larger public well fields on the
island.
However, between 1969 and the start of the project in 1971,
the fields in question and almost all of the surrounding land were
purchased or optioned by a local developer who began to construct
homes on the site. Despite this, it was hoped that perhaps the
operation could be handled in certain greenbelt areas within the
28
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development which would be beneficial for both the project and the
developer. Subsequent negotiations on this subject proved otherwise, as
the financial and operational conditions that were suggested by the
developer did not appear feasible. The costs would have vastly exceeded
the funds available for purchase of the lands and the restrictions would
have seriously hindered the success of the project.
Investigations were then conducted to find a new site for the
recharge operations. One important criterion for the alternative site
was that it be located on government-owned or controlled land. This
would avoid the necessity for the purchase or lease of the property, and
would give the government control over the operation and full possession
of the facility upon completion of the project.
In selecting an alternate site, the new primary treatment plant
was used as a center and all the government holdings within a radius of
three miles were determined from tax records. These included territorial
government, federal government, and Virgin Islands Port Authority lands
(see Figure 11). The current and future uses for the land were determined.
Much of the land, although presently not used, was scheduled for develop-
ment in the immediate future.
A study was then made of the general soil and geological
conditions existing at each site. For the soils investigations, two
reports published by the Soil Conservation Service of the U.S. Depart-
ment of Agriculture (USDA) proved extremely useful. These were: Soils
and Their Interpretations for Various Uses, St. Croix, American Virgin
Islands (McKinzie et al., 1965) and Soil Survey. Virginlslands of the
United States (Rivera et al., 1970). They delineated the soils and
their engineering and agricultural uses throughout the island. Their
concern has been with the characteristics of the profile of the upper 60
in. (152 cm) of the soil.. This layer is of primary interest to the
project due to its ability to permit infiltration and percolation of the
water to be recharged. An interpretive map in the first publication
which was of great value was entitled, "The soil limitations for resi-
dences with individual septic tanks." These limitations were based on
many of the characteristics such as percolation rate, shrink-swell
behavior, depth to water table, etc., that would also apply to the arti-
ficial recharge operation. On this map the soil conditions were inter-
preted as providing slight, moderate, or severe limitations to the use of
individual septic tanks. This information is shown on Figure 12. Areas
showing slight limitation were those considered most suitable for the
project, although others were considered.
Geological conditions have been characterized by Cederstrom
(1950) and Robison (1972) in separate U.S. Geological Survey (USGS)
publications concerning groundwater on St. Croix. This geological
information, modified by observations in the field, is shown in Figure
13. This was an aid in outlining the possible groundwater flow, the
29
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BOUNDARY OF
STUDY AREA
ORIGINAL SITES*-*
OF RECHARGE, /i
AREA ^V«srU
Hill
BARREN SPOT
WELL FIELD
Ctofl«h.
r OJd Worl
ADVENTURE
FIELD
Soirl
•"ja—vy OkHitrBb-La
\ REFINERY CORpAr/./
«—=--%-,
1r f :J*-?^^^^^^^^^^P
t:' ; ~~~~ **»*
-------
BOUNDARY
OF STUDY
'VT»
«, / l/si\».
DRAINAGE BASIN BOUNDARIES
3 MODERATE LIMITATIONS
-3 NOT CLASSIFIED
SEVERE LIMITATIONS
SLIGHT LIMITATIONS
-.--*^ STUDY AREA AND DRAINAGE
BASIN BOUNDARY
Figure 12. Soil limitations for septic tanks in central St. Croix.
-------
.
BOUNDARY OF
STUDY AREA
_ _ _
^^^^^^^
gex^ g^^^^^si^^^H^®^^^
ES2P-&
N
B
DRAINAGE BASIN
BOUNDARIES
STUDY AREA
j""* *-'" AND DRAINAGE
BASIN BOUNDARY
.'/.•/.•.•) ALLUVIUM
>V'.y'/>J (MARLS, SAND & GRAVEL.
AND/OR CLAYSI
MODERATELY PERMEABLE.
TYPICAL REPORTED YIELDS
5 TO 40 GPM
JEALOUSY FORMATION
(GREY CLAY) • NOT WATER
BEARING
ALLUVIUM
(GREY TO BROWN CLAY)
POORLY PERMEABLE.
TYPICAL REPORTED YIELDS
1/2 TO 2 GPM
MOUNT EAGLE VOLCANICS
SUPPLIES SMALL QUANTITIES
OF WATER
DIORITE EXTRUDED INTO
MT. EAGLi VOLCANICS
WEATHERED PORTION ISA
GOOD WATER BEARER
(MARL. CLAY & LIMESTONE)
MODERATELY PERMEABLE
TYPICAL REPORTED YIELDS
10 TO 40 GPM
Figure 13. Geological conditions in central St. Croix.
-------
relative subsurface permeabilities and the type of water-bearing
formations to be expected. Observations made in the field produced
specific information on soil conditions, current land usage, and
existing facilities such as wells, roads, available power, etc.
Several temporary roads were built and a trailer-mounted boring rig
was used to make soil borings at various locations. Samples were
evaluated in the field to determine the soil profile. Borings were
made at three different depths—4, 7, and 20 ft (1.2, 2.1, and 6.1 m).
The resulting 20-ft (6.1 m) holes were used for the placement of
piezometric tubes while the 4- and 7-ft (1.2 and 2.1 m) holes were
utilized for percolation tests. These latter two depths were selected
to give information on percolation capabilities of shallow ponds
versus a deeper trench arrangement. The results of the tests were
used to indicate the relative capacity for percolation between sites.
The data derived from the percolation tests in the four areas—Golden
Grove, Negro Bay, Adventure, and Barren Spot—are illustrated in
Figure 14.
Three sites were intensively investigated. These were in
Estates Adventure, Golden Grove, and Negro Bay. The site at Adventure
was discarded due to unfavorable soil conditions. The Negro Bay site
indicated some good percolation values and no water table but appeared
to contain some hard horizontal rock layers at depths from 8 to 20 ft
(2.4 to 6.1 m). The presence of a hard limestone layer is a situation
very typical of the Kingshill marls in which this site is located.
The Golden Grove site was very similar to the one at Barren
Spot. Both are located in alluvial valleys above a major public well
field and had relatively equivalent percolation results. However, the
groundwater at Golden Grove is closer to the surface than that at
Barren Spot.
The recharge area finally selected was one which made use of a
dual-site concept. Two separate sites were used, one at Negro Bay and
the other at Golden Grove. The sites selected were made up of two
entirely different soil and geological conditions but are located
quite close to each other. This permitted the use of one force main
and holding tank to supply both areas with only a slight additional
amount of piping. As these two formations comprise the bulk of the
geological composition of the coastal plain, the data obtained are
quite valuable in planning any expansion of the project to other areas
of the island.
The Golden Grove portion was the primary site of recharging
operations with the Negro Bay area used only for secondary
experimentation. The Golden Grove project area is part of a larger
parcel owned by the territory which is being developed into a
governmental complex. The entire parcel is 94 acres (38 ha) and will
ultimately be the site of a large building complex including an adult
correctional facility, a juvenile detention center, and the Public
Safety Headquarters. At the time of the initial studies the entire
33
-------
LLJ
S
u.
cc
to
I
o
cc
uj
ffl
_J
LLJ
>
UJ
_!
QC
UJ
NOTE: 7-ft GRAVEL-PACKED HOLES
PRESOAKED FOR 48 hr BEFORE
PERCOLATION TEST ON JUNE
13, 1971.
A ESTATE ADVENTURE
| ESTATE BARREN SPOT
0 ESTATE GOLDEN GROVE
ESTATE NEGRO BAY
20
40
60 80
TIME (minutes)
100
120
140
160
Figure 14. Results of percolation tests made at recharge sites under investigation.
-------
area appeared untouched and was overgrown with scrub growth.
Presently, the adult correctional facility and the public safety
building have been constructed.
In using this parcel, the permanent installations involved
with the recharging operations were located so that they will not
interfere with any of the future buildings planned for the area. This
again acted as another imposed restriction in the selection of land
for recharging. After extensive discussions, several small areas of
the parcel were set aside for project use by Lieutenant Governor Maas
who was supervising the development of the parcel at that time. These
areas were generally adjacent to the course of a meandering stream,
River Gut, which winds through the parcel.
The basic geological formation is an alluvial valley with the
soil types classified as being in the Coamo, Fraternidad, and
Fredensborg series (see Table 1). The actual soil boundaries are not
sharp in this area and the existence of some nonconforming lenses in
the soil profiles is common. The topographic features in the area
where the groundwater recharge operations in Estate Golden Grove will
take place are shown in Figure 15.
About one mile (1.6 km) down the alluvial valley is the Fair
Plains well field which is the major well field on the island with an
average production of about 0.24 mgd (908 cu m/day). It is this well
field that will be ultimately affected by the recharging operations at
Golden Grove.
The Negro Bay site consists of about 8 acres (3.3 ha) spread
over a slight saddle between two low hills. The underlying formation
is the Kingshill marl. The major soils in this area are classified in
the Fredensborg and Aguilita series (see Table 1). Borings made on
the site indicated that a hard layer of limestone existed under most
of the area at a depth of 8 to 20 ft (2.4 to 6.1 m). This has a mild
anticlinal shape with an axis in a northeasterly direction and a slope
of about 3 degrees. Recharging operations took place on the south
side of the axis.
Work in this secondary site was largely of an experimental
nature to see if the marls would have any potential for artificial
recharge as they are predominant along the coast of the central plain.
Although the major soil types in the area are classified as having
moderate to severe limitations for septic tank installations, initial
on-site percolation tests produced favorable results.
After the selection of the recharge area was accomplished, a
study area was defined for the project. This consisted of the surface
drainage area both above and below the recharge sites plus some
additional area to the south which was thought to be related by
groundwater flow. Within the study area, wells were selected for
monitoring water quality and water levels. These included wells which
35
-------
TABLE 1. SOIL CLASSIFICATIONS IN THE PROJECT AREA
Soil Classification
Description
Aguilita Series
Coamo Series
Fraternidad Series
Gently sloping to steep, well drained soils that
are shallow over soft limestone or marl. These
soils formed in residuum derived from limestone.
In a typical profile the surface layer is very dark
grayish brown and light brownish gray gravelly clay
loam about 6 in. (15 cm) thick. Below this is
mixed very dark grayish brown firm calcareous
gravelly clay loam that is 50 to 70 percent lime-
stone fragments. The substratum, at a depth of
about 10 inches, is mostly soft limestone but
contains hard limestone concretions. The soft
limestone material can be penetrated with a spade.
Drainage is good, and the permeability is moderate.
The water table is low.
Gently sloping well-drained soils that are deep
over volcanic and limestone rocks. These soils
occur on alluvial fans and terraces. They formed
in sediments derived from these rocks. The sedi-
ments range in texture from clay to sand.
In a typical profile the surface layer is very dark
grayish brown clay loam about 8 in. (20 cm) thick.
It contains a few rock fragments. The subsoil is
very dark grayish brown and yellowish brown, firm
clay. It also contains a few rock fragments. The
substratum, beginning at a depth of about 24 in.
(61 cm), is yellowish brown, friable, calcareous
clay loam stratified with sand and gravel.
Moderately well drained soils that formed in clayey
sediments derived from volcanic and limestone hills.
In a typical profile the surface layer is very dark
grayish brown clay about 13 in. (33 cm) thick.
Below this, to a depth of about 62 in. (157 cm),
is light olive brown calcareous, very firm clay.
Drainage is moderately good. Permeability is slow.
36
-------
TABLE 1 (CONTINUED).
Soil Classification
Description
Fredensborg Series
Well drained soils that formed in clayey, cal-
careous sediments over soft limestone or marl.
These soils occur near coastal areas, in valleys,
and on foot slopes below the limestone hills.
In a typical profile the surface layer is very pale
brown, very friable, calcareous silty clay loam.
At a depth of about 20 in. (51 cm) is a very pale
brown, soft marl or limestone.
The information for this table was adapted from the publication, Soil
Survey. Virgin Islands of the United States -1970.
37
-------
PUBLIC SAFETY
/ HEADQUARTERS
G G-6^1*^ —^ CHECK DAMS
6 IN. (15 CM)
SPUR LINE
TO C.V.I.
V
60
GOLDEN GROVE
RECHARGE AREA
I \
SPREADING BASINS
(TYPICAL)
NEGRO BAY
RAIN GAGE
SPREADING BASINS
AIR PLAINS
ELL FIELD
100,000 GAL
(380 CUM)
SURGE TANK
NEGRO BAY
RECHARGE AREA
6IN. (15 CM) FORCE
MAIN TO CONVEY
ENOVATED WASTEWATER i\
TO RECHARGE AREA \\\
SPRAY
/AREA
1000
0 100 200 300
Scale in Meters
I I ALLUVIUM
/ / /
PRIMARY WASTEWATER
TREATMENT PLANT
Figure 15. Surface geological features in the Golden Grove area.
-------
were above and below the recharge sites and some which were entirely
out of the drainage basin to use as controls.
DESCRIPTION OF THE STUDY AREA
The study area is outlined in Figures 11, 12, 13, and 16.
Figure 16 shows the area in detail including the existing wells and
recharge sites. This study area is about 8 sq miles (20.7 sq km) and
consists mainly of the drainage area for an intermittent stream called
River Gut. The main portion of this stream, referred to as the East
Branch, originates from springs located within Fountain Valley and
flows south-southeast through the area for a distance of about 6 miles
(9.7 km).
The northern part of the study area begins at the ridges of
the hills which surround Fountain Valley where they delineate the
drainage into the valley and downstream through River Gut. The ridge
line here ranges from 300 to 1,000 ft (91 to 305 m) in elevation, and
the slopes fall off sharply to the undulating valley floor.
Once south of the line which runs from the villages of Grove
Place to Coble, the study area becomes a gently sloping flat plain
that continues to the shore about 3 miles (4.8 km) to the south.
Low eroded hills on the southern end of the area divert the
flow of River Gut slightly to the east as they direct its course
through a gap in the hills known as Fair Plains. It is at this gap
where one of the government's largest well fields, the Fair Plains
well field, is located.
The east and west branches of River Gut wind through the study
area in a streambed that is generally depressed 2 to 10 ft (0.5 to 3 m)
below the land surface. Along its banks are older more established
trees which were left untouched during the years of cultivation. A
wide variety of trees are represented including, but not limited to,
mango (Mangifera indica), hog plum (Spondias mombin), West Indian
almond (Terminalia catappa), royal palm (Roystonea borinquena), and
licorice (Pithecel'lobium saman). These trees range from 40 to 50 ft
(12 to 15 m) in height and tower over the lower scrub growth of the
adjacent fields.
Visually, the animal density and diversity has appeared low in
the study area with the most frequently seen animals being the
mongoose (Herpestes auropunctatus) and the white-tailed deer
(Odocoileus virgimana).
Until about 1968 almost all of the flat portions of the study
area were used for pasture and for the cultivation of sugarcane by the
Virgin Islands Corporation. Aside from the golf course which occupies
the upper end of the study area, most of the rest of the land has been
39
-------
Mount
. , la?I,;
BODKIN
RAIN GAGE
Blue' (
Mountain "V\_
.
i rnu u n lu i M
o,
''
v)r
\\ STUDY i
GUT- / '\ AREA BOUNDARY
FOUNTAIN V \m ^ \ \
Bel/y •, l
^
ny s.
\f,
Ril
GUT7
RIVER
Upper)
Fredensborc
> ,
STUDY
AREA BOUNDARY
GUT-
HOLY CROSS'
>'ce .
V
GROVE PLACE I r ACXI F
RA.NGAGE f^ Su|KE
L""'vL t* /S>
Co
-------
allowed to naturally shift from pasture and cane to scrub growth.
This process has almost completely driven out the ratoon crops of
sugarcane by the rapid growth of Guinea grass (Pancium maximum) and
the spread of acacia (Acacia tortuosa), tan-tan (Leucaena glauca), and
thibet (Albizia lebbek) trees throughout the area. The change in
vegetation has been assisted by several fires which often sweep the
area during the dry seasons.
The main activity in the study area over the past 5 years has
been the clearing of land by bulldozing. Generally only a small
section of land is affected at a time but probably the whole area has
been cleared once and some parts several times. Fires have also
occurred in the area during times of drought. These usually will burn
entire fields and act as a clearing agent. Regrowth from both causes
is rapid and with the proper rainfall the main effects of clearing can
disappear within 3 to 6 months.
In 1972 a major wastewater interceptor was built alongside the
main and west branches of River Gut to serve the village of Grove
Place. About the same time a 100-unit multistory housing project,
Croixville, was built just north of the Adventure well field and two
large governmental complexes, the Public Safety Headquarters and an
adult correctional facility, were constructed in Estate Golden Grove.
In conjunction with the construction of the correctional facility,
about 1,000 ft (305 m) of River Gut was widened, straightened, and the
trees removed as part of a flood control plan.
Portions of the Golden Grove recharge area have been cleared
and planted in Bermuda grass, which gives better service and is easier
to maintain than the native Guinea grass. During clearing operations
the larger more desirable thibet and licorice trees were preserved on
the site.
The Negro Bay site, which is on the Kingshill marl, has
probably not been used agriculturally for at least 35 years. The soil
is not as rich as other parts of the coastal plain and the area had
been part of the U.S. Army base during World War II. Here the scrub
growth was lower in height but much denser and predominantly in thorn
trees such as acacia. The cleared areas have quickly moved to
revegetation with Guinea grass.
Groundwater Geology
Study Area. The knowledge of the groundwater geology in the
study area is somewhat fragmentary since it depends largely on
gathering information through actual coring of the mantle, either for
intellectual gratification or the actual construction of a well. This
has always been a rather expensive pursuit and currently costs
approximately $10/ft ($32.80/m) for a 6-inch (15 cm) uncased hole
using a cable tool drilling rig.
41
-------
An interpretive sketch of the geological formations in the
coastal plain that probably affect the flow and location of
groundwater in the study area is presented in Figure 17. This sketch
is based on a variety of source information but most notably on
observations by project personnel, Public Works Department well logs,
and publications by Cederstrom (1941, 1950) and Whetten (1963).
The major portion of the study area is in the coastal plain
which gently slopes up from the south shore to the hills of the
Northside Range. The geological base for this plain in the study area
is the Jealousy formation. Cederstrom (1950) mentions that this is a
gray clay, or mudstone, which contains some calcareous conglomerate in
its makeup. This formation is referred to locally as blue clay and it
has a reputation, not unfounded, for being an impermeable nonwater-
bearing stratum. Test drillings by Cederstrom found that this
formation had a thickness, adjacent to the study area, of over 1,398
ft (426 m) and hence when a local well driller encounters this
formation, he generally drills no further.
Lying on the Jealousy formation is the Kingshill marl which
Cederstrom (1950, p. 21) describes as consisting of "buff-to-white
moderately thick bedded limestone, alternating with soft cream or
white marl."
The limestone portion is generally quite hard while the marl
is comparatively soft and easily cut with a knife. The vertical
permeability of this formation is extremely low due to the intact
limestone layers, while the horizontal permeability can be quite high
due to solution cavities or other voids in the formation.
On the coastal plain the hills at Jealousy and Lower Love are
made up only partially from Kingshill marl while all of the hills
south of the Centerline Road consist of this formation. It probably
formed the entire plain but has been eroded by streams and the eroded
beds replaced by local alluvial deposition. This can best be seen in
the geological cross section of Estate Golden Grove, in Figure 18,
where a U-shaped valley has been eroded from the marl and filled with
the alluvial clays, sands, and gravels that make up the upper, most
recent formation on the plain.
This alluvial material becomes thinner as it proceeds
northward to the lower slope of the Northside Range. Within the
alluvium a number of defined gravelly aquifers exist separated by
thicker layers of silty clay. This clayey soil ranges from moderately
to highly impermeable, depending on the location. The existence of
alluvium is no guarantee of an underlying aquifer, as apparently the
deposition of sands and gravels has been nonuniform both horizontally
and vertically, which has resulted not only in the lack of aquifers in
the alluvium in some locations but isolated sand and gravel lenses in
others.
42
-------
600
500
NORTH NORTHWEST
CO
SOUTH SOUTH EAST
VILLAGE OF
GROVE PLACE
CROIXVILLE
HOUSING
PROJECT
CARIBBEAN SEA
SOUTH SHORE OF ST. CROIX
MT. EAGLE I
VOLCANICS^
ADVENTURE
WELL FIELD
GOLDEN GROVE
RECHARGE AREA
FAIR PLAINS
WELL FIELD
JP SEAJ
EXACT
INTERFACE
UNKNOWN
JEALOUSY FORMATION
(BLUE CLAY}
:%a^en
Vy^*~ v^'
300
4,000
8,000
12,000
HORIZONTAL DISTANCE (ft)
16,000
20,000
Figure 17. Geological cross section of the coastal plain.
-------
80
60
40
<
uj 20
SEA
LEVEL
20
KINGSHILL MARL-APPARENTLY NONWATER BEARING
EXCEPT IN FRACTURES, JOINTS, AND CAVITIES.
SANDY GRAVELLEY ALLUVIUM-MAJOR WATER
BEARING STRATA IN THE ALLUVIUM.
ALLUVIAL FINES-GENERALLY MONTMORILLONITIC CLAYS
AND SILTS. POORLY PERMEABLE.
INDICATES POTENTIOMETRIC SURFACE DURING THE FALL, 1972.
INDICATES PERMEABLE MATERIAL ENCOUNTERED.
EXCAVATION
FOR SEWER
1972
INTERCONNECTION MAY?
NOT EXIST AT THIS POINT.
&W8S8@&ms^G BASINS 'ffivy&jg - \
V 5$7^tj
wM^%
200
400
600
800
1,000
1,200
1,400
1,600
1,800
HORIZONTAL DISTANCE (ft)
Figure 18. Geological cross section of the Golden Grove area at right angles to the streambed.
-------
As seen in Figure 17 the alluvium and Kingshill marl
formations terminate in the north by contact with the Mount Eagle
volcanics. Cederstrom (1950, p. 16) mentions that "a large part of
the material is volcanic in origin, that much of it is stratified, and
that some limestone beds are interbedded with volcanics. Dark fine-
grained massive, laminated or slaty rocks, hard thin- to thick-bedded
limestone, and spotted or porphyritic rocks are most common." The
Mount Eagle volcanics generally yield minor amounts of groundwater in
their weathered portions and in the rock fractures and crevices. The
Mount Eagle volcanics make up the vast majority of the Northside Range
and it is believed that much of the water in the aquifers of the
coastal plain has its origin in these hills. The exact structure of
the interface, defined by the dashed circle in Figure 17, between the
coastal plain and the Northside Range is unknown and merely
hypothesized in this sketch. It is certainly a subject worthy of
further research efforts on the part of local geologists.
Not shown in Figure 17 is the geological structure of Fountain
Valley, which is in the northernmost part of the study area and
contains the springs which initially supply River Gut. Fountain
Valley has an alluvial valley floor but its walls are made up of not
only Mount Eagle volcanics but an intrusive igneous rock referred to
by Whetten (1968) as Fountain Gabbro. A plan view of the geological
formations exposed at the surface in central St. Croix is shown in
Figure 19.
Naturally the geology of the recharge areas is of great
concern to the project since this determines the ultimate disposition
of the recharged water after it enters the soil. As was mentioned,
two recharge areas were selected which are adjacent to each other but
yet geologically dissimilar. One contains alluvial deposits and the
other marls. These areas, Golden Grove and Negro Bay, contain the
geological formations that make up the vast majority of the land held
by the local government and therefore would be available for future
groundwater recharge utilization.
GOLDEN GROVE RECHARGE AREA
Using information obtained from old well logs, potentiometric
data plus borings, and new wells constructed in the area as part of
this project, three diagrams of the assumed geological configuration
in the Golden Grove area have been constructed. These are shown in
Figures 15, 18, and 20. Basically the area consists of alluvial
deposits laid down on top of the Kingshill marl. The alluvial deposit
is the one of concern in this area as far as recharging is concerned.
As shown in Figure 18 the deposit varies in thickness up to about 70
ft (21.3 m). Its predominant constituent is a montmorillonitic clay
which tends to be somewhat impervious.
45
-------
BOUNDARY
MOUNT EAGLE VOLCANICS
SUPPLIES SMALL QUANTITIES
OF WATER
DIORITE EXTRUDED INTO
MT. EAGLE VOLCANICS
WEATHERED PORTION IS A
GOOD WATER BEARER
JEALOUSY FORMATION
(GREY CLAYI - NOT WATER
BEARING
•S DRAINAGE BASIN p.-V.^/
1 ' BOUNDARIES fe**''
KINGSHILL MARL
(MARL. CLAY & LIMESTONE!
MODERATELY PERMEABLE
TYPICAL REPORTED YIELDS
1QT040GPM
ALLUVIUM
(GREY TO BROWN CLAYI
POORLY PERMEABLE.
TYPICAL REPORTED YIELDS
1/2T02GPM
AND/OR CLAYS)
MODERATELY PERMEABLE.
TYPICAL REPORTED YIELDS
5 TO 40 GPM
STUDY AREA
*—• AND DRAINAGE
BASIN BOUNDARY
Figure 19. Geological map of the coastal plain.
-------
I KINGSHILL MARL-APPARENTLY NONWATER BEARING
33 EXCEPT IN FRACTURES. JOINTS .AND CAVITIES .
I SANDY GRAVELLEY ALLUVIUM-MAJOR WATER
I BEARING STRATA IN THE ALLUVIUM.
plpjj ALLUVIAL FINES-GENERALLY MONTMORILLONITIC CLAYS
r----::,v;::< AND SILT. POORLY PERMEABLE.
-*- INDICATES POTENTIOMETRIC SURFACE DURING THE FALL, 1972.
£ INDICATES PERMEABLE MATERIAL ENCOUNTERED.
60
20 •
SEA
LEVEL
20
40
15) BORING
vBOTTOM OF GUT
WELL
pvvi WELL BORING
X P
WELL
WELL
FP8
1000
4000
2000 3000
HORIZONTAL DISTANCE (ft)
Figure 20. Geological cross section of the Golden Grove area along the plane of the streambed.
5000
-------
Spaced within the alluvial clays are thin horizontal aquifers
of clayey-sandy-gravelly material. These aquifers are usually no more
than 2 ft (0.61 m) in thickness and are probably not well
interconnected except due to boreholes in the vicinity and possibly at
the junction of two streambeds near the Fair Plains well field.
Groundwater studies have demonstrated that the potentiometric
head throughout the valley reflects the confined condition of the
water within the aquifer and does not represent a free water table.
In most of the study area and the island in general, an unconfined
water table does not exist. The water in the aquifers moves from
northeast to southeast below the recharge area. It must be kept in
mind that Figure 17 has the vertical scale exaggerated 15 times for
clarity and that the actual slope of the ground surface and aquifers
is less than 1 degree from the horizontal.
The upper aquifer, in Figure 18, is the aquifer mainly
affected by the surface recharge activities in the area. The material
between this aquifer and the ground surface tends to be a
nonhomogeneous soil with great variations taking place in the soil
types across the valley floor. The upper 18 inches of soil is a dark
clay with the lower material being lighter in color and containing a
higher percentage of silt and sand. This sand is of the silica
variety, which is rare on the island since calcareous sand is the
predominant form on the shoreline. Several beds of sand have been
encountered in the region but unfortunately they were not extensive in
area nor is it certain that they are interconnected. The gut which
winds through the valley depends on a base flow from springs located
at the head of the stream and other areas where the streambed cuts
into an aquifer and thus flows when the groundwater level is above -the
elevation of the bed.
The method of recharging proposed in the Golden Grove area was
by the use of spreading basins and existing streambeds. The limiting
factor was expected to be the permeability of the soil between the
recharging activity and the upper aquifer. The bottoms of the
spreading basins were therefore excavated below the extremely clayey
surface layer to utilize the increased permeability of the lower silty
horizons. This scheme did prove feasible and the recharge operations
were conducted mostly in the basins.
ft
The streambed in the Golden Grove area is below the
surrounding land from 2 to 8 ft (0.6 to 2.4 m) and thus somewhat
closer to the aquifer in question. Six small check dams 2 to 3 1,
(0.6 to 0.9 m) high were constructed in'the streambed to hold the
recharge water to facilitate infiltration and percolation.
Unfortunately the floods in October, 1974, severely damaged all of
these check dams before recharge experiments in the streambed could be
carried out.
48
-------
NEGRO BAY RECHARGE AREA
The geology of this area consists of calcareous material of
various types. Explorations in the recharge area were carried out by
shallow borings, to a depth of about 15 ft (4.6 m), and wells were
constructed to a maximum of 150 ft (46 m). A hypothesized
geological cross section of the Negro Bay recharge area is shown in
Figure 21.
The surface layer of about 6 to 12 in. (15 to 30 cm) is a dark
clay while the subsoil is of a calcareous nature, white to buff in
appearance and composed of a combination of a soft powder!ike material
interspersed with cemented nonstratified marl. Beginning at about 10
ft (3 m) below grade there are alternate hard and soft stratifications
of limestones and marl which continue to a depth of about 150 ft (46
m). Here the Kingshill marl rests on a montmorillonitic mudstone .
geologically designated as the Jealousy formation and commonly
referred to on the island as blue clay. Stratifications within the
Kingshill marl in this area are about 2 to 6 in. (5 to 15 cm) thick.
The movement of groundwater through the marl is by solution cavities
which apparently are rather small, generally having cross sections of
no more than about 20 sq in. (129 sq cm). These solution cavities
seem to run in specific strata in the formation but are not always
interconnected within the same strata.
During the summer of 1972 two wells were drilled, PW-2 and
PW-3, which confirmed the existence of alternate hard and soft layers
within the Kingshill marl. The formation was dry until the drilling
operation penetrated a hard limestone layer at an elevation of about 2
ft (0.61 m) below sea level and encountered water. This water proved
to be under pressure and rose in the well to about 15 ft (4.6 m) above
sea level. The two wells were constructed 250 ft (76 m) apart and
encountered water at the same elevation. The groundwater was confined
in both cases but production in one well was estimated at a rate of
only 2 gpm (0.13 I/sec) while the other produced at about 60 gpm (3.8
I/sec). Currently the latter well is being used by the Virgin
Islands' government as part of its public supply.
Recharging in the Negro Bay area involved the use of the
unconsolidated marls in the upper 10 ft (3 m) of the existing
formation. Numerous soil borings were made by the project in this
area to map out the extent of the unconsolidated marl and the
underlying limestone anticline. Long-term percolation tests indicated
that the upper softer marls were capable of receiving large quantities
of recharge water. This concept was tested on a full scale with
reclaimed wastewater, using surface methods such as spray irrigation
and spreading basins.
The recharged water from the site was expected to percolate
down to the first hard layer about 10 ft (3 m) below the surface which
would place it on the south slope of a mild anticline which has a
49
-------
en
o
80
ESTATE GOLDEN GROVE
ESTATIE NEGRO BAY
NEGRO BAY
RECHARGE AREA
mm ALLUVIUM
Xi^Vfi^t^&t-Q U NCONSO LI DATE D MARL
i^l^ym AQUIFERS
DRY STRATA :•':•'
HARD LIMESTONE;
AQUICLUDE ^xovx
,:.:: WATER CONFINED
SijS: BELOW
KINGSHII .MARL
1,000
2,000 3,000
HORIZONTAL DISTANCE (ft)
4,000
Figure 21. Geological cross section of the Negro Bay area.
-------
northeasterly axis. Indications were that this hard layer was
contiguous and probably impermeable. The water would then mound and
be available for recovery. This system would not involve any mixing
with the existing groundwater in the area as the groundwater is
located in strata about 80 ft (24 m) below the surface where it was
extremely improbable that the recharged water could reach.
Unfortunately the rate of infiltration and percolation of the
recharged water in Negro Bay did not prove to be up to expectation and
recharging operations were suspended in August, 1974.
HYDROLOGICAL DEVELOPMENTS IN THE STUDY AREA
Groundwater
In the normal groundwater recharge cycle on St. Croix, the
heavier rains occur between August and December; these tend to fill up
the aquifers which then slowly empty until the following fall when
they are refilled. There is also a short rainy season in the spring
and occasionally other times of heavy rains which aid in recharging,
but basically the aquifers must depend on these fall rains or any long
series of heavy rains which come in a pattern to permit maximum
infiltration and minimum runoff to the sea. Large amounts of rain
alone are unsatisfactory as much of the water can be lost in runoff.
The long-term relationship between the rain pattern and the water
levels in some wells in the study area is shown in Figure 3.
The groundwater in the study area at Golden Grove is entirely
dependent on infiltration possible from a tributary area of about 5.6
sq miles (14.4 sq km). Much of this area is surfaced with tight clays
and hence is limited as to its potential for infiltration and
permeability. The major aquifers in the Golden Grove area are of
gravelly sand with a thickness of less than 2 ft (0.6 m) and an
estimated width which varies from 250 to 1,000 ft (76 to 305 m).
There are several individual aquifers interspaced by clayey strata.
The major recharge activity appears to take place in the area north of
Center!ine Road after which the groundwater flows south-southeast to
the ocean.
This water is tapped in numerous places by government and
private wells which draw down on the stored water. A measure of the
amount of water existing in the aquifer at any time is the
potentiometric head on the aquifer at various points along the flow
network to the sea. Water level recorders were installed in various
key locations along the flow route which monitored the water levels in
these wells. Some accuracy is lost in these measurements since the
wells generally penetrate, and thus interconnect, more than one
aquifer.
51
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At the time of the first interim report (Black, Crow and
Eidsness, Inc.) in June, 1972, the study area was affected by a
surplus of groundwater. This hindered borings and required the
formulation of plans to reduce the amount of groundwater in the
recharging area to provide capacity in the aquifers to test the
feasibility of recharging. Plans to alleviate this situation were
carried out, but by the time of the second interim report (Black, Crow
and Eidsness, Inc.), in October, 1973, a contrary situation had
occurred in that a general deficit of precipitation during the
preceding 17 months had produced a circumstance where some of the
aquifers were nearly empty and others were producing at a reduced
capacity.
This deficit condition continued for an additional year and
marked one of the worst droughts in recent history. On July 22, 1974,
the island was proclaimed a federal drought disaster area. Many wells
went dry during this time and others, near the sea, had a significant
rise in salt content due to saltwater intrusion. Although the drought
condition was alleviated in August, 1974, by the first significant
rains in months, it definitely came to a close by November, 1974, when
record rains caused severe flooding over large portions of the island.
On November 15, 1974, the island was again declared a federal disaster
area, only this time it was due to flooding. Half the average annual
rainfall was received within a period of 25 days and the soil could
not handle the disposal of the water by infiltration. As a result,
billions of gallons of water ran off into the surrounding sea.
Although some recharge of the aquifers did occur during this
period, it was not concomitant with the amount of precipitation
experienced. Piezometric levels rose, but in the subsequent 8 months
only scant rainfall occurred and the levels rapidly dropped again. By
July, 1975, many of the piezometric levels had dropped close to the
previous spring's drought level. Although the quick shift from one
extreme to another in the water situation was caused by an unusual
rain condition, the overall long-range pattern of going from a surplus
to a deficit of water seems to be a regular, though unpredictable,
phenomenon for the island. This points up the utility of having a
method of artificial groundwater recharge working on the island which
will permit the leveling off of groundwater production at a constant,
predictable high rate, regardless of the climatic conditions.
Surface Water
The only significant surface flow in the study area occurs in
River Gut. In general, its base flow is dependent on the groundwater
level in the area. Runoff from storms makes up its flow on only a
small percentage of its total flow days. However, these runoffs can
be quite considerable and only a few days of heavy runoff can
represent the majority of the total annual flow. The amount of this
runoff contributing to streamflow is dependent on the rainfall
pattern, soil moisture, land surface, and vegetation conditions.
