DERR-2024-004641

4895-1244-6096\3
Water Monitoring Plan 2023-2024
Big Dutch Pete Hollow

This proposed plan is a continuation of the previous water management and monitoring strategies implemented at the Mayflower VCP
site (the “Site”). The 2022-2023 Water Monitoring Plan’s updated monitoring strategy was a successful approach to development of a
final remedy for water management at the Site. Accordingly, BLX Mayflower LLC (“BLXM”) will continue the same monitoring
approach in this plan. BLXM shall have the right to assign its monitoring obligations under this agreement to an affiliated party who
will take on the management of the Site.
BLXM will perform testing at the McHenry Campground sampling location every two weeks for Zinc and Cadmium by EPA Method
200.8, and Iron by EPA Method 200.7 through December 2024. BLXM will also perform additional metals testing as described in the
table below once every quarter through December 2024 at the McHenry Campground sampling location. The McHenry Campground
sampling location is identified on the site map attached as Exhibit A.
BLXM will also continue to measure groundwater levels in accessible groundwater wells and piezometers on a monthly schedule,
other than during April through June 2024, when the groundwater wells and piezometers will be measured twice a month.
On or around the middle of June 2024, BLXM will also perform water quality sampling of the groundwater wells (GW2 and GW4)
and piezometers (GW6, GW7c, GW8, GW9a) using EPA’s Low-Flow Sampling Methodology and the samples will be analyzed for
Arsenic, Barium, Cadmium, Chromium, Copper, Iron, Lead, Mercury, Selenium, Silver, and Zinc using the analytical methods
identified herein. The June 2024 groundwater sampling event will coincide with the final regularly scheduled RAP groundwater
monitoring. This groundwater sampling event will also coincide with the June 2024 sampling of McHenry Campground for the same
constituents. A summary chart of the sampling program is below:
Proposed Sample Location Sampling Frequency Contaminant of Concern Type of Analysis
Groundwater Monitoring Wells
GW2 and GW4 near the property
boundary, Property Line Sump
June 2024 Metals (Arsenic, Barium, Chromium,
Cadmium, Copper, Iron, Lead, Mercury,
Selenium, Silver, Zinc)
Dissolved Metals
Analysis
Water Quality monitoring at
Groundwater piezometers (GW6,
GW7c, GW8, GW9a)
June 2024

Metals (Arsenic, Barium, Chromium,
Cadmium, Copper, Iron, Lead, Mercury,
Selenium, Silver, Zinc)
Dissolved Metals
Analysis
McHenry Campground sampling
point (4997675)

Every two weeks
through December
2024
Metals (Cadmium, Zinc, Iron) Total Metals
Analysis
McHenry Campground sampling
point (4997675)

Quarterly (Second
week of April, second
week of July, second
week of October, and
final sampling event
during the second
week of December
2024)
Metals (Arsenic, Barium, Chromium
Cadmium, Copper, Iron, Lead, Mercury,
Selenium, Silver, Zinc)
Total Metals
Analysis
Water level monitoring of
accessible Groundwater Monitoring
Wells and Piezometers (GW6,
GW7c, GW8, GW9a, GW2, GW4)
Monthly from
December 2023 –
March 2024, twice a
month April 2024 –
June 2024, monthly
July 2024 – December
2024
Water levels will be
measured and
plotted on graphs to
show trends over
time

BLXM will pump water from the Property Line Sump and discharge the water into the on-site sanitary sewer system if, at any time,
analytical results from the sampling at the McHenry Campground sampling location exceed the site surface water quality screening
levels in the table below, with the exception of turbidity. At such time, BLXM will, in conjunction with DERR, reevaluate this water
monitoring program and implement corrective measures, as appropriate, in consultation with DERR.
BLXM will compile, tabulate, and assess water level and water quality trends and make submittals to the DERR monthly starting in
January 2024.

