5-4-CS27021-27211510-Preliminary Evaluation - AISP Well 2.pdf

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2

(WS002)

August 2026

Prepared For:

DFCM

4315 S 2700 W, 3rd floor

Taylorsville, UT 84129

Prepared By:

Mitchell Stratton, PE

Reviewed By:

Robert Rousselle, PE 08/24/2026

3/31/2027

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002)

Table of Contents

Glossary of Technical Terms ........................................................................................................ i

Abbreviations and Units ............................................................................................................. iii

Executive Summary ................................................................................................................... iv

Section 1 Introduction

1.1 System Information

1.2 Source Information

1.3 Designated Person

Section 2 Delineation Report

2.1 Geologic Data

2.1.1 Topology and Lithology

2.1.2 Regional Hydrogeology

2.2 Proposed Well Construction Data

2.3 Aquifer Data

2.3.1 Hydraulic Conductivity and Transmissivity

2.3.2 Aquifer Thickness

2.3.3 Groundwater Flow

2.3.4 Well Diameter

2.3.5 Porosity

2.3.6 Ambient Flow

2.4 Hydrogeologic Methods Used to Delineate DWSP Zones

2.4.1 Input Parameters of WhAEM

2.5 Wellhead Protection Zones

2.6 Aquifer Classification Status

Section 3 Inventory of Potential Contamination Sources

3.1 Potential Contaminant Sources (PCS)

3.2 Hazard Identification

3.2.1 Existing Park Well

3.3 Prioritized Inventory

3.4 Potential Contamination Source Location Map

Section 4 Identification And Assessment of Current Controls

4.1 Identification Of Current Hazard Control

Section 5 Land Ownership Map and List

5.1 Land Ownership

5.2 Land Ownership List

Section 6 Land Use Agreements

6.1 Land Use Agreements

6.2 Letters of Intent

6.3 Zoning Ordinances

Figures

Figure 1 – General Location Map and Wellhead Source Protection Plan

Figure 2 – Proposed Park Well No. 2 (WS002) Design

Figure 3 – Davis County Principal Basin Fill Aquifer Recharge Area Block Diagram

Tables

Table 2-1 – Hydrogeologic Parameters and Sources

Table 2-2 Dimensions of Protection Zones

Table 3-1 – Identified Potential Contamination Sources

Table 4-1 – Potential Contaminant Source – Identification of Control

Appendices

Appendix A References

Appendix B Existing Park Well No. 1 Flowing Well Drilling Log

Appendix C 15-22 Davis County Drinking Water Source Protection Ordinance

Appendix D Groundwater Flow Direction

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) i

Glossary of Technical Terms

Aquifer

Underground layer of permeable fractured rock, sediment, or soil yielding water.

Drinking Water

Water suitable to be ingested by humans. Sometimes referred to as Culinary or Potable Water.

Hydraulic Conductivity

Property of porous materials, soils and rocks, which describes the ease with which a fluid

(usually water) can move through the pore space or rock fractures.

Hydraulic Gradient

Change in water level per unit distance along the direction of maximum head decrease.

Non-Transient Non-Community Water System

A Non-Transient Non-Community Water System (NTNCWS) is a public water system that regularly serves at least 25 of the same nonresident persons per day for more than six months per year. Examples of such systems are those serving the same individuals (industrial workers, school children, church members) by means of a separate system.

Public Water System

A Public Water System (PWS) is a system, either publicly or privately owned, providing water through constructed conveyances for human consumption and other domestic uses, which has at least 15 service connections or serves an average of at least 25 individuals daily at least 60 days out of the year and includes collection, treatment, storage, or distribution facilities under the control of the operator and used primarily in connection with the system, or collection, pretreatment, or storage facilities used primarily in connection with the system but not under the operator’s control.

Source

Term used in irrigation or drinking water terminology to specify where the supply of water originates. Examples include groundwater wells and springs or treated surface water.

Static Pressure

The pressure exerted by a liquid or gas, especially water or air, on a body at rest.

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) ii

Static Water Level

The groundwater elevation before pumping.

Transmissivity

Rate at which groundwater flows horizontally through an aquifer. A measure of how much fluid

(usually groundwater) can flow through the entire saturated thickness of an aquifer (ft2/day).

Waterline

A line formed by the surface of the water on a structure.

Water Line

Pipe or conduit which contains and conveys water.

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) iii

Abbreviations and Units

AMSL Above Mean Sea Level

BGS Below Ground Surface

DEQ Department of Environmental Quality

Ensign Ensign Engineering and Land Surveying

EPA U.S. Environmental Protection Agency ft foot [length unit of measurement] ft3/day cubic feet per day [flow rate unit of measurement] gpd gallons per day [flow rate unit of measurement] gpm gallons per minute [flow rate unit of measurement] hr hour [time unit of measurement]

HSLA high strength low alloy

in. inch [length unit of measurement]

K horizontal hydraulic conductivity (ft/day)

L Length (ft) mi mile [length unit of measurement] min minute [time unit of measurement]

NTNCWS Non-Transient Non-Community Water System

PCS Potential Contamination Sources

PER Preliminary Evaluation Report

PWS Public Water System

Q Flow Rate or Peak Rate of Runoff (cubic feet second) s second [time unit of measurement]

T Transmissivity (ft2/day)

TOT Time - of – Travel

TVPID Tooele Valley Public Infrastructure District

UAC Utah Administrative Code

UDDW Utah Division of Drinking Water

VOC Volatile Organic Chemicals

WhAEM Wellhead Analytic Element Model for Windows

WHPA Wellhead Protection Area

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) iv

Executive Summary

This Preliminary Evaluation Report (PER) is for the Park Well No. 2, in Utah Division of Drinking

Water (UDDW) Public Water System (PWS) No. UTAH06023, and classified as Non-Transient

Non-Community Public Water System (NTNCWS) as defined by Utah Department of

Environmental Quality (DEQ). The proposed Park Well No. 2 (WS002) will be located approximately 7,532 feet North, 2,716 feet east from the Northwest Corner of Section 31

Township 4 North Range 3W SLBM, Salt Lake Base Meridian (SLB&M) as shown in Figure 1.