52
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During 1971 through early 1972 there was a continuous base flow in
River Gut as it passed through Golden Grove. But then due to the
depressed water table and lack of adequate precipitation, there was no
flow in the lower half of River Gut from March, 1972, to October,
1974, with the exception of two days of storm runoff and one week as a
result of a broken water main near the Adventure well field. A flash
flood occurred in October, 1974, and an even larger flood came again
in the following month. A sustained flow followed in River Gut which
continued until the latter part of December, 1974. From then until
September, 1975, there has been no flow in the streambed in the Golden
Grove area.
WATER AND WASTEWATER SYSTEMS ON THE ISLAND
The potable water distribution system on the island of St..
Croix has developed in small stages as finances permitted and politics
dictated. Its initial function was to service the two towns of
Christiansted and Frederiksted and the central sugar factories built
at several locations in the island. From this it was expanded or
converted to serve the expanding needs of the populace. Currently
both towns are supplied with potable water and portions of the central
coastal plain are included in the system.
The wastewater collection system was relatively simple up to
1970. Both towns collected and discharged their untreated wastewater,
via outfalls, into their respective harbors. Inland, most homes used
septic tanks while large housing developments employed small package
plants with discharge onto the fields or out to sea.
In 1966 a consultant surveyed the obvious defects in the
existing system and submitted a report and master plan (Camp, Dresser
and McKee, Inc.) for the collection, treatment, and ultimate disposal
of wastewater on St. Croix. This plan has been followed with only
minor deviations and today is well on its way toward completion.
Basically the plan called for a single treatment facility on
the south shore about midway between Christiansted and Frederiksted.
The wastewater from the two towns and the central portion of the
island would be transported to this facility by gravity interceptors
and force mains, given primary treatment, and discharged to sea via a
long ocean outfall. The system and its design are excellent; however,
since the designers were apparently neither informed by the local
government of its desire for eventual water reuse nor able to foretell
the generally unpredictable future on the island, the system was not
designed to cope with the complex problem of wastewater reclamation.
This fact, combined with the system of water distribution, has caused
considerable problems for the reclamation project.
The system of water distribution and wastewater collection on
the island is crucial to the successful reuse of water on St. Croix.
The distribution system has a variety of point sources which add water
53
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of differing qualities to the system at various locations. Table 2
names these point sources and lists the quantity and quality of the
water added to the system. Figures 22 and 23 show the sources of
wastewater and outline the relationship between chloride content from
these sources and the flows in the entire collection system on the
island. Figure 22 shows the situation as it was in June, 1974, when
the reclamation project was in operation. At this time only the
central portion of the island was contributing wastewater to the
treatment plant at Bethlehem Middle Works.
This limited area of collection is the reason that the amount
of wastewater available for processing in the AWWTP was so limited
during the operational phase of the project. The water used in this
area is a combination of groundwater from the Adventure, Barren Spot,
and Fair Plains well fields plus some of the desalinized water from
the Martin Marietta Company. Additionally, of course, each building
in the island supplies collected rainwater from its own cistern.
The most serious problem with the reuse of water on the island
comes from the total dissolved solids (TDS) in the waste stream. Most
notable are the chlorides which affect the taste of the water and its
suitability for agricultural purposes. Table 2 shows the great range
of chloride concentrations from the various sources. Some of this
groundwater for the central area is mixed in the 10 mil gal (37,850 cu m)
storage tank at Kingshill before distribution; but the final chloride
content of water used, and hence wastewater produced, is really a
function of the day-to-day production of each source. Figure 24 is a
graph of the chloride content of the influent to the AWWTP during the
operational phase of the project. The chloride content ranged from
about 300 to 2,500 mg/1 during this operational period.
Figure 23 shows the relationship of the chlorides in the
various sources of wastewater and the flows in the entire collection
system which went to the central primary treatment plant in September,
1975. The sources of wastewater have been increased by flows from the
town of Frederiksted. Aside from a large increase in wastewater,
there was now the addition of about 0.08 mgd (300 cu m) of seawater
which is used in Frederiksted for flushing purposes in several of the
major housing projects. This collection configuration became
effective in October, 1974, with the activation of the wastewater pump-
ing station in Frederiksted. The chloride content in the wastewater
being processed at the AWWTP increased immediately to about 2,000 mg/1.
This made the reclaimed wastewater unsuitable for present reuse
purposes. The artificial recharge of groundwater was discontinued
while the local government tried to resolve the problem. Although
progress has been made towards resolution, the situation still existed
in September, 1975.
-------
TABLE 2. MAJOR WATER SOURCES ON ST. CROIX
Source
Desalinized water
WAPA Stern Rogers plant
Martin Marietta Alumina Co. plant
Groundwater
Fair Plains well field
Barren Spot well field
Adventure well field
Concordia well field
Mahogany Road-La Grange well field
Rainwater collected in cisterns
Total of homes on island (estimate)
Average daily
contribution to
the water supply
(mgd) (cu m/day)
0.74 2,800
0.65 2,460
0.22 830
0.14 530
0.09 340
0.07 265
0.13 490
0.3 1,135
Average
chloride
content
(mg/1)
2
4
1,100*
670
230
390
250
10
*Extremely variable, this value is based on a mean of the samples taken
1971-1974.
55
-------
en
as
FREOERIKSTED TOWN
HARRIGAN COURT HD
HODGE PAVILLIONHD
MARKOE SCHOOL
GROVE PLACE VILLAGE
SiU HOUSING
LORRAINE VILLAGE HD
WILLIAM'S DELIGHT HD
PARADISE Ml LLSHD
PUMPING
STATION
NOT
OPERATIONAL
FREDERIKSTED
BYPASS
(FORCE MAIN)
CAMPO RICO
HD
WHIM HD
1
2% OF
TOTAL FLOW
220mg/l
CHLORIDES
GROVE PLACE VILLAGE
CROIXVILLE HD
CENTERLINE HD
GOLDEN GROVE PARK
TERRITORIAL PRISON
95% OF
TOTAL FLOW
450 mg/l
CHLORIDES
DIAMOND
INTERCEPTOR
]
SOUTHWEST "*
INTERCEPTOR
MON BIJOU HD
FREDENSBURG HD
STRAWBERRY HILL HD
AUREO DIAZ HEIGHTS HD
CENTRAL HIGH SCHOOL
1%OF
TOTAL FLOW
190 mg/l
CHLORIDES
2% OF
TOTAL FLOW
300 mg/l
CHLORIDES
GOLDEN
GROVE
INTERCEPTOR
BETHLEHEM GUT
INTERCEPTOR
FUTURE INTERCEPTOR
TO CHRISTIANSTED
RECLAIMED ^
WASTEWATER"
CENTRAL \/
COLLECTION^
STRUCTURE
IONS
REj-
AWWTP
PRIMARY
TREATMENT
PLANT
HD = HOUSING DEVELOPMENT
TO OCEAN
OUTFALL
Figure 22. The source of wastewater flows in June, 1974.
-------
en
-q
FREDERIKSTEDTOWN
HARRIGAN COURT HD
HODGE PAVILLION HD
MARKOE SCHOOL
GROVE PLACE VILLAGE
SIU HOUSING
LORRAINE VILLAGE HD
WILLIAM'S DELIGHT HD
PARADISE MlLLSHD
50% OF
TOTAL FLOW
3,300 mg/l
CHLORIDES
GROVE PLACE VILLAGE
CROIXVILLE HD
CENTERLINE HD
GOLDEN GROVE PARK
TERRITORIAL PRISON
45% OF
TOTAL FLOW
350 mg/l
CHLORIDES
FREDERIKSTED
BYPASS
(FORCE MAIN)
CAMPO RICO
HD
WHIM HD
i
1%OF
TOTAL FLOW
220 mg/l
CHLORIDES
DIAMOND
INTERCEPTOR
SOUTHWEST
INTERCEPTOR
MON BIJOU HD
FREDENSBURG HD
STRAWBERRY HILL HD
AUREO DIAZ HEIGHTS HD
CENTRAL HIGH SCHOOL
2% OF
TOTAL FLOW
380 mg/l
CHLORIDES
2% OF
TOTAL FLOW
320 mg/l
CHLORIDES
GOLDEN
GROVE
INTERCEPTOR
BETHLEHEM GUT
INTERCEPTOR
FUTURE INTERCEPTOR
TOCHRISTIANSTED
CENTRAL \/
COLLECTION^
STRUCTURE
ioJn
RE_J—
RECLAIMED
WASTEWATER
AWWTP
PRIMARY
TREATMENT
PLANT
i
TO OCEAN
OUTFALL
HD = HOUSING DEVELOPMENT
Figure 23. The source of wastewater flows in September, 1975.
-------
O1
oo
3,000 .
2,500 •
2,000' •
UJ
O
O
UJ 1,500
Q
OC
O
X
o
1,000
500
0
TESTING FREDERIKSTED
PUMPING STATION
(SALTWATER)
INFLUENT DILUTED
BY FLOODWATERS
START OF REGULAR
OPERATION
FREDERIKSTED PUMPING
STATION
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
4 ^— H
I . I
TIME (months)
Figure 24. Chloride content of the incoming wastewater to the AWWTP in 1974.
-------
SECTION VI
DESCRIPTION OF THE PROJECT FACILITIES
ADVANCED WASTEWATER TREATMENT PLANT (AWWTP)
Purpose
The purpose of the AWWTP within the project framework was to
upgrade the quality of the wastewater to a level where it could be
safely and efficiently used for artificial recharge of the groundwater
on St. Croix.
Goal
The goal of the AWWTP was to produce a clear, odor-free
effluent which would be extremely low in organics, suspended solids,
and microorganisms. Certain operational guidelines were drawn up and,
aside from normal organic reduction, it was desired that the effluent
have a turbidity of less than 3 Formazin Turbidity Units (FTUs) and
preferably less than 1. At the same time, the effluent should have a
free chlorine residual (FCR) after a 30-minute contact time of 1 mg/1
or more, at 1 FTU; and 3 mg/1 or more, at 3 FTUs.
The purpose of using these guidelines was two-fold. One was
the protection of public health and hence the desire to reduce
exposure of the public to possible pathogenic organisms to a
negligible degree. Additionally it was realized that the soil in the
main recharge area was predominately clays and,silts and that this
type of soil could be expected to clog readily if any significant
biological activity or mechanical entrapment took place. By adhering
to the guidelines, it enabled the project to minimize these problems
and efficiently utilize the small amount of land available for
recharging.
Design Assumptions
In the design of the plant, certain assumptions were made. A
discussion of the most significant of these follows with pertinent
comments on their validity.
Assumption 1. The primary plant and the associated wastewater
collection system in the western and central portions of the island
would be completed and operating with a total flow of about 1 mgd
(3,785 cu m/day) by the time the reclamation of wastewater began.
59
-------
In actuality the construction of the plant and interceptor
network was delayed at all stages, with the primary plant not being
placed in operation until August, 1972, and the important western end
of the collection system not being completed until October, 1974.
Thus incoming wastewater flows were below expectation during the
operational phase of the project.
Assumption 2. The incoming wastewater to the primary plant
would have a high biochemical oxygen demand (BOD) and ammonia-nitrogen
(NH3-N) content.
The local environmental health officials on St. Croix were
quite insistent on designing for a high incoming BOD. The basis for
this idea, at the time, was quite reasonable. Several package
treatment plants had been recently constructed in the territory to
service various large housing developments. Although different types
of plants were used, the results were often very poor as the high
organic loading to the plants had caused them to operate badly and, in
many cases, such as the package plant at Mon Bijou, to become a
community nuisance. This high BOD was the result of low water usage,
often only 15 to 40 gpd/person (57 to 151 1/day/person) due to the
severe shortage and high cost of fresh water. A health department
report (Grigg et al., 1971) on package treatment plants on neighboring
St. Thomas, which has similar water problems, showed a range in BOD of
incoming wastewater from 6 to 693 mg/1.
Since no interceptors existed at the time of design in the
central portion of the island, with the exception of the vicinity of
Mon Bijou, opportunities for testing were limited; and in view of the
package plant problems, it does not seem like an unreasonable
assumption. Samples of the incoming wastewater at the Mon Bijou plant
and the Frederiksted pumping station in July, 1971, were analyzed and
had a BOD of 1,000 and 260 mg/1, respectively; while the NH3-N level
was 90 and 56 mg/1, respectively. For design purposes it was
estimated that the BOD to the secondary portion of the plant would
range from 200. to 750 mg/1.
In actuality at the same time as the design of the AWWTP was
taking place, construction began on numerous multistory housing
projects in central and western St. Croix. These were completed in
late 1973 and had a capacity for about 8,000 residents, which is about
20 percent of the population of the island. A decision was made to
connect these units to the public potable water system and in most
cases to supply unmetered water to the tenants as part of the basic
monthly rental.
The result was a tremendous increase in the average water
usage and a concomitant reduction in the BOD of the wastewater which
entered the collection system from the central and western portions of
the island. The mean value of the BOD, determined on a bimonthly
60
-------
basis during 1974, for incoming effluent for the AWWTP ranged from 68
to 140 mg/1. Hence the plant has plenty of excess aeration capacity.
Assumption 3. Surface methods of artificial recharge would be
employed.
In actuality that is what happened.
Assumption 4. The saltwater flushing system in Frederiksted
would be converted to fresh water to avoid contaminating the
wastewater to be used for reclamation.
In actuality although the local government knew of the
situation, steps were not taken to alleviate the potential conflict.
Since the Frederiksted wastewater system was not connected to the
central collection until October, 1974, there was not really a problem
until then. After the connection, due to flooding damage on the
island, no positive action was taken on removing the salt water until
a governmental study group was formed by the governor in June, 1975,
to look into the problem. It is hoped that this saltwater situation
will be resolved during the fall of 1975. Until then, the project
cannot use its product water for agricultural irrigation or for
groundwater recharge.
Basic Design
The plant was designed to be an extended aeration activated
sludge plant followed by units to permit chemical coagulation,
filtration, and disinfection. A block diagram of the plant is shown
in Figure 25 and an aerial photo of the facility appears in Figure 26.
A list of major components with their specifications is shown in Table
3 while the major design parameters for the activated sludge section
are shown in Table 4.
These parameters make it apparent that this is basically a
standard extended aeration plant, but with a higher volumetric loading
and aeration capacity to minimize the size of the aeration tanks. The
use of a completely mixed extended aeration plant with sludge recycle
gave the facility an inherent ease of operation and the ability to
handle moderate shock loads. The prolonged residence time and excess
aeration capacity were expected to provide the environment for the
growth of nitrifying organisms which would act to convert ammonia
compounds to nitrates. This, in turn, would reduce the ultimate
chlorine demand at the time of disinfection.
After being aerated and continously agitated, the mixed liquor
moves from the aeration tanks to a circular clarifier for solids
separation, with provisions for a maximum of 100 percent sludge
recycling. After clarification the flow goes to a solids contact unit
(a reactor-clarifier) where chemical addition facilitates the removal
61
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INCOMING
RAW
WASTEWATER
PRIMARY
TREATMENT
PLANT
OS
to
LIFT
STATION
"I
TO OCEAN
OUTFALL
AERATION BASIN
AERATION BASIN
HEAVY LINE
REPRESENTS
NORMAL FLOW
PATTERN
PUMPING
STATION
T
CONTROLLED
OVERFLOW
SOLIDS
CONTACT
UNIT
CXD
CHLORINE
CONTACT
CHAMBER
TO RECHARGE
AREAS
MONITORING FOR:
TURBIDITY
CHLORINE RESIDUAL
FLOW
CONDUCTIVITY
GATE OR VALVE
LIMITS OF
RECLAMATION
PLANT
Figure 25. Flow diagram of the AWWTP.
-------
Figure 26. Aerial view of the AWWTP.
63
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TABLE 3. EQUIPMENT USED IN THE ADVANCED WASTEWATER TREATMENT PLANT
Equipment
Quantity Manufacturer
Additional Information
Oi
Influent sewage pumps 2
Aerators, surface 4
Clarifier 1
Sludge return pumps 2
Solids contact unit 1
Chemical feed pumps 2
Filters, mixed media 2
Backwash pump 1
Chlorinator 1
Chlorine analyzer 1
Effluent pumps 2
Total effluent flow meter 1
Turbidity meter 1
Conductivity meter 1
Flygt
Mixco (Lightning)
Eimco
Morris
Eimco
Wallace & Tiernan
Jet Flo (Reyco)
Worthington
Wallace & Tiernan
Wallace & Tiernan
Worthington
Leopold & Stevens
Hach
Beckman
4 in. (10 cm) CP-3126, 350 gpm at 60 ft TDH (22
I/sec at 18 m), 1,750 rpm.
25 hp (18.6 kw), Transfer 1,800 Ib (817 kg) of
oxygen/day/unit.
Type C, 35 ft (10.6 m) ID x 11 ft (7.6 m) SWD.
3 in. (7.6 cm) 3HS10, 175 gpm at 25 ft TDH (11
1/sec.at 7.6 m), 880 rpm.
Type HRB, 22 ft (6.7 m) ID x 11 ft (3.3 m) SWD.
Model A747.
Gravity, 10 ft (3 m) ID.
Model 12M90, 40 hp (30 kw), 950 gpm at 115 ft
TDH (60 I/sec at 35 m), 1,750 rpm.
Series 91-100, 100 Ib (45.4 kg)/day.
Model A-767, with recorder.
Model 10L22, 40 hp (30 kw), 350 gpm at 300 ft
TDH (22 I/sec at 91 m), 1,750 rpm
Model 61R, recorder and totalizer, 90° V-notch.
Model 1720, Rustrak recorder.
Model RQ1-7-CHIC-R1K, recorder.
-------
TABLE 4. DESIGN AND ACTUAL PARAMETERS FOR THE
BIOLOGICAL SECTION OF THE AWWTP
Parameters
Design
Actual*
Flow through the aeration tanks
(mgd)
(cu m/day)
Aeration tank capacity
(mil gal)
(cu m)
Detention time (hr)
Aeration tank MLSS (mg/1)
BOD (mg/1)
Food-to-microorganism ratio
(Ib BOD/lb MLSS) or (g BOD/g MLSS)
Rated oxygen transfer of aerators
Ib/hr
kg/hr
0.5
1,892
0.6
2,270
29
4,000 - 6,000
750
0.13
350
160
0.25 - 0.4
0.33 Estimated
Averaget
945 - 1,515
1,250 Estimated
Averaget
0.3t,#
l,135t,#
1,350$
133$
0.1$
175§,.#
80§,#
*Based on averages for the period January, 1974, through October, 1974.
tThe plant flow meter was located at the effluent portion of the AWWTP.
Since February, 1974, a portion of the influent entering the operation
tanks was bypassed back to the primary plant after the clarifier, but
before the flow meter. Thus the total influent could not be measured.
Meters have now been installed to measure the influent flow.
$Based on the average for the 8-month period.
§0nly 2 of the plant's 4 surface aerators* were used. During the
majority of operation only 1 of these aerators was used at one time and
hence the actual operating value would be one-half of this.
#0nly one aeration tank was used during actual operations.
65
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of remaining suspended matter including colloidal material. This
chemical, aluminum sulfate (alum), is mixed in the reactor turbine
section of the unit. Solids removal is by coagulation and
flocculation, which results in precipitation in the clarifier section
and agglomeration aiding filtration in the subsequent sand filters.
The filtration unit is composed of two gravity sand filters
which operate in parallel. The design filter loading rate is
approximately 2.2 gpm/sq ft (90 1/min/sq m) when both filters are in
operation. Backwash water is obtained from the chlorine contact
chamber and the backwashing is controlled by automatic timers.
Detention time is a minimum of 30 minutes in the chlorine
contact chamber before the effluent passes over a weir to the wet well
for transfer to the recharge areas by two vertical turbine pumps.
Special Design Features
Certain features were built into the AWWTP to increase its
flexibility and usefulness to the project. The most important of
these are discussed in the following paragraphs.
The aeration unit is separated into two equal tanks with
the water surface of one being 2 ft (0.61 m) above the water
surface of the other. This permits the tanks to be operated
singly, in parallel, or in series without additional pumping
required.
There are provisions for bypassing either the solids
contact unit, the filter, or both.
The effluent from the plant can be directed to either the
recharge areas, the head of the primary plant, or into the
ocean outfall.
The plant is monitored by recording instruments to give a
continuous record of the effluent turbidity, conductivity,
residual chlorine, and flow.
Plant Construction
Bids were opened in January, 1972, for the construction of the
AWWTP. The award was made to the Pizzagalli Corporation of South
Burlington, Vermont, and construction began in April, 1972, with a
contract completion date of January, 1973. The bid price was
$6.98,400.
Although the original structural work on the project proceeded
rapidly, there were delays in the fabrication and delivery of some of
the proprietary devices for the plant and additional delays on the
66
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site involving subcontractors, scheduling, quality control etc The
olant was provisionally accepted in October of 1973 while final
^cceptanceTd not take place until May, 1974. Start-up began during
the fall of 1973 with the plant operational by January, 1974.
Operation
The plant mode of operation was dictated by two important
factors- low flows and a low BOD. In early 1974 the flows through
the Plant averaged less than 0.25 mgd (946 cu m/day) and the influent
Ds raned below 100 mg/1. In order to compensate for this the
^r«^
solids contact unit (SCU) in maintaining a chennca sludge blanket in
thP reaction zone To correct this problem, the flow pattern was
m iffeS D° spmiing the cUrifier effluent "d returning a por ion
of the high flows back to the primary P ant. This return flow was
"»•
by dilution and a reduced production level from the plant.
Successful operation of the plant was very sensitive to the
(g/g).
A comparison of the actual average 1»«£wftctors with the
s
operation toxic materials, the sludge concentration was
reduced in the aeration tank.
67
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TABLE 5. OPERATING DATA FOR THE AWWTP (AVERAGE VALUES FOR THE
PERIOD JANUARY TO OCTOBER, 1974)
Parameter
BOD
COD
Total P
N03-N
NH3-N
C03
HC03
Total Hardness
Ca
Mg
Chlorides
Conductivity
PH
Turbidity
MLSS
SVI
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1 as CaC03
mg/1 as CaC03
mg/1 as CaC03
mg/1 as CaC03
mg/1 as CaC03
mg/1
umhos/cm2 at 25° C
FTU
mg/1
ml/g
Influent Effluent
113 12
206 31
12.3 9.0
0.6 12.9
22.6 6.8
0 0
318 123
289
114
172
456
1,778
7.4 6.7
1.3
—
—
Aeration Tank
—
—
—
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1,351
75
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Nitrification did occur within the secondary units, as shown
by the ammonia and nitrate data in Table 5. But this process,
especially reinforced by excess aeration and possibly other factors,
made solids separation difficult in the clarifier. The amount of
aeration was always a compromise between enough to keep the aeration
tanks mixed and hold a reasonable dissolved oxygen content,but not too
much to induce bulking and subsequent excess solids carry-over in the
clarifier.
The modification of the plant to permit the addition of alum
to the effluent of the aeration tanks improved settling
characteristics considerably. A dose rate of from 14 mg/1 to 25 mg/1
was found to be effective.
While nitrification did reduce the chlorine demand during
disinfection, it also created a problem by setting the stage for
denitrification in the clarifier. This problem is noted by Sawyer
(1967) and Busch (1971) who suggest the expeditious removal of the
sludge before it can be buoyed to the surface by entrapped or attached
nitrogen gas bubbles. This problem would generally occur in the early
morning hours when the flow from the primary plant was reduced. This
often permitted the sludge underflow in the clarifier to jam in the
telescope valve, if the latter was not set exactly right, causing the
sludge to start to build up at the bottom of the tank. This soon was
buoyed up and drastically increased the solids loading to the solids
contact unit and the filters, generally clogging the latter.
Continuation of this process for any length of time usually resulted
in a serious reduction of MLSS and, in general, unsatisfactory plant
performance.
In operating the solids contact unit, an alum dose of between
20 mg/1 and 35 mg/1 was found to produce a good sludge blanket.
Automatic sludge withdrawal was adjusted to keep the top of the sludge
blanket at least 5 ft (1.5 m) from the surface.
Alum was used as it was relatively inexpensive, functioned
without pH adjustments, was simple in operation, and worked. Some
experimentation was made using commercial polymers but the results did
not justify the extra cost and problems.
While alum worked quite well during the project's operational
period, it may be that in the future when the mineral content of the
wastewater changes due to shifts in the water source to desalinized
water, other coagulants and filter aids will need to be employed.
Not only does alum react with the bicarbonate in the
wastewater as follows:
A12(S04)3 + 6HCQ',1* 2A1(OH)3 + 350?+ 6CO
-------
to form a voluminous, gelatinous floe to aid in clarification, but it
also combines with phosphates in this reaction:
Al 2(504)3 + 2PO"43 + 2A1P04 + 3SO;2
Gulp (1971, p. 27) mentions that the "two reactions compete for
aluminum ions. At pH values above 6.3, the phosphate removal
mechanism is either by incorporation in a complex with aluminum or by
adsorption on aluminum hydroxide floe."
The pH of the wastewater at the point of alum application was
about 7.2. The pH was reduced in the AWWTP by approximately 0.6 units
due to alum addition and disinfection. Total phosphorus reduction did
occur but the removal rate was not consistent. Removals ranged from
about 10 to 60 percent within the plant. Phosphorus removal was not a
goal of plant design and only occurred as a by-product of
clarification. Phosphorus was expected to cause no problems in
recharging and would be removed in the upper soil layers by the clays
and silts in the area.
Disinfection was accomplished by the use of gas chlorination.
Originally 150-lb (68 kg) cylinders were used to supply the gas but
early in the project this system was converted to 1-ton (908 kg)
cylinders. This reduced the cost of the chlorine from approximately
$0.50/lb ($0.23/kg) to about $0.25/lb ($0.11/kg). Dosage varied with
effluent quality but generally ranged from 20 to 30 mg/1 . This was
more than was actually needed since a steady rate of chlorine feed was
used to maintain the minimum FCR desired at all flow levels. Thus the
selected rate chlorinated the high flows and organic surges at the
proper FCR and overchlorinated during the low flows. A programmed
proportional feeder could reduce the usage of chlorine considerably.
The results of disinfection were excellent, with a reduction
of coliform bacteria from a magnitude of 107 colonies/100 ml in the
AWWTP influent to a value of 0 and occasionally 1 colony/100 ml in the
effluent.
Plant Production
When the interim report for this project was published in
October, 1973 (Black, Crow and Eidsness, Inc.), it predicted that it
would only be possible to produce a maximum of 750,000 gal/wk (2,839
cu m/wk). This was attributed to the expected low wastewater flows to
the primary plant, the pattern of pumping associated with the primary
plant, and the lack of personnel to man the AWWTP on a 24-hour basis.
This situation would have been substantially improved with the
addition of the wastewater flow from Frederiksted,but it was decided
70
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to continue ahead with the project without waiting for completion of
that phase of the wastewater collection system. As it was, work was
not completed on the crucial Frederiksted pumping station, whose
operation about doubled the flow to the primary plant, until October,
1974.
However, by making certain modifications to the basic plant
design and operations schedule, it was possible to exceed the
estimated maximum production level; and by the time the recharge work
was suspended, in October, 1974, the plant was averaging over 1 mil
gal/wk (3,785 cu m/wk) and had boosted its maximum daily production to
about 300,000 gpd (1,135 cu m/day). This represents effluent actually
delivered to the recharge areas. Actual production in sections of the
plant was higher.
A bar graph showing the actual weekly production and delivery
of reclaimed wastewater to the recharge area is shown in Figure 27.
These data exclude water produced and not pumped to the recharge area
and water used for backwashing.
Delivery of water to the recharge areas was halted if the
guidelines for turbidity or free chlorine residual were exceeded or if
the chloride content exceeded 500 mg/1 to 550 mg/1. Generally the
plant operated at a turbidity level of about 1.5 FTU and a FCR of 4
mg/1.
Operational Problems
Aside from the low flows to the pi ant,power input problems
plagued the plant throughout its operation. Failures in the island's
power distribution system are common. The manner in which the power
would be cut off to the plant would often cause the control circuits
to register an overload and to open their automatic circuit breakers,
which required manual resetting. If this occurred on weekends or
evenings when the plant was not manned, then the plant would not
function properly and production was lost.
Difficulties with various pumps posed the next most
troublesome problem in the operation of the plant. The reliability of
the pumps was probably affected by their remaining idle for a long
period of time when the plant was delayed in completion and then
operating under a salty tropical condition. More production was lost
due to pump difficulties than from any other mechanical cause.
Initial troubles centered around the submersible pumps on the influent
station. These initially had two manufacturing defects which took
considerable time to finally locate. Then one of the pumps had to be
completely overhauled due to a seal failure. However for the past 18
months they have been operating without problems.
The plant water pump has burnt out once and lost its impeller
on another occasion. The vertical turbine effluent pumps had a series
71
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Figure 27. AWWTP production utilized for artificial groundwater recharging.
72
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of problems during the summer of 1974. The motor on one of the pumps
shorted out and required rewinding, and the pump assembly on the other
required a complete overhaul. Since these incidents occurred within a
few days of each other in July, it adversely affected the plant's
ability to transfer treated effluent to the recharge area for about 5
weeks until repairs were effected. The distance from the mainland and
the difficulty in obtaining spare parts and service turns a small
incident like this into a major problem.
An algal problem was experienced in the clarifier, solids
contact unit, filters, and chlorine contact chamber. In the clarifier
the algae formed on the effluent trough and baffle. This was handled
by scrubbing down the affected area twice a week before the algae
built up to an unmanageable degree. The problem was severe in the
solids contact unit and the final solution was to cover the unit with
an opaque polypropylene fabric which was custom-made by a local
sailmaker. This has worked excellently and has solved the difficulty.
The algal buildup in the filter was controlled by the chlorine in the
backwash water and a plywood cover over the splitter box.
The direct sunlight on the chlorine contact chamber not only
created an algal problem but it caused a higher chlorine demand during
the daylight hours. Initially a temporary opaque plastic cover was
placed over the chamber but this was later replaced by the
construction of a 50 x 20 ft (15 x 6 m) steel building over the
chamber. This not only served the purpose of covering the chamber but
it provided extra storage room for chemicals (alum) and tools plus an
office and shower area for the operators.
Plant Expansion
The present capacity of the AWWTP is adequate to permit the
artificial recharge and recovery of sufficient groundwater to
economically justify its operation. If there is a viable market for
additional reclaimed wastewater and if there is a reliable long-term
supply of wastewater of a quantity that merits treatment, then the
expansion of the AWWTP should be considered.
However extensive capital outlays should not be made on
expansion until a reasonable plan has been agreed to for the
disposition of the high chloride wastewater from both the Frederiksted
and the Christiansted areas.
The AWWTP has the capability for inexpensive expansion of
capacity built into many of the units, so that outright duplication of
the units would not be necessary. The following is a discussion of
each major unit operation as it applies to future plant expansion.
Influent Pumping. This is an item that needs correction
immediately^The influent to the AWWTP is erratic due to the diurnal
73
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pattern of flows in the interceptors and the nature of the high
capacity pumps used in the primary plant lift station. With their
present installation the flat rate 350 gpm (22 I/sec), AWWTP influent
pumps either do not get enough to pump or cannot handle all that is
available from the ocean outfall line.
It is suggested that the present AWWTP lift station be
abandoned and the pumps be relocated at the effluent end of the
primary clarification basins. These basins will act as large
equalization tanks permitting the pumps to deliver a continuous flow
to the AWWTP.
The proper location of the pumps will allow the rakes to
function unimpaired, although 'the surface skimmers will be inoperative
while the level of the tank is below the effluent weir. Certain
adverse currents may be induced during low flow operations; but since
the product will be receiving additional treatment in the AWWTP, it
should not be a great disadvantage.
It is suggested that 8-in. (20 cm) cast or ductile iron pipe
be used from the pumps to the AWWTP along with throttling valves to
adjust the head. This will reduce the friction head over the longer
distance so that the original pumps can still be used. It will also
provide capacity so that the pumps can be operated at higher rates
when desired. When in dual, parallel operation using the new
pipeline, it is believed that the present pumps will be able to
deliver up to 550 gpm (35 I/sec).
The installation of this change now could probably increase
the reliable output of the AWWTP by about 0.1 mgd (378 cu m/day). The
need to bypass and return a portion of the flow in the secondary
clarifier would be largely eliminated. A smooth flow, steady organic
loading, and efficient chemical addition could be maintained 24 hours
per day.
Aeration. The aeration section of the plant is overdesigned
for the wastewater now being processed; and by operating both aeration
tanks, there should be little problem in handling up to 700 gpm (44
I/sec) both from a hydraulic and oxygen transfer standpoint. This is
assuming that the wastewater characteristics do not change in the
future.
Clarification. The design loading is about 540 gpd/sq ft (22
cu m/day/sq m) of surface area in the clarifier. However with the use
of coagulants such as alum and the proper operation of the aeration
tank, this loading can probably be exceeded without problems. The
higher level must be determined by actual experimentation since it
will depend on the makeup of the wastewater and the selection and
dosage of coagulants used.
74
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During plant operations extended trial runs were made adding
alum to the effluent from the aeration tank to improve solids
separation in the clarifier. This enabled plant personnel to bypass
the solids contact unit (SCU) and transfer the clarifier effluent
directly to the filters. This eliminates the SCU from use and it
could be utilized, with some modifications, as an additional clarifier
to work in parallel with the present one. Keeping the same design
surface loading rate, this would allow the clarification of an
additional 0.2 mgd (757 cu m/day) of mixed liquor suspended solids.
However there are some disadvantages to keep in mind.
The SCU acts as a backup for the clarifier. If the clarifier
malfunctions and permits solids carry-over, the solids are usually
handled in the SCU. Without the SCU the solids would rapidly clog the
filter.
The second major disadvantage is that there are no provisions
for surface skimming nor underflow solids return to the aeration tank
from the SCU.
Filtration. It is doubtful that this unit can increase its
production capacity. It is suggested that if additional filtration
capacity is needed, another filter unit capable of handling at least
350 gpm (22 I/sec) be purchased and installed.
Effluent Pumps. To increase production it would be necessary
to purchase new pumps with a higher capacity. These could be
installed in the same location as the old pumps. These should be
selected and equipped with throttling valves so that the rate of
discharge can be matched to the production level of the plant. This
will prevent the wet well from being emptied too rapidly and thus
reducing the cycling of the pumps. The old pumps could be utilized,
at a later time, at a booster station to transfer reclaimed water from
a storage facility at the Department of Agriculture's Lower Love
facility to various points for irrigation purposes.
Expansion Plan. It is recommended the expansion of plant
capacity be carried out in 3 phases. After each phase, performance of
the system should be reevaluated and modifications made, as necessary
to the next phase. These phases, along with a generalized cost
estimate are discussed in the following paragraphs.
Phase 1 - 0.5 mgd (1,892 cu m/day) - Move the influent
pumps to the effluent end of the primary settling tanks.
Construct the line to transfer the wastewater from the primary
plant to the aeration tank. Install throttle valves on the
influent and effluent pumps. Expand the recharge area.
Estimated cost $30,000.
It is suggested that these improvements be made as soon
as possible.
75
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Phase 2-0.75 mgd (2,725 cu m/day) - Install an
additional 350 gpm (22 I/sec) gravity filter. If the
clarifier cannot handle the new load, then repipe the solids
contact unit in parallel. Install effluent pumps with a
capacity of 700 gpm (44 I/sec). Expand recharge areas.
Estimated cost $70,000.