2
4895-1244-6096\3
Screening Level Table:

Analyte Surface Water
Screening Level
(mg/L)
Groundwater
Screening Levels
(mg/L)
Analytical Testing
Method for Surface
Water
Analytical Testing
Method for Groundwater
Arsenic 0.010 0.010 EPA Method 200.8 EPA Method 6020
Barium 1.0 2.0 EPA Method 200.7 EPA Method 6010
Cadmium 0.00239 0.005 EPA Method 200.8 EPA Method 6020
Chromium 0.268 0.1 EPA Method 200.8 EPA Method 6010
Copper 0.0305 1.3 EPA Method 200.8 EPA Method 6010
Iron 1.0 14.0 EPA Method 200.7 EPA Method 6010
Lead 0.0186 0.015 EPA Method 200.8 EPA Method 6020
Mercury 0.000012 0.002 EPA Method 245.1 EPA Method 7470
Selenium 0.0046 0.05 EPA Method 200.8 EPA Method 6020
Silver 0.0411 0.10 EPA Method 200.8 EPA Method 6010
Zinc 0.388 5.0 EPA Method 200.8 EPA Method 6010
Turbidity (NTU) < 20 NTU Goal Field Meter Stabilization in accordance
with EPA Low-Flow
Sampling Methodology

Quality Assurance (QA) and Quality Control (QC)
Chemtech-Ford Analytical Laboratory (Chemtech) has a robust quality control (QC) program that is required for their State Certification.
They monitor the precision and accuracy of their analytical procedures through analysis of laboratory QC samples. Laboratory Analysis
will be performed under the direction of Chemtech’s Laboratory Director, in accordance with appropriate Accreditations and
Certifications.

The National Environmental Lab Accreditation Program and United States Environmental Protection Agency quality control standards
will be met for all samples analyzed by Chemtech. All laboratory analytical reports will include Level 3 documentation, including a
Case Narrative provided by Chemtech. On a frequency of one for every five sampling events (10% of samples) BLXM will also collect
a field duplicate sample for analysis. BLXM will collect one Field Blank during the sampling program to assess potential sample
contamination due to sample bottles, preservative, ambient site conditions, or cross-contamination during transport.

The field duplicate will be collected closely in time and location to the actual sample and will be placed in an identical sample container
fixed with nitric acid (HNO3). The duplicate sample will be handled in the same way as the other samples and will be secured in the
same cooler for laboratory analysis. The field duplicate will measure the additive effects of field precision (i.e. sample collection,
handling, and transportation) and lab precision (such as sample handling and analysis).

Chain-Of-Custody Documentation
All samples submitted for laboratory analysis will be accompanied by completed Chain-of-Custody (COC) forms. Forms will be
completed and submitted with the samples to the laboratory during each sampling event. The COC will identify the contents of each
shipment and maintain the custodial integrity of the samples. Samples will be in the custody of the sampler, locked up, or kept in a
secured area that is restricted to authorized personnel. Samples will remain in the custody of the sampler until released to Chemtech.
Upon arrival at the lab, the sampler will sign the COC form in the “relinquished by” box and note date and time.

0 125 250 375 500Feet
!.
!.
!.!.
!.!.!.
@?
@?
@?
@?
@?
@?
@?
@?
@?
@?
PropertyLine Sump
GW7c
GW2
GW4
GW9a
GW8
GW6
McHenryCampground(4997675)
Cunningham TunnelSampling Location
GW5(abandoned)
GW7b(abandoned)
GW1(abandoned)US40CulvertOutletGW9(abandoned)
GW13
GW12
GW11
GW10
Sampling LocationsBLX Mayflower Water ManagementWasatch County, Utah¯
Legend
@?2023 Monitoring Wells
@?Monitoring Well
!.McHenry Campground (4997675) Big Dutch Pete Hollow Sampling Location
!.Cunningham Tunnel Sampling Location
!.US40 Culvert Outlet
!.Abandoned Piezometers and Borings
Property Line Sump