The UDDW requires a Preliminary Evaluation Report (PER) for all new public drinking water sources in accordance with Utah Administrative Code (UAC) R309-600, Drinking Water Source

Protection for Groundwater Sources. This PER characterizes and outlines source water areas

(recharge areas), identifies threats to water quality (pollution sources), and assesses the potential risks these threats pose to the water supply. All of the sections required by the UDDW for a PER are contained in this report, which include the following:

• Delineation Report (Section 2)

• Inventory of Potential Contamination Sources (Section 3)

• Identification And Assessment of Current Controls (Section 4)

• Land Ownership Map and List (Section 5)

• Land Use Agreements (Section 6)

The proposed well will be drilled to an approximate depth of 500 feet. The Proposed Park Well

No. 2 will be completed with 8-inch diameter stainless steel production casing and well screen.

The well is expected to be flow tested for three days with an expected artesian flow at the wellhead released to atmosphere of about 200 gpm and maximum design flow rate of 100 gpm under pressure into the water distribution system’s 3,000-gallon transfer tank.

The Wellhead Analytic Element Model for Windows (WhAEM) Version 3.3.2 (EPA, 2018) was used to delineate Zones Two, Three and Four Drinking Water Source Protection (DWSP) area boundaries. The Zone One area is a 100-foot radius circle around the well. We delineated the

DWSP zones using a flow rate 100 gpm.

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 1

Section 1 Introduction

This Preliminary Evaluation Report (PER) is for the proposed Park Well No. 2 (WS002) for

Antelope Island State Park, which is the Utah Division of Drinking Water (UDDW) Public Water

System (PWS) No. UTAH06023 and classified as a NTNCWS. The proposed well is located approximately 0.5 miles northeast from the Antelope Island Marina along the south side of

Antelope Island Causeway Road, Davis County, Utah.

1.1 System Information

System information is provided as follows:

1.2 Source Information

Source information is provided as follows:

PWS Name Antelope Island - North

PWS ID UTAH06023

Systems Address 4528 West 1700 South, Syracuse, Utah 84075

New or Existing System Existing

Public or Non-Public Public

PWS Type NTNCWS

Source Name: Park Well No. 2

Proposed New or Existing Source:

New

Spring, Well, or Tunnel Well

Individual Source, Well field or Spring field

Individual Source

Description of Location approximately 7,532 feet North, 2,716-feet East from the

Northwest Corner of Section 31 Township 4 North Range 3W, Salt Lake Base Meridian (SLB&M)

SANDY

45 W 10000 S, Suite 500 Sandy, UT 84070 Phone: 801.255.0529

LAYTON

Phone: 801.547.1100

TOOELE

Phone: 435.843.3590

CEDAR CITY

Phone: 435.865.1453

RICHFIELD

Phone: 435.896.2983

WWW.ENSIGNENG.COM

DESIGNED BY

PROJECT NUMBER

PROJECT MANAGER

PRINT DATE PARK WELL NO. 2 (WS002)

DNR ANTELOPE ISLAND WELL REPLACEMENT

4528 WEST 1700 SOURTH, SYRACUSE, UTAH 84075

FIGURE 1 - GENERAL LOCATION MAP

15098

RJR

FIG. 1

2026-08-21

MJS

EXISTNG FLOWING

PARK WELL NO. 1

ANTE

LO

PE IS

LA

ND CAU

SEWAY

PROPOSED PARK WELL No. 2

ANTELOPE ISLAND MARINA

ANTELOPE ISLAND

VISITOR CENTER

BUFFALO

BAY

HORIZONTAL GRAPHIC SCALE

( IN FEET )

HORZ: 1 inch = ft.1000

1000 500 1000 2000

WELLHEAD

WELLHEAD

WHPA ZONE 1

WHPA ZONE 2

WHPA ZONE 3

WHPA ZONE 4

GREAT SALT LAKE

TO

SYRACUSE

CITY

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 3

1.3 Designated Person

Owner: UTAH STATE PARKS & RECREATION

1594 W North Temple, Suite 116

Salt Lake City, Utah 84116

Owner’s Representative: Chad Bywater

435-720-0331 cbywater@utah.gov

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 4

Section 2 Delineation Report

This section presents the information and analyses used to delineate the Drinking Water Source

Protection (DWSP) zones for the proposed wells. The report contains (1) the geologic data, including the topography, lithology, and regional hydrogeology of the project area, (2) the proposed well construction data, (3) the aquifer data used in the delineation analysis, including transmissivity, hydraulic conductivity, aquifer thickness, groundwater flow direction and gradient, porosity, and ambient flow, (4) the hydrogeologic methods and procedures used to delineate the protection zones using the U.S. Environmental Protection Agency’s (EPA) Wellhead Analytic

Element Model for Windows (WhAEM), (5) the resulting wellhead protection zones, including maps and tables summarizing the dimensions of Zones 1, 2, 3, and 4 under various pumping scenarios and (6) the aquifer classification status and concludes whether the source is classified as a protected or unprotected aquifer in accordance with Utah Administrative Code (UAC)

R309-600-9(7).