Phase 3 - 1 mgd (3,785 cu m/day) - Install an additional
clarifier, new influent pumps, and expand the recharge area.
Make general plant improvements to handle higher loading.
Estimated cost $140,000.
RECHARGE AREAS
The development of the recharge facilities took place in
stages during the construction and operational phases of the project.
The initial facilities developed covered those types of surface
recharge methods which appeared to offer the most promise as far as
recharge in the existing soil strata was concerned. As noted
previously, it was expected that the AWWTP would produce about 750,000
gal/wk (2,840 cu m/wk) in the period following start-up and the
recharge facilities were sized to handle this capacity.
As operations continued and information was collected, the
data were evaluated and the facilities were modified, expanded, or
phased out as the situation dictated. The original recharge
facilities consisted of spreading basins, spray irrigation, and
spreading in a dry streambed. All of these facilities were built with
flexibility to permit modification to ensure maximum efficiency.
Although the effluent from the AWWTP was conveyed to the recharge
areas in a permanent ductile iron force main, the final portion of the
piping from the force main to the basins, etc.,-employed portable
aluminum and PVC pipe so that changes could be readily made by project
personnel with a minimum of effort and expense.
As discussed in the section on preliminary investigations,
recharge was planned to take place in two separate areas, Golden Grove
and Negro Bay, which were geologically different but located very
close to each other and hence easily served by the same force main and
storage tank. Golden Grove was to be the major facility, with the
Negro Bay site to be used for secondary experimentation.
As part of the final selection and location process for the
recharge sites, a series of wells were drilled in the two areas to
further define the geological strata. The logs of these wells and a
chart of the soil borings appear in the Appendix and the well
locations are shown on Figure 6.
Three of these nine wells, PW-1, PW-2, and PW-4, were
transferred to the Public Works Department (PWD), which activated them
76
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for use in its potable water system. At the time of drilling and
initial pump tests these wells had a demonstrated aggregate total
capacity of about 100 gpm (6.31 I/sec). This addition of
approximately 140,000 gpd (530 cu m/day) to the potable water system
was meant to aid the PWD in building up its freshwater reserves so
that it would be able to switch the saltwater flushing system in
Frederiksted to fresh water when the town's wastewater was diverted to
the new primary treatment plant at Bethlehem Middle Works.
However as drought conditions persisted on the island, the
yield of the wells decreased to approximately 60 percent of their
initial rates. Still, this would be sufficient production to allow
substitution of potable water for salt water in Frederiksted where the
saltwater usage is approximately 75,000 to 80,000 gpd (284 to 302 cu
m/day).
The active project well in Negro Bay, PW-2, was located where
it should not, due to the geology of the area, be affected by the
recharging operations at the Negro Bay site. However the two wells in
Golden Grove, PW-1 and PW-4, should be affected to some degree by the
recharge operations in that area. PW-1 was located approximately 200
ft (61 m) from the edge of the nearest spreading basin, while PW-4 was
about 300 ft (91 m) from the same basin. Although the wells were
hydrologically upstream of the recharge site, they were expected to
extract a small diluted portion of the artificially recharged water.
The recharging was also expected to increase the yields of these wells
since water was being added to one of the aquifers being pumped. This
increase, however, would not necessarily be directly and entirely from
the recharged water but most probably would be due to a combination of
recharge flows and impounded aquifer flows resulting from the damming
up of the aquifer by the artificial mound created at the recharge site
immediately downstream.
The recharge areas were developed and constructed within the
project by renting heavy equipment for the earth-moving portions and
performing the minor work remaining using project personnel. The
development and operation of the two areas are described in the
following discussion.
Golden Grove Recharge Area
Description. The Golden Grove recharge area consists of six
spreading basins and six small check dams in the adjacent riverbed. A
sketch of the facility is shown in Figure 28 and an aerial photograph
showing a portion of the basins is seen in Figure 29.
The six spreading basins were constructed with a total bottom
area of about 45,000 sq ft (4,180 sq m). During construction the
upper layer of the soil was removed in each case to expose the more
porous lower horizons. Due to the extremely clayey soil between the
77
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BURIED 4" WELL WAT.ER
COLLECTOR LINE
*$ TANK ......
?;
BURIED 6" FORCE MAIN
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Figure 28. The Golden Grove recharge area.
78
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PWR
WESTERN LIMIT
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Figure 28. (Extended)
GRAVITY
WASTEWATER
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0 10 20 30
79
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Figure 29. Aerial view of the Golden Grove recharge area.
-------
upper aquifer and the one immediately below it, the upper one acts as
a conduit to move the new water horizontally with minimal leakage
between the two.
Bermuda grass was developed in the recharge basins and
surrounding areas. This grass was selected as it is tolerant to a
high level of dissolved solids and is quite resistant to dry periods,
prolonged flooding, and heavy traffic. The grass aids in stabilizing
the soil, reducing erosion while creating root channels to encourage
infiltration and percolation. Due to normal uptake and metabolism, a
portion of the nutrients contained in the recharged water is
incorporated in the plant material. This low grass is easily cut,
harvested, and mechanically removed from the recharge area. This
effectively removes some of the nutrients from the system. No
definitive studies were undertaken on the nutrient uptake by the
Bermuda grass but the grass grew luxuriantly during a time of severe
drought on the island.
Water was brought to each spreading basin by a 4-in. (10 cm)
diameter aluminum irrigation pipe. The water was discharged into the
basin by impinging it upon a splash block and a pile of large stones.
This dissipated the energy in the water so that it could enter the
basin without eroding the bottom.
Each pond was first tested for a short period to ascertain its
relative ability for infiltration and percolation. After this, two
ponds were selected to determine how long the wet cycle of operation
could be extended without a noticeable drop in infiltration
efficiency.
During recharging operations the selected basin, or basins,
were filled to a height of 3 to 3.5 ft (0.9 to 1.1 m). Then the flow
to the pond was adjusted to maintain the same water depth. This meant
that the water was entering the pond at the same rate that it was
being lost by infiltration and evapotranspiration. It proved
relatively easy, in practice, to hold the depth to within 0.5 ft (0.15
m) through the use of adjustable valves at the force main standpipes.
The results of the operation are outlined in the section on results
and discussion.
The work using the check dams in Golden Grove was scheduled to
begin in November, 1974. Unfortunately recharge operations were
suspended due to the high TDS of the wastewater and the floods during
that month; therefore no data were collected on that phase of the
project.
Design Considerations. One of the best guides to the design
and operation of a groundwater recharge system using wastewater
effluent is a report entitled "Soil Mantle as a Wastewater Treatment
System" by McGauhey and Krone (1967). This was based on considerable
81
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experience with septic tank studies and was broadened to include other
soil-oriented treatment systems involving wastewater. Aside from an
extensive literature review and discussion of the the theoretical
aspects of the subject, the authors present some recommendations for
the design and operation of an engineered soil system. As part of
these recommendations they developed eight criteria for optimizing
such a system. These criteria from the report (McGauhey, 1967, p.
144) are quoted below; and following each one is a discussion of its
application to the system constructed in Golden Grove on St. Croix.
In reviewing these criteria and subsequent discussions it must
be kept in mind that they were developed for a soil-aquifer system
which was meant to act as a treatment process for wastewater. In the
St. Croix project the soil-aquifer system is meant to be a treatment
process only in the sense of a polishing of the extensive processing
that has already taken place in the AWWTP. The system also acts as a
safety barrier against any occasional deficiencies in the treatment
process. Hence it is expected that the soil system will reduce
nutrients and remove most organics, bacteria, and viruses,but it is
not to be expected to bear the brunt of the oxidation and filtration
processes that a system using settled wastewater or septic tank
effluent might experience.
"Criterion 1: The infiltrative surface should be no less
permeable than any undisturbed parallel plane within the system."
As part of the construction of the basins the upper, less
permeable, layer was removed to expose a more permeable soil horizon.
Soil borings in the area indicate that permeability does not decrease
below the newly exposed horizon before the upper aquifer is reached.
"Criterion 2; The soil surface should be managed in such a
manner as to disperse clogging material."
One of the suggestions made by McGauhey and Krone was to grow
vegetation on the areas to provide root channels and expand the soil.
This was done using Bermuda grass which additionally stabilized the
banks of the basins to permit foot traffic and incorporated a portion
of the applied nutrients in their plant material for removal by
harvesting.
"Criterion 3: There should be no abrupt change in particle
size between coarse trench fill or surface cover material and soil at
the infiltrative surface."
Since the existing soil structure is the infiltrative surface,
this is no problem as no larger material, such as gravel, is applied
to this surface.
"Criterion 4: The infiltrative system should provide a
maximum of sidewall surface and a minimum of bottom surface."
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The use of a basin design entirely violates this criterion.
The cost of construction, ease of maintenance, and simplicity in.
operation were deciding factors in selecting spreading basins over
trenches. Additionally the use of vegetation for dispersing any
clogging material (Criterion 2) and nutrient uptake can be maximized
with the basin configuration.
"Criterion 5; Continuous inundation of the infiltrative
surface must be avoided."
By using a system design, such as the one in Golden Grove,
containing many basins; the flow can be diverted to any of the basins,
allowing some to be utilized while others are allowed to dry out.
Successful management of the facility depends on having sufficient
basin area so as to provide for alternative loading and drying cycles
during operation. The area required in the future has been
reevaluated on the basis of the results obtained and is discussed
under the section on monitoring activities.
"Criterion 6: Aerobic conditions should be maintained in the
soil system."
This is to promote aerobic metabolism by the soil biota to
prevent the buildup of undesired anaerobic by-products such as
clogging slimes or taste and odor-causing compounds. This can be
maintained in several ways. The first is to use alternate loading
cycles, wet and dry, in the operation of the spreading basins.
Another is to remove the water accumulating in and above the aquifer
under the spreading basin as rapidly as possible so as to prevent the
groundwater mound from building up until it reaches the bottom of the
basin. The section on recommendations for future development covers
this situation.
"Criterion 7: The entire infiltrative surface should be
loaded uniformly and simultaneously."
Since the bottom area of the spreading basins is the primary
infiltrative surface, it will be loaded rather uniformly as the
bottoms are relatively level. The sidewalls, however, are loaded
differentially, but they do not contribute as much to the total
recharge effort.
"Criterion 8: The amount of suspended solids and nutrients in
the applied water should be minimized."
The design of the treatment process for this project was
oriented towards a high reduction of suspended solids and organic
material. The problem of a mat forming on the surface of the soil and
clogging the pores did not manifest itself to any noticeable extent in
the project during normal operations.
83
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Nutrients were not fully removed in processing at the AWWTP,
with ammonia generally converted to the nitrate form and the
phosphates only partially removed. Undoubtably the growing and
harvesting of Bermuda grass in the spreading basins aided in the
removal of additional nutrients while the soil itself is capable of
handling phosphate removal.
Negro Bay Recharge Area
Description. In the Negro Bay area two types of recharge
met iods were tested: spreading basins and spray irrigation. A sketch
of the facilities is shown in Figure 30. The spray irrigation portion
consisted of a gently sloping (0.031) field 250 ft by 250 ft (76 m by
76 m). The water was transferred from the permanent standpipe to the
field by 4-in. (10 cm) aluminum irrigation pipe. In the spray area
grids containing 8 spray heads each were set in the field. The feed
in the grid loops was by 2-in. (5 cm) PVC pipe. The spray heads were
Rainbird 30 B-TNT with an 11/64 x 3/32 nozzle that was rated for a
92-ft (28 m) diameter circular spray pattern at 40 psi (258 kg/sq cm)
with an individual feed of about 7 gpm (0.44 I/sec). These spray
heads were placed on 2.5-ft (76 cm) risers at 60 ft x 60 ft (18 m x 18
m) spacing. The actual rate of surface loading was about 2 gpd/sq ft
(0.08 cu m/day/sq m).
The normal mode of operation was to run the entire system 3.5
to 13 hours at a time with the total loading ranging from 0.3 to 1.1
gal/sq ft (0.012 to 0.044 cu m/sq m). Higher loading than this caused
surface runoff and erosion of the soil.
The entire area was seeded with Bermuda grass which, due to
the poor soils in the area, did not fill out as thickly as it did in
the Golden Grove spreading basins.
The results of the tests were not encouraging. Water did not
build up in the various piezometric tubes installed in the area. If
the spraying time or amount of water applied at a single time was
increased, runoff occurred. The rate of application was far below
that of the ponds. What apparently occurred is that the soil moisture
in the upper layer was increased during spraying periods; but in the
periods between spraying, the water was removed by evapotranspiration
aided by the capillary nature of the marly soil which acted as a wick
for the water incorporated in the soil. To decrease erosion a better
vegetative cover could have been developed by leaving more of the
clayey soil on the surface. However this would also act as a further
barrier to the infiltration of water applied by spraying.
The two spreading basins in the Negro Bay section were run on
an alternating wet and dry cycle. Each pond has an average bottom
area of about 2,500 sq ft (232 sq m). The ponds are built on a slight
slope so that the water depth is limited by the downslope side. The
84
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FORCE MAIN
STANDPIPE
DIRT ROAD
4-in. DIAMETER ALUMINUM
IRRIGATION PIPE
BASIN NO. 8
BASIN NO. 7
2-in. DIAMETER
PVC PIPE
DIRT
WINDROW
SPRAY
IRRIGATION
AREA
10 20 30
POWER POLE
POWER POLE
16 SPRAY HEADS
MOUNTED ON 30-in
PVC RISERS
DIRT ROAD
POWER POLE
Figure 30. The Negro Bay recharge area.
-------
marls neither lend themselves well to the construction of berms around
the ponds nor to stabilized banks as do the soils in Golden Grove.
Erosion of the sidewalls contributed to the plugging of the bottom
surface of the basins.
Each pond was initially run on a constant-head basis where the
ponds were filled to a certain depth and then the flow was throttled
down to try to maintain that depth. This was not satisfactory over a
long-term basis as the ponds took so little water that the setting had
to be too low for effective operation. The average percolation rate
based on bottom area was so low that work in the Negro Bay area was
suspended and the remaining efforts were applied in the Golden Grove
area.
86
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SECTION VII
MONITORING ACTIVITIES DURING THE PROJECT
As part of the project an extensive monitoring program was
established to provide data for a "before, during, and after" look at
the various parameters that might be affected by the recharge
operations. It was desired to carefully monitor surface and
groundwater quality and quantity in the study area and, in addition,
monitor the operation of the AWWTP.
WATER QUALITY
A water quality laboratory was established within 3 months of
project operation on St. Croix. This was first located in the field
office, then in laboratory space donated by the Martin Marietta
Alumina Company, and finally in February, 1973, in the permanent
laboratory which was constructed as part of the AWWTP facility.
The number of parameters analyzed was increased as laboratory
facilities improved. Initially a chemist was brought in from the
mainland to do the work and to train local people for the work so that
he could phase himself out.
In addendum No. 1 of the original project proposal (FWPCA-
1970), a list of analyses to be performed during the project was noted
and is as follows:
Specific conductivity
Chemical oxygen demand
Biochemical oxygen demand
Total nitrogen
Ammonia nitrogen
Nitrite nitrogen
Nitrate nitrogen
Phosphate
Total organic carbon
Chloride
Coliform
To these tests were added those for alkalinity, calcium, and total
hardness plus operational tests for the AWWTP.
87
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All of these analyses were performed on St. Croix with the
exception of the total organic carbon and total nitrogen measurements
which were performed in the Black, Crow and Eidsness laboratory in
Gainesville, Florida.
A survey of the entire study area was made and wells, both
public and private, were selected for monitoring purposes. These were
located above and below the theorized groundwater flow at the proposed
recharge areas. Only active wells were selected for water quality
monitoring purposes. These were wells that were being actively
pumped, thus assuring a fresh sample of the groundwater for analysis.
Additionally sampling points were selected along the course of River
Gut where surface water could be sampled. These sampling stations are
shown on Figure 16.
To avoid needless duplication of sampling and analysis, the
selected wells were divided into two groups, primary and secondary,
with the primary wells being considered the most important.
A sampling schedule (see Table 6) was then devised which
included all of the sampling stations and all of the analyses
scheduled in a systematic fashion that included all of the sampling
points in a full analytical time cycle. These time cycles were 4
weeks in length and permitted the chemist time to sample and perform
the analyses with a minimum of storage time, and sufficient extra time
to maintain the laboratory, prepare reagents, and do the necessary
paperwork associated with the laboratory.
In sampling, problems were encountered throughout the project.
The greatest was in simply obtaining the samples. Most wells had no
provision for sampling taps and these had to be added where
permissible so as to sample the water before it-was mixed in a storage
cistern. Often it was not possible to add these taps, or if they
existed, they sometimes were removed at a later time by the owner or
alterations were made to the premises which then prevented access to
the taps. One has to keep in mind that sampling has continued at some
stations for over 4 years.
It was easy to install taps on most of the government-owned
wells but these were soon discovered by people who used them during
dry periods to either fill up drums of water to take home to fill
their cisterns, to provide water to wash cars, or both. This abuse of
the government wells often provoked the Public Works Department to
remove the sampling taps altogether.
The wells that were drilled adjacent to the Golden Grove
recharge area for the purpose of monitoring the changing water levels
during recharging were also sampled. Since these had no pumps
installed nor easily available power; they were simply dipped, using a
project-constructed torpedo sampler. Despite being dipped a few times
88
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-------
at each sampling, this was obviously an inferior method of sampling
and the data obtained from these wells should be viewed with this in
mind.
The water quality data for the project are presented in
tabular form in the Appendix.
GROUNDWATER QUANTITY AND MOVEMENT
A study of groundwater quantity and movement was made using
water level data from wells selected in the study area. These wells
were generally inactive nonpumping wells on public and private
property. Water level recorders were placed on a series of wells to
ascertain what continual variations took place while other wells were
simply measured by using a tape measure at regular intervals. Since a
free water table does not exist in the study area south of the Center!ine
Road, these water levels represent the potentiometric surface of the
groundwater rather than the actual depth of the aquifer.
Aside from these data, additional information on the
potentiometric surface was gathered by installing small diameter, 3/4-
in. (1.9 cm) PVC, tube wells in the vicinity of the proposed recharge
area. Holes for these wells were dug using a 4-in. (10 cm) soil
boring rig with an auger bit. This gas-powered drilling rig was
mounted on a trailer which could be moved rapidly from site to site.
Although the rig could drill holes quickly in the tight clayey soil,
it could not penetrate far below the existing water in the soil as the
sides of the holes in the vicinity of the water would collapse as the
sectioned auger was being removed to clear the hole. Since all of the
holes were drilled during a period of excess groundwater in the area,
the resultant tube wells were not deep enough to toe usable during the
extended period of dry weather that occurred during the last 2.5 years
of the project. Additionally the majority of the tube wells
downstream of the recharge area were destroyed during the construction
of the adult correctional facility. Most of the tube wells upstream
of the recharge area were lost in two fires which swept the area and
those that survived went down to the blades of a large government-
owned cane cutter which made intermittent unpredictable forays into
the area to cut forage for the island's cattlemen.
However, the tube wells did furnish useful information in
initially calculating the flow pattern of groundwater in the area,
which aided in the final placement of the recharge structures.
Moreover the actual boring of the holes produced valuable data on the
soil horizons in that part of the study area.
The water level data for wells in the study area are presented
in graphical form in the Appendix.
90
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RAINFALL DATA
Initially three recording rainfall gages of the weighed bucket
type were installed in various parts of the study area to collect
rainfall data.
On the aggregate this data collection system was not even a
moderate success. The gages suffered from mechanical breakdown, human
abuse, and animal interference.
The clock portion of the gages continually broke down.
Repairs were difficult to procure on the island and the replacement
spring-driven clocks cost close to $100 each. Several replacements
were purchased but they soon failed in operation.
Additionally, the rain gages seemed to exude a magnetic pull
for human curiosity and at two of the locations the security lock was
frequently twisted off the case and the gage thoroughly examined. At
the Negro Bay location the gage was located adjacent to a government
well and was repeatedly broken into to obtain the bucket, which
apparently was used in conjunction with the well to wash cars.
Another problem was animal interference, which at the Bodkin
location above Fountain Valley, took the form of the gage being used
as a rubbing post by cattle. There was also the general problem of
the local tree lizards, Anolis acutus, which would occasionally be
found living in the gage. This selection of dwelling place was no
doubt accidental on their part and probably the result of falling
through the narrow funnel-shaped opening which directs the rain to the
weighing bucket. Once trapped inside, the lizard would repeatedly
jump on the recording needle, thus distorting the recording. They
would eventually die, attracting large numbers of ants who would
invade the gage to consume the body.
The only gage remaining after the first 3 years was the one
installed at the fire station in Grove Place. This gage remained
relatively unscathed but has suffered from numerous and continuous
clock failures.
Fortunately, the U.S. Department of Agriculture maintains a
rain gage at Bethlehem Upper Works, which is on the eastern edge of the
study area on a hill just above the Golden Grove recharge area. This
gage, which is protected and attended daily, has produced far more
reliable information and its data have been used in this report.
ADVANCED WASTEWATER TREATMENT PLANT
The operation of the advanced wastewater treatment plant was
monitored as to flow, power consumed, chemicals used, influent and
91
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effluent quality, etc. This work was performed by both the plant
operators and the project chemist.
The sample log pages displayed in Figures 31 and 32 show how
the various plant functions were recorded. These logs required a fair
portion of the operator's time to complete every day; but in filling
them out and examining the various recorded data that had to be
entered into the log, he obtained a better understanding of the
plant's operation. The effluent flow chart, Figure 31, was especially
helpful in recognizing small problems in operation before they became
major disasters. The operating data for the plant have been
statistically analyzed and presented in the Appendix of this report.
92
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t>AV 3MEET flMLV
TOTAL &&JLV PLOW-
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OVZilu SfSTEMT
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REATMENT PL&HJT &T
ST. CROIX. U.S. V.I
Figure 31. A typical page from the AWWTP operator's log showing the effluent flow chart
C16TE I To" / ~T / *VJ |
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-------
SECTION VIII
RESULTS AND DISCUSSION
WATER QUANTITY CHANGES DUE TO RECHARGING
Infiltration and Percolation
A key factor in the economic success of a surface method of
artificial recharge is the rate of infiltration. This determines the
land area required per unit of recharged water. On the Virgin Islands
land is expensive, averaging about $10,000/acre ($4,050/ha).
In comparing the rates of infiltration between the 8 basins as
shown on Figure 33, it is apparent that there is a distinct difference
between the rates in the 2 basins in Negro Bay and the 6 basins in
Golden Grove. The sustained infiltration rate in Negro Bay was less
than 5 gpd/sq ft (0.2 cum/day/sq m) while infiltration rates in the
Golden Grove basins ranged from 10 to 28 gpd/sq ft (0.4 to 1.1 cu m/
day/sq m).
Negro Bay. In the Negro Bay area, which is located on the
Kingshill marl, two methods of surface recharge were tried: spray
irrigation and spreading basins. Neither method of surface application
proved to be sufficiently successful to warrant further investigations.
The spray irrigation was limited in the rate and extent of
application by surface runoff on the spray area. The spray area was
constructed on a location with a gentle slope of about 0.031. The water
was applied at the rate of approximately 2 gpd/Sq ft (0.08 cu m/day/sq
m) and once the loading reached about 0.4 to 0.6 gal/sq ft, (0.016 to
0.024 cu m/sq m), any additional water would tend to runoff down the
Slope causing soil erosion. This meant that spraying periods were
limited to between 5 and 7 hours in a 24-hour period if erosion was to
be controlled. During the intervening drying period, evapotranspiration,
through the vegetation and the capillary action of the marl, removed the
water in the upper soil horizons. The result was no net gain in water
entering the marl formation.
. One of the main reasons for this infiltration problem is the
structure of the upper soil horizon in the spray area. Covering the
95
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30
BASIN NO. 3
(GOLDEN GROVE)
~
in
a>
<
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H
ii.
z
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cc
20 -.
*~BASIN NO. 1
(GOLDEN GROVE)
NO. 6
(GOLDEN GROVE)
10
\ BASIN NO. 8
\ (NEGRO BAY)
. AX
•^&«t
fc BASIN NO. 7
(NEGRO BAY)
BASIN NO. 5
(GOLDEN GROVE)
BASIN NO. 2
.(GOLDEN GROVE)
\
\
I
LENGTH OF DRY PERIOD
BETWEEN REUSE OF BASIN
FOR RECHARGING
100 200 300 400 500 600 700
CUMULATIVE AMOUNT OF INFILTRATION(gal/sq ft)
800
900
Figure 33. Infiltration rates in the recharge basins.
-------
actual marl formation is a cap of soil approximately 8 in. (20.3 cm)
thick. All but 2 to 3 in. (5 to 7.6 cm) of this clayey organic material
was removed and windrowed to prepare the area for surface application.
It was realized that when wet the clay would swell and tend to be
impervious. However, this upper top soil was necessary to serve as a
base for growing grasses. The grasses would aid in preventing soil
erosion while at the same time they would remove a portion of the
nutrients in the applied effluent.
Adjacent to the spray area (see Figure 30) two spreading basins,
basins 7 and 8, were each operated for approximately 2 weeks. The
resulting sustained rate of infiltration was less than 4 gpd/sq ft (0.16
cu m/day/sq m). This was a better infiltration rate than for the spray
irrigation site, but it was not high enough when compared to the rates
in Golden Grove to justify continued operation. Additionally, the banks
of the marl basins were unstable when wet. The fine material from the
banks was eroded to the bottom of the basin, which contributed to the
sealing of pore spaces in the exposed marl. Marl, by itself, will
support only sparse vegetation to a very limited degree so the use of
grass for stabilization was not possible.
In summary the results of the work in Negro Bay showed that
artificial recharge by spray irrigation or spreading basins in that
area was not justified when compared to the alternative available.
This alternative is in Golden Grove where the sustained recharge rates
are 4 to 7 times higher and hence the land area required would be
proportionally less. Recharge operations in Negro Bay were abandoned
in August, 1974, and all subsequent efforts were concentrated on the
Golden Grove facility.
Golden Grove. This recharge area, which is located in an
alluvial valley, was in operation from February through October, 1974.
All the recharging work in this area was accomplished by the use of
spreading basins. The resulting rates of infiltration for the various
basins are shown in Figure 33. These data show a high sustained rate
for infiltration and percolation for all of the basins with the minimum
rate being in the order of 11 gpd/sq ft (0.45 cu m/day/sq m). The best
infiltration rate was encountered in operating basin 5 which had a
maximum sustained rate of infiltration in the range of 25 gpd/sq ft
(1.0 cu m/day/sq m).
The rate of infiltration is a function of both the soil
structure on, and immediately below, the bottom of the basins and the
inherent ability of the underlying formation to conduct the percolating
water away from the vicinity. If the underlying formation will not
remove the introduced water at the same rate that it is being applied,
then ponding will occur.
97
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In order to test the long-term ability of the underlying
formation to handle recharging, basin 2 was operated continuously for
60 days. A sustained decline in infiltration rate was not apparent
until the final 10 percent of the run. By that time a cumulative
loading of about 660 gal/sq ft (26.9 cu m/sq m) had been applied to
the basin for a total flow of about 6.6 mil gal (24,981 cu m).
Basin 5 was also operated for an extended period of time to
test its capabilities. After a dry cycle of 126 days the basin was
operated at a high rate of loading for 18 days. During this time the
rate of infiltration averaged about 22 gpd/sq ft (0.9 cu m/day/sq m)
compared with 11 gpd/sq ft (0.45 cu m/day/sq m) for basin 2 discussed
in the preceding paragraph. The total loading for the run was about
400 gal/sq ft (16.32 cu m/sq m). The infiltration rate dropped off
drastically during the final portion of the run and there were indi-
cations of ponding at that time. These were manifested by some
dampness at the bottom of the adjacent structure, basin 6.
The decrease in infiltration rates which occurred in both
basins 2 and 5 could be caused by clogging of the soil in the basin
due to deposition of suspended solids and/or biological growth; or,
to the mounding of the water table to the point where it reached the
bottom of the basin. Based on observations, examination of water
level information, and comparison of infiltration rate data, it is
believed that clogging of the soil was involved in both cases but that
the mounding water level under the basins also played a part. This is
especially true in the case of basin 5 during its final extended run.
The clogging condition of the soil due to deposition of organic
suspended solids and biological activity is readily reversed by a
period of drying so that stable aerobic conditions are restored to the
upper soil horizons. This permits aerobic metabolic activity to occur
in that area.
The low turbidity and organic content of the wastewater effluent
used in this recharging reduced considerably the potential suspended
solids involved in mechanical entrapment, while also reducing the food
available for microbial growth. In order to continue the long periods
of inundation which are vital to the economics of the recharge
operations, it is important to continue the operation of the AWWTP
so that the present low levels of turbidity and organic content are
maintained, or reduced.
The short span of recharge operations in 1974 did not permit
sufficient data to be collected to determine the most efficient time
period to use for either the inundation of the ponds (wet days) or the
intervening drying period (dry days). It will probably take several
years of operation and careful monitoring to correctly arrive at the
98
-------
answer. It is likely that there will be different values for each pond
due to the difference in underlying strata.
For the present, however, operations should be carried out on
the basis of 10 wet days, followed by 5 dry days. This will give a
complete cycle of 15 days for which an average value for the entire
cycle of 8 gpd/sq ft (0.33 cu m/day/sq m) can be used for loading
purposes. When operations are renewed then these figures can be
updated as experience dictates.
Groundwater Movement in the Golden Grove Area
St. Croix's physiography in general and stratigraphy in
particular create some problems for the groundwater hydrologist. The
island's groundwater situation is studied most easily on a broad plane
where generalizations can be made on well yields, aquifer flows, and
transmissibility. The USGS has done this in useful reports such as
those recently published by Jordan (1973) and Robison (1972). These
reports combined collected data to present an overall view of the
groundwater potential on the island.
As the area of study in St. Croix is reduced to a single
drainage basin, or portion thereof, the difficulties involved in accurate
analysis can increase drastically. This project has intensively studied
the portion of River Gut where it passes through Golden Grove. The area
of interest is the alluvium in the valley into which the artificially
recharged water is introduced. Information about the alluvium has been
gained mainly by soil borings, well construction, pumping tests, water
level monitoring, chemical analysis of water samples, and field
observations.
The results of all of these investigations have shown that
this area is one of extreme complexity when studied as a separate
small system. The alluvium is of recent geologic origin and its
placement has been a result of years of deposition of material
weathered from the basin's surrounding hills. This was deposited by
both normal stream sediment transport and by occasional turbulent
flooding conditions. The result has been a formation of an alluvial
material which is generally heterogeneous and anisotropic in character.
It is estimated that field permeability (Kf) values for the alluvium
range from 0.01 to 10,000 gpd/sq ft (0.0004 to 410 cu m/day/sq ft)
and vary in both horizontal and vertical planes. While all of the
material will conduct water to some extent, the main aquifers composed
predominately of sand and gravel conduct the major portion of the flow.
Based on borings, well construction samples, and observations, these
aquifers are neither consistent in thickness, material content, nor
horizontal extent. Their thickness ranges from 0.5 to 15 ft (0.15 to
4.57 m) but generally in the order of 1 to 2 ft (0,3 to 0.6 m) thick.
99
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Pumping Test Analysis. Pumping tests were performed on selected
wells in the area. However, analyzing the data to provide valid,
meaningful results as to permeability (K), transmissibility (T), and
the coefficient of storage (S), for each well is not possible to any
reasonable degree of accuracy.
The reason for this is that many of the assumptions on which the
accepted theories and calculations for these parameters are based are
not valid in the situation at hand. Of the 7 assumptions listed by
Kruseman and DeRidder (1970, p. Ill) which are basic to any conventional
analysis, 3 of them cannot be fulfilled. These are:
The aquifer has an apparently infinite areal extent.
The aquifer is homogeneous, isotropic, and of uniform
thickness over the area influenced by the pumping test.
Prior to pumping, the piezometric surface and/or phreatic
surface are (nearly) horizontal over the area influenced by the
pumping test.
In the first assumption, the aquifers in Golden Grove have a
very real boundary situation where the horizontal extent of the aquifer
varies from only 200 to 1,200 ft (60 to 365 m).
In the second assumption the aquifer is not homogeneous,
isotropic, or uniform in thickness.
As for the final assumption, the potentiometric surface slopes
steeply at the rate of 50 to 70 ft/mile (10 to 13 m/km) within the
alluvium.
Aquifers in the Recharge Area. There are a number of aquifers
in the alluvium, some of which are shown in Figures 18 and 20. They
are not necessarily connected horizontally, and isolated sand and gravel
lenses are not uncommon. Precise knowledge of the strata can only come
from additional deep borings; the more borings the better will be the
knowledge of the area. However based on borings and well logs avail-
able, information on recharge rates and water levels, observations in
the field, and engineering judgment; certain tentative conclusions can
be made as to the nature of the water-bearing strata in the vicinity
of the recharge area. These conclusions are discussed in the following
paragraphs.
There are one and possibly two main aquifers that transmit the
major portion of the groundwater in the upper aquifers through the
recharge area. The theorized location of these aquifers is shown orr
Figure 34. The field permeability (Kf) value in the most porous section
of the main aquifer is in the range of 3,000 to 7,000 gpd/sq ft (122 to
100
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PUBLIC SAFETY
HEADQUARTERS
G G-S-oWxr-f" CHECK DAMS
GUT
GGL-3B
6*3-4
SECONDARY
FLOW
(15CM)\
R LINE >
.V.I.
V
NEGRO BAY: MAIN FLOW
RAIN GAGE
SPREADING BASINS
FAIR PLAINS
WELL FIELD
100,000 GAL
(38° CU M)
TANK
NEGRO BAY
RECHARGE AREA
6 IN. (15 CM) FORCE
JFfp MAIN TO CONVEY
RENOVATED WASTEWATER
TO RECHARGE AREA
SPRAY
1000
Scale Feet
0 500
0 1O"0 200 300
Scale \n Meters
BMW-1
PRIMARY WASTEWATEFfN
MB-5 _ __===>, * TREATMENT PLANT
Figure 34. Hypothesized flow of groundwater in the upper aquifer in Golden Grove.
-------
285 cu m/day/sq m). This was determined by approximating the system
during recharging as a constant head parameter. The resulting Kf
value checks with the range of K values for aquifers with sands and
gravels given by Todd (1959, p. 53) and Davis and DeWiest (1966,
p. 164). The average temperature of groundwater on St. Croix is
about 27° C which decreases viscosity and increases the K by
approximately 33 percent (Todd, 1959, p. 51).
It is believed that a portion of the main aquifer was partially
exposed during the excavation of the new stream channel recently
constructed just south of the adult correctional facility. Based on
the recharge operations, it is estimated that the major aquifer below
the basins has a main transmitting area of approximately 600 sq ft
(55 sq m). This aquifer traces the course of an old streambed across
the area.
Basins 1, 4, 5, and 6 are located wholly, or in part, over the
probable location of the main channel. Basin 2 is interconnected to it
by a thinner sand lens. The nature of the interconnection of basin 3
is not clearly understood due to its limited period of recharging. None
of the project wells are located within the main channel in Golden Grove
since its presence was not suspected until after the wells were con-
structed. Wells PW-7 and PW-8 are apparently isolated from the main
aquifer while wells PW-5 and PW-6 are connected to it via sand lenses.
Wells PW-1 and PW-4 are located on either side of the main aquifer but
are probably connected to it by a thin transverse aquifer which continues
north underneath the stream.
Water Level Response to Recharging. An examination of the water
levels in the various wells in the area compared with the rainfall and
periods of artificial recharge reveals many points of interest.
In Figure 35, the general water levels during 1973 dropped due
to the lack of sufficient natural recharge from rainfall. Both wells
GG-3 and GG-5 are upstream of the recharge area. GG-3 was selected as
the control well since activity in the recharge area did not appear to
affect it. After recharging began in 1974, GG-5 was almost immediately
affected, as can be seen in Figure 35. The flattening of the slope of
this well beginning in March was due to the hindrance of the normal flow
in the upper aquifers due to the recharge water added to the same
aquifer.
Figure 36 compares the immediate boundary wells on the approaches
to the recharge area with a well, PW-8, within the. area. GG-13 is 1,500
ft (425 m) north of the area. A-18 is 3,700 ft (1,130 m) northwest of
the recharge area at the upper end of the aquifer which flows under the
basins. GG-3 is in the same general aquifer system as A-18 and 1,300 ft
(400 m) upstream of the basins. The lack of activity in these boundary
wells indicates that outside influences such as rainfall are not
102
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ELEVATION
42.4
GOLDEN GROVE
1973
EAST RECHARGE BASINS (5 and 6)
WEST RECHARGE BASINS (1, 2, 3, and 4)
GOLDEN GROVE
1974
JAN I FEB
XfamS&SS & « S3 n*fKvarf*rsf*xx .V^^^^.Y^V^WB.VV.
APRI 1 MAY r JUN I JUL I AUG I SEP ' OCT ' NOV
TIME
Figure 35. Comparison of wells GG 3 and GG-5,1973-1974.
103
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EAST RECHARGE BASINS (5 and 6)
WEST RECHARGE BASINS (1, 2, 3, and 4)
GOLDEN GROVE
1974
OCT I NOV I DEC
JUN I JUL
TIME
Figure 36. Comparison of wells A-18, GG-3, GG-13, and PW-8,1974.
-------
disturbing the groundwater system. Hence the reaction of PW-8 is, in
fact, caused by the artificial recharge operations taking place within
the localized area of Golden Grove.
Figure 37 is significant in two ways. First it shows the extent
of water level alterations caused by recharging, as measured in wells in
the vicinity of the basins during 1974. Well PW-6 is plotted along with
control well GG-3. During 1975, when no recharging took place, the
rainfall during the first 7 months was very similiar to that of the
previous year. Again PW-6 and GG-3 are plotted and it should be noted
that they move almost in unison. The inference is that this is the
pattern that the water levels would have taken during 1974, had arti-
ficial recharge not taken place.
The second manner in which Figure 37 is significant is in the
response that PW-6 exhibits when recharging is switched from the eastern
to the western basins during the first week in April, 1974. Whereas PW-6
responded almost immediately to recharge in the eastern basins, there
was a delay of approximately 15 days before it responded to the operation
of basin 4. This delay is attributed to the initial slaking of the soil
and filling of the pore space combined with the hydraulic travel time
from the basin to the monitor well. This response pattern is repeated
in the latter part of August with a similiar switch from an eastern to
western basin.
The response of PW-8 to recharging (see Figure 38) is indicative
of a well which is located within a sand lens that is not interconnected
to the aquifer carrying the major portion of flow from the basins. The
lens is, however, adjacent to the eastern basins.
The response of PW-6 to recharging appears to demonstrate that
it is in a sandy lens which is interconnected to the lower part of the
main aquifer area. The interconnection is hydraulic and does not
consist of water flowing rapidly through the lens.
PW-7 is isolated from the basins and main aquifer area. Its
water level variations are damped out considerably and they depend on
seepage through a less porous soil.
Recharged water entering the upper aquifer system from the
basins moves laterally through the aquifers in a general east-south-
easterly direction. As the water moves along the aquifer it satisfies
the storage demand of any of the unsaturated soil in the vicinity. The
main lateral velocity is believed to be in the range of 15 to 25 ft/day
(4.6 to 7.6 m/day) in the vicinity of the recharge area while under
the direct influence of basin loading. When the groundwater mounding
under the basin subsides, and/or if the aquifer dimensions increase
substantially, the velocity decreases considerably.
105
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EAST RECHARGE BASINS (5 and 6)
WEST RECHARGE BASINS (1,2, 3, and 4)
ELEVATION
21.6
GOLDEN GROVE
1974
'
JAN FEB MAR APR MAY JUN JUL AUG SEP ' OCT ' NOV ' DEC
ELEVATION
46.7
ELEVATION
33.8
GOLDEN GROVE
1975
JAN FEB MAR APR MAY JUN ' JUL ' AUG ' SEP ' OCT ' NOV ' DEC
TIME
Figure 37. Comparison of wells GG-3 and PW-6, 1974-1975.
106
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EAST RECHARGE BASINS (5 and 6)
WEST RECHARGE BASINS (1,2, 3, and 4]
ELEVATION
35.6
ELEVATION
34.7
ELEVATION
22.7
GOLDEN GROVE
1974
TIME
Figure 38. Comparison of wells GG 3, PW-8, and PW-9,1974.
-------
A generalized view of the changing potentiometric surface in the
Golden Grove area during the entire period of the project can be seen in
Figures 39 and 40.
Groundwater Augmentation by Artificial Recharge
By comparing two identical sections of the groundwater system,
one without and the other with artificial recharging, an approximate
idea of the net effect of recharging can be ascertained. Only the imme-
diate area containing, and adjacent to, the spreading basins is considered
in this analysis. Once the artificially recharged water has entered the
groundwater aquifers and starts its horizontal flow, it is considered as
normal groundwater, subject to the same losses that existed without the
project.
Figure 41 shows two typical vertical sections of the Golden
Grove valley. Each section has the important water inputs and outputs,
one section with and the other without a recharge operation taking
place. By comparison, the major changes will be in the addition of
recharge water and the subsequent increase in flow in the aquifer.
Increased consumptive losses will be the added evaporation from the
shallow water-filled basin. It can also be expected that evapotrans-
piration will be increased to some degree in the immediate area
due to the additional water available for this either in the aquifer
or in the percolating water forming the mound underneath the basin.
Percolation between aquifers is believed to be minimal, based upon
drilling observations, but might increase with the increased hydraulic
head available beneath the inundated basins. However, since extraction
of groundwater will take place from all the aquifers in the alluvium,
the transfer of water between them will not change the ultimate amount
of product.
Thus the major new loss to the recharged system is in the added
evapotranspiration due to the available moisture in the pond and soil.
Meyer (1952) reported that the average annual evaporation from an open
pan in the Anna's Hope area, in central St. Croix, over a 10-year
period was 70.2 in./yr (177.8 mm/yr), which averages about 0.19 in./day
(4.87 mm/day). This is probably high for the basins due to the rapid
turnover of water and consequently its lower temperature. This also
neglects the evapotranspiration that no longer occurs from the soil
covered by the water in the basin.
Increased evapotranspiration for the sections shown in Figure
41 may be approximated by the difference between Bowden's (1968) highest
and lowest monthly evapotranspiration estimates for the Kingshill area
adjacent to Golden Grove, which come to 0.12 in./day (3 mm/day). This
represents the possible rise in evapotranspiration due to the increased
availability of water in the area which, according to Meyer, is a prime
factor to be considered.
108
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OCT 20,1973
FEB20, 1974
(1 WEEK BEFORE
RECHARGING BEGAN)
OCT 20,1972
I ARTIFICIAL I
RECHARGE
AREA
UJ
WELL FP-9
1,000
2,000
3,000 4,000 5,000
HORIZONTAL DISTANCE (ft)
6,000
7,000
Figure 39. Potentiometric groundwater levels in Estate Golden Grove, 1972-1974.
-------
\
LU
>
UJ
LU
GO
LU
c
2C
o
<
LU
_J
LU
70
60
50
40
30
20
10
GROUND SURFACE
, MAY 20,1974
(11 WEEKS AFTER
| RECHARGING STARTED)
FEB 20,1974 X
(1 WEEK BEFORE
RECHARGING BEGAN) |
WEEKS AFTER
MAJOR FLOOD)
WELL FP-9
| ARTIFICIAL I
RECHARGE
r-«- AREA
_E
±
_h
1,000
2,000
3,000 4,000 5,000
HORIZONTAL DISTANCE (ft)
6,000
7,000
Figure 40. Potentio metric ground water levels in Estate Golden Grove, 1974-1975.
-------
NORMAL
GROUNDWATER
CONDITION
EVAPOTRANSPI RATION
FROM TREES
EVAPOTRANSPI RATION
FROM SOI LAND GRASS
AQUIFER
FLOW IN
LEAKAGE BETWEEN^
MAJOR AQUIFERS
EVAPOTRANSPIRATION
FROM SOIL AND GRASS
ARTIFICIAL
RECHARGING
OF THE
GROUNDWATER
AQUIFER
FLOW IN
AQUIFER
FLOW OUT
POSSIBILITY OF INCREASED
EVAPOTRANSPIRATION
DUE TO MORE AVAILABLE
GROUNDWATER
DIRECT
EVAPORATION
1 INCREASED LEAKAGE 1
QCT\A/CCM
f AQUIFERS AND t
INTO MARLS
INCREASED
AQUIFER
FLOW OUT
Figure 41. Water balance in Golden Grove with and without artificial recharging.
Ill
-------
For the largest basin, basin 4, this means a possible total
added evapotranspiration loss of about 1,500 gpd (5.5 cu m/day) which
may be compared to the average daily infiltration for this basin of
approximately 125,000 gpd (473 cu m/day). This represents a loss of
about 1.2 percent of the influent to the basin after initial slaking
of the soil has taken place at the beginning of every inundation.
Other losses do occur, but these are common to both naturally and
artificially recharged water in the aquifers. Probably the largest
loss of this sort in Golden Grove is that due to the evapotranspiration
involved with the large deep-rooted trees adjacent to River Gut.
These trees are protected by Virgin Islands law; and although they
supply shade, a windbreak, and soil stabilization along the stream
bank, they do extract an undetermined quantity of water from the soil.
Attempts of quantifying the amount has not been overly
successful. One recent researcher, Rex Meyer (1952, pp. 23-26),
discussed transpiration of length in a Department of the Interior
report and finally commented that "the difference in plant species
and climatic conditions on the island of St. Croix makes it imprac-
ticable to apply transpiration ratios determined elsewhere on similiar
plants to the vegetation on the island." He concluded his section on
transpiration by saying that "it is not possible with the available data
to make a reliable estimate of transpiration in any part of St. Croix."
This investigation could not improve on this statement but strongly
recommends that local research efforts be made in this direction in
the future. It is possible that increased soil moisture caused by
recharging would increase consumptive use by these trees.
Groundwater extraction efficiency will play a large part in the
ultimate economies of the water reuse system. Fortunately the ground-
water geology of Golden Grove as portrayed in Figure 18 keeps the
groundwater flow within defined bounds where it is relatively easy to
tap and withdraw with a minimum of loss. However, the aquifer is thin
and in some areas in Golden Grove it is limited in its transmissibility.
The entrance losses from these thin alluvial aquifers into the well
casing generally would limit the extraction by individual well
to about 20 to 30 gpm (1.3 to 1.9 I/sec).
Based on operating results and engineering judgment, the best
mode of operation of the recharge facility in the future is to plan to
extract 85 percent of the recharged water in the immediate area of the
spreading basins. The remainder should be permitted to flow down the
aquifer to be used to protect the Fair Plains well field from further
saline degradation. The pumping at the Fair Plains well field can then
be adjusted to a rate that will efficiently remove the groundwater
without permitting a decrease in overall water quality in the area.
112
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WATER QUALITY CHANGES DUE TO RECHARGING
Negro Bay
The operations in Negro Bay did not affect the underlying
groundwater to any detectable degree. The two reasons for this are
first, little, if any, recharged water reached the marl-limestone
interface that was located 15 ft (4.6 m) below the area. This was
due to the low rate of infiltration and percolation combined with the
high rate of evapotranspiration. Second, even if water did arrive at
this interface, it would need to penetrate approximately 60 ft (18 m)
of horizontally layered limestone which is above a confined aquifer.
The early termination of operations in Negro Bay combined with
the physical difficulties mentioned above essentially preclude the
possibility that recharged water reached the aquifer.
Golden Grove
The water artificially recharged into the Golden Grove area
had only a minor effect on the groundwater quality in that basin. In
order for the monitoring to be valid, only continuously pumped wells
were considered in the final evaluation of the project's effects.
Monitor Wells. Due to their location the key wells considered
for monitoring the recharge operations were GG-8 and FP-8, downstream
of the recharge area, .plus PW-1 and PW-4 immediately upstream of the
basins. The changing chloride content of these wells was judged to be
significant as chloride in groundwater is essentially a refractory
substance. As such it is not likely to undergo changes due to bio-
logical or physiochemical effects such as phosphates, nitrates, ammonia,
and degradable organics can, which is why chlorides are often used as
a tracer.
A change of chloride content is possible in the wells if water
with a different chloride concentration joins or replaces the existing
water source. This would be the case in the pumping wells being
monitored when the artificially recharged water, with a different
chloride content, moves through the aquifer and encounters them. A
graph of the chloride content for these wells and the recharged water
is shown in Figure 42.
Well A-16. Figure 42 compares the chloride levels with the
rainfall and the quantities of recharged water used during 1974. Well
A-16 is a control well and is located above the recharge area at the
head of the alluvial valley at Adventure. The location of this well
is such that it cannot be affected by the recharging. The changes in
chloride content shown for A-16 are those normally experienced by wells
in the area.
113
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1
I
J 2
<
< 3
s
I 1-5
z:
i_J
I 1.0
Q
LLJ
a
cc
£ 0.5
a
BE
"I
^
f™!^
FP-8 _
Vy
GG-8
RECHARGE WATER
PW-4
A-16
MOV I DEC
1973
/**•
EAST RECHARGE BASINS (5 and 61
EST RECHARGE BASINS II. 2, 3. and 4
JAN
FEE
JUN I JUL 1 AUG SEP OCT
1974
TIME
Figure 42. Chloride content of monitor wells in the study area.
NOV
JAN FEB | MAR
1975
700
600
500
400
300
200
100
-
C/]
_
G
a.
~
-------
Well PW-1. Well PW-1 is located about 200 ft (61 m) upstream
of the edge of basin 1. By examination of Figure 42 it is apparent
that the recharging affected the chloride content in both June, to a
slight degree, and again in September and October. Both of these times
were periods when either basins 1 or 2 were in operation. We can expect
that the rapid increase during September and October could have been
higher had the water added to the aquifer by heavy rainfall in August
not occurred. An apparent rise in nitrates from 5.4 mg/1 to 6.7 mg/1
also occurred at this time but it cannot be substantiated as there is
insufficient background data on this well. A pump was not installed
on PW-1 until January, 1974, so the data available are limited.
Well PW-4. Well PW-4 also showed some indications of a chloride
rise but it was minor. Although this well is only 300 ft (91 m) from
basin 1, it is believed that the intervening aquifer structure is
connected only in an indirect manner. The water from this well was
reduced in chloride concentration during November due to the heavy
rains and flooding which naturally recharged the soil over the entire
area.
Well GG-8. Well GG-8 is located about 1,500 ft (460 m) downstream
of basin 6. The water from this well generally has a chloride content
higher than the artificially recharged water. However, this well, like
many others on St. Croix, derives its water from more then one aquifer.
The method of well drilling on the island is such that it is not possible
to separately test the aquifers encountered for water quality.^ However
from field observations and tests made while drilling, indications are
that the water in the different aquifers is often of sharply varying
chemical character. Thus changes in chemical characteristics in a well
water are often caused simply by a variation in the contribution to a
well that each aquifer makes. Indications are that the recharge water
is probably increasing the chloride content in an aquifer which normally
acts as a source of dilution water for well GG-8. The reaction to the
early recharging operations is delayed in time due to the rate of flow
of the recharged water from the basins to the well itself. The effect
of the later periods of recharge are obscured by the heavy rains that
occurred in the fall. This well water has had a trend toward increasing
chloride content since sampling began in 1971. The mean chloride values
for 1971, 1972, and 1973 are 426, 453, and 507 mg/1, respectively. The
variation in the other parameters for water from that well fell within
a standard deviation of past performance and cannot be considered
significant.
Well FP-8. Well FP-8 is located approximately 3,300 ft (1,000 m)
downstream of basin 6 when measured along the assumed course of the main
aquifer. It is likely that FP-8 receives water from both the River Gut
and the Bethlehem Gut drainage basins. FP-8 is probably well 45a
referred to by Cederstrom (1950, p. 68). This well was drilled to a
115
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depth of 225 ft (68.6 m) through the alluvium and marl and 17 ft (5.2 m)
into the Jealousy formation.
Cederstrom reports (1950, p. 84) that the chloride content in
1940 was 510 mg/1. In 1971, 1972, and 1973 the mean chloride content
was 640, 649, and 670 mg/1, respectively.
Inspection of Figure 42 shows some indication of increasing
chlorides in FP-8 during the latter part of 1974. Although it could
be due to the recharged water it cannot, with certainty, be said that
this is the cause for the increased chloride content. The water in the
Fair Plains well field has been undergoing a general increase in chlorides
over the past few years. During 1974, 3 out of the 9 wells in Fair Plains
were abandoned due to excess IDS. The water in the adjacent well, FP-7,
showed a continuous increase in chlorides from 1973 up to September, 1974.
This may have had an influence on FP-8.
The other chemical and biological parameters monitored in the
water from the wells did not show significant changes during this
period. Had the recharging operations continued longer and/or the
floods not occurred, then it is possible that additional changes in
the groundwater might have occurred.
With many of the parameters measured it is likely that the
concentration of the substance in question underwent changes during
the recharging operations. A basic discussion of changes which can
occur appears in several reports concerning land disposal of waste-
water (McGauhey and Krone, 1967; Drivers et al., 1972). In the
following paragraphs several of the most important parameters are
discussed with relation to their possible fate in the soil system.
This discussion is only a summary and the references cited can be
consulted for greater detail.
Nitrates. The average nitrate nitrogen concentration measured
in the recharge water during the period of January through October,
1974, was 12.9 mg/1. The groundwater in the area of the recharge
basins has a natural concentration that ranges between 3 and 7 mg/1.
Nitrates are not readily absorbed by the soil and thus tend to move
through the soil in solution. Reduction in concentration can occur
by plant uptake and denitrification (Murrmann and Koutz, 1972, p. 71).
A report sponsored by the Corps of Engineers (Driver et al., 1972),
mentions that the removal of nitrogen by denitrification is dependent
on the soil type and length of inundation of infiltration ponds,with
clay soils and long inundation times promoting nitrogen removal. Based
on plotted data (Driver et al., 1972, p. 93), a 10-day inundation
period would remove about 35 percent of the applied nitrogen.
Nitrate uptake by plants will occur most rapidly during the
dry period of the wet-dry cycle when plant growth is the most rapid
116
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in the basins. Uptake will be limited to the amount of nitrates
available in the soil moisture remaining after recharging has ceased.
During operation of the project the grass in the basins was frequently
mowed and removed from the area.
It is probable that a combination of these two mechanisms
reduced the nitrate level in the applied recharge water in Golden Grove.
The chief concern with nitrates is to keep the level in water consumed
by the public to below 10 mg/1 as N03-N. This is to prevent the
occurrence of methemoglobinemia in infants. Dilution of the water
pumped from municipal wells in the recharge area with other sources
of water contributing to the island's water supply maintains an
acceptable nitrate concentration in the water supply.
Ammonia. The average ammonia-nitrogen concentration in the
applied recharge water was about 7 mg/1 during the period of January
through October, 1974. The normal concentration in the groundwater in
Golden Grove ranges up to about 0.5 mg/1.
Ammonia at a neutral pH, 6 to 7, is readily adsorbed onto clay
soil particles (Murrmann and Koutz, 1972). This will act to hold the
ammonia for use by plants at a generally slower rate of uptake. The
effluent used in recharging generally had a pH between 6.5 and 7.0.
The rapid growth of vegetation on the basins between inundation periods
followed by mowing and harvesting should continue to remove ammonia
from the system.
Phosphorus. The average concentration of all forms of phosphorus
in the applied recharge water was about 9 mg/1 as P during the period
January to October, 1974. The normal concentration in the groundwater in
Golden Grove ranges up to about 0.1 mg/1.
Phosphorus acts similarly to ammonia and is adsorbed in the soils
especially on clay particles which are prevalent at the recharge site.
The phosphorus will also be utilized by vegetation in the area and can
be removed from the system through plant harvesting.
Coliforms. The level of standard coliforms in the applied
effluent was very low due to the effective disinfection process at the
AWWTP. The effectiveness of soils in removing bacterial pathogens is
documented and discussed in detail by McGauhey and Krone (1967, pp.
70-78) and in a recent report issued by the Corps of Engineers (Driver
et al., 1972, pp. 49-55). These reports mention the mechanisms of
mechanical filtration and adsorption along with natural dieback of
pathogens in the soil. These are especially effective in clayey and
silty soils which predominate in Golden Grove.
The background data on all of the public wells in the study
area show a substantial level of coliforms in many of the wells. The
117
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operation and sanitation of these wells was not under project control
during this study. Many public wells on St. Croix were not sealed
properly to prevent surface leakage and contamination until rather
recently. Disinfection of the wells before, or during, operation is
generally not practiced. Under these conditions it is not possible to
correlate recharge operations with any change in coliforms in pumping
wells in the area. Based on the disinfection practices used and the
literature cited, it is highly doubtful that any bacterial contamination
of the pumping wells did, or will, occur due to recharging operations in
Golden Grove.
BOD, COD, and TOC. The water applied to the recharge basins had
an average BOD of 11.5 mg/1 and a COD of 30 mg/1. The ability of a soil
system to reduce this oxygen demand caused by organics is discussed in
many reports (McGauhey and Krone, 1967; Driver et al., 1972; Broadbent,
1973). The organic loading from the AWWTP effluent on the soil system
was low. Evidence of increased organic concentrations in the monitored
wells was not apparent and it is likely that the organic content was
diminished due to oxidation.
In studying the results of the analysis of the monitoring wells
in the study area for BOD and COD, as presented in the Appendix, two
facts must be kept in mind. The first is that BOD and COD measurements
at a low level of 0 to 20 mg/1 are not very dependable since any minor
contamination, or laboratory error, will dramatically affect the results.
The second problem is that all of the pumping public wells monitored are
equipped with a vertical turbine pump whose shaft bearings are lubricated
by dripping oil down the space between two concentric shafts in the
well. This oil, up to about 0.5 gal/month (2 I/month), accumulates and
floats on the surface of the water inside the well. Depending on the
level of the water in the well in relation to the-pump, this oil can be
intermixed with the water and pumped out of the well in varying con-
centrations. This, then, also has noticeable effect on TOC measurements
taken on samples. Due to the circumstances of pump start-up and
throttling required for the homogenation and entrance of the oil into
the pumped water, it will happen at irregular times without necessarily
a definite pattern being detected.
Summary of Water Quality Changes. The previous paragraphs have
reviewed the possible reasons behind the water quality changes observed
in the monitored pumped wells in the study area in the vicinity of the
recharge facilities.
Other wells closer to the spreading basins were also sampled and
tested for the same parameters during recharge operations. These were
wells PW-6, PW-7, and PW-8. The primary purpose of these wells was to
monitor water level information and hence they were not equipped with
pumps. Samples were obtained by the use of a torpedo sampler. Although
the sampler was filled several times before taking a sample for labo-
ratory analysis the procedure did not cause much movement of water
within the 8-in. (20 cm) well casing.
118
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The monthly data for the analysis of the samples appear in the
Appendix. The data do not show the changes, especially in chloride
concentrations, that could be expected. This is probably due to two
reasons. First the wells are believed to be located in sand lenses
which are not directly connected to the main flow path of groundwater
through the area. Second the wells were not pumped so that a continuous
interchange of water could occur in the wells. Had continuous pumping
occurred, the location of the wells away from the main path of flow
would probably have been less significant. As it is, the data are
included only for general background information for future studies.
WATER QUALITY IN FUTURE OPERATIONS
Once the problem of saltwater flushing in Frederiksted is
resolved the artificial recharge operations can resume. If, at that
time, the distribution of potable water is planned so as to transfer
the low TDS desalinized water to the western end of the system, then
it will result in the collection of wastewater with a low chloride
concentration. Judging from the anlysis of wastewater from villages
served wholly by desalinized water (Black, Crow and Eidsness, Inc.,
1973, pp. 3-12), it can be expected that the wastewater will have a
chloride content of about 100 to 150 mg/1.
The use of processed effluent with a low level of chlorides
for recharge operations in Golden Grove should eliminate the chloride
problems experienced during the project's operations in 1974. With
proper extraction control, it could lead to partial restoration of the
Fair Plains well field.
AWWTP OPERATIONS
The operations of the AWWTP was discussed in detail in the
earlier sections. The data obtained from the operation have been
tabulated and presented in a statistical format in Tables E-l and
E-2 of the Appendix.
The production of the plant which was used for recharge
purposes is shown in Figure 27 and the average operating parameters
in Tables 4 and 5.
These data cover the period January through October, 1974.
January marked the beginning of normal operation after the start-up
phase. The project ceased recharge operations during the last week
of October due to the high TDS wastewater, while at the same time
the heavy rains began to affect the plant performance due to excessive
inflow. In early November, 1974, the flooding on the island damaged
portions of the interceptors so that much of the influent to the plant
consisted of the streamflow from Bethlehem Gut. During subsequent
119
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repairs of this interceptor and the one to Frederiksted, which took
place over the following 6 months, flows were interrupted and/or bypassed
so that normal operation of the AWWTP was not possible. In view of this,
the data presented are limited to the period stated.
COST FACTORS
Cost factors, based on the operation of the AWWTP and the
recharge facilities, have been projected for the production of
artificially recharged groundwater. These data are shown in Table 7
and include treatment in the AWWTP, recharge operations, and ground-
water recovery by wells.
Cost factors are presented for production at the present
design capacity of 0.5 mgd (1,890 cu m/day) and also for expanded
operation at the level of 0.75 mgd (2,840 cu m/day) and 1 mgd
(3,785 cu m/day).
The information upon which the costs are determined is
presented in the table along with the assumptions used. If
circumstances, assumptions, or prices change; then the cost factors
can be restructured within the table to arrive at a revised unit
cost.
A large percentage of the total cost of reclaiming water is
centered around secondary treatment. At present only primary treat-
ment is used by the government before discharge of wastewater into
the sea. If secondary treatment were required, then the cost of
this portion of the facility could, in a large part, be allocated
to sanitation instead of reclamation. Only the additional costs
of tertiary treatment and recharging could be directly attributable
to reclamation. This would then decrease the unit cost considerably
in an accountant's view, although the government would continue to
pay the total cost. However with secondary treatment of all waste-
water before reclamation or discharge to the sea, the economies of
scale would begin to reduce the unit cost of production. This is
especially true in the matter of labor where the difference in
staffing between a 1 mgd (3,785 cu m/day) and a 5 mgd (18,925
cu m/day) plant would not be significant. This is especially true
if the recommendation to combine the management of the primary and
reclamation plant is followed.
120
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TABLE 7. PROJ ECTED COSTS FOR THE PRODUCTION AND RECOVERY OF
RECLAIMED WASTEWATER BY GROUNDWATER RECHARGE
PRODUCTION-ANNUAL COSTS*
1. Depreciation (20 yr straight line)
Initial cost $800,000
Phase 1 improvements t 30,000
Phase 2 improvements t 70,000
Phase 3 improvements f 140,000
Total Depreciation
II. Maintenance and repair
III. Labor
Project director @ $20,000/yr
Plant superintendent @ 15,000/yr
Operator, chief @ 10,000/yr
Operator @ 8,500/yr
Operator, trainee @ 7,000/yr
Chemist @ 12,000/yr
Secretary @ 7,000/yr
Labor Subtotal
15 percent fringe benefits
Total Labor
TOTAL ANNUAL COST
PRODUCTION-UNIT COSTS ($/thousand gal)
The annual cost on a unit basis with 15 percent
downtime
Coagulant-aluminum sulfate
50mg/lat $0.10/lb($0.22/kg)
Chlorine
20 mg/l at $0.25/lb ($O.S5/kg)
Power
Total Production Costs
RECOVERY-UNIT COSTS ($/thousand gal)
If 85 percent of recharged water is recovered by wells
Cost of groundwater recovery^
TOTAL COST-PRODUCTION AND RECOVERY
($/thousand gal)
($/cum)
AWWTP
0.5 mgd
(1,890 cum/day) (2
$ 40,000
1,500
-
^•I^MMHH
41 ,500
36,000
20,000
15,000
10,000
17,000
14,000
12,000
3.500
91 ,500
13.725
$105,225
$182,725
1.18
0.042
0.042
0.30
1.56
1.85
0.30
2.15
0.57
Production Capacity
0.75 mgd 1.0 mgd
,840 cu m/day) (3,785 cu m/day)
$ 40,000
1,500
3,500
^MW^H
45,000
42,000
20,000
15,000
10,000
34,000
14,000
12,000
3.500
108,500
16.275
$124.775
$211,775
0.91
0.063$
0.042
0.30
1.32
1.55
0.30
1.85
0.49
$ 40,000
1,500
3,500
7.000
52,000-
48,000
20,000
15,000
10,000
34,000
21 ,000
12,000
3.500
115,500
17.325
$1 32.825
$232,525
0.75
0.042
0.042
0.30
1.13
1.34
0.30
1.64
0.43
'Includes operation of the recharge facilities.
fSee the section on project facilities for a discussion of the work involved in each phase of plant expansion.
(Dose rate of 75 mg/l.
Includes all costs of drilling and operating the wells.
121
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SECTION IX
MAJOR PROBLEM AREAS ENCOUNTERED IN THE PROJECT
As In any large undertaking, there have been a considerable
number of problems that have occurred during the course of the
project. The vast majority of these were solvable as the project
progressed. Some of them required minor changes in the direction of
the project while others caused considerable delay in the completion
of the project itself. The following is a discussion of some of the
major problem areas within the project that became apparent as the
work proceeded.
CONCEPTUAL
The reuse of water cannot be treated as an isolated event in
the water resource plans of an area. The concept must be integrated
into both the water supply and wastewater treatment systems. However
this project was, by definition and funding, an experimental facility
built to determine whether the concept was feasible. Thus major
changes in the existing system and future construction could not
really be expected until the feasibility was proven.
This meant that the concept of reuse had to be fitted into a
system that was basically designed without that idea in mind. Since
St. Croix has a variety of water sources, ranging from distilled to
brackish to seawater, that feed into the wastewater system at different
points; it makes it essential to coordinate the entire operation.
Hence certain problems were already built, or designed, into the system
and either had to be compensated for during the project or will require
modification in the future.
The most notable problem resulting from this conceptual gap is
the high chloride level of the incoming wastewater. In order for
project operations to proceed at all, a chloride level of up to 500
mg/1 had to be tolerated and used for recharge purposes. This was the
result of the brackish well water that was being used in the section
of the island whose wastewater supplied the project.
Even more critical is the use of seawater for fire and
flushing purposes in the towns of Christiansted and Frederiksted. It
was the connection of the wastewater collection network of
Frederiksted, with its salty wastewater, to the central primary
122
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treatment plant that finally closed the project down in October, 1974.
Although the problem in Frederiksted will be resolved, at least
temporarily, in the fall of 1975, the potential chloride problem posed
by the connection of Christiansted to the system in 1977 lies ahead.
COORDINATED PLANNING
There are numerous agencies within the territorial government
which have an interest and responsibility for the production,
distribution, and usage of public potable water plus the collection,
treatment, and disposal of the island's wastewater. This split
responsibility has caused confusion and occasional problems in
fulfilling the project goals.
CHANGING CONDITIONS
Under actual field conditions on a project of this magnitude
and time span, unwanted changing conditions had to be accepted. Many
of these changes would not be tolerated in a laboratory operation
where it is desirable to hold conditions the same while varying
selected parameters, preferably one at a time. There were four main
areas where these changing conditions caused problems.
Weather
Several extreme, and unseasonable, variations in the amount of
precipitation occurred during the project. This resulted in excess
groundwater during the exploratory and design phase. Then an extreme
deficiency occurred during the recharge operations. The operations
were finally terminated by record rains and floods that severely
damaged the facilities. This has been followed by another unusual and
extended drought period. These swings have affected the quality of
wastewater received, the well yields, aquifer conditions, and surface-
water activity.
Water Sources
The changing production levels of the various sources of water
on the island affected the quality of the subsequent wastewater to a
large extent. This is especially true in the western portion of the
island where any reduction in the production of desalinized water from
the Martin Marietta plant meant an immediate increase in the
proportion of brackish well water used. This had an effect on the
quality of water produced at the reclamation plant due to the change
in the mineral content of wastewater received.
123
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Construction Activity
This activity occurred both in the drainage areas tributary to
the recharge area and those associated with the wastewater collection
system. In the immediate area, the construction of a large
penitentiary complex adjacent to the recharge area resulted in the
loss of a large number of piezometers and the use of a portion of the
streambed that had been planned for recharge operations.
The large amount of public housing constructed during project
development which contributed its wastewater to the interceptor system
changed the expected character of that wastewater. All during the
project the interceptor system was being expanded. This meant that
the volume of wastewater was increasing and changing as areas with
different water sources were sewered.
Groundwater Extraction
The quantity of groundwater removed from the study area was
varied to meet local demand or to inversely match the output of the
desalinization plants. The project had no control, besides
suggestive, over the operation of these wells.
PROJECT LOCATION
It was implicitly assumed that the reclamation plant would be
located adjacent to the newly constructed central primary treatment
plant on the island. This latter facility was located on the island
with hydraulic transport and outfall disposal characteristics in mind.
This location, along with the funding limitations in constructing a
force main, restricted the choice of recharge areas.
DELAYS
The wide scope of the project made it extremely vulnerable to
delays due to complications in some stage of either this project or
one of the many other activities that affected this project. The most
significant delays are discussed in the following paragraphs.
The completion of the interceptor sewers was delayed in
schedule, which greatly reduced the amount of wastewater that the
project had available to process and reuse. This delay has to be
weighed against the benefit of not completing the Frederiksted pumping
station on time. It permitted the operation of the recharge phase
without the flow of salt water that accompanied the Frederiksted
wastewater.
124
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The construction of the AWWTP was delayed due to shipment and
procurement problems with some of the proprietary devices, problems
with subcontractors, and construction difficulties.
The shipment of spare parts for the repair of equipment was
often delayed during plant operation. The customs status of the
territory and the distance between the mainland United States and the
Virgin Islands caused numerous difficulties in obtaining spare parts
and manufacturers' service. Airfreighting of shipments was no
guarantee that they would arrive in a reasonable time. Most spare
parts were unavailable locally.
EQUIPMENT OUTAGES
Problems were experienced with several pieces of equipment in
the AWWTP. These were mainly pumps which required numerous repairs.
During the periods when these pumps were out of service, the
production of the AWWTP was reduced, often to no usable output at all.
NATURAL DISASTERS
Flooding occurred on the island during October and November in
1974, seriously damaging the recharge facility and necessitating
extensive repairs to the basins, roadways, and pipelines. The floods
also damaged the primary treatment plant and many of the major
wastewater interceptors so that the amount of wastewater supplied to
the AWWTP was severely restricted for several months and that which
was received was difficult to handle due to the high percentage of
clay it contained.
SUMMARY
Despite all of these problems experienced during the project
and all those that will occur during its future operation, the
economics of the system will make it worthwhile to continue. The
cost of fresh water is too high on St. Croix to use it only once and
throw it away.
125
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SECTION X
OTHER ACTIVITIES ASSOCIATED WITH
THE WASTEWATER RECLAMATION PROJECT
Although the purpose of the project was to determine the
feasibility of artificial groundwater recharge, it did encourage other
uses for reclaimed wastewater. The purpose of this was two-fold;
first, to explore alternative uses for treated wastewater. This is
especially important if these alternative uses can replace potable
water, which is both expensive and in short supply on the island.