2.1 Geologic Data

The purpose of this section is to identify, characterize, and map the extent of: (1) geologic units which provide groundwater storage and flow (aquifers); (2) geologic units which may provide vertical and horizontal limits to groundwater flow (aquitards or confining beds); (3) faults which may be barriers or preferential paths to groundwater flow; and (4) fractures and/or karst features which may provide local and regional controls on groundwater flow. This section describes the regional geology and provides background information for understanding the local geology of the source protection zones.

2.1.1 Topology and Lithology

Antelope Island is located in the east portion of the Great Salt Lake, approximately 20 miles NW of Salt Lake City situated within the in East Shore groundwater area of the Great Salt Lake.

Antelope Island is typically surrounded by the Great Salt Lake. Drought has caused the Great

Salt Lake’s water levels to drop exposing the lake bed east of Antelope Island.

The East Shore Area is bound by the Wasatch Range to the east and the eastern portion of the

Great Salt Lake to the west. The mountain blocks consist of Precambrian Farmington Canyon

Complex metamorphic and igneous basement rocks, below Paleozoic metasedimentary and

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 5 sedimentary rocks and Tertiary sedimentary rocks. Faults run generally north-south. The East

Shore Area is a graben with as much as 10,000 feet of displacement along the Wasatch Fault

Zone.

Groundwater in the East Shore Area is principally found in unconsolidated valley-fill deposits. In the area of the proposed well, the aquifer consists of multiple layers of sand deposits between confining clay layers. The aquifer is under confined conditions with the potentiometric surface above the land surface.

The thickness of this basin-fill material varies in the East Shore Area ranging from thin at the valley margins to upwards of 700 feet in the deeper, central parts of the basin. Based on gravity data, the value fill material above bedrock is thought to be about 500 feet thick in the vicinity of the proposed well. Driven by topography, surface drainage and groundwater flow originate in the Wasatch Mountain range and migrates westward and downward toward the central areas of the basin where it ultimately discharges to the Great Salt Lake.

2.1.2 Regional Hydrogeology

According to the hydrology and groundwater flow simulation for the Weber-Delta Groundwater

Basin, the groundwater level varies from several hundred feet below ground surface near the mountain from to above land surface near and under the Great Salt Lake. A review of potentiometric contour data indicates that groundwater flows toward the southwest, with a hydraulic gradient of approximately 0.00065 feet per foot (Reference Appendix D).

2.2 Proposed Well Construction Data

Park Well No. 2 (WS002) will be constructed using either cable tool or dual tube air rotary drilling methods with an 8-inch diameter stainless steel production casing installed to a depth of

500 feet below ground surface (BGS). From 445 to 495 feet BGS, an 8-inch diameter screen will be installed. Below the screen, a 5-foot section of blank stainless-steel casing with a welded end cap will be placed to accommodate sediment accumulation and casing centralizers.

Drilling the well will be performed using either cable tool or air rotary methods (refer to Figure 2 for the well design). A temporary 14-inch high-strength low-alloy (HSLA) steel casing will be installed during drilling to stabilize the flowing sands. The temporary casing will be removed as the gravel pack and certified surface seal are placed. The well will be equipped with an 8-inch

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 6 diameter welded x 6-inch diameter flange tee capable of allowing flows of up to 100 gallons per minute (gpm) at the 3,000-gallon transfer tank approximately 3,000 linear feet to the southwest of the well site. The well is anticipated to draw water from 445 to 495 feet BGS, 5 feet above the bottom of the aquifer. The ground surface elevation at the proposed location for Park Well

No. 2 is approximately 4209.50 feet above mean sea level (AMSL).

WATER BEARING UNITS CONTAINING

EXCESSIVE FINES CONTAMINATED OR

POOR WATER QUALITY MUST BE SEALED

OFF FROM WELL

PERMANENT 8-INCH WELL CASING MUST BE

CENTERED IN WELL BORE HOLE TO ALLOW

THE SEAL MATERIAL AND GRAVEL/FILTER

PACK TO EVENLY SURROUND THE WELL

UNPERFORATED 8-INCH STAINLESS STEEL WELL

CASING MUST EXTEND AT LEAST 5-FEET INTO THE

CONFINING STRATUM OVERLYING THE ARTESIAN

WATER-BEARING ZONE

DRILL AND DRIVE TEMPORARY 14-INCH Ø

0.25-INCH WALL STEEL CASING TO BE

REMOVED AS GRAVEL PACK AND GROUT

SEAL ARE PLACE AROUND 6-INCH

PERMANENT CASING AND SCREEN

CERTIFIED CEMENT

GROUT WELL SEAL

DEPTH = 0 TO 160-FEET

CASING CENTRALIZERS @ (TYP.)

3/16-INCH T X 1.5" W SS

STEEL STRAP WELDED TO SS

CASING AT 60-FOOT CENTERS,

4 STRAPS PER CENTER

8/16-INCH GRAVEL PACK/FILTER MATERIAL

OR FORMATION STABILIZER

8-INCH DIA STAINLESS STEEL STD FLO

SHUTTERED SCREEN (0.12-IN SLOTS)

(50 FEET TOTAL WELL SCREEN LENGTH)

14-INCH DRIVE SHOE WELDED TO BOTTOM

OF TEMPORARY 14-INCH CASING

CASING CENTRALIZERS 5-FEET

FROM BOTTOM @ 60-FOOT ON CENTER

NO CENTRALIZERS IN

SCREENED SECTION

AN

TI

CI

PA

TE

D

IN

TE

RB

ED

DE

D

CL

AY

S, S

AN

DS

, A

ND

G

RA

VE

LS

TOP

SOIL

BENTONITE PLUG

DEPTH 160 - 165 FEET

TOP OF SCREEN

DEPTH = 445 FEET

NOTES:

THE SURFACE SEAL MUST BE PLACED FROM GROUND SURFACE TO THE DEEPEST OF THE FOLLOWING OPTIONS AS APPLICABLE:

1. A MINIMUM DEPTH OF 100 FEET AND FOR A THICKNESS OF AT LEAST 30 FEET THROUGH A PROTECTIVE CLAY LAYER (R309-600-R(1)(V), R309-204-6(6)(I))

2. FROM STATIC WATER LEVEL TO GROUND SURFACE IN UNCONSOLIDATED FORMATIONS (NO CONFINING UNIT)

3. AT LEAST 5 FEET INTO A CONFINING UNIT IN CLAY STRATIFIED UNCONSOLIDATED FORMATIONS: AND

4. AT LEAST 5 FEET INTO COMPETENT CONSOLIDATED FORMATIONS

5. IN ARTESIAN FORMATIONS, THE SURFACE SEAL MUST EXTEND FROM GROUND SURFACE TO A MINIMUM DEPTH OF 100 FEET AND BE

ANCHORED AND PRESSURE-GROUTED SECURELY INTO THE CONFINING STRATUM OVERLYING THE ARTESIAN AQUIFER TO

PREVENT SUB-SURFACE LEAKAGE OR BOREHOLE BLOWOUTS.

180 LINEAR FEET OF 1.5-INCH

GRAVEL/FILTER PACK FEED

PIPE BANDED TO

OUTSIDE OF CASING AT

40-FOOT CENTERS

GROUT FROM 0

BGS TO 160-FEET

5-FEET OF BLANK 14-INCH SS CASING WITH BOTTOM

CAP FOR SEDIMENT AND CENTRALIZERS

8-INCH NONPERFORATED

PERMANENT 0.25-INCH WALL

STAINLESS STEEL CASING

ENGINEERED FILL PER

SITE IMPROVEMENT PLANS

APPROXIMATE WELL DEPTH 500 FEET

8-INCH Ø PERMANENT

SS WELL CASING

NOT TO SCALE

SANDY

45 W 10000 S, Suite 500 Sandy, UT 84070 Phone: 801.255.0529

LAYTON

Phone: 801.547.1100

TOOELE

Phone: 435.843.3590

CEDAR CITY

Phone: 435.865.1453

RICHFIELD

Phone: 435.896.2983

WWW.ENSIGNENG.COM

DESIGNED BY

PROJECT NUMBER

PROJECT MANAGER

PRINT DATE PARK WELL NO. 2 (WS002) WELL SECTION

DNR ANTELOPE ISLAND WELL REPLACEMENT

4528 WEST 1700 SOUTH, SYRACUSE, UTAH 84075

FIGURE 2 - PROPOSED PARK WELL NO. 2 (WS002) DESIGN

15098

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FIG. 2

2026-08-24

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Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 8

2.3 Aquifer Data

The following hydrogeologic parameters were used to delineate drinking water source protection

(DWSP) Zones 2, 3 and 4 using the U.S. Environmental Protection Agency’s (EPA) Wellhead

Analytic Element Model for Windows (WhAEM) Version 3.3.2 (EPA, 2018).

2.3.1 Hydraulic Conductivity and Transmissivity

Technical Publication 93 (Reference (1), Appendix A) reports transmissivity values in the East

Shore Area ranging from 2,500 to 100,000 ft /day, with 2,500 occurring in the area of the proposed well. Thus, a transmissivity of 2,500 ft2/day was used. With an anticipated 50-foot total aquifer thickness a hydraulic conductivity of 50 ft/day was calculated. These values will be updated along with the protection zones after the actual transmissivity/hydraulic conductivity has been determined from a constant-rate pump test.

2.3.2 Aquifer Thickness

A saturated thickness of 50 feet was used with the design screened interval of 50 feet.

2.3.3 Groundwater Flow

According to the Map in Figure 1, the groundwater flow direction is West 25 degrees South with a hydraulic gradient of 0.00065 ft/ft.

2.3.4 Well Diameter

The diameter of the well casing will be 8-inches with the screen diameter of 8-inches.

2.3.5 Porosity

The material in the vicinity of the proposed wells is a mixture of sand and clay, based on data from the existing Park Well No. 1 log (Appendix B). Technical Publication 93 reports a porosity for sand in the East Shore Area as 30%. It is anticipated that the sand layers encounter by the proposed well will be finer-grained then much of the sand in the East Shore Area and so a conservative value of 0.25 was used to model the aquifer. The hydrogeologic parameters and sources are listed in Table 2-1.

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 9

2.3.6 Ambient Flow

The ambient flow was calculated by multiplying the hydraulic gradient (0.00065 ft/ft) by the transmissivity (2,500 ft2/day) to yield an ambient flow of 1.625 ft2/day.