Secondly, it was a means of encouraging community-wide interest and
support for the idea of wastewater reclamation and water reuse. If
another organization or agency actually worked with water reuse and
was successful, then it could mean more support for the continuance of
the project once the local government assumed operations. The project
personnel were successful in encouraging other people to experiment
with the reclaimed water and several of these activities are discussed
below.
IRRIGATION
One of the biggest hindrances to the development of a sound
agricultural industry on St. Croix, in the area of fruits and
vegetables, is the lack of water. A large amount of water is needed
in agriculture to counteract the excessive evapotranspiration rate
caused by the high ambient temperature and steady tradewinds. Only a
week without water can severely damage many vegetable crops on the
island. Rainfall has traditionally been extremely unreliable in its
time patterns on the island. The rainfall pattern in the last three
years has been such that a vegetable enterprise without supplemental
irrigation would have faced disaster. Unfortunately, the potable
water is too expensive, at $1,300/acre-ft ($1.05/cu m), to be used;
the groundwater is limited in quantity; and in many areas the
groundwater's sodium absorption ratio (SAR) and/or chloride content is
too high for prolonged use.
Reclaimed wastewater with a controlled SAR and chloride level
could be used, in many cases, for agricultural irrigation. Initial
uncontrolled experiments were carried out in this area by personnel at
the AWWTP in growing ornamental plants and vegetables in a small
nursery. Chlorinated effluent from the AWWTP was used for the
necessary irrigation. This was an extremely effective public
126
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relations feature for the project. If visitors could not fully
comprehend the workings of the biological and chemical treatments
going on within the AWWTP, they could easily appreciate the profusion
of flowers and vegetables that were grown with the finished product.
This was especially true since the rest of the island was parched and
brown due to one of the longest droughts in recent times.
This created sufficient interest that a cooperative venture by
the V.I. Extension Service and the V.I. Experiment Station financed
and built a 3,000-ft (915 m) spur line that will permit the transfer
of reclaimed wastewater directly to the St. Croix campus of the
College of the Virgin Islands. There it will be used for research
into the uses and effectiveness of irrigation under the subtropical
conditions existing in the territory. This research activity was
halted due to the high chloride content in the wastewater but is
expected to resume in the fall of 1975.
CLAM CULTURE
Using the nutrients available in the wastewater effluent from
the AWWTP, a project to culture freshwater clams (Rangia cuneata) has
been started. This project is under the direction of the biological
oceanography section of the Lamont-Doherty Geological Observatory of
Columbia University. It has a facility on St. Croix which has been
conducting research on the use of ocean nutrients for production of
shellfish for the past 6 years. The clam operation is quite similar
in that it utilizes the nutrients remaining in the wastewater effluent
to grow algae which are fed to clams. Presently the clam-raising
facilities, which are actually large chemostats, have been constructed
on the grounds of the AWWTP and began operations in August, 1975. The
first phase consists of stabilizing the algal growth in the
chemostats. Extensive preliminary tests have already been run at the
Columbia University laboratory in St. Croix to select the algae
strains to be used and to approximate the growth rate to be expected.
The ultimate purpose of the clams will be to use them for a
protein source for poultry on the island. When the clams reach the
desired size, both the meat and shells will be ground up and the
mixture fed to chickens.
PISCICULTURE
This project also uses the nutrients in the effluent of the
AWWTP to grow algae. In this case it will be used to grow Talapia
aurea which are a freshwater herbivorous food fish.
This project is sponsored primarily by the V.I. Agricultural
Experiment Station. Four ponds have been constructed in the vicinity
127
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of the recharge area in Estate Golden Grove and fish are being raised
in one of them. Each of these ponds has a capacity of about 0.1 mil
gal (380 cu m). The fish will grow in cages suspended in the water.
The effluent from the ponds will be used for irrigation purposes. It
is proposed that these fish will be used for human consumption.
INTERRELATIONSHIP
In addition to these three activities involving water reuse
that have been developed in cooperation with the wastewater
reclamation project, other projects have been suggested by local
groups and citizens interested in utilizing this valuable resource.
Many of these additional suggestions require further definition and
sound financing. The local government, in cooperation with the Water
Resources Research Center in St. Thomas, is developing better
guidelines and regulations applicable to wastewater reclamation and
reuse.
Since water is precious in the territory, all of these
activities help to complete the water resources picture on St. Croix.
Figure 43 shows the interrelationships between the existing water
sources and the reclamation project with all of its various associated
activities.
128
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STORAGE
IRRIGATION
PISCICULTURE
to
to
WASTEWATER RECLAMATION
PLANT (AWWTP)
CLAM
CULTURE
OCEAN
DISCHARGE
PRIMARY
TREATMENT
1
PRIMARY
TREATMENT
GROUND-
WATER
RECHARGE
DESALINIZED AND
RAINWATER
WELL
WATER
DOMESTIC USAGE
(FREDERIKSTED)
SALT
WATER
DOMESTIC USAGE
(CHRISTIANSTED)
LOW CHLORIDE
WASTEWATER
HIGH
CHLORIDE
WASTEWATER
Figure 43. Proposed interrelationships between water use and reuse activities on St. Croix.
-------
REFERENCES
Black, Crow and Eidsness, Inc., 1972. "Wastewater reclamation at St.
Croix, U.S. Virgin Islands—An interim progress report for
April 1971 to May 1972." Gainesville, Florida: Black, Crow
and Eidsness, Inc.
Black, Crow and Eidsness, Inc., 1973. "Wastewater reclamation at St.
Croix, U.S. Virgin Islands—The second interim progress report
covering the period from June 1972 to September 1973."
Gainesville, Florida: Black, Crow and Eidsness, Inc.
Bowden, M. J., 1968. Water Balance of a Dry Island. Hanover, New
Hampshire: Dartmouth College.
Broadbent, F. E., 1973. "Organics" .In.: Proceedings on the Joint
Conference on Recycling Municipal Sludges and Effluent on Land,
Washington, D.C.: National Association of State Universities
and Land Grant Colleges.
Busch, A. W., 1971. Aerobic Biological Treatment of Waste Waters.
Houston: Oliodynamic Press.
Camp, Dresser and McKee, Inc., 1966. "Report on sewerage and sewage
treatment. CDM-389-1. U.S. Virgin Islands." Boston: Camp,
Dresser and McKee, Inc.
Cederstrom, D. J., 1941. "Notes of the physiography of St. Croix,
Virgin Islands." Amer. J. Sci. Vol. 239, No. 8, August
1941, 553-576.
Cederstrom, D. J., 1950. "Geology and ground-water resources of
St. Croix Virgin Islands." USGS Water Supply Paper 1067.
Gulp, R. L. and Culp, G. L., 1971. Advanced Wastewater Treatment.
New York: Van Nostrand Reinhold Company.
Davis, S. N. and DeWiest, R. J., 1966. Hydrogeology. New York:
John Wiley & Sons, Inc.
Driver, C. H., Hrutfiord, B. F., et al., 1972. "Assessment of the
effectiveness and effects of land disposal methodologies of
wastewater management." Wastewater Management Report 72-1.
Corps of Engineers. Department of the Army.
130
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Engineering Science, Inc., 1966. "Water reclamation for the U.S.
Virgin Islands." Arcadia, California: Engineering Science, Inc.
English, J. N., Linstedt, K. D., and Bennett, E. R., 1975. "Research
required to establish confidence in the potable reuse of waste-
water." A paper presented at WPCF 48th Annual Conference.
Miami Beach. October 5-9, 1975.
Environmental Protection Agency, 1975. "Environmental Protection
Agency—Interim primary drinking water standards." Federal
Register, Vol. 40, No. 51, March 14, 1975, 11990-11998.
FWPCA, 1970. Application for Class II Demonstration grant entitled
"Wastewater Reclamation at St. Croix, U.S. Virgin Islands."
Federal Water Pollution Control Administration, Atlanta,
Georgia.
Grigg, D. I., Shatrosky, E. L., and Van Eepoel, R. P, 1971. "Operating
efficiencies of package sewage plants on St. Thomas, V.I.,
August-December, 1970." Government of the Virgin Islands
Water Pollution Report No. 12. St. Thomas: Caribbean Research
Institute.
Jordan, D. G., 1973. "A survey of the water resources of St. Croix,
Virgin Islands." USGS Caribbean District open-file report,
San Juan.
Koenig, L., 1966. "Studies related to market projections for advanced
waste treatment." FWPCA Publication No. WP-20 AWTR-17.
Cincinnati: FWPCA.
Kruseman, G. P. and DeRidder, N. A., 1970. Analysis and Evaluation
of Pumping Test Data. Wageningen, The Netherlands:
International Institute for Land Reclamation and Improvement.
McKinzie, W. E., Scott, B. F., Rivera, L. H., 1965. Soils and their
Interpretations for Various Uses, St. Croix, American Virgin
Islands. Spartanburg, South Carolina: Soil Conservation
Service.
McGauhey, P. H. and Krone, R. B., 1967. "Soil mantle as a wastewater
treatment system." SERL Report No. 67-11. Berkeley: University
of California.
Meyer, R. R., 1952. "Geology and hydrology of dam sites on the Island
of St. Croix, Virgin Islands." USGS and the Office of
Territories, Department of the Interior.
131
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Murrmann, R. P. and Koutz, F. R., 1972. "Role of soil chemical processes
in reclamation of wastewater applied to land." In: "Wastewater
management by disposal on the land." Cold Regions Research and
Engineering Laboratory Special Report 171. Hanover, New
Hampshire: Corps of Engineers, U.S. Army.
Rivera, L. H., Fredrick, W. D., et al., 1970. Soil Survey. Virgin
Islands of the United States. Washington: Soil Conservation
Service.
Robison, T. M., 1972. "Ground water in central St. Croix, U.S. Virgin
Islands." USGS Caribbean District open-file report, San Juan.
Sawyer, C. N. and McCarty, P. L., 1967. Chemistry for Sanitary Engineers,
New York: McGraw-Hill Book Company.
Stolz, S. B., 1975. "Water quality management, new Golden Grove well
field St. Croix." Letter to K. Euros (Black, Crow and Eidsness,
Inc.) July 7, 1975. Christiansted: Government of the V.I.,
Division of Natural Resources Management.
Todd, D. K., 1959. Ground Water Hydrology. New York: John Wiley &
Sons, Inc.
Whetten, J. T., 1962. Geology of St. Croix, Virgin Islands. Princeton
University Ph.D. dissertation. Ann Arbor: University Microfilms.
132
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APPENDIX
Part Page
A LOGS OF PROJECT WELLS 135
Part A contains the drilling logs of the nine wells
which were constructed as part of the project. The
locations of these wells are shown in Figure 16.
B PRIMARY WELLS-ANALYTICAL DATA 144
Part B contains monthly data on the analysis of water
samples taken from the primary wells monitored during the
project. Data for the period April through September,
1975, are furnished through the courtesy of the Caribbean
Research Institute of the College of the Virgin Islands.
The locations of these wells are shown in Figure 16.
C SECONDARY WELLS—ANALYTICAL DATA 178
Part C contains monthly data of the analysis of water
samples taken from the secondary wells monitored during
the project. .Data for the period April through September,
1975, are furnished through the courtesy of the Caribbean
Research Institute of the College of the Virgin Islands.
The locations of these wells are shown in Figure 16.
D STREAM SAMPLES--ANALYTICAL DATA 2°0
Part D contains monthly data of the analysis of surface
water samples taken from the stream referred to as River
Gut. Data for the period April through September, 1975,
are furnished through the courtesy of the Caribbean
Research Institute of the College of the Virgin Islands.
The locations of the sampling points are shown in
Figure 16.
E AWWTP OPERATIONAL DATA 206
Part E contains a statistical presentation of the
operational data from the AWWTP for the period January
through October, 1974.
133
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APPENDIX (CONTINUED).
Part Page
F SOIL BORING INFORMATION 208
Part F contains a figure showing the driller's logs of
the soil borings taken in the Golden Grove area.
G WATER LEVELS IN PROJECT WELLS 210
Part G contains graphs of the water levels in various
wells in relation to the amount of rainfall. The
locations' of these wells are shown in Figure 16.
H ENGLISH-TO-METRIC CONVERSION 244
In recognition of the advance of the United States to
the metric system, the text of this report is written
with metric equivalents following the English units of
measurement. To avoid confusion and space problems some
of the tables and illustrations do not have these
equivalents. The following table is a list of English
units used and their metric equivalents to assist in
making individual conversions. The standard abbrevi-
ations for the respective units are used.
134
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APPENDIX - PART A
TABLE A-l. LOG FOR PROJECT WELL NO. 1 (PW-1)
Description
Thickness
of strata
ft
Depth of
strata*
ft
Elevation
of stratat
ft
Alluvium
Topsoil 2
Silty clay 13
Clayey sand trace gravel and silt,
water encountered at elevation 33 ft 9
Sandy silty clay trace gravel 3
Clayey silty gravel (water bearing) 4
Silty clay 4
Clayey sand with gravel (water bearing) 3
Silty clay trace sand & gravel 10
Sandy gravel trace clay (water bearing) 4
Clayey silty gravel (water bearing) 2
Silty clay 6
Clay trace silt 7
Kingshi 11 marl
White limestone, seashells 9
2
15
24
27
31
35
38
48
52
54
60
67
76
51
38
29
26
22
18
15
5
1
-1
-7
-14
-23
Casing perforations:
3 slots/ft
3 slots/ft
3 slots/ft
3 slots/ft
3 slots/ft
15
28
35
48
68
25
32
40
55
74
Well location: Golden Grove
Casing used: 8 in. steel - 78 ft
First encountered water at elevation:
33 ft
Date drilled: July 1972
Ground elevation: 53 ft
Test pumping of aquifer located at elevation -1 ft yielded 13 gpm in
August 1972. The combined aquifers were pumped at 45 gpm.
Static water level in August 1972 was at elevation 41 ft.
Feet x 0.3048 = meters
*Depth to bottom of strata.
tElevation of the bottom of the strata.
135
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TABLE A-2. LOG FOR PROJECT WELL NO. 2 (PW-2)
Description
Thickness Depth of Elevation
of strata strata* of stratat
ft ft ft
Kirighill marl
Topsoil
White stratified limestone (dry)
White limestone, very hard layer
Encountered water just below hard
layer
White limestone stratified
Casing perforations: 1 1/2 slots/ft
3 1/2 slots/ft
2
77
1
20
2
79
80
100
30 - 65
65 - 95
74
-3
-4
-24
Well location: Negro Bay
Casing used: 8 in. steel - 103 ft
First encountered water at elevation: -4 ft
Date drilled: July 1972
Ground elevation: 76 ft
In August 1972, the well was test pumped at 60 gpm (limit of the pump).
The static water level in August 1972, was at elevation 14 ft.
Feet x 0.3048 - meters
*Depth to bottom of strata.
tElevation of the bottom of the strata.
136
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TABLE A-3. LOG FOR PROJECT WELL NO. 3 (PW-3)
Description
Thickness Depth of Elevation
of strata strata* of stratat
ft ft ft
Kingshill marl
Topsoil
White stratified limestone
White limestone, very hard layer
Encountered water just below hard
layer
White limestone soft
Jealousy Formation
Blue clay
2
77
1
72
3
2
79
80
152
155
76
-2
-3
-75
-78
Casing - only an 8 ft piece of casing at the top of the well. Supported
by angle iron at the surface.
Well location: Negro Bay
Casing used: 8 in. steel - 8 ft
First encountered water at elevation: -3 ft
Date drilled: July 1972
Ground elevation: 77 ft
In August 1972, the well was test pumped at 2 gpm when 100 ft deep and
again at 2 gpm when 155 ft deep.
The static water level in August 1972 was at elevation 33 ft.
Feet x 0.3048 = meters
*Depth to bottom of strata.
tElevation of the bottom of the strata.
137
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TABLE A-4. LOG FOR PROJECT WELL NO. 4 (PW-4)
Description
Thickness
of strata
ft
Depth of
strata*
ft
Elevation
of stratat
ft
Alluvium
Silty clay 5
Silty clay with angular gravel 5
Sandy clayey gravel 4
Gravel, encountered water 1
Sandy gravel 3
Clay with some gravel 4
Clay, very hard layer at depth
27-28 ft 6
Sandy clay with a trickle of water 7
Sandy gravel trace clay (water bearing) 2
Clay trace gravel 13
Clay, hard layer 5
Kingshill marl
white soft marl 21
White stratified limestone 4
White soft marl 30
5
10
14
15
18
22
28
35
37
50
55
76
80
no
45
40
36
35
32
28
22
15
13
0
-5
-26
-30
-60
Casing - only the top 62 ft of the well
is cased. Perforations are as follows:
7 slots/ft
7 slots/ft
7 slots/ft
13 - 18
33 - 43
56 - 61
Well location: Golden Grove
Casing used: 8 in. steel - 65 ft
First encountered water at elevation: 36 ft
Date drilled: July 1972
Ground elevation: 50ft
In August 1972 the well was test pumped at 25 gpm when 65 ft deep and at
27 gpm when 110 ft deep.
The static water level in August 1972 was at elevation 39 ft.
Feet x 0.3048 = meters
*Depth to bottom of strata.
tElevation of the bottom of the strata.
138
-------
TABLE A-5. LOG FOR PROJECT WELL NO. 5 (PW-5)
Description
Thickness
of strata
ft
Depth of
strata*
ft
Elevation
of stratat
ft
Alluvium
Silty clay
Silty clay trace sand
Silty clay trace gravel
Clayey sandy silt trace gravel
Sandy clayey gravel, trickle of water
at elevation 30 ft
Clayey gravel
Sandy silty clay trace gravel, sticky
Sandy clay trace gravel, hard layer
Sandy clay trace gravel
8
4
6
2
7
3
2
6
2
8
12
18
20
27
30
32
38
40
47
43
37
35
28
25
23
17
15
Casing perforations:
7 slots/ft
7 slots/ft
20 - 27
33 - 40
Well location: Golden Grove
Casing used: 6 in. PVC - 42 ft
First encountered water at elevation: 30 ft
Date drilled: August 1972
Ground elevation: 55 ft
In August 1972 the well was test pumped at less than 5 gpm.
The static water level in August 1972 was elevation 34 ft.
Feet x 0.3048 = meters
*Depth to bottom of strata.
tElevation of the bottom of the strata.
139
-------
TABLE A-6. LOG FOR PROJECT WELL NO. 6 (PW-6)
Description
Thickness
of strata
ft
Depth of
strata*
ft
Elevation
of stratat
ft
Alluvium
Clay
Sandy clay trace gravel
Clay, very sticky
Sandy clay trace gravel
Clay, very fine smooth
Sandy clay trace gravel
Sandy clay trace gravel, trickle of
water at elevation 17 ft
Sandy gravelly clay
Clay, sticky
5
5
2
8
7
3
4
1
4
5
10
12
20
27
30
34
35
39
43
38
36
28
21
18
14
13
9
Casing perforations: 7 slots/ft
21 - 39
Well location: Golden Grove
Casing used: 8 in. steel - 42 ft
First encountered water at elevation: 17 ft
Date drilled: August 1973
Ground elevation: 48 ft
The well was moist but had no water in August 1973.
The static water level in May 1975 was at elevation 25 ft.
Elevation to top of casing is 51 ft. The casing was buried to the top
edge during construction of the fish ponds in 1973.
Feet x 0.3048 = meters
*Depth to bottom of strata.
tElevation of the bottom of the strata.
140
-------
TABLE A-7. LOG FOR PROJECT WELL NO. 7 (PW-7)
Thickness Depth of Elevation
Description of strata strata* of stratat
ft ft ft
Alluvium
Clay
Clayey sand
Sandy clay
Gravelly clayey sand
Sandy clay, sticky
Sandy silty clay, sticky
3
2
7
2
1
5
3
5
12
14
15
20
44
42
35
33
32
28
Casing perforations: 7 slots/ft 1 - 20
Well location: Golden Grove Date drilled: August 1973
Casing used: 8 in. steel - 21 ft Ground elevation: 47 ft
First encountered water at elevation: None encountered
The well was moist but had no water in August 1973.
The static water level in February 1975 was elevation 31 ft.
Feet x 0.3048 = meters
*Depth to bottom of strata.
tElevation of the bottom of the strata.
141
-------
TABLE A-8. LOG FOR PROJECT WELL NO. 8 (PW-8)
Description
Thickness
of strata
ft
Depth of
strata*
ft
Elevation
of stratat
ft
Alluvium
Clay trace sand
Sandy clay trace gravel
Sandy gravelly clay
Sandy clay
Clay trace sand
Clayey gravel
Clayey sand, trickle of water at
elevation 24 ft
Clay
5
5
2
2
5
3
6
2
5
10
12
14
19
22
28
30
42
37
35
33
28
25
19
17
Casing perforations:
7 slots/ft
7 slots/ft
8-12
19 - 29
Well location: Golden Grove
Casing used: 8 in. steel - 33 ft
First encountered water at elevation: 24 ft
Date drilled: August 1973
Ground elevation: 47 ft
The well had no water in August 1973.
The static water level in January 1975 was at elevation 35 ft.
Feet x 0.3048 = meters
*Depth to bottom of strata.
tElevation of the bottom of the strata.
142
-------
TABLE A-9. LOG FOR PROJECT WELL NO. 9 (PW-9)
Description
Thickness
of strata
ft
Depth of
strata*
ft
Elevation
of stratat
ft
Alluvium
Clay trace sand
Clayey sand trace gravel
Clayey sand
Sandy clay
8
7
2
3
8
15
17
20
41
34
32
29
Casing - The elevation 29 to 41, an 8 in. steel casing is used. This is
slotted 10 shots/ft in its upper 6 ft. Above this is a 2 in. galvanized
pipe which goes to the surface. At the connection of the two is a con-
crete seal. The purpose of the well was to test the feasibility of an
injection well.
Well location: Golden Grove Date drilled: August 1973
Casing used: See above Ground elevation: 49 ft
First encountered water at elevation: No flow encountered
The well was moist but had no water in August 1973.
The static water level in February 1975 was at elevation 33 ft.
Feet x 0.3048 = meters
*Depth to bottom of strata.
tElevation of the bottom of the strata.
143
-------
TABLE B-1. ANALYSIS OF SAMPLES TAKEN FROM WELL A-16
Date
1971 Jul
Aug
Sep
Oct
Nov
Dec
Mean
StdDev
1972 Jan
Feb
Mar
Apr
May
Jun
July
Aug
Sep
Oct
Nov
Dec
Mean
StdDev
1973 Jan
Feb
Mar
Apr
May
Jun
Chlorides
mg/l
145
170
160
_ .
145
153
10
200
160
150
150
150
120
120
150
180
180
170
150
163
24
150
145
150
160
180
180
Conductivity
JUmhos/cm2
at 25° C
1,500
1,420
1,400
1,480
_
1,500
1,441
40
1,300
1,430
1,450
1,450
,400
,400
,400
,400
,400
,400
,400
,400
1,320
324
1,300
1,400
1,400
1,400
1,400
1,300
Total
Hardness
mg/l as
CaCOj
—
254
272
252
_
272
262
10
260
280
280
288
268
276
280
272
272
272
268
268
274
10
284
262
260
284
280
272
Ca
mg/l as
CaCOj
mm
78
100
108
-
112
103
12
112
100
120
108
112
88
88
92
92
100
100
100
100
9
104
88
104
116
112
108
Mg
mg/l as
CaCO,
176
172
144
-
160
159
12
148
180
160
180
156
188
192
180
180
172
168
168
174
12
180
174
156
168
168
164
COj
mg/l as
CaCOj
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HCO,
mg/l as
CaCOj
523
530
575
576
568
554
26
576
584
568
576
572
568
564
568
564
568
560
564
569
7
560
600
536
516
527
536
NO.VN NO2-N
mg/l mg/l
_ __
-
-
- -
— _
- -
- _
-
-
-
-
-
- _
-
<1
<1
<1
- <1
4.1 <1
3.8 <1
4.0
0.2
3.9 <1
-
-
2.8 0.010
3.1 0.004
2.7
NH,-N
mg/l
-
-
-
_
-
_
-
-
-
-
-
-
-
0.36
0.37
0.34
0.40
0.39
0.40
0.38
0.02
0.42
-
0.81
-
0.46
0.47
Total
P
mg/l
_
_
-
M
-
_
_
_
_
-
-
-
-
0.027
0.037
0.033
0.035
0.025
0.040
0.03
0.01
0.035
-
0.029
0.035
0.060
0.134
COD BOD TOC
mg/l mg/l mg/l
mm mm
_ _ _
_ — _
_
I ~ ~
-
__
— — —
_ _ _
_ — —
_ — ..
_
_ — —
— — —
_ _ -
_ 30
2.6
- _ -
— _ —
-
16.3
19.4
8
-
16
-
- <5 12
- <5
Standard
Coliforms
Colonies/
100ml
M
_
_
-
~
0
_
10
—
6
9
_
_
-
-
_
-
-
-
_
—
-
-
0
0
0
1
J,
T3
m
z
o
>— *
X
1
-o
— 1
CO
-------
TABLE B-1 (CONTINUED).
cn
Date
1973
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std
1974
1975
Dev
Jan
Feb
Mar
Apr
May
Jun
July
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
July
Aug
Sep
Chlorides
mg/l
200
170
170
170
150
170
170
33
180
160
160
-
130
170
170
170
170
180
-
170
170
170
210
—
190
190
175
180
180
Conductivity
fAnhos/cm2
at 25° C
1,400
1,500
1,500
1,400
1,300
1,400
1,385
61
1,350
1,400
1,300
-
1,400
1,400
1300
1,200
1,200
1,300
-
1,300
1,300
1,300
1,350
-
1,300
1,400
1,300
1,300
1,300
Total
Hardness
mg/l as
CaC03
280
304
288
260
260
276
13
300
256
272
-
260
256
248
248
260
260
-
-
_
260
-
—
_
272
-
345
-
Ca
mg/l as
CaCOj
120
112
126
104
100
108
10
112
68
100
-
96
80
104
100
92
96
-
-
_
108
-
—
_
97
-
76
-
Mg
mg/l as
CaCOj
140
192
142
156
160
166
15
188
188
172
-
164
176
144
148
168
164
-
-
_
152
-
—
_
175
-
269
-
CO.,
mg/l as
CaCOj
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
-
_
0
-
-
_
0
-
0
-
HCO.,
mg/l as
CaC03
556
520
524
512
504
536
27
528
496
532
-
530
536
416
516
516
508
-
-
_
524
-
—
_
524
-
513
-
NOj-N
mg/l
3.6
3.3
3.2
-
2.9
3.8
3.2
0.4
3.4
3.2
3.0
-
3.5
3.6
3.4
3.3
3.3
-
-
3.3
3.6
-
3.2
-
3.8
-
3.2
3.7
3.4
NOj-N
mg/l
100
- 0
-
<5
-------
TABLE B-2. ANALYSIS OF SAMPLES TAKEN FROM WELL BMW-3
Date
1972
1973
Oct
Feb
Mar
Apr
May
Jun
July
Aug
Sep
Oct
Nov
Dec
Mean
Std
1974
1975
Dev
Jan
Feb
Mar
Apr
May
Jun
July
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Chlorides
mg/l
520
510
530
570
600
580
600
490
470
550
560
550
546
43
600
580
610
—
590
580
590
610
570
560
- '
530
590
600
Conductivity
£lmh os/cm2
at 25° C
2,800
2,800
3,000
2,800
3,000
2,800
2,800
2,600
2^00
3,000
2,600
2,800
2,818
140
2,800
2,800
2,800
—
3,000
3,000
2,700
2,600
2,200
2,400
-
2,400
2,600
2,600
Total
Hardness
mg/l as
CaC03
260
254
264
256
288
280
284
268
280
288
300
275
17
296
308
304
—
276
280
272
-
296
272
-
-
308
308
Ca
mg/l as
CaC03
100
120
124
140
144
140
128
128
132
132
132
132
8
156
140
152
—
132
132
136
-
140
136
-
-
140
140
Mg
mg/l as
CaCOj
160
134
130
116
144
140
156
140
148
156
168
143
15
140
168
252
—
144
148
136
-
156
136
—
-
168
168
CO.,
mg/l as
CaCO.!
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
-
-
0
0
HCO3
mg/l as
CaCO.,
640
696
616
596
588
620
620
596
616
600
592
614
31
624
624
624
-
612-
608
616
-
596
586
-
-
608
624
N03-N
mg/l
4.2
5.4
5.1
4.1
4.7
5.3
5.0
5.3
4.9
0.5
4.6
4.4
4.9
—
4.4
5.2
5.1
5.4
5.2
4.4
~
3.4
4.8
5.2
NOrN
mg/l
0.004
0.003
0.001
_
-------
TABLE B-2 (CONTINUED).
Date
1975
Mar
Apr
May
Jun
July
Aug
Sep
Chlorides
mg/l
600
580
600
600
588
538
540
Conductivity
//mhos/cm
at 25° C
2,600
2,600
2,600
2,800
2,800
2,800
2,600
Total
Hardness
mg/l as
CaC03
_
310
306
314
-
-
-
Ca
mg/l as
CaCOj
_
124
136
148
-
-
-
Mg
mg/l as
CaCO,
•*
186
170
166
-
-
-
CO,
mg/l as
CaC03
0
0
0
0
_
-
-
HCO,
mg/l as
CaCO,
_,_
604
588
596
_
-
-
NO3-N
mg/l
5.1
-
5.0
-
5.0
4.2
1.3
NO2-N
mg/l
—
-
0.001
0.003
0.002
0.002
-
NH.,-N
mg/l
0.13
-
0.14
0.13
0.12
0.09
0.09
Total Standard
P* COD BOD TOC Coliforms
Colonies/
mg/l mg/l mg/l mg/l 100ml
<5
_ o
_ - - - _
- 0
_ - -
_ - - - _
-
*Not measured since phosphates are added to water at the well by the owner.
-------
TABLE B-3. ANALYSIS OF SAMPLES TAKEN FROM WELL BMW-4
00
Date
1972 jut
Oct
1973 Mar
Apr
May
Jun
Jul
Aug
Mean
Std Oev
Total
Chlorides Conductivity Hardness
/Anhos/cm2 mg/l as
mg/l at25°C CaCOj
250
230
280
420
440
440
440
—
404
70
WELL INOPERATIVE
1974 May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
1975 Jan
Feb
Mar
Apr
May
Jun
410
440
360
410
340
430
-
400
400
390
400
340
390
380
1,700
1,700
1,900
2,200
2,400
2,300
2,400
—
2,240
207
SEPT 1973- APRIL
2,400
2,600
2,000
2,000
1,700
2,200
-
2,000
2,200
2,100
2,200
2,200
2,200
2,200
236
240
204
208
-
192
196
200
200
6
1974
180
192
188
188
212
208
-
-
188
192
-
217
196
202
Ca
mg/l as
CaCO,
112
132
92
96
-
92
92
96
94
2
84
88
96
76
80
84
-
-
76
96
-
85
90
85
Mg
mg/l as
CaCO;,
124
108
112
102
-
100
104
104
104
5
96
104
92
112
132
124
-
-
112
96
-
132
106
117
CO,
mg/l as
CaCO.,
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
-
0
0
-
0
0
0
HCOj
mg/l as
CaCO.,
536
548
556
592
-
620
600
612
596
25
620
628
592
616
576
612
-
-
616
620
-
580
596
600
NO.,-N
mg/l
-
_
3.1
4.4
-
4.8
-
4.1
0.9
3.4
4.6
4.4
4.5
,_
4.3
-
3.7
3.8
4.2
3.9
-
4.0
-
NO2-N
mg/l
-
_
-------
TABLE B-4. ANALYSIS OF SAMPLES TAKEN FROM WELL BMW-5
Chlorides Conductivity
/lmhos/cm2
Date mg/l at 25° C
1973
Mean
Jul
Aug
Sep
Oct
Nov
Dec
Std Dev
1974
1975
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
340
330
290
320
350
326
23
360
340
360
-
390
400
410
420
350
460
190
-
320
330
_
350
360
380
396
420
2,500
2,600
2,600
2,400
2,400
2,500
100
2,400
2,200
2,200
-
2.400
2,600
2,200
2,200
2,000
2,200
1,600
-
2,200
2,100
_
2,200
2,200
;2,200,
2,400
2,400
Total
Hardness
mg/l as
CaC03
320
384
396
392
373
36
412
352
328
-
324
328
332
344
336
348
-
-
380
380
_
365
388
377
. -
373
Ca
mg/l as
CaC03
104
176
184
176
160
38
172
172
160
-
158
148
160
168
140
160
-
-
132
142
_
140
167
175
-
159
Mg CO3
mg/l as mg/l as
CaCO3 CaCO3
216
208
212
216
213
4
240
180
148
-
166
180
172
176
166
188
-
-
248
238
_
225
221
202
-
214
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HCO3
mg/l as
CaCO3
720
804
784
748
764
37
780
692
676
-
688
708
688
680
692
696
-
-
760
736
_
696
716
708
-
680
NO3-N
mgfl
0.9
1.2
3.0
2.8
2.5
2.1
.1
2.0
1.9
0.9
-
_
-
1.2
1.4
__
6.0
-
5.4
5.0
5.0
4.3
-
3.5
-
4.2
2.6
NO2-N NH3-N
mg/l mg/l
0.016
-
0.002
0.004
_
-
0.004
0.001
0.002
-
0.002
0.002
0.002
0.005
0.003
0.002
-
-
0.003
0.003
_
-
0.005
0.021
0.128
0.024
0.18
0.47
-
0.19
0.11
0.24
0.16
0.04
0.04
-
<0.01
0.23
0.17
0.19
0.19
0.24
0.30
-
-
0.38
0.45
0.18
-
0.16
0.19
0.12
0.14
Total
P
mg/l
0.098
0.128
0.136
0.114
0.122
0.120
0.010
0.095
0.120
0.116
-
_
-
0.145
0.160
0.144
0.168
-
0.150
0.160
0.144
0.125
-
0.118
0.122
0.125
0.118
COD
mg/l
-
-
<5
<5
_.
-
5
100
>100
>100
5
0
_
-
0
0
0
-
0
0
0
0
10
0
-
-
4
1
_
51
-
10
-
0
Sep
2.7
0.002
0.08 0.117
-------
TABLE B-5. ANALYSIS OF SAMPLES TAKEN FROM WELL FP-5
Date
1971 Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
1972
Jan
Feb
Mar
Apr
May
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std
1973
Dev
Jan
Feb
Mar
Apr
May
Jun
Chlorides
mg/l
1,035
940
1,090
1,060
1,070
1,039
59
1,090
1,120
1,050
1,100
1,100
1,150
1,130
1,160
1,120
800
980
1,073
103
980
995
1,090
1,230
1,360
1,460
Conductivity
jLOnh os/cm2
at25°C
4,100
4,200
3,900
4,200
3,700
4,100
4,033
197
4,000
4,100
4,000
3,900
4,200
4,000
3,000
4,000
4,000
3,000
3,500
3,791
428
3,500
4,000
4,000
4,000
4,250
4,500
Total
Hardness
mg/l as
CaC03
675
580
856
680
704
699
100
700
692
-
704
740
740
760
748
769
464
672
699
88
684
714
780
836
976
1,036
Ca
mg/l as
CaC03
336
308
372
372
356
348
27
364
376
-
368
372
368
364
380
384
248
300
352
44
272
368
408
456
504
528
Mg C03
mg/l as mg/l as
CaC03 CaC03
339
272
484
308
348
350
81
336
316
-
336
368
372
396
368
385
216
372
347
52
412
346
372
380
472
508
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HCO3
mg/l as
CaC03
488
508
545
516
528
517
21
524
524
-
540
520
528
528
532
520
544
540
530
9
540
556
504
480
488
496
NO3-N NO2-N NH3-N
mg/l mg/l mg/l
-.