Table 2-1 – Hydrogeologic Parameters and Sources

2.4 Hydrogeologic Methods Used to Delineate DWSP Zones

Wellhead protection zones two, three, and four as defined in the state regulation R309-600-9, were delineated using the U.S. Environmental Protection Agency’s (EPA) Wellhead Analytic

Element Model for Windows (WhAEM) Version 3.3.2 (EPA, 2018). WhAEM is a ground-water flow model designed to facilitate capture zone delineation and protection area mapping based on radius methods, wells in uniform flow solutions, and geohydrologic modeling methods. The method used for this project was to utilize the uniform flow feature to model the path lines and capture zones to the well. It is anticipated Park Well No. 2 would be the primary source and the existing Park Well No. 1 will be used as a redundant emergency source. Parks intends to only

Aquifer Parameter Value Utilized Source

Transmissivity: 2,500 ft2/day Obtained from Technical Publication 93

(1990) (Reference (1) Appendix A)

Hydraulic conductivity 50 feet/day Calculated with a presumed aquifer thickness of 50 ft

Aquifer Saturated Thickness 50 feet also, the proposed screened interval in the well

Groundwater Flow Direction W25°S Inferred from regional potentiometric groundwater surface (shown in Appendix D )

Groundwater Gradient: 0.00065 ft/ft Estimated from Figure 47 (Technical

Publication 93, Reference (1) Appendix A )

Flow Rate 100 gpm Anticipated discharge rate

Ambient Flow 1.625 ft2/day Multiplying the hydraulic gradient by the transmissivity.

Porosity: 25% Estimated for a finer-grained sand (Technical

Publication 93, Reference (1) Appendix A)

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 10 produce one well at a time, so the WhAEM model was run for each well separately and not with the two wells producing simultaneously.

Generalized descriptions of the four protection zones delineated by the Preferred Delineation

Procedure follow:

Zone One - 100-Foot Fixed-Radius circular Accident Prevention Zone: Zone One is a 100- foot fixed radius circle around a spring or well head and is referred to as the accident prevention zone. Its purpose is to prevent accidents and to protect the spring or well from contamination.

Zone Two - 250-Day Attenuation Zone: Zone Two is the 250-day time-of-travel (TOT), the boundary of the aquifer(s) which supplies water to the source, or the groundwater divide, whichever is closer. Zone Two is sometimes referred to as the attenuation zone. Its purpose is to reduce concentrations of pathogenic microorganisms and some chemicals to levels below maximum contaminant levels before groundwater reaches a well, spring or tunnel. Zone Two represents a moderate level of protection.

Zone Three - 3-Year Waiver Criteria Zone: Zone Three is the area within a 3-year TOT to the source, the boundary of the aquifer(s) which supplies water to the source, or the groundwater divide, whichever is closer. Zone Three is referred to as the waiver criteria zone. This zone has been established to provide a basis for granting monitoring waivers in the future. Use waivers may be granted for either the volatile organic compounds (VOC) or the pesticide parameter group. To qualify for a use waiver, a system must verify that none of the chemicals or pesticides in the parameter groups has been used in the three-year time-of-travel zone. If a system does not qualify for a use waiver, it may still qualify for a susceptibility waiver. Susceptibility wavier allows the use, disposal, storage, transport, and manufacture of chemicals within Zone Three as long as they are controlled in such a manner as to prevent contamination of the system’s well or spring. The DWSP Plan must verify that land management strategies are implemented that will control the chemicals being used in Zone Three.

Zone Four - 15-Year Remedial Action Zone: Zone Four is the area within a 15-year TOT to the source, the boundary of the aquifer(s) which supplies water to the source, or the groundwater divide, whichever is closer. Its purpose is to provide protection to the drinking water source and to afford sufficient time for remediation or development of a new source in case of a contamination incident. Zone Four represents a moderate level of protection.

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 11

2.4.1 Input Parameters of WhAEM

WhAEM and the data in Table 2-1 were utilized to simulate the 250-day (Zone 2), 3- Year (Zone

3), and 15- Year (Zone 4) capture zones.

2.5 Wellhead Protection Zones

Table 2-2 depicts the protection zones for Park Well No. 2, at a flowing rate of 100 gpm.

Detailed dimensions for each protection zone are summarized in Table 2-2

Table 2-2 Dimensions of Protection Zones

2.6 Aquifer Classification Status

The existing Park Well No. 1 (WS001) was completed into a confined and protected aquifer.

The well log shows a total of 323 feet of clay with clay layers over the following depths:

12 ft – 70 ft

75 ft – 137 ft

143 ft – 160 ft

168 ft – 186 ft

209 ft – 225 ft

250 ft – 280 ft

292 ft – 302 ft

316 ft – 338 ft

340 ft – 345 ft

357 ft – 423 ft

442 ft – 447 ft

459 ft – 468 ft

475 ft – 480 ft

Zone Identification and Methodology

Maximum Length (ft)

Maximum Width (ft)

Zone 1 100 100

Zone 2 - 250 Day TOT (Attenuation Zone)

406 404

Zone 3 - 3 Year TOT (Waiver Criteria Zone)

853 863

Zone 4 - 15 Year TOT (Remedial Action Zone)

2,053 2,128

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 12

The proposed Park Well No. 2 (WS002) is located 171 ft from the Park Well No. 1 and based on the geology, it is anticipated the same lithology will be encounter in the proposed well, it will be confined, and meet the requirements for a protected aquifer.

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 13

Figure 3 – Davis County Principal Basin Fill Aquifer Recharge Area Block Diagram

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 14

Section 3 Inventory of Potential Contamination Sources

This section identifies existing potential contamination sources located within each delineated well head protection zone. The potential contaminant sources are listed in order of priority for each zone along with a discussion of the methods utilized to rank each of the sources. Figure 1 shows the locations of the PCS and the land ownership boundaries in relation to the proposed wells sites in accordance with R309-600-10.

While the Great Salt Lake, North Davis Sewer District wastewater treatment plant effluent, and potential road pollutants from the nearby Antelope Island Causeway are surface-level contaminant sources, they are not considered active Potential Contaminant Sources (PCS) for the Park Wells. This is because the underlying aquifer is fully confined beneath multiple impermeable clay layers as listed above, effectively isolating the groundwater supply from surface runoff, spills, and effluent discharges. Further, the aquifer is under artesian pressure with a potentiometric surface above the land surface. A pump will not be used in the Park Well

No. 2, so the potentiometric surface will remain above the land surface even when the well is flowing.

3.1 Potential Contaminant Sources (PCS)

Inventories of potential contamination sources (point, non-point, negligible risk) located within the delineated well head protection zones and potential methods of management and control were identified and enumerated in Table 3-1.

Table 3-1 – Identified Potential Contamination Sources

PCS

Total Quality

(all zones) Within Zone 1

Within Zone 2

Within Zone 3

Within Zone 4

Existing Park Well 1 0 1 0 0

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 15

3.2 Hazard Identification

3.2.1 Existing Park Well

The existing Park Well No. 1 located approximately 171-feet southwest of Park Well No. 2 is completed in the same aquifer as the proposed Park Well No. 2. The existing well, completed within the same confined aquifer, represents a potential conduit for groundwater contamination if its structural integrity is compromised. Although the target aquifer is naturally protected by multiple overlying confining layers, any existing borehole effectively punctures this natural barrier. If the older well has a degraded, insufficient, or non-existent annular grout seal, or if the casing has corroded over time, it can create a vertical pathway for poor-quality surface runoff, or shallow groundwater to bypass the confining layers and directly enter the deeper aquifers. The existing Park Well No. 1 over the last year has received improvements to treat the existing well casing and improve it under DDW File #13586.

3.3 Prioritized Inventory

Not Applicable

3.4 Potential Contamination Source Location Map

Not Applicable

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 16

Section 4 Identification And Assessment of Current Controls

4.1 Identification Of Current Hazard Control

The table below lists the current control conditions for each potential contamination source under the numbered headings using best management and pollution prevention practices.

Table 4-1 – Potential Contaminant Source – Identification of Control

Potential Contaminant

Source

1.

Practices

2.

Willing to Continue

3. Prevention 4.

Adequately controlled

5.

Frequency of

Reassessment

Zone 1 (100-ft Radius)

N/A - - - - -

Zone 2 (250-Day Time of Travel)

Existing Park Well No. 1

(WS001)

Water Quality Testing

Y

Water Quality Testing and

Inspections of Well Head

Condition by Antelope

Island State Park

Personnel

Controlled

Testing as required by

Utah Division of Drinking

Water

Zone 3 (1,095-Day Time of Travel)

N/A - - - - -

Zone 4 (5,475-Day Time of Travel)

N/A

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 17

Section 5 Land Ownership Map and List

5.1 Land Ownership

Davis County has an established Drinking Water Source Protection Ordinance (Appendix C).

This ordinance was established to protect source protection zones. Per UAC R309-600-

13(2)(c), if an ordinance is used to protect land located within Zones 1 and 2 a land ownership map and list are not required.

5.2 Land Ownership List

The causeway is owned by State Lands, but the existing and proposed wells are maintained by

Antelope Island State Park. The Weber-Delta aquifer is mentioned under Davis County’s established Drinking Water Source Protection Ordinance (Appendix C).

Preliminary Evaluation Report for Antelope Island (PWS UTAH06023) Park Well No. 2 (WS002) 18

Section 6 Land Use Agreements

6.1 Land Use Agreements

All DWSP Zones are located in Davis County with PCS management accomplished via the

County’s Drinking Water Source Protection Ordinance (Appendix C). This DWSP ordinance controls and limits the types of activity and development that can take place within the DWSP zones. These ordinances are in accordance with Utah State rules and regulations for DWSP zones.

The Wells may be eligible for a use wavier as the Volatile Organic Chemicals (VOC) defined in

R309-200 table 200-3 have not been used, disposed, stored, transported, or manufactured within the past five years within Zone’s 1-3. The Wells can qualify for a VOC use wavier by listing which chemicals are used, disposed, stored, transported, or manufactured at each PCS within Zones 1, 2, or 3 where the use of a chemical listed in the VOC group is likely. Also, a dated statement which is signed by the systems designated individual must be submitted that demonstrates that none of the VOCs within the respective groups have been used disposed, stored, transported, or manufactured in the last five years within Zones 1, 2, or 3.

Susceptibility waivers may also be applicable for the new Wells if the use wavier is determined to not be needed. To qualify for a susceptibility wavier neither a reliability and consistently or a use wavier can have been issued for the Wells. Also, to qualify for a VOC suppressibility wavier a PWS must follow the steps outlined in R309-600-16(4). The susceptibility waiver tolerates the use, disposal, storage, transport, and manufacture of chemicals within Zones 1, 2, or 3 if the

PWS can demonstrate that the source is not susceptible to contamination.

6.2 Letters of Intent

Not required due to the presence of Davis County’s DWSP Ordinance.

6.3 Zoning Ordinances

As previously mentioned in the report, Davis County has a DWSP ordinances located in

Appendix C of this report.