_ _
_
_
_
_ _ _
<1 0.49
<1 0.47
<1 0.49
<1 0.52
<1 0.49
4.7 <1 0.43
0.48
0.03
4.8 <1 0.48
_
3.1 - 0.80
4.1 <0.01 0.22
3.8 0.004 0.67
3.4 - 0.22
Total
P COD
mg/l mg/l
_
_
-
-
-
_
0.020
0.047
0.047
0.041
0.033
0.047
0.040
0.010
0.055
-
0.042
0.018
0.064
0.082
BOD TOC
mg/l mg/l
_
_ _
_
-
_
_
17
-
28
_
9.2
5.5
15
10
21
_
_
-
<5 IS
<3
Standard
Conforms
Colonies/
100ml
20
0
>100
-
6
>100
_
-
-
—
_
-
-
_
-
-
-
>100
>100
0
>100
-------
TABLE B-5 (CONTINUED).
Date
Jul
Aug
Sep
Oct
Nov
Mean
Std Dev
1974 Jan
Feb
Mar
Apr
May
Jun
Chlorides
mg/l
1,460
1,540
1,530
1,600
1,710
1,350
261
1,610
1,780
1,850
-
2,040
1,920
PUMP INOPERATIVE
1975 Jul
Aug
Sep
1^70
1,880
1,900
Conductivity
pbnhos/cm
at25°C
5,000
5,000
5,000
5,000
5,000
4,477
553
5,000
5,500
6,000
-
7,000
7,000
DUE TO BRUSH
5,500
5,000
5,500
Total
Hardness
mg/l as
CaC03
1,032
1,160
_
1,220
1.304
974
216
1,168
1,372
1,490
-
1,500
—
FIRE JUL
_
1,400
—
Ca
mg/l as
CaCOj
516
596
_
616
652
492
118
604
668
700
-
790
—
1974-JUN
_
722
—
Mg C03
mg/l as mg/l as
CaCO3 CaCO3
516
564
_
604
652
483
105
564
704
790
-
710
—
1975
_
678
~
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/l as
CaC03
484
468
_
464
468
494
32
472
460
430
-
460
—
_
458
~
NO3-N
mg/l
4.0
5.8
3.7
4.0
-
4.1
0.8
_
3.8
4.0
-
3.4
3.8
_
4.1
0.4
NOj-N
mg/l
0.003
<0.001
_
-
0.002
_
-
_
0.003
0.004
-
0.022
—
0.011
0.008
0.006
NH3-N
mg/l
0.23
0.46
0.49
0.18
0.33
0.41
0.21
0.32
0.10
-
<0.01
0.19
—
_
0.11
0.08
Total
P COD
mg/l mg/l
0.038
0.040
0.068
0.048
<5
0.050
0.020
— —
0.055 < 5
0.052 <5
- -
0.041 7
0.062
_ _
_
— —
BOD TOC
mg/l mg/l
8
<5 2
_ —
<5
<5 11
11
7
<5
<5 3.5
<5
-
<5
_ —
_ _
-
— —
Standard
Coliforms
Colonies/
100ml
0
7
>100
c*
c
_
-
0
c
-
-
27
—
_
>100
—
*Confluent colonies.
-------
TABLE B-6. ANALYSIS OF SAMPLES TAKEN FROM WELL FP-6
Date
1971 Jun
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
1972 Jan
Feb
Mar
Apr
May
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
1973 Jan
Feb
Mar
Apr
May
Jun
Chlorides
mg/l
620
600
660
660
640
636
26
620
610
590
520
580
650
680
610
620
570
570
602
43
570
560
600
700
700
980
Conductivity
/Km h os/cm
at25°C
3,300
3,200
3,000
3,000
3,100
3,100
3,050
3,107
110
2,800
3,000
3,000
2,800
2,900
2,900
3,000
2,900
3,000
2,900
2,900
2,918
75
2,600
2,800
3,000
2,900
3,100
3^00
Total
Hardness
mg/l as
CaC03
527
500
536
532
524
524
14
524
484
496
488
484
480
488
492
500
392
400
475
41
500
470
508
532
580
756
Ca
mg/l as
CaC03
232
236
248
236
248
240
8
252
232
224
216
216
160
228
208
224
180
180
211
27
208
218
232
252
272
328
Mg C03
mg/l as mg/l as
CaCO3 CaCOj
295
264
288
296
276
284
14
272
252
272
272
268
320
260
284
276
212
220
264
29
292
252
276
280
308
428
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/l as
CaCO3
532
532
575
548
572
552
21
588
568
552
564
560
560
568
564
556
520
560
560
16
560
588
532
512
520
504
NO3-N
mg/l
~
-
-
_
-
_
-
-
-
_
-
-
-
_
4.2
4.1
4.2
0.1
4.6
-
3.5
4.0
4.0
3.1
NO2-N NH3-N
mg/l mg/l
-
- -
_
_ —
-
__ _
_ _
-
-
_ _
<3 0.34
<1 0.33
<1 0.38
<1 0.38
<1 0.87
<1 0.44
0.49
0.21
<1 0.42
- -
0.63
<0.010 0.09
0.004 0.72
0.41
Total
P
mg/l
"**
-
-
_
-
—
-
-
-
_
0.069
0.090
0.085
0.083
0.035
0.066
0.070
0.020
0.083
_
0.090
0.085
0.094
0.096
COD BOD TOC
mg/l mg/l mg/l
_
_
_
_ .. _
-
— — __
_ _ -
_
- - -
— _ _
- - 27
_ _ _
39
7.6
_
6
20
16
— _ —
_ _ _
11
_
<5 14
<5 7
Standard
Coliforms
Colonies/
100ml
0
_
0
_
-
0
0
-
0
-
-
-
—
_
-
_
-
_
-
0
0
„
>100
-------
TABLE B-6 (CONTINUED).
en
GO
Date
1973 Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
1974 Jan
Feb
Mar
Apr
Chlorides Conductivity
Jttihos/cm2
mg/l at25°C
1,260
1,540
1,590
1,660
1,800
-
1,087
492
1,680
1,960
2,250
-
4,000
5,000
5,500
5,500
5,500
-
3,945
1,199
5,000
6,000
7,000
-
Total
Hardness
mg/l as
CaC03
964
1,220
_
1,652
1,532
-
871
450
1,372
1,620
1,950
-
Ca
mg/l as
CaC03
448
560
_
620
708
-
385
186
624
748
865
-
Mg C03
mg/l as mg/l as
CaC03 CaCO3
516
660
_
1,032
824
-
487
270
748
872
1,085
-
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/l as
CaCO3
488
460
_
472
408
-
505
51
456
436
400
—
N03-N
mg/l
4.1
3.6
3.5
4.1
3.6
-
3.8
0.4
_
3.6
3.5
-
NO2-N
mg/l
-------
TABLE B-7. ANALYSIS OF SAMPLES TAKEN FROM WELL FP-8
cn
Date
1971 Jun
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
1972 Jan
Feb
May
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std
1973
Dev
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Chlorides
mg/l
660
600
650
630
660
640
26
660
700
660
690
640
680
690
620
500
649
62
460
650
650
700
800
700
700
670
Conductivity
/Jmh os/cm
at 25° C
3,500
3,200
3,400
3,000
3,200
3,050
3,050
3,200
189
3,000
3,200
3,200
3,000
3,000
3,000
3,000
3,000
3,000
3,044
88
2,400
3,000
3,000
2,900
3,100
3,000
3,000
3,000
Total
Hardness
mg/l as
CaC03
442
412
440
460
440
439
17
428
424
432
456
432
416
436
408
372
423
23
408
440
472
452
484
456
440
448
Ca
mg/l as
CaCO3
210
204
240
224
232
222
15
220
224
220
176
192
188
196
200
188
200
17
180
220
252
220
248
224
216
216
Mg C03
mg/l as mg/l as
CaCO3 CaCO3
232
208
200
236
208
217
16
208
200
212
280
240
228
240
208
184
222
28
328
220
220
232
236
232
224
232
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HCOj
mg/l as
CaC03
545
572
605
608
568
580
27
596
580
580
510
580
576
560
592
612
576-
29
616
608
588
540
568
548
560
548
N03-N
mg/l
-
-
-
_
-
-
4.9
4.3
4.6
0.4
4.2
-
-
4.0
3.9
3.4
3.6
5.7
N02-N NH3-N
mg/l mg/l
•~ •"
-
<1 0.49
<1 0.44
<1 0.46
<1
<1 0.50
<1 0.25
0.43
0.10
<1 0.46
_
0.49
0.010 0.06
0.004 0.36
0.49
0.014 0.18
0.47
Total
P
mg/l
-
-
0.069
0.081
0.070
0.059
0.071
0.047
0.070
0.010
0.060
-
0.051
0.098
0.096
0.084
0.068
0.076
COD BOD
mg/l mg/l
™" *™
_
- -
_
-
_
—
_
_
- -
_
-
_
<5
- <5
<5
-
- <5
Standard
TOC Coliforms
Colonies/
mg/l 100ml
-
-
20
-
15
-
6.6
6.0
12
7
24
-
-
12
_
7
-
<0.1
"~
-
—
_
-
-
—
0
_
-
0
-
0
4
21
0
0
4
-------
TABLE B-7 (CONTINUED).
en
en
Date
1973 Sep
Oct
Nov
WELL NOT
Mean
Std Dev
1974 Jan
Feb
Mar
Apr
May
jun
Jul
Aug
Sep
Oct
Nov
Chlorides Conductivity
pmhos/cm2
mg/1 at25°C
680
690
670
OPERATING
670
81
700
680
680
-
690
700
680
680
720
720
-
PUMP TURNED OFF NOV
1975 Jan
Feb
Mar
May
Jun
Jul
Aug
Sep
730
750
750
680
750
692
700
700
3,000
3,000
2,800
2,927
190
3,000
3,000
3,000
-
3,000
3,000
2,800
2,600
2,400
2,800
-
1974-JAN
2,800
2,800
2,800
2,800
3,000
2,800
2,800
3,000
Total
Hardness
mg/l as
CaCO3
432
480
451
23
492
488
452
-
440
408
416
416
460
444
-
I975
_
464
-
-
458
-
441
—
Ca
mg/l as
CaC03
_
212
220
221
19
224
216
232
-
212
204
212
204
216
204
-
_
228
-
-
217
-
217
—
Mg C03
mg/l as mg/l as
CaCO3 CaCO3
.
220
260
240
33
268
272
220
-
228
204
204
212
244
240
-
_
236
-
-
241
-
224
—
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/l as
CaCO3
_
552
540
567
28
536
540
548
-
548
544
536
536
540
532
-
_
544
-
-
540
-
542
—
NO3-N
mg/l
3.9
4.9
4.4
4.2
0.7
_
4.1
4.4
—
3.9
4.2
4.3
4.2
_
-
-
4.3
4.8
4.2
5.8
-
4.4
4.1
3.6
N02-N
mg/l
_
0.004
-
-
-
0.002
<0.001
0.004
—
0.014
0.005
0.002
0.005
0.003
0.004
0.003
0.007
0.004
<0.001
0.002
0.008
0.006
0.005
0.006
NH3-N
mg/l
0.37
0.20
0.15
0.32
0.16
0.10
0.08
-
0.02
0.22
0.17
0.34
0.30
<0.01
-
0.15
-
0.27
0.16
—
0.10
0.16
0.11
0.23
Total
P
mg/l
0.116
0.081
0.076
0.080
0.020
_
0.092
0.070
—
0.060
0.073
0.101
0.063
0.076
-
-
0.077
0.066
0.059
0.070
0.083
0.082
0.064
0.062
Standard
COO BOO TOC Coliforms
Colonies/
mg/l mg/l mg/l 100ml
_ __
<5
<5 <5
14
— — 9
<5 <5
<5 <5 3.5
<5 <5
— — -»
<5 <5
7 <5
<5 <5 16
8 — —
<5
<5
<5 - -
<5
•J __ _
<5
— — —
_
-
_
™ "" "™
1
0
0
-
—
0
0
0
—
4
0
2
0
49
1
—
-
0
-
—
0
-
0
"
-------
TABLE B-8. ANALYSIS OF SAMPLES TAKEN FROM WELL GG-1
en
Date
1971 Sep
Oct
Nov
Dec
Mean
Std Dev
1972 Jan
Feb
Mar
Apr
May
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
1973 Jan
Feb
Mar
Apr
May
Jun
Chlorides Conductivity
pmh os/cm2
mg/l at25°C
200
200
190
200
196
5
210
210
210
230
185
210
230
240
240
210
210
217
17
220
210
_
260
280
260
WELL DISMANTLED
Aug
Sep
—
-
1,675
1,800
1,630
1^00
1 ,726
87
1,650
1,770
1,750
1,650
1,800
1,800
1,700
1,700
1,700
1,700
1,500
1,703
84
1,700
1,600
_
1,700
1,700
1,650
Total
Hardness
mg/l as
CaC03
368
292
300
306
317
35
296
300
304
312
296
320
297
320
304
320
360
312
19
320
352
_
352
336
340
Ca
mg/l as
CaC03
316
204-
140
116
194
89
140
120
128
116
120
104
108
128
128
128
152
125
14
144
128
-
156
140
156
Mg C03
mg/l as mg/l as
CaCO3 CaCO3
52
88
160
190
123
64
156
180
176
196
176
216
189
292
176
292
208
205
46
176
224
_
196
196
184
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HCO3 NO3-N
mg/l as
CaCO3 mg/l
636
675
660
640
653
18
660
636
640
652
644
642
648
640
624
640
632
643
8
640
664
2.9
572 2.5
592 2.3
600 2.6
NO2-N NHj-N
mg/l mg/l
_ _
-
-
— —
_
<1 0.42
<1 0.41
<1 0.40
<1 0.46
<1 0.49
<1 0.46
0.44
0.04
<1 0.44
-
0.76
0.010 0.12
0.004 0.41
0.56
Total Standard
P COD BOD TOC Conforms
Colonies/
mg/l mg/l mg/l mg/l 100ml
_
-
-
—
-
0.056
0.065
0.058
0.059
0.057
0.051
0.060
0.001
0.060
-
0.073
0.085
0.096
0.084
_ _ _
_
-
— — —
_
25
_ _ -
44
5
-
14.3
22
- - 17
_ _ _
7
12
— - -
- <5 17
- <5
44
225
17
-
45
93
-
-
-
—
-
-
—
-
—
-
-
5
10
40
55
FOR DISINFECTION
_
-
_
-
_
-
_
-
0
0
_
-
0.49
0.35
-
-
_
- - -
8
0
-------
TABLE B-8 (CONTINUED).
en
Date
1973
Mean
Oct
Nov
Dec
Std Dev
1974
1975
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Chlorides
tng/1
380
370
400
298
75
490
520
520
-
540
530
550
590
600
620
_
260
280
260
270
270
270
270
264
300
300
Conductivity
/^mhos/cm
at25°C
2,000
2,000
2,200
1319
217
2,400
2,400
2,600
-
2,800
2,600
2,200
2,400
2,400
2,400
_
1,600
1,600
1,600
1,600
1,700
1,800
1,700
1,700
1,800
1,700
Total
Hardness
mg/l as
CaC03
456
440
424
378
53
412
404
444
-
424
416
400
416
_
428
_
-
464
452
-
438
450
446
-
418
-
Ca
mg/l as
CaCO3
196
192
160
159
24
160
140
176
-
164
172
160
160
_
164
-
-
182
192
-
166
182
179
-
175
-
Mg CO3 HCO3
mg/l as mg/l as mg/l as
CaCO3 CaC03 CaCO3
260
248
264
219
35
252
264
268
-
260
244
240
256
_
264
-
-
282
260
-
272
268
265
-
243
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
556
554
536
589
44
542
500
548
-
540
520
536
528
_
526
-
-
604
600
-
592
584
572
1 -
588
-
N03-N
mg/l
-
1.9
2.4
0.4
2.5
1.6
1.2
-
1.2
0.9
1.5
0.8
_
1.0
-
1.0
1.9
1.8
1.3
—
1.3
-
1.3
1.3
1.4
NO2-N NH3-N
mg/l mg/l
_
0.001
0.001
0.370
0.200
0.100
0.001
0.002
-
0.002
0.001
0.001
0.002
-
0.002
0.003
-
0.002
0.002
-
—
0.002
0.003
0.002
0.001
0.002
0.09
0.30
0.22
0.08
0.01
0.01
0.01
-
0.12
0.31
0.23
0.29
0.24
0.30
0.32
-
—
0.27
0.38
0.17
—
0.41
0.16
0.07
~
0.85
Total Standard
P COD BOD TOC Coliforms
Colonies/
mg/l mg/l mg/l mg/l 100ml
__
-
0.084
-
—
0.066
-
0.052
—
0.046
0.040
0.088
0.055
0.027
0.048
-
0.086
0.090
0.088
0.079
—
0.076
0.074
0.088
0.075
0.067.
_
<5
<5
-
—
9
<5
23
—
<5
<5
<5
<5
8
<5
5
—
11
<5
<5
•~
~
—
-
~
-
<5
<5 12
7
11
4
<5
<5 3.5
<5
— —
<5
6
<5 12
— —
-
- -
- -
— "•
-
<5
— —
~~ ~~
-
— —
— —
~~ ~~
-
28
38
10
-
—
54
400
10
—
0
20
0
4
-
128
-
—
192
8
—
131
305
—
—
0
-
-------
TABLE B-9. ANALYSIS OF SAMPLES TAKEN FROM WELL GG-8
cn
oo
Date
1971 Jun
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Oev
1972 Jan
Feb
Mar
Apr
May
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
1973 Jan
Feb
Mar
Apr
May
Jun
Chlorides
mg/l
445
410
420
430
426
14
440
400
450
-
450
445
460
480
500
450
450
453
26
450
-
450
470
500
500
Conductivity
/Umhos/cm
at25°C
2,650
2,500
2,650
2,400
2,400
2,500
2,500
122
2,450
2,250
2,500.
-
2,600
2,400
2,400
2,400
2,200
2,400
2,200
2,380
130
2,200
2,400
2,600
2,400
2,800
2,500
Total
Hardness
mg/l as
CaCO3
273
284
288
272
279
8
284
272
284
-
272
272
264
280
292
260
292
111
11
292
-
264
260
284
228
Ca
mg/l as
CaC03
111
128
124
112
119
9
124
132
88
-
120
98
104
108
128
108
120
113
14
108
-
112
116
132
132
Mg C03
mg/l as mg/l as
CaCO3 CaC03
162
154
164
160
160
4
160
140
196
-
152
174
160
172
164
152
172
164
16
184
-
152
144
152
96
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HCO3
mg/l as
CaC03
571
564
592
592
580
14
608
580
564
-
584
590
600
600
568
592
612
580
16
612
-
580
572
580
588
NO3-N NO]-N NH3-N
mg/l mg/l mg/l
_
_
- — -
_
— — —
_ _ _
_
_
— - -
_ _ _
<1 0.50
<1 0.43
<1 0.48
<1 0.44
_
- - -
0.46
0.03
6.3 <1 0.64
_
4.2 - 0.78
5.2 <0.01 0.09
5.4 0.004 0.64
4.6 - 0.58
Total
P COD BOD TOC
mg/l mg/l mg/l mg/l
_
_
- — — -
_ _ _ _
— — — —
_ _ _ _
_
_
- - - -
_ _ _
0.066 - -- 2.3
0.092 -
0.070 - - 4.1
0.075 -
- 4.5
0.068 -
0.070 4
0.010 - - 1
0.070 - - 5.5
- - -
0.070 -
0.082 -
0.090 - <5 14
0.084 - <5
Standard
Coliforms
Colonies/
100ml
1
-
26
—
—
0
-
0
3
-
-
-
—
-
-
—
_
-
~
-
0
0
0
5
-------
TABLE B-9 (CONTINUED).
Date
1973
Mean
Jul
Aug
Sep
Oct
Nov
Dec
Std Dev
1974
1975
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Chlorides
mg/I
540
530
530
530
530
550
507
36
550
550
560
—
550
570
550
520
560
580
_
500
530
540
540
530
530
540
528
560
-
Conductivity
/^mhos/cm2
at 25° C
2,600
2,700
2,800
2,800
2,600
2,800
2,600
195
2,700
2,700
3,000
-
3,000
3,000
2,600
2,400
2,200
2,500
-
2,200
2,400
2,400
2,400
2,400
2,400
2,600
2,400
2,600
-
Total
Hardness
mg/I as
CaC03
296
296
-
292
284
308
280
24
292
264
304
-
288
280
284
-
320
308
-
-
300
312
-
295
_
307
-
293
-
Ca
mg/I as
CaCO3
124
148
_
140
128
104
132
22
156
92
136
-
128
132
124
-
128
128
-
-
136
144
-
121
_
124
-
126
-
Mg
mg/I as
CaCO3
172
148
_
152
156
204
156
28
136
172
168
-
160
148
160
-
192
180
-
-
164
168
-
174
_
183
-
167
-
C03
mg/I as
CaCO3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/I as
CaCO3
580
572
-
588
. 580
576
583
12
580
560
600
-
596
612
588
-
580
582
-
-
584
588
-
584
-
600
-
580
-
NO3-N
mg/I
5.6
2.0
4.9
6.1
5.8
5.7
5.2
1.0
5.3
6.3
1.3
-
4.7
5.7
3.3
5.5
_
5.0
-
4.7
4.8
5.7
5.7
5.6
5.7
-
5.1
5.4
5.4
NOj-N
mg/I
0.001
<0.001
_
_
0.001
<0.001
_
-
0.001
0.001
0.001
-
0.001
<0.001
0.001
<0.001
0.002
0.002
0.001
-
0.002
0.005
-
-
0.004
-
0.001
0.002
-
NH3-N
mg/I
0.15
0.39
0.39
0.02
0.39
0.24
0.39
0.25
<0.01
0.04
-
0.02
0.20
0.37
0.38
0.47
0.21
0.24
-
-
0.11
0.23
0.13
-
_
0.12
0.11
-
-
Total
P
mg/I
0.060
0.068
0.114
0.087
0.060
0.076
0.080
.0.020
0.081
0.073
0.075
-
0.068
0.065
0.094
0.066
_
0.093
-
0.072
0.077
0.070
0.065
-
0.067
0.077
0.064
-
0.028
COD
mg/I
-
_
-
<5
<5
_
-
6
<5
12
—
<5
7
<5
<5
<5
<5
<5
-
5
<5
<5
-
..
-
-
' -
_
Standard
BOD TOC Conforms
Colonies/
mg/I mg/I 100ml
<5 2
<5
<5
<5
11
<5 9
8
— 5
<5
<5 4
<5
- -
<5 5.25
5
<5 6
-
_
- -
-
-
<5
-
_
-
_ _
-
-
-
_
0
1
0
1
2
0
_
-
1
0
0
-
0
1
10
-
0
0
-
--
0
-
-
0
„
0
-
0
-
-------
TABLE B-10. ANALYSIS OF SAMPLES TAKEN FROM WELL GG-9
Date
1971 Jun
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
& 1972 Jan
0 Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
Chlorides
mg/l
_
-
200
210
220
220
250
220
19
240
260
240
-
_
200
250
230
240
250
220
230
236
17
Conductivity
/^mhos/cm
at 25° C
1,625
1,600
1,600
1,550
1,675
1,650
1,700
1,628
51
1,600
1,600
1,600
-
_
1,600
1,600
1,500
1,500
1,500
1,500
1,500
1,550
53
Total
Hardness
mg/l as
CaC03
-
378
372
372
380
392
379
8
380
376
-
-
_
380
308
380
388
400
400
384
377
27
Ca
mg/l as
CaCO3
-
152
170
172
172
172
168
9
172
172
-
-
_
168
168
140
164
168
168
168
165
10
Mg
mg/l as
CaC03
-
226
202
200
208
220
211
11
208
104
-
-
_
212
140
240
224
232
232
216
201
47
C03
mg/l as
CaCO3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HCOj NO3-N
mg/l as
CaCO3 mg/l
-
483
476
520
532
556
513
34
528
504
-
- -
_ _
504
508
508
504
492
508 2.6
500 2.9
506 2.8
10 0.2
NOj-N NHj-N
mg/l mg/l
_
-
-
_ _
-
- -
_ _.
-
_
-
-
-
_ _
_
<1 0.27
<1 0.38
<1 0.40
<1 0.48
<1 0.62
<1
0.43
0.13
Total
P COD BOD
mg/l mg/l mg/l
..
_
_
_ _ _
_
- - -
« —
- -
— _
_
„
- - -
_ _
_
0.076
0.081
0.080
0.083
0.083
0.085
0.080
_
TOC
mg/l
-
--
-
_
-
-
„.
-
__
-
-
-
_
-
17
-
12
4.0
5.2
4.5
9
6
Standard
Conforms
Colonies/
100ml
-
--
-
21
-
-
_
-
2
-
0
0
49
-
12
52
>100
25
-
-
_
-
PUMP BEING REPAIRED
1973
Apr
May
260
260
1.500
1,500
600
200 400
0
0
468
1.7
1.6
0.004 0.43 0.094
<5
<5
14
-------
TABLE B-10 (CONTINUED).
Date
1973 Jun
Jul
Aug
PUMP NOT
Oct
Nov
Dec
Mean
Std Dev
Chlorides
mg/l
300
250
RUNNING
330
270
260
276
29
Conductivity
p&tih os/cm2
at25°C
1,500
1,600
1,900
1,600
1,600
1,600
141
Total
Hardness
mg/l as
CaCO3
420
440
540
500
456
493
68
Ca
mg/l as
CaCOj
196
196
232
216
192
205
16
Mg
mg/l as
CaC03
224
244
308
284
264
287
63
C03
mg/l as
CaCO3
0
0
0
0
0
0
0
0
HCO3
mg/l as
CaCO3
480
460
_
460
456
465
10
NO3-N
mg/l
4.8
5.7
1.1
— .
0.4
1.2
2.4
2.0
NOj-N
mg/l
0.002
<0.001
_
0.002
<0.001
_
-
NH3-N
mg/l
0.59
0.14
0.42
0.19
0.06
0.07
0.27
0.21
Total
P
mg/l
0.092
0.100
0.082
„
0.056
0.084
0.080
0.020
COD
mg/l
-
-
_
<5
<5
-
-
BOD
mg/l
-
<5
<5
<5
<5
_
-
TOC
mg/l
8
-
1
_
10
4
7
5
Standard
Conforms
Colonies/
100ml
-
-
_
7
4
-
-
a>
DENIED ACCESS TO PUMP BY OWNER - SAMPLING DISCONTINUED
-------
TABLE B-1 1. ANALYSIS OF SAMPLES TAKEN FROM WELL MB-1
OS
to
Date
1971 Jul
Aug
Sep
Nov
Dec
Mean
Std Dev
1972 Jan
Feb
Mar
Apr
May
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
1973 Jan
Feb
Mar
Apr
May
Jun
Chlorides
mg/l
_
1,775
1,810
1,810
1,800
1,799
17
1,790
1,820
1,860
1,650
1,670
1,830
1,860
1,890
1,900
1,840
1,700
1,800
88
1,680
1,680
1,670
1,870
1,800
1,860
Conductivity
^mhos/cm2
at2S°C
7,000
6,800
6,800
6,000
6,500
6,620
390
6,000
6,100
6,000
6,100
6,500
6,000
6,000
6,000
6,000
6,000
6,000
6,064
151
6,000
6,000
6,000
6400
6,000
6,000
Total
Hardness
mg/l as
CaC03
_
362
453
-
456
424
53
440
444
388
468
456
460
460
464
448
448
436
447
22
508
436
436
440
__
472
Ca
mg/l as
CaCO3
_
216
244
244
232
234
13
236
224
168
248
248
204
164
220
240
224
216
218
29
248
280
232
240
^_
252
Mg
mg/l as
CaCO3
_
146
209
-
224
193
41
204
220
220
220
208
256
296
244
208
224
220
229
27
260
156
204
200
_
220
C03
mg/l as
CaCO3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HCO3
mg/l as
CaC03
_
425
444
-
452
440
14
468
472
392
464
460
468
464
472
456
460
480
460
23
484
188
452
440
_
456
N03-N
mg/l
_
-
-
-
-
_
-
_
-
-
-
_
-
-
-
_
6.3
5.3
5.8
0.7
5.8
-
4.2
4.3
5.0
4.5
NO2-N NH3-N
mg/l mg/l
_ m.
~
..
— —
-
-
- -
_ _
-
_
— -
_ _
<1
<1 0.39
<1 0.38
<1 0.43
<1 0.33
<1 0.30
0.37
0.05
1 0.35
-
0.73
<0.01 0.20
0.34
0.35
Total
P COD BOD
mg/l mg/l mg/l
_~ _ »
..
..
— — —
_
_ _ _
— — —
_ _
_
_
— -
— — —
0.015
0.047
0.042
0.015
0.023
0.012
0.026
0.015
0.01 5
_
0.01 6 ~
0.01 0 -
0.021 - <5
0.032 - <5
TOC
mg/l
_
-
-
—
-
-
-
_
-
-
-
-
7
--
15
7
~
—
10
5
-
6.5
15
—
..
12
Standard
Coliforms
Colonies/
100ml
_
-
-
—
0
-
-
>100
-
2
20
-
-
-
-
_
-
—
_
—
-
2
69
—
9
8
-------
TABLE B-11 (CONTINUED).
Date
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
,_, 1974 Jan
O> Feb
CO
Chlorides
mg/l
1,880
1,810
1,830
1,810
1,820
1,800
1,793
75
1,810
1,810
WELL INOPERATIVE
Conductivity
pmh os/cm2
«25°C
6,000
6,000
7,000
6,000
6,000
6,000
6,125
311
6,000
6,000
FEB 1974-
Total
Hardness
mg/l as
CaC03
492
464
464
500
444
460
465
26
480
-
Ca
mg/l as
CaCO3
256
240
240
252
232
240
247
14
232
-
Mg
mg/l as
CaCO3
236
224
224
248
212
220
219
27
248
-
C03
mg/l as
CaC03
0
0
0
0
0
0
0
0
0
0
HC03
mg/l as
CaC03
464
448
_
452
424
436
424
85
444
-
N03-N
mg/l
5.7
5.4
5.1
5.6
5.1
5.6
5.1
0.6
4.4
5.1
NO2-N
mg/l
0.027
0.001
..
-
<0.001
-
_
-
0.01
-
NH3-N
mg/l
0.05
0.48
0.34
0.17
0.21
0.02
0.29
0.20
<0.01
-
Total
P
mg/l
0.012
0.016
0.072
0.030
0.024
0.017
0.024
0.017
0.010
0.026
COD BOD
mg/l mg/l
<5
<5
<5
<5
5 <5
<5
- -
— —
<5 12
- -
TOC
mg/l
4
_
-
12
—
10
5
-
-
Standard
Coliforms
Colonies/
100ml
0
>100
2
C*
2
0
-
—
4
-
*Confluent colonies.
-------
TABLE B-12. ANALYSIS OF SAMPLES TAKEN FROM WELL MB-2
Date
1971 Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
1972 Jan
Feb
Mar
Apr
May
Jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
1973 Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Chlorides
mg/l
270
280
270
270
290
276
9
280
270
270
-
250
255
290
330
280
260
-
276
24
H
240
280
260
280
300
300
270
Conductivity
/jtmhos/cm2
at2S°C
1,950
1,840
1,900
1,900
1,950
1,908
46
1,750
1,900
1,900
-
1,900
1,800
1^00
1,800
1,800
1,800
-
1,828
57
_
1,800
1,800
1,710
1,750
1,700
1,500
1,800
Total
Hardness
mg/l as
CaCO3
248
252
256
276
248
256
12
268
252
236
-
248
250
264
252
264
256
-
255
10
_
252
248
264
268
260
276
264
Ca
mg/l as
CaCO3
104
104
104
112
104
106
4
112
112
100
—
100
106
104
104
112
100
-
106
5
_
107
120
112
112
116
124
112
Mg C03
mg/l as mg/l as
CaC03 CaC03
144
148
152
164
144
150
8
156
140
136
—
148
144
160
148
152 •
156
-
149
8
_
145
128
152
156
144
152
152
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HCO3
mg/l as
CaC03
564
552
600
600
584
580
22
564
592
576
—
584
576
456
580
456
580
-
552
55
-
616
572
540
548
560
572
540
NO3-N NO2-N NH3-N
mg/l mg/1 mg/l
_ _ —
_
_
— — —
_
_ _ -
- - -
_ _ -
_
_
— — —
_ _
_
<1 0.41
<1 0.49
<1 0.50
<1 0.40
5.2 <1 0.40
0.44
0.05
5.7 <1 0.46
_
3.9 - 0.54
2.6 <0.01 0.05
4.5 0.004 0.55
4.2 - 0.57
5.1 0.005 0.16
<0.001
Total
P
mg/l
..
-
-
—
-
-
-
_
-
-
—
-
-
0.042
0.042
0.041
0.047
0.043
0.043
0.002
0.045
-
0.055
0.046
0.050
0.060
0.032
-
Standard
COD BOD TOC Coliforms
Colonies/
mg/l mg/l mg/l 1 00 ml
_ _ _
_
_
— — —
_
_
— — —
_ _ _
_
„
— — —
_
20
„
16
— — 5
6.4
5.0
10
— — 7
_
15
_
- -- -
<5 18
<5
<5
<5 < 0.1
..
-
-
—
0
-
••
0
-
-
0
-
-
-
—
-
-
-
_
—
-
-
1
0
0
3
0
5
-------
TABLE B-12 (CONTINUED).
05
01
Date
1973
Sep
Oct
Nov
Dec
Mean
Std
1974
1975
Dev
Jan
Feb
Mar
Apr
May
Jun
jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Chlorides
mg/1
280
290
280
290
279
18
290
290
290
-
290
290
280
290
29P
300
_
300
300
310
__
320
340
320
345
360
340
Conductivity
/Arch os/cm
at25°C
1,800
1,900
1,700
1,800
1,751
102
1,800
1,800
1,900
-
1,900
1,800
1,700
1,600
1,500
1,600
_
1,600
1,700
1,700
_.
1,800
1,800
1^00
1,800
1,800
1,900
Total
Hardness
mg/l as
CaC03
_
280
268
280
266
11
312
288
284
-
272
260
256
248
288
280
-
-
288
284
_
295
295
272
_
304
-
Ca
mg/l as
CaC03
_
124
148
128
120
12
128
112
120
-
112
—
112
96
108
92
-
-
112
120
_
121
132
101
-
129
-
Mg
mg/l as
CaC03
—
156
120
152
146
12
184
176
164
-
160
-
144
152
180
188
-
-
176
164
_
174
163
171
-
175
-
C03
mg/l as
CaCO3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/l as
CaC03
_
556
540
-
560
25
548
540
572
-
560
-
-
548
540
546
-
—
572
564
-
552
544
548
-
550
-
N03-N
mg/l
4.0
5.1
4.1
4.1
4.3
0.9
4.4
4.2
-
-
_
4.7
4.7
4.6
_
3.8
3.4
—
4.2
4.4
-
-
-
-
4.4
4.3
4.0
N02-N
mg/l
„
-
<0.001
<0.001
-
—
_
<0.001
0.001
-
<0.001
<0.001
<0.001
0.002
0.001
0.001
0.002
—
-
-
-
—
0.003
0.003
0.002
0.002
0.008
NHj-N
mg/l
0.06
0.26
0.09
0.05
0.28
0.23
<0.01
-
-
0.08
0.20
0.24
0.36
0.42
0.18
0.29
-
—
0.29
0.44
0.16
—
0.18
0.14
0.15
0.18
0.06
Total
P
mg/l
0.062
0.076
0.045
0.058
0.053
0.012
0.037
0.050
-
—
-
0.051
0.088
0.043
0.073
0.070
-
0.058
0.056
0.055
-
—
-
0.052
0.058
0.051
0.052
COD
mg/l
_
-
<5
<5
-
—
-
<5
<5
—
<5
6
<5
<5
<5
<5
10
~
-
-
—
—
-
—
—
~
-
Standard
BOD TOC Coliforms
Colonies/
mg/l mg/l 1 00 ml
<5
<5
<5 10
<5 4
- -
— _
<5
<15 3
<5
"~ **
<5 4.8
<5
<5 6
— —
-
-
— —
*~ •*•
<5
—
— —
« «
_
" —
— —
"™ ™"
-
0
0
0
0
--
—
0
0
0
"~
0
1
2
0
0
—
—
~*
0
6
—
0
-
0
—
0
-
-------
TABLE B-13. ANALYSIS OF SAMPLES TAKEN FROM WELL NB-3
Date
1975 Feb
S Mar
0> Apr
May
Jun
Ju!
Aug
Chlorides
mg/l
290
320
300
320
330
325
335
Conductivity
Jllmh os/cm2
at2S°C
1,650
1,700
1,700
1,700
1,800
1,800
1,900
Total
Hardness
mg/l as
CaC03
280
279
287
_
-
—
Ca
mg/l as
CaCO3
108
117
116
_
-
—
Mg
mg/l as
CaCO3
172
162
171
_
-
—
C03
mg/l as
CaCO3
0
0
0
0
0
0
0
HCO3
mg/l as
CaC03
568
552
—
_
-
-?
NO3-N
mg/l
2.9
3.8
_
2.8
—
NO2-N
mg/l
0.004
0.004
0.002
0.002
0.002
NH3-N
mg/l
0.19
0.46
0.46
0.13
—
Total
P
mg/l
0.042
0.042
0.046
0.050
0.039
COD BOD
mg/l mg/l
9
<5
— —
_
-
—
Standard
TOC Conforms
Colonies/
mg/l 100ml
8
0
— —
_
-
.,
-------
TABLE B-14. ANALYSIS OF SAMPLES TAKEN FROM WELL NB-4
Date
OS 1975 Feb
-* Mar
Apr
May
)un
Jul
Chlorides
mg/l
290
310
310
330
330
—
Conductivity
^mhos/cm2
at25°C
1,600
1,700
1,700
1,700
1^00
—
Total
Hardness
mg/l as
CaC03
296
-
322
330
330
~
Ca
mg/l as
CaCO3
124
-
109
136
136
—
Mg
mg/l as
CaCO3
172
-
213
194
194
~
C03
mg/l as
CaC03
0
0
0
0
0
0
HC03
mg/l as
CaCO3
560
-
540
540
540
~~
NO3-N
mg/l
4.1
-
5.3
-
™~
NO2-N
mg/l
0.005
-
-
0.001
0.003
~~
NH3-N
mg/l
.
0.14
-
0.35
-
0.08
Total
P
mg/l
_
0.039
-
0.036
0.063
~"
COD BOD TOC
mg/l mg/l mg/l
9
<5
-
— — —
_
~ "
Standard
Coliforms
Colonies/
100ml
0
-
1
—
-
"
-------
TABLE B-15. ANALYSIS OF SAMPLES TAKEN FROM WELL NB-5
Hi
0
QO
Date
1975 Feb
Mar
Jul
Aug
Chlorides
mg/I
350
380
426
440
Conductivity
ftmb os/cm2
at25°C
MOO
2,220
2,200
Total
Hardness
mg/I as
CaC03
372
384
Ca
mg/I as
CaC03
172
145
Mg
mg/I as
CaC03
200
239
C03
mg/I as
CaC03
0
0
0
0
HCO3
mg/I as
CaC03
528
533
NO3-N
mg/I
7.3
7.8
NO2-N
mg/I
0.001
0.002
0.003
NH3-N
mg/I
0.17
0.08
Total
P
mg/I
0.650
0.067
COD BOD
mg/1 mg/I
7 —
_
Standard
TOC Conforms
Colonies/
mg/I 1 00 ml
0
0
-------
TABLE B-16. ANALYSIS OF SAMPLES TAKEN FROM WELL P-1
Date
1971 Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
1972 Jan
Feb
Mar
jul
Aug
Sep
Oct
Nov
Dec
Mean
Std Dev
1973 Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Chlorides
mg/l
1,240
1,130
1,050
1,160
1,140
1,144
68
1300
1,300
1,250
1,340
1,290
1,250
1,300
1,200
1,300
1,281
41
1,280
1,350
1,300
1,410
1,400
1,400
1,400
1,440
Conductivity
fJmh os/cm
at25°C
5,100
5,000
4,550
5,000
5,000
4,930
215
5,100
5,200
5,000
5,000
5,000
5,000
5,000
5,000
5,000
5,033
71
6,000
5,500
5,500
5,000
5,000
5,000
5,000
5,500
Total
Hardness
mg/l as
CaC03
372
332
260
368
320
330
45
420
396
-
424
380
384
440
380
400
403
23
452
478
432
436
436
440
468
488
Ca
mg/l as
CaC03
228
200
164
220
180
198
27
248
232
-
240
180
188
200
180
180
206
29
224
288
268
268
256
260
280
292
Mg C03
mg/l as mg/l as
CaCO3 CaCO3
144
132
96
148
140
132
21
212
164
-
184
200
196
240
200
220
202
23
228
290
164
168
180
180
188
196
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Total Standard
HCO3 NO3-N NO2-N NHj-N P COD BOD TOC Conforms
mg/1 as Colonies/
CaCO3 mg/l mg/l mg/l mg/l mg/l mg/l mg/l 100ml
648 - - _____
632 - _____
700 - _..___
668 - _____
652 - _____
660 - -
26- - _____
692 - _____
672 - ~ _____
678 - _____
680 - _____
668 - _____
660 - _____
664 - _____
654 - - __..__
_____
671 - - _____
12 - ___.._
672 - - _____
741
f*f| — — rrr .* — —••
652 - - 0.55 0.029 -
616 1.7 <0.010 0.04 0.028 -
640 0.8 0.004 0.84 0.060 - <5 39
632 3.1 - 0.42 0.046 - <5
652 1.8 0.002 0.18 0.012 - - 14
636 2.2 <0.001 0.42 0.026 <5 3
_
-
-
-
-
_
-
3
-
-
—
_
-
_
—
-
_
-
_
_
0
0
0
0
0
0
-------
TABLE B-16 (CONTINUED).
Date
1973
Sep
Oct
Nov
Dec
Mean
Std
1974
1975
Dev
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Chlorides
mg/l
1,460
1,460
1,450
1,320
1,383
63
1,520
1,490
f,420
-
1,360
1,400
1,410
1,260
1,420
1,520
*.
1,390
1,350
1,320
_
1,310
1,320
1,340
1350
1,500
-
Conductivity
/Ltmh os/cm
at 25° C
5,500
5,500
5,500
5,500
5,375
311
6,000
5,500
6,000
-
6,000
5,500
5,000
4,000
4,500
5,000
_
5,000
5,000
4,500
_
4,500
4,500
5,000
5,000
5,000
-
Total
Hardness
mg/l as
CaCO3
520
460
424
458
29
544
432
488
-
404
352
444
368
452
480
_
-
400
376
_
384
400
396
_
411
-
Ca
mg/l as
CaC03
196
264
248
259
28
304
220
288
-
232
180
264
220
256
224
—
-
212
232
_
214
225
225
-
186
-
Mg
mg/l as
CaC03
„
324
196
176
208
52
240
212
200
-
172
172
180
148
196
256
_
-"
188
144
_
170
175
171
-
225
-
C03
mg/l as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/l as
CaC03
_
644
604
716
655
41
652
576
644
-
652
580
632
628
632
584
-
-
_
632
-
628
636
632
-
525
-
NO3-N
mg/l
1.4
2.4
3.3
2.1
2,1
0.8
2.0
2.3
2.4
-
2.8
2.9
2.8
2.9
0.9
-
-
3.9
5.8
5.5
4.6
_
4.9
-
4.1
4.9
-
N02-N
mg/l
__
-
<0.001
<0.001
_
-
<0.001
<0.001
<0.001
-
<0.001
<0.001
0.002
0.002
0.001
-
0.051
-
0.002
0.004
-
-
0.002
0.003
0.001
0.001
0.002
NH3-N
mg/l
0.26
0.17
0.32
0.08
0.33
0.24
0.06
0.12
-
0.03
0.34
0.22
0.40
0.59
<0.01
-
--
-
0.19
0.29
0.14
-
0.16
0.15
0.11
0.11
0.08
Total
P
mg/l
0.047
0.032
0.022
0.080
0.040
0.020
0.006
0.034
0.023
—
0.019
0.027
0.056
0.250
0.052
-
-
0.032
0.035
0.032
0.022
-
0.021
0.036
0.035
0.024
-
COD
mg/l
_
-
6
5
6
1
8
<5
<5
™
<5
6
-
6
9
—
11
—
17
7
8
—
-
-
•-
—
-
Standard
BOD TOC Coliforms
Colonies/
mg/l mg/l 1 00 ml
_
<5
<5 27
<5 3
17
16
<5
<5 4.5
<5
—
<5
5
<5
~ ~"
-.
— —
-
— ~
<5
- -
-
— —
-
— —
-
— —
-
1
0
0
0
-
—
0
11
0
~"
75
C*
0
0
0
1
-
--
44
11
—
0
-
0
—
—
-
^Confluent colonies.
-------
TABLE B-17. ANALYSIS OF SAMPLES TAKEN FROM WELL PW-1
Chlorides Conductivity
pmhos/cm2
Date mg/1 at 25° C
1972 Jul
1974 Jan
Feb
May
Jim
lul
Aug
Sep
Oct
Nov
Dec
1975 Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
210
310
300
300
320
280
270
310
460
._
270
290
300
310
310
320
330
304
310
300
1,500
1,800
1,700
1,700
1,900
1,600
1,500
1,600
1,800
_
1,400
1,500
1,500
1,600
1,700
1,650
1,700
1,800
1,700
1,700
Total
Hardness
mg/I as
CaC03
388
520
516
468
384
372
368
-
268
_
-
396
416
-
415
_
415
-
411
-
Ca
mg/I as
CaCOj
180
240
232
192
168
172
164
-
120
_
-
148
184
-
179
_
186
-
183
-
Mg C03
mg/I as mg/I as
CaCOj CaCO3
208
280
284
276
216
200
204
-
148
„
-
248
232
-
236
_
229
-
228
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HCO3
mg/I as
CaC03
500
512
524
468
456
500
500
-
276
_
-
440
464
-
480
-
484
-
492
-
N03-N
mg/I
;
-
5.8
2.8
-
5.4
_
4.4
7.8
5.5
4.7
-
4.7
-
4.5
3.7
3.4
NO2-N NH3-N
mg/I mg/I
;
-
0.004
0.029
0.008
0.002
0.002
-
0.002
0.002
-
-
_
0.003
0.002
0.005
0.002
;
-
0.16
0.11
0.20
0.33
_
-
0.15
0.29
0.18
—
0.35
-
0.13
0.11
0.08
Total
P
mg/I
;
-
0.075
0.030
.0.075
0.065
_
0.069
0.083
0.066
0.048
—
0.044
0.052
0.048
0.045
0.020
Standard
COD BOD TOC Coliforms
Colonies/
mg/I mg/I mg/I 100ml
; ; ;
- - -
5 <5 12
<5
<5
<5
<5
- — -
6 <5 -
5 — —
<5
— — —
_
_
- - -
— — —
_
;
-
_
1
-
-
_
-
0
0
-
1
-
1
-
87
-
-------
TABLE B-18. ANALYSIS OF SAMPLES TAKEN FROM WELL PW-2
-a
to
Date
1972 jul
1973 May
jun
Jul
A tig
Sep
Oct
Nov
Mean
Std Dev
1974 Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
1975 Jan
Feb
Mar
Apr
Chlorides
mg/l
230
240
340
240
230
220
230
250
45
230
240
240
-
250
240
240
240
260
310
-
240
270
260
260
250
Conductivity
/Jmhos/cm2
at25°C
1,700
1,700
1,500
1,700
1,700
1,700
1,600
1,650
84
1,600
1,600
1,700
-
1,700
1,700
1,600
1^00
1,500
1,700
-
1,500
1,600
1,550
1,600
1,600
Total
Hardness
mg/l as
CaC03
216
224
224
216
236
244
229
11
268
220
260
-
224
204
224
256
_
272
-
-
248
240
-
245
Ca
mg/l as
CaCO3
40
92
104
104
104
116
104
8
112
72
104
-
100
84
100
96
_
108
-
-
84
100
-
93
Mg COj
mg/l as mg/l as
CaC03 CaC03
176
132
120
112
132
128
125
9
156
148
156
-
124
120
124
160
_
164
-
-
164
140
„
152
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/l as
CaC03
620
576
530
564
568
564
560
18
568
500
564
-
560
540
552
552
.
560
-
-
584
584
-
568
NOj-N
mg/l
-
-
2.7
-
-
-
..
2.7
2.6
0.3
_
2.8
-
1.5
2.6
2.8
2.7
-
NOVN
mg/l
< 0.001
< 0.001
-
< 0.001
0.002
0.002
-
0.002
0.006
0.007
0.004
0.001
0.002
0.001
-
0.004
0.003
-
0.001
NH3-N
mg/l
0.30
0.34
0.32
0.03
0.07
0.04
-
<0.01
0.26
0.17
0.37
0.53
0.28
0.18
-
-
0.12
0.26
0.16
-
Total
P
mg/l
-
-
_
0.043
-
-
_
0.035
0.078
-
0.063
0.062
-
0.037
0.037
0.032
0.033
-
COD
mg/l
8
-
7
<5
<5
-
<5
<5
<5
<5
<5
<5
<5
-
-------
TABLE B-18 (CONTINUED).
Date
1975
May
jun
Jut
Aug
Sep
Chlorides
mg/1
250
240
254
250
260
Conductivity
Jim h os/cm2
at25°C
1,600
1,700
1,650
1,600
1,700
Total
Hardness
mg/l as
CaCO3
248
268
-
243
-
Ca
mg/l as
CaC03
97
101
-
103
-
Mg
mg/l as
CaC03
151
167
-
140
-
C03
mg/l as
CaCO3
0
0
0
0
0
HCO3
mg/l as
CaC03
528
580
-
572
-
NO3-N
mg/l
2.6
-
2.3
2.3
2.4
N02-N
mg/l
0.005
0.003
0.001
0.002
0.002
NH3-N
mg/1
0.19
0.13
0.13
0.12
0.19
Total
P COD BOD
mg/l mg/l mg/l
0.030
0.039
0.042
0.035
0.028
Standard
TOC Coliforms
Colonies/
mg/1 1 00 ml
_
0
-
1
-
'Confluent colonies.
CO
-------
TABLE B-19. ANALYSIS OF SAMPLES TAKEN FROM WELL PW-4
Date
1972 Jul
Aug
Mean
Std Dev
1973 Jul
Aug
Sep
Mean
Std Oev
^j
r^
-q
•*- 1974 Jan
Feb
Chlorides Conductivity
(tmh os/cm
mg/l at 25° C
230
290
260
42
290
280
285
7
290
290
NOT IN OPERATION MAR
jun
Jul
Aug
Sep
Oct
Nov
Dec
1975 Jan
Feb
Mar
Apr
May
Jun
300
280
300
310
320
—
240
320
310
330
300
330
310
1,850
1300
1,900
1,850
71
1,800
1,800
1974-MAY
1,900
1,700
1,600
1,500
1,650
-
1,500
1,700
1,700
1,700
1,900
1,700
1,800
Total
Hardness
mg/l as
CaCO3
216
368
292
107
376
396
388
1974
348
356
372
-
448
-
-
396
396
-
385
392
385
Ca
mg/l as
CaCO3
40
140
90
71
164
180
176
160
168
156
-
180
-
-
156
168
-
171
172
171
Mg
mg/l as
CaCO3
176
228
202
37
212
216
212
188
188 '
216
-
268
-
-
240
228
-
214
220
214
C03
mg/l as
CaCO3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HCO3
mg/l as
CaC03
620
564
592
40
548
548
556
552
540
536
-
536
-
-
536
544
-
528
528
532
NO3-N
mg/l
-
-
2.5
__
2.7
2.4
-
2.8
-
2.0
3.7
3.7
3.6
-
_
-
NO2-N
mg/l
<0:001
0.001
<0.001
—
0.001
0.002
0.001
0.002
0.001
-
0.002
0.003
-
—
0.002
0.003
NH3-N
mg/l
0.45
0.09
0.08
0.19
0.28
0.26
0.14
0.11
-
-
0.33
0.40
0.09
-
0.22
0.07
Tout
P
mg/l
-
-
0.065
_
0.078
0.059
0.093
0.090
-
0.058
0.063
0.070
0.045
-
_
0.063
COD BOD TOC
mg/l mg/l mg/l
_
6 <5
<5 <5 4
_ ,,
<5 <5 6.8
<5 - -
<5
<5
<5
_
<5 <5
<5
<5
--
_ _
_
Standard
Coliforms
Colonies/
100ml
1
0
0
0
3
0
3
0
-
2
-
-
0
1
~
5
_
15
-------
TABLE B-19 (CONTINUED).
Date
Total Total
Chlorides Conductivity Hardness Ca Mg CO3 HCO3 NO3-N NOj-N NH3-N P COD BOD
/Anhos/cm mg/l as mg/l as mg/l as mg/l as mg/l as
mg/l at 25° C CaCO3 CaCO3 CaCO3 CaCO3 CaCO3 mg/l mg/l mg/l mg/l mg/l mg/l
Standard
TOC Conforms
Colonies/
mg/l 100ml
1975 Jul
Aug
Sep
304
300
310
1,700
1,700
1,700
380
171
209
0
0
0
534
0.002
0.001
0.002
0.16
0.06
0.08
0.050
0.058
0.040
en
-------
TABLE B-20. ANALYSIS OF SAMPLES TAKEN FROM WELL PW-6*
Date
1974 Aug
Sep
Oct
Nov
Dec
1975 Jan
Jul
Aug
Sep
Chlorides
mg/l
350
370
330
-
60
_,
345
330
340
Conductivity
A/mhos/cm
at25°C
1,500
1,600
1,500
-
650
..
1,600
1,600
1,600
Total
Hardness
mg/l as
CaCO3
468
-
412
-
-
_
-
441
*-
Ca
mg/l as
CaC03
172
-
180
-
-
_
-
190
—
Mg
mg/l as
CaC03
296
-
232
-
-
_
-
' 251
—
C03
mg/l as
CaCO3
0
0
0
0
0
0
0
0
0
HCO3
mg/l as
CaCO3
424
-
436
-
-
_
-
336
—
NO3-N
mg/l
0.3
-
0.7
-
0.4
_
-
0.4
3.7
NO2-N
mg/l
0.068
0.034
0.002
0.029
-
..
0.072
0.019
0.032
NH3-N
mg/l
1.11
0.24
1.06
-
-
0.38
0.26
-
0.26
Total
P
mg/l
0.220
0.036
0.068
-
0.026
_
-
0.092
0.035
COD BOD
mg/l mg/l
5
<5
<5
<5
--
—
_
-
— _
Standard
TOC Coliforms
Colonies/
mg/l tOO ml
_
_ _
-
-
«•
..
_
— ~
^Samples obtained from a nonpumped well with a torpedo sampler.
-------
TABLE B-21. ANALYSIS OF SAMPLES TAKEN FROM WELL PW-8*
Date
1974
197S
Aug
Sep
Oct
Nov
Dec
Jan
Jul
Aug
Sep
Chlorides
mg/l
250
280
290
-
340
_
335
330
330
Conductivity
JJmh os/cm2
at2S°C
1,400
1,500
1,500
-
1,600
_
1,800
1,800
1,600
Total
Hardness
mg/l as
CaC03
340
-
346
-
-
_
-
342
™
Ca
mg/l as
CaC03
152
-
116
-
-
_
-
95
—
Mg
mg/l as
CaC03
188
-
230
-
-
_
-
247
—
C03
mg/l as
CaCO3
0
0
0
0
0
0
0
0
0
HC03
mg/l as
CaC03
540
-
526
-
-
_
-
496
—
NO3-N
mg/l
<0.1
-
0.5
-
0.4
_
-
0.6
0.5
NO2-N
mg/l
0.088
0.022
0.026
0.366
-
_
0.022
0.018
0.016
NH3-N
mg/l
0.24
0.07
0.73
-
-
0.71
0.10
-
0.11
Total
P
mg/l
0.028
0.075
0.070
-
0.035
_
-
0.029
0.023
COD BOD
mg/l mg/l
<5
6
<5
8
-
_. _
_ _
-
— —
Standard
TOC Coliforms
Colonies/
mg/l 100ml
_ _
- -
-
-
_•
.. _
_
- -
* Samples obtained from a nonpumped well with a torpedo sampler.
-------
TABLE C-l. ANALYSIS OF SAMPLES TAKEN FROM WELL BMW-1
-q
00
Date
1971 Jul
Aug
Sep
Oct
Nov
Dec
1972 Jan
Feb
Mar
Jun
Jul
Aug
Sep
Oct
Chlorides
mg/l
1,600
1,600
1,610
1,660
1,670
168
1,720
1,650
1,780
1,810
1,810
1,570
1,720
Conductivity
umhos/cm2
at 25° C
5,600
5,600
5,600
5,900
6,000
6,000
6,000
5,900
5,600
6,000
6,000
6,000
6,000
6,000
Total
hardness
mg/l as
CaC03
„
888
892
856
—
876
912
940
—
968
836
880
868
908
Ca
mg/l as
CaC03
mf —
396
396
336
392
400
400
408
—
416
368
208
336
388
Mg
mg/l as
CaC03
«
492
496
520
--
476
512
532
--
552
468
672
532
520
CO 3
mg/l as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/l as
CaC03
._
484
472
520
532
492
524
484
—
492
500
496
472
492
Standard
col i forms
Colonies/
100 ml
__
—
--
T3
m
0
X
0 ,
-o
?0
__ — H
o
—
—
—
—
Nov
1,400
6,000
680
260
0
460
PUMP INOPERATIVE
-------
TABLE C-2. ANALYSIS OF SAMPLES TAKEN FROM WELL BMW-2
Date
1972 Jan
Feb
Mar
Jim
Jul
Aug
Sep
Oct
Nov
Dec
1973 Jan
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Chlorides
mg/l
1,750
1,480
1,980
1,850
1,840
1,810
1,740
1,970
1,850
1,800
1,370
1,660
2,000
2,000
1,860
1,800
2,400
1,440
2,050
2,020
2,060
Conductivity
vimhos/cm2
at 25° C
5,900
5,100
6,200
6,100
6,000
6,000
6,000
6,000
6,000
6,000
6,000
6,000
6,000
6,000
5,500
6,000
6,000
5,000
6,000
6,000
6,500
Total
hardness
mg/l as
CaC03
948
752
—
1,004
988
880
960
1,152
1,000
1,020
908
928
1,128
1,070
1,060
1,000
1,200
750
1,190
1,130
1,136
Ca
mg/l as
CaC03
448
368
—
492
408
208
448
520
440
312
376
444
508
480
490
460
572
380
590
530
544
Mg
mg/l as
CaC03
500
384
—
512
580
672
512
632
560
708
532
484
620
590
570
540
628
370
600
600
592
CO 3
mg/l as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/l as
CaC03
492
492
--
480
476
496
476
468
460
480
476
456
452
450
460
480
436
470
430
450
430
Standard
col i forms
Colonies/
100 ml
0
—
0
—
__
—
—
—
__
—
__
—
—
--
—
--
--
—
_
__
—
-------
TABLE C-2 (CONTINUED).
00
o
Date
1974 Jan
Feb
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
1975 Jan
Feb
Mar
May
Jun
Jul
Chlorides
mg/1
2,260
1,920
1,890
2,070
1,960
1,380
1,990
1,840
2,082
1,480
1,460
1,940
1,940
1,770
1,990
1,785
Conductivity
ymhos/cm2
at 25° C
7,000
6,000
6,000
7,000
6,000
4,500
5,000
5,000
5,500
5,000
4,500
5,500
5,500
5,000
5,500
5,000
Total
hardness
mg/1 as
CaC03
1,400
1,048
964
1,080
1,044
650
1,032
944
1,040
740
760
• 984
920
846
982
854
Ca
mg/1 as
CaC03
600
530
456
520
452
310
484
436
468
368
212
408
420
392
458
400
Mg
mg/T as
CaC03
800
518
408
560
592
340
548
508
572
372
548
576
500
454
524
454
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
430
460
440
440
424
460
436
436
436
448
440
404
440
432
428
416
Standard
col i forms
Colonies/
100 ml
._
—
—
—
__
—
—
—
__
—
__
—
—
—
__
—
-------
TABLE C-3. ANALYSIS OF SAMPLES TAKEN FROM FP-1
CD
Date
1971 Jul
Aim
••— j
Sep
** r
Oct
Nov
Dec
1972 Jan
Feb
Mar
Jun
SAMPLING
Oct
PUMP NOT
Dec
1973 Jan
Feb
Mar
Apr
Chlorides
mg/1
795
870
910
930
960
1,020
1,100
1,140
1,240
TAP REMOVED
1,440
RUNNING
1,350
1,350
1,380
1,380
1,540
Conductivity
umhos/cm2
at 25° C
3,450
3,500
3,600
3,800
3,500
3,800
3,800
4,000
4,000
4,500
6,000
4,500
4,000
5,000
5,000
5,500
Total
hardness
mg/1 as
CaC03
„.
469
496
512
536
560
640
616
—
728
888
860
908
904
908
1,056
Ca
mg/1 as
CaC03
« •
240
276
284
288
316
336
336
—
400
--
464
472
482
508
536
Mg
mg/1 as
CaC03
• •—
229
220
228
248
244
304
280
—
328
—
396
432
422
400
520
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
__
468
464
510
504
512
492
488
— -
468
—
464
452
498
444
416
Standard
coli forms
Colonies/
100 ml
—
—
—
3
—
0
2
""
—
—
—
-•—
— —
_*_
-------
TABLE C-3 (CONTINUED).
00
to
Chlorides
Date mg/1
1973
1974
PUMP
PUMP
May
Jun
Jul
Aug
Sep
Oct
Nov
Jan
Feb
Mar
1
1
1
1
1
1
1
,600
,600
,620
—
,670
,700
,660
__
,220
—
Conductivity
umhos/cm2
at 25° C
5
5
5
5
5
5
4
,000
,000
,000
—
,500
,500
,500
__
,500
—
Total
hardness
mg/1 as
CaC03
1,050
1,080
1,080
—
1,120
1,130
1,130
— —
520
--
Ca
mg/1 as
CaC03
540
590
560
—
600
600
580
_ _
230
—
Mg
mg/1 as
CaC03
510
490
520
—
520
530
550
__
290
—
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
430
500
450
--
--
470
430
__
330
--
Standard
coliforms
Colonies/
100 ml
.. _
—
0
48
1
5
C*
0
0
17
NOT RUNNING
May
REMOVED
1
,230
4
,000
396
140
256
0
260
—
*Confluent colonies.
-------
TABLE C-4. ANALYSIS OF SAMPLES TAKEN FROM WELL FP-3
oo
CO
Date
1971 Jul
Aug
Sep
Total
Chlorides Conductivity hardness
ymhos/cm2 mg/1 as
mg/1 at 25° C CaC03
_.
1,950
1,350
PUMPING DISCONTINUED OCT
Dec
1972 Jan
Feb
Mar
Jun
Aug
Sep
2,180
2,120
2,160
2,240
2,295
2,590
2,480
6,000
6,200
5,000
1971 -DEC 1971
6,700
6,200
6,800
6,800
7,000
8,000
8,000
„
1,240
920
1,440
1,410
1,460
—
1,630
1,844
1,980
Ca
mg/1 as
CaC03
„.
580
440
780
720
730
—
820
856
942
Mg
mg/1 as
CaC03
..
660
480
660
690
730
—
810
988
1,038
C03
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
„
415
472
424
448
436
—
440
436
420
Standard
col i forms
Colonies/
100 ml
—
--
38
9
—
0
--
__
—
PUMPING DISCONTINUED OCT 1972 DUE TO HIGH CHLORIDES-PUMP REMOVED
-------
TABLE C-5. ANALYSIS OF SAMPLES TAKEN FROM WELL FP-4
00
Date
1971 Jul
Aug
Sep
Oct
Nov
Dec
1972 Jan
Feb
Mar
Jun
Jul
Aug
Sep
Oct
Dec
1973 Jan
Feb
Mar
Apr
Chlorides
mg/1
„
985
650
— •
1,260
1,250
970
940
860
980
1,220
1,220
1,170
1,300
780
1,270
1,640
1,860
2,280
Conductivity
ymhos/cm2
at 25° C
3; 800
4,000
3,050
—
4,500
4,600
3,700
3,700
3,500
3,800
5,000
5,000
4,000
5,000
3,500
3,500
5,500
6,000
6,100
Total
hardness
mg/1 as
CaC03
_.
672
480
—
880
920
684
660
—
700
876
' 856
864
1,024
532
972
1,258
1,532
1,868
Ca
mg/1 as
CaC03
„
316
240
--
480
448
332
312
--
340
372
360
377
480
232
464
610
748
864
Mg
mg/1 as
CaC03
M •»
356
240
--
400
472
352
348
—
360
504
496
487
544
300
508
648
784
1,004
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
mm mm
490
528
—
512
520
520
520
—
516
500
512
500
492
—
__
524
452
444
Standard
col i forms
Colonies/
100 ml
mM —
—
—
0
*».
0
2
—
1
--
--
—
—
--
—
__
—
—
—
PUMP BEING REPAIRED, APR 1973-MAY 1974
-------
TABLE C-5 (CONTINUED).
CO
01
Date
1974
1975
Jun
Jul
Aug
Sep
Oct
Jan
Feb
Mar
Chlorides
mg/1
3,740
3,720
3,420
3,225
--
2,270
2,340
2,560
Conductivity
pmhos/cm2
at 25° C
10,000
10,000
10,000
8,000
—
6,000
6,000
6,000
Total
hardness
mg/1 as
CaC03
3,130
3,080
3,090
2,700
—
1,932
1,916
1,936
Ca
mg/1 as
CaC03
1,528
1,480
1,515
1,352
—
712
912
936
Mg
mg/1 as
CaC03
1,602
1 ,600
1,575
1,648
—
1,220
1,004
1,000
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
410
400
390
390
--
436
456
440
Standard
col i forms
Colonies/
100 ml
__
1
0
~ ~
0
__
0
--
PUMPING DISCONTINUED APR 1975 DUE TO HIGH CHLORIDES
-------
TABLE C-6. ANALYSIS OF SAMPLES TAKEN FROM WELL FP-7
00
01
Date
1971 Jim
Jul
Aug
Sep
Oct
Nov
Dec
1972 Jan
Feb
Mar
Jun
Jul
Aug
Sep
Oct
Dec
1973 Jan
Feb
Mar
Apr
Chlorides
mg/1
*• «•
—
470
460
480
480
470
480
470
380
470
500
530
510
520
460
350
480
450
500
Conductivity
ymhos/cm2
at 25° C
2,700
2,700
2,650
2,600
2,700
2,600
2,600
2,550
2,600
2,400
2,600
2,500
2,600
2,600
2,600
2,600
2,000
2,600
2,600
2,600
Total
hardness
mg/1 as
CaC03
__
__
362
348
348
364
360
352
344
—
360
396
372
388
388
368
408
388
936
404
Ca
mg/1 as
CaC03
__
--
164
164
196
164
168
172
188
—
172
168
168
156
164
164
184
176
192
204
Mg
mg/1 as
CaC03
__
—
198
184
152
200
192
180
156
—
188
228
204
232
224
204
224
212
744
200
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
— —
—
563
568
620
620
612
620
636
—
612
620
614
616
612
624
632
700
596
624
Standard
col i forms
Colonies/
100 ml
— _
—
--
-—
1
--
0
1
—
21
--
—
--
—
—
—
--
--
--
--
-------
TABLE C-6 (CONTINUED).
00
-3
Date
1973 May
Jun
Jul
Aug
Sep
Oct
Nov
1974 Jan
Feb
May
Jun
Jul
Aug
Sep
Oct
1975 Jan
Feb
Mar
Jun
Chlorides
mg/1
500
500
540
480
490
490
480
510
540
550
580
560
590
710
—
620
600
610
608
Conductivity
ytnhos/cm2
at 25° C
2,600
2,400
2,400
2,600
2,800
2,600
2,440
2,440
2,800
2,800
2,600
2,700
2,600
2,400
—
2,600
2,600
2,500
2,600
Total
hardness
mg/1 as
CaC03
420
400
430
430
380
420
392
416
416
448
418
416
—
500
—
488
476
440
481
Ca
mg/1 as
CaC03
230
200
190
190
200
200
200
192
196
212
194
200
--
200
--
240
216
192
229
Mg
mg/1 as
CaC03
190
200
240
240
180
220
192
224
220
236
224
216
--
300
—
248
260
248
252
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
600
590
600
580
580
590
580
580
580
572
578
572
--
578
—
572
596
604
580
Standard
col i forms
Colonies/
100 ml
_ _
—
0
0
4
0
2
0
0
1
2
54
2
--
6
__
5
—
—
Jul
0
-------
TABLE C-7. ANALYSIS OF SAMPLES TAKEN FROM WELL FP-9
00
00
Date
1971 Jul
Aug
Sep
Oct
Nov
Dec
1972 Jan
Feb
Mar
Jun
Jul
Aug
Sep
Oct
Dec
1973 Jan
Feb
Mar
Apr
May
Jun
Chlorides
mg/1
• •»
305
270
360
290
340
330
330
305
310
300
330
350
320
370
340
330
330
380
360
360
Conductivity
ymhos/cm2
at 25° C
2,200
2,150
1,800
2,350
1,950
2,050
1,920
2,100
1,900
2,000
1,900
2,000
2,000
2,000
2,200
2,000
2,200
2,200
2,100
2,200
2,000
Total
hardness
mg/1 as
CaC03
• «•
420
340
484
400
384
400
400
--
368
372
388
.400
420
452
492
440
432
460
460
460
Ca
mg/1 as
CaC03
— —
170
160
232
188
168
180
204
—
168
176
168
120
160
196
188
206
200
208
220
260
Mg
mg/1 as
CaC03
«i ••
250
180
252
212
216
220
196
-_
200
196
220
280
260
256
304
234
232
252
240
200
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
..
586
520
710
628
612
620
604
—
616
612
628
636
640
692
__
810
652
672
630
650
Standard
coli forms
Colonies/
100 ml
--
—
—
__
—
_.
—
--
—
• •
—
—
—
0
0
—
2
—
__
—
-------
TABLE C-7 (CONTINUED).