Appendix A References

1. Ground-Water Resources and Simulated Effects of Withdrawals in the East Shore Area of

Great Salt Lake, Utah; Technical Publication No. 93; 1990

2. Ground-Water Quality Classification for the Principal Basin-Fill Aquifer, East Shore Area, Davis County, Utah; Prepared for the Davis County Health Department; 2011

3. Utah Administrative Code; Sections R309-200, R309-600

4. CWI Water Quality Interpretation Tool, 2026

5. U.S. Environmental Protection Agency (EPA, n.d); Wellhead Analytic Element Model

(WhAEM) 2018

6. Groundwater Quality Classification For the Principal Basin-Fill Aquifer, East Shore Area, Davis County, Utah

7. Groundwater Quality Classification for Discharge Zone of the shallow, Unconfined Basin-Fill

Aquifer, East Shore Area, Davis County, Utah

Appendix B Existing Park Well No. 1 Flowing Well Drilling Log

Appendix C 15-22 Davis County Drinking Water Source Protection Ordinance

Chapter 15.22 DRINKING WATER SOURCE PROTECTION Section 15.22.110 Short Title And Purpose Section 15.22.120 Definitions Section 15.22.210 Establishment Of Drinking Water Source Protection Zones Section 15.22.220 Allowed Uses Section 15.22.230 Prohibited Uses Section 15.22.240 Overly Protective Protection Zones Section 15.22.250 Administration Section 15.22.310 Appendix A Section 15.22.320 Appendix B

Section 15.22.110 Short Title And Purpose

A. This ordinance shall be known as the "Drinking Water Source Protection Ordinance."

B. The purpose of this ordinance is to ensure the provision of a safe and sanitary drinking water supply to the residents of Davis County (hereinafter "County"), by the establishment of drinking water source protection zones surrounding the wells and springs located in or used by public water systems in the County and by the designation and regulation of property uses and conditions that may be maintained within such zones. Included under this ordinance are all source protection zones or portions thereof falling within the County, which protect public drinking water sources not owned operated by the County.

(Ord. 03-2008, Add, 06/25/2008)

Section 15.22.120 Definitions

When used in this ordinance the following words and phrases shall have the meanings given in this section:

A. "Abandoned Well" means a well whose purpose and use has been permanently discontinued or a well that is in a state of disrepair and its intended purpose cannot reasonably be achieved. A well can be abandoned only after being properly sealed according to the requirements of the State of Utah Administrative Rules for Water Well Drillers, R655-4-12.

B. "Allowed Uses" means (A) a use, activity or practice of which does not create a risk of contamination in the specified zone significant enough to require the implementation of regulatory requirement and Best Management Practices and, therefore, the use is allowed.

C. "Best Management Practices," means a practice or combination of practices determined to be the most effective practicable means of conducting a land use activity to minimize the potential for becoming a pollution source (including technological, economic and institutional considerations).

D. "Collection Area" means the area surrounding a ground-water source which is underlain by collection pipes, tile, tunnels, infiltration boxes or other ground-water collection devices.

E. "Design Standard" means established State or National Standards for the design, construction, placement or maintenance of a potential contamination source to prevent discharges to the ground water. See also "secondary containment."

F. "Hazardous Waste" means a waste with properties that make it dangerous or potentially harmful to human health or the environment.

G. "Land Management Strategies" means land use and non land use controls which include, but are not limited to, the following: land ordinance, site plan reviews, design and operating

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H. "Pollution Source" means point source discharge of contaminants to ground water or potential discharges of the liquid forms of "extremely hazardous substances" which are stored in containers in excess of "applicable threshold planning quantities" as specified in SARA Title III.

Examples of possible pollution sources include, but are not limited to, the following: storage facilities that store the liquid forms of extremely hazardous substances, septic tanks, drain fields, Class V underground injection wells, landfills, open dumps, land filling of sludge and septage, manure piles, salt piles, pit privies and animal feeding operations with more than ten animal units. The following clarify the definition of pollution source:

1. "Animal Feeding Operation" means a lot or facility where the following conditions are met: animals have been or will be stabled or confined and fed or maintain for a total of 45 days or more in any 12 month period and crops, vegetation forage growth or post-harvest residues are not sustained in the normal growing season over any portion of the lot or facility. Two or more animal feeding operations under common ownership are considered to be a single feeding operation if they adjoin each other, if they use a common area or if they use a common system for the disposal of wastes.

2. "Animal Unit" means a unit of measurement for any animal feeding operation calculated by adding the following numbers: the number of slaughter and feeder cattle multiplied by 1.0, plus the number of mature dairy cattle multiplied by 1.4, plus the number of swine weighing over 55 pounds multiplied by 0.4 plus the number of sheep multiplied by 0.1, plus the number of horses multiplied by 2.0.

3. "Extremely Hazardous Substances" means those substances which are identified in the Sec. 302(EHS) column of the "TITLE III LIST OF LISTS- Consolidated List of Chemicals Subject to Reporting under SARA Title III," (EPA 560/4-91-011).

I. "Potential Contamination Source" means any facility or site, which employs and activity or procedure, which may potentially contaminate ground water. A pollution source is also a potential contamination source.

J. "Prohibited Uses" (X) means a use, activity or practice of which creates a substantial risk or contamination in the specified zone. The use is not permitted.

K. "Regulatory Agency" means any governmental agency (local, state, and/or federal) with jurisdiction of hazardous waste as defined herein.

L. "Restricted" (R) means that the nature of the use, or some element of the use, represents a "Potential Contamination Source." The use may be permitted only after review and approval by the land use authority. As part of this review, recommendations from the Davis County Health Department and other applicable regulatory agencies shall be considered.

M. "Sanitary Landfill" means a disposal site where solid wastes, including putrescible wastes or hazardous wastes are disposed of on land by placing earth cover thereon.

N. "SARA Title III" means the Superfund Amendment and Reauthorization Act section found on 40 CFR 300-302, pertaining to emergency response and right-to-know.