Chlorides
Date mg/1
1973
Jul
Aug
Sep
Oct
PIPELINE BEING
1974
Jan
Feb
Mar
May
Jun
Jul
Aug
Sep
340
370
370
—
Conductivity
ymhos/cm2
at 25° C
2,000
2,200
2,200
--
Total
hardness
mg/1 as
CaC03
420
480
470
—
Ca
mg/1 as
CaC03
230
220
240
—
Mg
mg/1 as
CaC03
190
260
230
—
CO 3
mg/1 as
CaC03
0
0
0
0
HC03
mg/1 as
CaC03
610
640
650
--
Standard
coli forms
Colonies/
100 ml
77
0
0
6
REPAIRED-PUMP OFF
300
300
—
310
310
300
330
340
1,800
1,900
--
2,000
1,900
2,000
1,900
1,900
408
392
—
372
358
324
408
388
168
172
—
180
162
160
180
180
240
220
—
192
196
164
228
208
0
0
0
0
0
0
0
0
576
568
--
—
560
556
584
596
0
0
0
0
0
0
7
—
Oct
PUMPING DISCONTINUED OCT 1974-JAN 1975
0
1975
Jan
Feb
Mar
300
310
330
1,700
1,900
1,800
368
380
376
180
172
172
188
208
204
0
0
0
496
544
568
0
0
-------
TABLE C-8. ANALYSIS OF SAMPLES TAKEN FROM WELL F-l
to
o
Date
1971 Jul
Aug
Sep
Oct
Nov
Dec
1972 Jan
Feb
Jul
Aug
Sep
Oct
Nov
Dec
1973 Jan
Feb
Mar
Chlorides
mg/1
._
99
110
110
110
130
130
130
100
110
100
100
120
100
100
no
100
Conductivity
ymhos/cm2
at 25° C
730
900
900
950
920
1,000
920
1,000
800
800
800
900
800
750
650
850
850
Total
hardness
mg/1 as
CaC03
..
371
388
384
400
400
420
434
372
368
364
340
368
400
376
364
368
Ca
mg/1 as
CaC03
„
168
208
212
218
220
216
224
184
184
192
184
152
188
184
190
192
Mg
mg/1 as
CaC03
„.
203
180
172
182
180
204
210
188
184
172
156
216
212
192
174
174
C03
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
„.
328
338
--
364
364
368
384
348
352
348
—
--
—
H_
358
316
Standard
coliforms
Colonies/
100 ml
„
—
—
--
_ _
—
__
—
—
—
—
—
—
—
__
--
—
SAMPLING TAP REMOVED APR 1973
-------
TABLE C-9. ANALYSIS OF SAMPLES TAKEN FROM WELL F-2
CO
Date
1972 Feb
Jul
Aug
Sep
Oct
Nov
Dec
1973 Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
1974 Jan
Feb
Chlorides
mg/1
105
no
130
100
110
120
no
140
90
no
180
120
100
100
no
no
no
100
no
no
100
Conductivity
ymhos/cm2
at 25° C
850
850
850
900
800
900
900
850
950
900
900
900
850
875
950
1,000
950
1,000
1,000
900
950
Total
hardness
mg/1 as
CaC03
312
308
320
332
368
340
344
380
312
320
332
340
344
352
344
356
356
376
288
320
336
Ca
mg/1 as
CaC03
164
160
168
172
180
132
208
204
190
118
196
208
200
196
208
212
220
228
228
204
204
Mg
mg/1 as
CaC03
148
148
152
160
188
208
136
176
122
202
136
132
144
156
136
144
136
148
60
116
132
CO 3
mg/1 as
CaC03
0
0
0
0
20
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0 •
HC03
mg/1 as
CaC03
368
364
372
384
348
400
382
388
414
352
364
356
368
460
364
368
368
380
384
384
364
Standard
col i forms
Colonies/
100 ml
_.
—
--
—
—
—
—
__
—
—
—
—
—
—
—
—
—
—
—
__
—
-------
TABLE C-9 (CONTINUED).
to
10
Date
1974
1975
May
Jun
Jul
Aug
Sep
Oct
Nov
Jan
Feb
Mar
May
Jun
Jul
Chlorides
mg/1
90
90
100
no
105
116
140
230
170
160
150
160
152
Conductivity
ymhos/cm2
at 25° C
900
900
950
950
1,000
900
1,000
1,050
1,050
1,000
1,050
1,000
950
Total
hardness
mg/1 as
CaC03
352,
318
320
424
356
372
452
456
412
376
376
396
396
Ca
mg/1 as
CaC03
244
152
204
196
200
220
224
256
200
220
229
232
229
Mg
mg/1 as
CaC03
208
166
116
228
156
152
228
200
212
156
147
164
167
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
368
380
368
372
372
388
420
376
388
372
360
372
374
Standard
coli forms
Colonies/
100 ml
_ _
--
__
—
—
--
—
__
—
—
—
__
—
-------
TABLE C-10. ANALYSIS OF SAMPLES TAKEN FROM WELL GG-6
CO
CO
Date
1971 Jul
Aug
Sep
Oct
Nov
Dec
1972 Jan
Feb
Jun
Jul
Aug
Sep
Oct
Nov
Dec
1973 Jan
Apr
May
Chlorides
mg/1
„
290
260
310
320
330
330
310
330
300
300
310
330
310
300
330
400
400
Conductivity
^mhos/cm2
at 25° C
2,200
2,200
1,750
2,200
2,200
2,200
2,100
1,800
2,100
2,000
2,000
2,000
2,000
2,000
2,000
2,000
2,200
2,200
Total
hardness
mg/1 as
CaC03
„
402
324
396
404
400
400
388
432
404
408
404
392
392
380
332
468
480
Ca
mg/1 as
CaC03
._
198
164
192
208
192
192
176
196
172
173
160
164
156
80
160
200
220
Mg
mg/1 as
CaC03
„
204
160
204
196
208
208
212
236
232
235
244
228
236
300
172
268
260
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
..
596
480
685
652
692
688
660
644
648
644
648
620
612
640
632
660
670
Standard
coli forms
Colonies/
100 ml
—
--
—
__
—
__
—
--
—
__
—
--
—
--
__
—
—
WELL DRY, JUN 1973-DEC 1974
-------
TABLE C-10 (CONTINUED).
Date
1975
Jan
Feb
Mar
Chlorides
mg/1
700
650
570
Conductivity
ymhos/cm2
at 25° C
3,000
3,000
2,000
Total
hardness
mg/1 as
CaC03
992
920
692
Ca
rng/1 as
CaC03
360
384
248
Mg
mg/1 as
CaC03
632
536
444
CO 3
mg/1 as
CaC03
0
0
0
HC03
mg/1 as
CaC03
464
476
512
Standard
col i forms
Colonies/
100 ml
« V
—
—
ENTRANCE TO WELL SEALED UP, SAMPLING IMPOSSIBLE
to
*>.
-------
TABLE C-ll. ANALYSIS OF SAMPLES TAKEN FROM WELL MB-4
Date
1971 June
Aug
Sep
Nov
Dec
1972 Jan
Feb
Mar
Jun
Jul
Aug
Sep
Oct
1973 Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Chlorides
mg/1
__
640
1,040
670
670
1,050
1,060
920
680
920
680
770
730
710
750
1,140
1,440
1,200
1,240
1,540
1,270
Conductivity
umhos/cm2
at 25° C
3,400
3,050
4,500
3,200
3,200
4,200
4,200
3,900
3,300
4,000
3,000
3,500
3,000
3,500
3,500
4,900
5,000
4,250
5,000
5,500
5,000
Total
hardness
mg/T as
CaC03
._
356
514
372
368
560
516
—
364
472
360
396
396
420
432
600
700
610
640
776
650
Ca
mg/1 as
CaC03
„
168
228
180
168
228
220
--
172
196
160
156
160
198
200
276
290
300
280
336
340
Mg
mg/1 as
CaC03
„
188
186
182
200
332
296
—
192
276
200
240
236
222
232
324
410
310
360
440
310
CO 3
mg/1 as
CaC03
0
0
0
0
0
12
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
„
524
524
548
528
548
540
—
552
552
544
540
544
610
524
528
510
530
530
508
510
Standard
col i forms
Colonies/
100 ml
„
—
—
--
—
__
—
—
--
—
--
--
—
—
—
—
— —
_-
0
1
>100
-------
TABLE C-ll (CONTINUED).
to
o>
Date
1973
1974
1975
Oct
Nov
Dec
Jan
Feb
Mar
May
Jun
Jul
Aug*
Sep
Oct
Nov
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Chlorides
mg/1
1,330
1,500
1,350
990
1,200
—
1,450
1,120
1,220
600
670
1,410
1,020
1,340
1,240
1,400
—
1,310
1,280
1,005
•. •_
Conductivity
vimhos/cm2
at 25° C
5,000
5,500
5,500
4,000
.5,000
—
6,000
4,000
4,500
2,800
2,600
4,500
4,000
4,500
4,500
4,500
—
4,500
4,500
3,750
™*~
Total
hardness
mg/1 as
CaC03
690
748
680
524
650
—
700
578
610
404
452
708
532
664
584
600
--
621
621
513
— «•
Ca
mg/1 as
CaC03
280
324
288
240
280
--
304
224
250
172
168
296
228
260
256
284
—
256
261
217
~~
Mg
mg/1 as
CaC03
410
424
392
284
370
—
396
354
360
232
284
412
304
404
328
352
—
365
360
296
*~ ~
C03
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
510
500
516
524
520
—
500
522
520
528
516
514
448
500
516
520
--
432
512
517
~ ~
Standard
col i forms
Colonies/
100 ml
0
4
0
1
9
0
1
0
0
0
0
0
--
--
—
8
0
—
0
—
0
*Water contaminated with some type of petroleum product that smells like kerosene, Aug 1974-Jul 1975,
-------
TABLE C-12. ANALYSIS OF SAMPLES TAKEN FROM WELL MB-5
Date
1971 Nov
Dec
1972 Jan
Feb
Mar
PUMP BROKEN
1974 May
Jun
Jul
Aug
Sep
Oct
Nov
1975 Mar
May
Jun
Jul
Chlorides Conductivity
ymhos/cm2
mg/1 at 25° C
710
710
710
710
740
APR 1972-APR
690
690
700
680
610
748
730
760
760
--
742
3,200
3,400
3,400
3,200
3,400
1974
3,500
3,000
3,000
2,800
2,800
2,800
3,000
2,800
2,800
—
3,000
Total
hardness
mg/1 as
CaC03
340
328
340
348
—
364
320
328
346
292
372
376
340
361
—
384
Ca
mg/1 as
CaC03
168
156
168
164
—
172
152
164
144
168
164
196
168
166
--
186
Mg
mg/1 as
CaC03
172
172
172
184
—
192
168
164
202
124
208
180
172
195
__
198
C03
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
560
530
552
528
—
524
550
524
516
510
520
524
540
508
• —
513
Standard
col i forms
Colonies/
100 ml
—
__
--
—
0
--
0
—
0
—
--
—
—
21
—
-------
TABLE C-13. ANALYSIS OF SAMPLES TAKEN FROM WELL MB-29
CO
00
Date
1971
1972
1973
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Jun
Jul
Oct
Nov
Dec
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Chlorides
mg/1
920
890
960
930
970
1,000
1,080
1,000
940
980
890
1,130
980
950
990
1,060
1,040
1,040
1,060
1,020
1,450
Conductivity
ytnhos/cm2
at 25° C
4,000
4,000
4,000
4,000
3,700
4,000
4,500
4,000
4,000
4,000
4,000
4,000
4,000
4,000
4,000
4,000
4,000
3,750
4,000
4,000
4,500
Total
hardness
mg/1 as
CaC03
372
376
384
384
388
400
432
—
356
400
368
436
408
396
400
428
430
430
440
440
440
Ca
mg/1 as
CaC03
164
164
176
172
168
192
172
--
164
152
140
160
148
180
180
184
190
210
230
192
210
Mg
mg/1 as
CaC03
208
212
208
212
220
208
260
—
192
248
228
276
260
216
220
244
240
220
210
248
230
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
532
532
570
564
560
542
568
--
536
568
580
572
568
—
528
544
530
540
540
524
520
Standard
col i forms
Colonies/
100 ml
__
--
--
--
--
__
--
--
--
__
--
—
—
—
--
—
--
__
0
4
--
-------
TABLE C-13 (CONTINUED).
CO
co
Date
1973
1974
Oct
Nov
Dec
Jan
Feb
May
Jun
Jul
Chlorides
mg/1
1,030
1,060
1,090
1,080
1,060
1,090
1,100
__
Conductivity
iamhos/cm2
at 25° C
4,000
4,000
5,000
4,000
4,500
4,500
4,000
__
Total
hardness
mg/1 as
CaC03
440
450
448
500
412
404
366
• __
Ca
mg/1 as
CaC03
230
240
208
220
188
188
140
__
Mg
mg/1 as
CaC03
210
210
240
280
224
216
226
__
CO 3
mg/1 as
' CaC03
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
540
540
532
550
512
536
494
_ _
Standard
col i forms
Colonies/
100 ml
90
0
0
3
1
—
>100
>100
-------
TABLE D-l. ANALYSIS OF STREAM SAMPLES TAKEN FROM RIVER GUT-CENTERLINE ROAD STATION
Date
1971 Jul
Aug
Sep
Oct
Nov
to Dec
0
o
1972 Jan
Feb
Mar
Jul
Aug
NO NATURAL FLOW
1974 Nov
1975 Jan
Feb
Chlorides Conductivity
ymhos/cm2
mg/1 at 25° C
145
80
90
100
140
150
170
120
160
180
IN RIVER
100
200
180
1
1
1
1
1
1
1
,250
,300
700
680
930
,100
,090
,150
980
,300
,300
GUT AT THIS STATION
1
1
580
,300
,300
Total
hardness Ca
mg/1 as mg/1 as
CaC03 CaC03
_.
386
236
224
272
312
320
316
—
360
356
SEPT 1972-OCT
248
484
440
« •
156
112
112
140
140
152
142
—
152
140
1974
172
236
232
Mg
mg/1 as
CaC03
— —
230
124
112
132
172
168
174
—
208
216
76
248
208
C03
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
« •>
558
244
270
384
424
448
444
__
516
532
188
484
520
ja
•o
-o
m
0
»— *
X
i
5
5
o
-------
TABLE D-2. ANALYSIS OF STREAM SAMPLES TAKEN FROM RIVER GUT-FOUNTAIN STATION
to
Date
1971
1972
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Mar
NO NATURAL FLOW
1974
1975
Nov
Jan
Feb
Mar
May
Chlorides
mg/1
„
125
150
130
100
130
55
60
IN RIVER
120
130
140
170
200
Conductivity
ymhos/cm2
at 25° C
980
950
980
900
800
1,000
580
650
GUT AT THIS STATION
650
800
850
950
1,000
Total
hardness Ca
mg/1 as mg/1 as
CaC03 CaC03
„
450
448
400
332
400
276
—
APRIL
272
444
440
424
508
• M
228
280
224
178
220
176
—
1972-OCT 1974
160
248
236
224
283
Mg
mg/1 as
CaC03
.„
222
168
176
154
180
100
—
112
196
204
200
225
C03
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
.„
428
348
358
352
364
304
--
180
308
304
300
316
Jun 210 1,000 523 287 236 0 336
-------
TABLE D-3. ANALYSIS OF STREAM SAMPLES TAKEN FROM RIVER GUT-GOLDEN GROVE STATION
to
0
DO
Date
1971 Jul
Sep
Oct
Nov
Dec
1972 Jan
Feb
Mar
Chlorides
mg/1
..
220
95
150
220
230
240
180
Conductivity
pmhos/cm2
at 25° C
1,700
1,450
740
1,220
1,400
1,500
1,600
1,280
Total
hardness
mg/1 as
CaC03
340
232
320
376
380
380
—
Ca
mg/1 as
CaC03
132
112
156
180
176
168
—
Mg
mg/1 as
CaC03
208
120
164
196
204
212
—
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
-
HC03
mg/1 as
CaC03
472
272
440
544
_-.
544
--
NO FLOW IN RIVER GUT AT THIS STATION FROM APR 1972-OCT 1974
-------
TABLE D-4. ANALYSIS OF STREAM SAMPLES TAKEN FROM RIVER GUT-HOLY CROSS STATION
to
o
CO
Date
1971
1972
NO
1974
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
NATURAL FLOW
Nov
1975 Jan
Feb
Mar
May
Chlorides Conductivity
vimhos/cm2
mg/1 at 25° C
180
170
95
90
110
150
165
no
IN RIVER
100
170
150
150
200
1
1
1
1
,400
,250
750
900
950
,120
,200
950
GUT AT THIS STATION
1
1
1
1
650
,100
,100
,000
,300
Total
hardness
mg/1 as
CaC03
437
404
248
284
316
356
376
—
FROM APR
268
476
416
392
489
Ca Mg
mg/1 as mg/1 as
CaC03 CaC03
208
208
124
160
156
180
180
—
1972-OCT 1974
136
216
188
188
245
229
196
124
124
160
176
186
—
132
260
228
204
244
C03
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
597
436
300
364
376
436
444
—
200
404
380
380
508
Jun 220 1,400 528 242 286 0 532
-------
TABLE D-5. ANALYSIS OF STREAM SAMPLES TAKEN FROM RIVER GUT-RIVER STATION
to
1971
Date
Jul
Aug
Sep
Oct
Nov
Dec
1972 Jan
NO
1974
1975
Feb
Mar
Jul
Aug
NATURAL FLOW
Nov
Jan
Feb
Mar
May
Jun
Jul
Chlorides Conductivity
umhos/cm2
mg/1 at 25° C
• ••
85
90
60
50
70
80
100
75
70
90
IN RIVER
80
190
130
150
150
150
152
980
920
700
500
560
660
750
770
640
500
850
GUT AT THIS STATION
480
800
800
900
1,000
1,100
1,000
Total
hardness
mg/1 as
CaC03
„'
339
272
180
220
236
288
284
-_
312
320
FROM SEPT
212
368
372
384
423
433
442
Ca Mg
mg/1 as mg/1 as
CaC03 CaC03
156
124
92
108
120
152
144
—
144
152
1972-OCT 1974
108
192
180
176
198
221
225
183
148
88
112
116
136
140
—
168
168
104
176
196
208
225
212
217
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
..
464
280
198
252
268
332
316
— -
404
408
152
324
316
320
396
420
433
-------
TABLE D-6. ANALYSIS OF STREAM SAMPLES TAKEN FROM RIVER GUT-USGS STATION
to
o
en
Date
1971 Aug
Sep
Oct
Nov
Dec
1972 Jan
Feb
Mar
Apr
Jun
Jul
Chlorides
mg/1
255
140
105
130
210
200
225
170
250
190
310
Conductivity
ymhos/cm2
at 25° C
1,800
960
750
1,100
1,550
1,400
1,500
1,270
1,800
1,600
2,000
Total
hardness
mg/1 as
CaC03
394
284
240
300
376
364
348
—
400
336
400
Ca
mg/1 as
CaC03
172
152
108
152
164
180
160
—
160
152
128
Mg
mg/1 as
CaC03
222
132
132
148
202
184
188
—
240
184
272
CO 3
mg/1 as
CaC03
0
0
0
0
0
0
0
0
0
0
0
HC03
mg/1 as
CaC03
672
300
287
408
516
516
536
—
668
580
648
NO NATURAL FLOW IN RIVER GUT AT THIS STATION FROM AUG 1972-OCT 1974
-------
TABLE E-1. OPERATING DATA FOR THE AWWTP, JANUARY-OCTOBER, 1974
to
o
Time
Period
1974
Jan-Feb
1974
Mar-Apr
1974
May-Jun
1974
Jul-Aug
1974
Sep-Oct
1974
Jan-Oct
Range
Upper
Lower
Mean
StdDev
Range
Upper
Lower
Mean
Std Dev
Range
Upper
Lower
Mean
Std Dev
Range
Upper
Lower
Mean
Std Dev
Range
Upper
Lower
Mean
Std Dev
Mean
BOD
mgft
79
56
68
9
-
-
-
-
184
56
118
49
289
56
140
27
143
19
107
26
113
COD
mg/l
280
102
194
46
203
128
168
27
296
158
219
46
259
96
215
53
370
63
209
76
206
N09-N
mg
0.8
0.2
0.4
0.3
1.4
0.3
0.6
0.5
2.7
0.1
0.6
0.9
0.3
0.1
0.2
0.1
1.0
0.3
0.6
0.4
0.6
NH3-N
25.5
10.5
17.8
5.5
27.5
11.6
19-5
6.5
34.5
15.0
24.9
6.3
30.5
14.0
25.3
9.1
44.5
8.0
22.7
12.4
22.6
Influent Data
Total Chlorides
P
12.0
6.8
10.8
2.8
18.7
9
12.6
4.2
41.0
10.9
19.5
12.1
12.6
7.6
10.3
2.0
11.8
3.0
8.0
3.0
12.3
500
340
409
48
480
420
449
24
680
430
486
67
790
300
480
119
980
301
453
153
456
Conductivity
2,000
1,500
1,763
48
2,000
1,500
1,775
206
2,500
1,400
1,990
355
2,600
1,300
1,817
358
2,800
1,200
1,677
320
1,778
Total
Hardness
274
168
220
35
296
240
261
26
360
180
283
61
416
260
318
59
808
248
348
177
289
Ca
100
56
83
13
112
96
105
8
160
88
120
25
152
100
125
19
232
96
133
41
114
Mg
180
92
137
28
184
132
156
24
208
80
163
42
264
152
193
42
576
116
204
142
172
C03
0
0
0
-
0
0
0
-
0
0
0
--
0
0
0
-
0
0
0
-
0
HC03
428
316
355
37
372
316
344
26
356
264
321
38
356
248
312
39
336
164
274
51
318
pH
--
-
-
—
7.7
7.2
7.4
0.2
8.1
7.2
7.6
0.4
7.6
7.2
7.4
0.1
7.8
6.8
7.3
0.2
7.4
3>
-o
-o
m
o
»— i
X
1
•o
3>
;g
m
-------
TABLE E-2. OPERATING DATA FOR THE AWWTP, JANUARY-OCTOBER, 1974
Time
Period
1974 Range
Jan-Feb Upper
Lower
Mean
Std Dev
1974 Range
Mar-Apr Upper
Lower
Mean
Std Dev
0 1974 Range
"^ May-Jun Upper
Lower
Mean
Std Dev
1974 Range
Jul-Aug Upper
Lower
Mean
Std Dev
1974 Range
Sep-Oct Upper
Lower
Mean
Std Dev
BOD
mg/l
10
2
5
4
-
-
-
-
11
2
6
4
25
6
14
7
32
11
22
8
COD
mg/»
43
5
26
11
76
20
39
19
64
7
25
13
53
18
37
10
48
4
31
13
NO3-N
mg/l
24
4.8
12.6
8.5
16.8
1.5
9.0
6.3
19.8
6.5
12.1
4.3
21.6
9.6
16.7
5.0
20.2
0.1
11.8
9.0
NH3-N
mg/l
6.5
2.0
3.6
1.8
6.0
1.5
3.4
1.9
18.0
1.5
9.3
7.0
18.0
3.5
9.6
5.7
16.5
<0.1
6.2
5.3
Effluent Data
Total CO3
P mg/l as
mg/l CaCO3
9.4
0.7
5.2
4.3
12.2
7.9
9.8
1.8
11.0
5.1
8.8
2.3
10 J
4.6
6.7
2.0
6.4
1.1
4.7
1.7
0
0
0
-
0
0
0
-
0
0
0
-
0
0
0
-
0
0
0
_
HC03
mg/l as
CaC03
236
136
199
33
220
152
181
31
140
40
92
33
72
44
53
10
260
40
95
69
PH
7.2
7.2
7.2
7.2
7.3
6.5
6.8
0.2
7.7
6.7
7.0
0.3
6.8
6.4
6.5
0.1
7.2
5.7
6.6
0.4
Turbidity
FTU
5
0.6
1.5
0.9
1.8
0.1
1.3
0.5
3.0
0.4
1.4
0.6
1.5
0.8
1.0
0.3
3.0
1.0
1.4
0.5
Aeration Tank
MLSS SVI
mg/l mg/l
1,980
300
922
482
1,620
545
962
328
4,630
395
1,707
780
3,850
490
1,638
951
2,190
760
1,334
326
404
55
104
68
250
39
84
54
337
31
81
56
96
22
64
15
62
27
46
9
AWWTP
Electric
Power
kwh
27,120
62,1 60
69,720
62,400
60,960
1974
jan-Oct
Mean
12
31
12.9
6.8
9.0
123
6.7
1.3
1,351
75
28,236*
^Average kwh/month.
-------
APPENDIX - PART F
QW Well-graded gravels, gravel-sand mixtures,
little or no fines.
GM Silty gravels, poorly graded gravel • sand
silt mixtures.
GC Clayey gravels, poorly graded gravel • sand-
clay mixtures.
SW Well-graded sands, gravelly sands, little or
no fines.
DESCRIPTION
SM Silty sands, poorly graded sand-silt mixtures.
SC Clayey sands, poorly graded sand-clay mixtures.
ML Inorganic silts and very fine sands, rock flour, silly,
or clayey fine sands with slight plasticity.
CL Inorganic clays of low-to-medium plasticity, gravelly
clays, sandy clays, silty clays, lean clays.
Poorly graded sands, gravelly sands, little or
no fines.
CH Inorganic clays of nigh plasticity, fat clays.
^ SURVEY MONUMENT
100 200 300 400 500
Figure F-1. Soil boring locations in Golden Grove.
208
-------
^ , STRUCK WATER
DURING BORING
UNIFIED SOIL CLASSIFICATION SYSTEM USED
Figure F-1. (Extended)
209
-------
APPENDIX - PART G
__ 'L'J f,'_ _Jfc^nki^~ .—fc-^-J—*-****^^**""*"™^
JAN I FEB I MAR I APR I MAY I JUN I JUL I AUG I SEP I OCT I NOV I DEC
Figure G-1. Water levels in well A 15,1971-1972.
210
-------
MAR ' APR ' MAY ' JUN ' JUL AUG SEP ' OCT ' NOV ' DEC
JAN ' FEB ' MAR ' APR ' MAY ' JUN ' JUL ' AUQ
TIME
Figure G-2. Water levels in well A-15,1973-1974.
211
-------
§
£
LLJ
73
71
69
67
65
63
61
"
57
TOP OF CONCRETE
PUMP BASE-EL. 86,4
JAN ' FEB MAR ' APR MAY ' JUN ' JUL ' AUG ' SEP ' OCT ' NOV ' DEC
6
u.
z
3<
cc
Figure G-3. Water levels in well A-15, 1975.
212
-------
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62
UO
!,B
>54
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>50
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or
LU
4H
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44
40
(U.
258
TOP OF CONCRETE
PUMP BASE - EL. 77.2
A-18
1971
Jfe
JAN FEB MAR APR MAY
JUN JUL AUG
1
SEP OCT
1
NOV
DEC
<
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cc
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111
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TIME
Figure G-4. Water levels in well A-18.1971-1972.
c
• —
Z
<
a;
213
-------
62
60
Z 58
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LU 54
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52
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£ 48
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44
42
40
A-18
1973
TOP OF CONCRETE
PUMP BASE -EL. 77 2
1
JAN
FEB MAR APR 'MAY JUN JUL
AUG
SEP OCT
NOV
DEC
4_,
_i
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LL
3?
CC
2
JAN
FEB ' MAR APR MAY JUN JUL ' AUG ' SEP ' OCT T NOV DEC
TIME
Figure G-5. Water levels in well A-18, 1973-1974.
214
-------
62
60
|58
256
$«
111
w 52
£ 50
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J3_
J
1
4<
<
30:
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JAN ' FEB MAR ' APR MAY JUN JUL AUG SEP OCT NOV DEC
TIME
Figure G 6. Water levels in well A 18, 1975.
215
-------
88
86
§84
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I 82
> 80
HI
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TOP OF CONCRETE
PUMP BASE- EL. 88.0
LU
>
LU
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76
74
72
70
66
A-19
1971
Ufa m -JL
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JAN
FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
TIME
Figure G-7. Water levels in well A-19,1971.
216
-------
14
12
£10
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5 6
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LU
OC
LU
H
JAN
14
12
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1971
TOP OF CASING - EL. 30.6
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FP-2
1972
6
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TIME
Figure G-8. Water levels in well FP-2,1971-1972.
217
-------
14
1?
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5
TOP OF CASING - EL. 30.6
FP-2
1973
6
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14
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$6
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LU 4
LU
_l
cc.
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FEB
MAR APR MAY JUN JUL
AUG
3
SEP OCT
NOV
DEC
FP-2
1974
JL
LJ_
z
3 <
CC
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT
TIME
Figure G-9. Water levels in well FP-2,1973-1974.
NOV
DEC
218
-------
14
12
«10
Z
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jl 8
> 6
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j
6
5
c
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A -J
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li.
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3 <
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2
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TIME
Figure G-10. Water levels in well FP-2, 1975.
219
-------
z
o
48
46
44
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38
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28
26
48
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242
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JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
3<
JQC
GG-3
1973
LJL
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
TIME
Figure G 11. Water levels in well GG-3, 1972-1973.
6
LL
Z
220
-------
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
48
46
44
> 40
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U 38
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LU
34
30
28
26
•11
JAN
11
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TIME
Figure G-12. Water levels in well GG-3. 1974-1975.
221
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50
48
4d
£ "
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O 4?
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1974
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36
34
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TIME
Figure G 13. Water levels in well GG-4, 1974-1975.
LL
z
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222
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46
44
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Figure G-14. Water levels in well GG-5, 1971-1972.
OCT ' NOV ' DEC
3<
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223
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46
£.44
2
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1973
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Figure G 15. Water levels in well GG-5,1973-1974.
224
-------
48
46
£ 44
0 42
> 40
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36
34
30
26
TOP OF CONCRETE BASE - EL 53.8
GG-5
1975
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TIME
Figure G-16. Water levels in well GG-5,1975.
Z
3<
225
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18
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LLJ
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53 6
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1971
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1972
I
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
TIME
Figure G-17. Water levels in well GG-7,1971-1972.
4<
LL
2
32
226
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Z
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< 12
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1973
4_J
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JAN
FEB MAR APR MAY JUN JUL AUG
SEP OCT NOV DEC
JAN ' FEB ' MAR' APR ' MAY ' JUN ' JUL AUG SEP OCT NOV DEC
TIME
Figure G-18 Water levels in well GG-7,1973-1974.
227
-------
18
£16
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TIME
Figure G 19. Water levels in well GG-7,1975.
228
-------
48
46
§ 44
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O42
^40
ill
jjj38
•
LU36
LLJ
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TIME
Figure G-20. Water levels in well GG-13,1973-1974.
229
-------
48
46
*-. 44
Z
2 42
UJ
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DC
LU
5
36
34
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28
26-
TOP OF CASING-EL. 87
J3_
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LL
-r
NOV ' DEC
JAN
FEB T MAR I APR ' MAY I JUN ' JUL ' AUG ' SEP
TIME
Figure G-21. Water levels in well GG-13, 1975.
230
-------
FEB ' MAR ' APR MAY ' JUN ' JUL ' AUG
18
16
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ill 8
> 6
LU
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CE
LU
NB-3
1975
6
PUMP INSTALLED
JAN. 1976
3<
DC
EL
JAN I FEB I MAR ' APR ' MAY ' JUN T JUL
TIME
Figure G 22. Water levels in welt NB-3, 1974-1975.
SEP ' OCT ' NOV ' DEC
231
-------
38
36
§34
Z
O 32
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LU
DJ 28
•
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PW-1
1973
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1974
PUMC INSTALLED
JUN. 1974.
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JAN ' FEB ' MAR APR MAY ' JUN ' JUL AUG SEP OCT NOV ' DEC
TIME
Figure G 23. Water levels in well PW-1,1973-1974. .
<
LL.
z
3 <
CC
232
-------
38
36
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5
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MARn APR ' MAY ' JUN ' JUL ' AUG ' SEP OCT
TIME
Figure G 24. Water levels in well PW-3, 1973-1974.
233
-------
38
36
£ 34
Z
2 32
I-
> 30
LLJ
UJ 28
LU
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3 20-
18
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TOP OF CASING - EL. 80.5
PW-3
1975
6
JL
z
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JAN ' FEB ' MAR ' APR MAY ' JUN ' JUL
TIME
Figure G-25. Water levels in well PW-3, 1975.
AUG ' SEP ' OCT ' NOV ' DEC
234
-------
38
36
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Z
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< 30
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01
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TIME
Figure G 26. Water levels in well PW-5,1973-1974.
235
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LU
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1
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TIME
Figure G-27. Water levels in well PW-5, 1975.
SEP ' OCT ' NOV ' DEC
z
3<
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236
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TIME
Figure G-28. Water levels in well PW-6, 1973-1974.
DEC
237
-------
£
O
38
36
32
TOP OF CASINO- ei.51.0
PW-6
1975
UJ
£26
DC 24
UJ
< 22
20
18
16
JAN ' FEB ' MAR ' APR MAY ' JUN ' JUL
TIME
Figure G-29. Water levels in well PW-6, 1975.
AUG SEP ' OCT ' NOV ' DEC
238
-------
43
41
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237
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111
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TIME
Figure G-30. Water levels in well PW-7,1973-1974.
239
-------
43
41
£ 39
Z
O 37
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1975
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Figure G-32. Water levels in well PW-8, 1973-1974.
241
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JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV
TIME
Figure G-33. Water levels in well PW-8,1975.
DEC
242
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-------
APPENDIX - PART H
TABLE H-l. ENGLISH-TO-METRIC CONVERSION
English unit
acre
acre-ft
cu ft
ft
gal
gal
gpd/sq ft
gpm
hp
in.
Ib
mgd
mile
sq ft
sq in.
sq miles
Multiplier
0.405
1,233.5
0.028
0.3048
0.003785
3.785
0.0408
0.0631
0.7457
2.54
0.454
3,785
1.61
0.0929
6.452
2.590
Metric unit
ha
cu m
cu m
m
cu m
1
cu m/day/sq m
I/sec
kw
cm
kg
cu m/day
km
sq m
sq cm
sq km
244
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-76-134
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
WASTEWATER RECLAMATION PROJECT,
ST. CROIX, U.S. VIRGIN ISLANDS
5. REPORT DATE
June 1976 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Oscar Krisen Buros
8. PERFORMING ORGANIZATION REPORT NO,
540-70-83
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Black, Crow and Eidsness, Inc.
7201 NW llth Place
Gainesville, Florida 32602
1O. PROGRAM ELEMENT NO.
WRD/1BC611
11. CONTRACT/GRANT NO.
11010 GAK
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES
16. ABSTRACT
St. Croix is a subtropical semiarid island in the Territory of the U.S. Virgin
Islands. The expanding population and rising standard of living have resulted in a
level of potable water consumption above the available supply of surface and ground-
water. Seawater desalinization plants are currently being used to produce the
needed water. The cost of this desalinized water ranges up to $7/thousand gal
($1.84/cu m).
Since 1971 work has been proceeding on a project to use tertiary-treated waste-
water effluent for artificial recharge of the groundwater on St. Croix. A 0.5 mgd
(1,890 cu m/day) advanced wastewater treatment plant and recharge facilities were
designed and constructed. Background data on water quality and quantity in the
surrounding area were collected for 2-1/2 years before recharging began. Recharge
operations were carried out for 8 months during 1974, using both spray irrigation
and spreading basins. The best method of recharging proved to be the use of
spreading basins in an alluvial valley. The cost for the wastewater treatment,
recharge operations, and recovery of groundwater was estimated to be about $2.15/
thousand gal ($0.57/cu m) at 0.5 mgd (1,890 cu m/day) with a reduction in estimated
costs to $1.64/thousand gal ($0.43/cu m) if the operation is expanded to 1 mgd
(3,785 cu m/day).
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Waste treatment
Water reclamation
Ground water recharge
Wastewater reclamation
Artificial groundwater
recharge
Water reuse
13B
8. DISTRIBUTION STATEMENT
Release to PUblic
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
259
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
245
4USGPO: 1976 — 657-695/5443 Region 5-11
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