O. "Secondary Containment" means a type of system that is used to provide release detection prevention, such as trays under containers, floor curbing or other systems designed to hold materials or liquids that may discharge from containers holding regulated substance. Examples include a double-walled tank, a double-walled integral piping system or a single-walled tank or

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P. "Septic Tank/Drain-field Systems" means a system, which is comprised of a septic tank and a grain-field, which accepts wastewater from buildings or facilities for surface or subsurface treatment and disposal.

Q. "Source Protection Zone" means the specified surface and subsurface area surrounding a ground-water source of drinking water supplying a Public Water Supply, through which contaminants are reasonable likely to more toward and reach such ground-water source. These zones shall have the approval of the State of Utah, Division of Drinking Water as described in R309-600 Source Protection: Drinking Water Source Protection for Ground-Water Sources and stated in Section Three herein.

R. "Underground Storage Tank" means a tank or combination of tanks and underground pipes and impact valves connected to tanks being used or having been used to contain regulated substances and which has at least ten per cent of the total volume of the tank and underground portions of pipes connected to the tank underground.

S. "Wellhead" means the upper terminal of a well, including adapters, ports seals valves and other attachments.

(Ord. 03-2008, Add, 06/25/2008)

Section 15.22.210 Establishment Of Drinking Water Source Protection Zones

There are hereby established use districts to be known as zones one, two, three, and four, of the drinking water source protection area, or alternatively the Management Area. These zones shall have the approval of the State of Utah, Division of Drinking Water as described in R309-600 Source Protection: Drinking Water Source Protection for Ground-Water Sources and are identified and described as follows:

A. Zone one is the area within a 100-foot radius from a wellhead or margin of the collection area.

B. Zone two is the area within a 250-day ground-water time to travel to a wellhead, the boundary of the aquifer(s) which supplies water to the ground-water source, or the ground-water divide, whichever is closer, as specified on the "Drinking Water Source Protection Zone Map" on file with the County.

C. Zone three (waiver criteria zone) is the area within a 3-year ground-water time of travel to a wellhead or margin of the collection area, the boundary of the aquifer(s) which supplies water to the ground-water source, or the ground-water divide, whichever is closer, as specified on the "Drinking Water Source Protection Zone Map" on file with the County.

D. Zone four is the area within a 15-year ground-water time of travel to a wellhead, the boundary of the aquifer(s) which supplies water to the ground-water source or the ground-water divide, whichever is closer, as specified on the "Drinking Water Source Protection Zone Map" on file with the County. In some cases, such as bedrock areas, zones two, three, and four are overlapping, due to the inability to determine time of travel. These are sensitive areas. In these cases, the zone should be protected as for zone two.

E. Management area means the area outside of zone one and within a two-mile radius where the Optional Two-mile Radius Delineation Procedure has been used to identify a protection area as described in the Utah, Division of Drinking Water R309-600 source Protection: Drinking Water Source Protection for Ground-Water Sources. This area shall be treated as for zone two.

(Ord. 03-2008, Add, 06/25/2008)

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Section 15.22.220 Allowed Uses

The following uses shall be permitted within drinking water source protection zones:

A. Any use permitted within existing agricultural, single family residential, multi-family residential and commercial districts so long as uses conform to the rules and regulations of the regulatory agencies.

B. Any other open land use where any building located on the property is incidental and accessory to the primary open land use.

(Ord. 03-2008, Add, 06/25/2008)

Section 15.22.230 Prohibited Uses

The following uses or conditions shall be and are hereby prohibited within drinking water source protection zones, whether or not such uses or conditions may otherwise be ordinarily included as part of a use permitted under Section 4 of the ordinance.

A. Zone one - The location of a potential contamination source as defined herein.

B. Zone two and Management area - The location of pollution sources as defined herein unless their contaminated discharges are controlled with design standards.

C. Zones three and four - The location of potential contamination sources, unless they are controlled through land management strategies.

To further clarify uses and prohibitive uses in protective zones, refer to Table 1, Use Matrix for Potential Contamination Sources in Appendix A. For a generic list of regulated substances, see Appendix B. This list and table are for clarification and planning purposes. They are not all inclusive. Substances that are not in this table and list may need further clarification.

(Ord. 03-2008, Add, 06/25/2008)

Section 15.22.240 Overly Protective Protection Zones

If management areas were delineated using the Optional Two-Mile Radius Delineation Procedure or if protection zones appear to be excessively conservative (too large), they may be disputed according to the following procedure:

A. Submit written comments to the Land Use Authority stating the reasons that the delineated management area or protective zones should be reconsidered.

B. If the Land Use Authority concurs, it may authorize a new hydrogeologic investigation at the expense of the entity requesting changes to the delineated management area or protective zones.

C. The new hydrogeologic investigation must then be submitted to the Utah Division of Drinking Water for their review.

D. If the Division of Drinking Water finds that the new hydrogeologic investigation is protective and meets the requirements of a Delineation Report according to the Utah Drinking Water Source Protection for Ground Water Sources Rule (R309-600), the Land Use Authority may enforce this ordinance according to the new protection zones.

(Ord. 03-2008, Add, 06/25/2008)

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Section 15.22.250 Administration

A. The policies and procedures for administration of any source protection zone established under this ordinance, including without limitation those applicable to existing nonconforming uses, exception, enforcement and penalties, shall be the same as provided in the existing land use ordinance for Davis County, as presently enacted except that the Land Use Authority can not grant a variance until the request is reviewed and recommendation is provided by the Davis County Health Department. If it is necessary to have additional expertise evaluate the variance, it shall be at the expense of the entity requesting the variance. The recommendation relative to the requested variance shall be documented and returned to both the requester and the Davis County Land Use Authority.

B. If there are noncompliant potential contamination source found in the source protection zones that cannot be resolved by the water…