Page 1 800-662-9278 | www.michigan.gov/deq 10/2018

The Michigan Department of Environmental Quality (DEQ), Michigan Department of Health and Human Services (MDHHS), and the Livingston County Health Department (LCHD) are working together to evaluate the potential for health risks that could be occurring from historic releases of chemicals, including trichloroethylene (TCE). The releases contaminating the groundwater originate from a manufacturing property known as the ACO-Pittsfield Products (ACO) facility located at 461 North Dexter, Pinckney, Michigan. The contaminated groundwater plume undergoing treatment by ACO extends over a third of a mile southwest of this property. ACO is performing response activities to address the groundwater contamination under a consent decree entered with the DEQ in 1995.

Recent developments concerning exposure to TCE vapors through the indoor air pathway (vapor intrusion) have resulted in a re-evaluation of soil gas (vapors) emanating from the plume in the residential areas. A map of the groundwater contamination plume and its area of concern are included in this update.

The DHHS and the DEQ determined that concentrations of TCE in the groundwater within the ACO plume may pose risk in the residential areas, particularly for the school located over the center of the contamination plume. To address the immediate concern of potential vapor intrusion risk to the school, the DEQ staff collected two soil gas vapor samples and four (4) indoor air samples within the school in July 2018. The soil gas and indoor air results indicated that plume chemicals were not present in the soil gas and the indoor air when the samples were collected. Later in the summer, ACO voluntarily installed two soil gas wells over the centerline of the plume in residential areas east and west of the school. Analytical results from the west soil gas well located near Unadilla and Stuart Street did not detect vapors from the groundwater contamination. However, analytical results from the east soil gas well located on Hamburg Street east of William Street detected TCE in soil gas at 340 ug/m3, five (5) times above its site-specific criteria. The evaluation of this data by the DEQ, DHHS and Livingston County HD resulted in a decision to request that ACO evaluate residents at risk of vapor intrusion by requesting permission for the collection of sub-slab soil gas samples (lowest level of the home) coupled with indoor air samples. Since ACO did not commit to perform these response activities, the DEQ are providing funds necessary to evaluate vapor intrusion risk within residential structures over the plume. Recently, the DEQ requested 17 home owners to allow access for this purpose.

ACO agreed to install and collect quarterly sample from three soil gas wells between its facility and the impacted soil gas well to evaluate concentrations of TCE and other chemicals in soil gas emanating from the groundwater contamination plume. The soil gas wells will be installed and sampled by late October 2018. This information will be used by the DEQ to further prioritize residential sub-slab and indoor air sampling.

The DEQ has hired a consultant experienced in vapor intrusion investigation work to collect sub-slab soil gas and indoor air samples for home owners granting permission to install at least one vapor pin at the lowest level of their structure, collect a soil gas sample and co-located indoor air sample. A household chemical survey is conducted so that chemicals suspected to be present in household products related to the plume may be removed prior to

ACO-PITTSFIELD PRODUCTS SITE INVESTIGATION PINCKNEY, MICHIGAN Project Update and Information

Find more information on the DEQ Web site at www.michigan.gov/vaporintrusion.

Primary Site Contacts:

DEQ: Rebecca Taylor, Project Manager taylorr@michigan.gov 517-284-5160

Livingston County HD: Matt Bolang, Director of Environmental Health MBolang@livgov.com l 517-552-6870

DHHS: Lisa Quiggle, Toxicologist Quigglel@michigan.gov 517-284-4812

Page 2 800-662-9278 | www.michigan.gov/deq 10/2018

ACO-Pittsfield Project Vapor Intrusion Investigation

sampling. Building, heating and cooling characteristics are also recorded to help determine placement of the vapor pin and evaluate the analytical results. Typically, soil gas and indoor air samples are collected seasonally to evaluate vapor migration variability for the school and residential areas.

If a vapor intrusion exposure or risk of exposure is identified, the DEQ are installing sub-slab depressurization (SSD) mitigation systems or upgrading existing radon systems, if applicable. If a vapor intrusion exposure is identified, DHHS and LCHD staff will determine if the residence may be occupied prior to mitigation of the vapors. In most cases, an air purifying unit is provided to clean the air prior to installation of the SSD system. SSD systems operate in a similar manner to radon systems but are installed with extra testing to ensure proper function and removal of chemical vapors and naturally occurring radon gas. A few days after installation, the indoor air is tested at every level of the home to ensure that TCE vapors are mitigated to safe levels.

After this initial investigation, the DEQ may continue investigating residences within and near the groundwater plume for vapor intrusion if indicated by the data. If the vapor intrusion investigation continues, the DEQ and may ask for permission to enter your home at your convenience to evaluate if TCE and other chemical vapors may have reached your property and into your home. This will help us understand what actions, if any, should be taken to address the matter. If you were contacted by the DEQ for permission to enter your property and have not returned a signed access agreement, please contact Ms. Rebecca Taylor at 517-284-5160, as soon as possible to discuss a sampling agreement and to schedule an appointment.

The following is a map showing the DEQ investigation area, groundwater plume and treatment areas. Refer to the fact sheet titled “What is Vapor Intrusion and how is it investigated” for a description of vapor intrusion and the investigation process.

#

#

SG-2

SG-1

TCE ND ug/m3

TCE 340 ug/m3

VP-2

VP-1

RW-1RW-2

RW-3

RW-4RW-5

MW-1s

MW-2sMW-3s

MW-4sMW-5s

MW-6s

MW-7s

MW-8s

MW-9s

MW25s

MW-10s

MW-11s

MW-13s

MW-14sMW-15s

MW-16sMW-17s

MW-18s

MW-19s

MW-20s

MW-21s

MW-22s

MW-23s

MW-24s

MW-26s

MW-27s

NA

NA

4.84'8.66'

5.43'2.32'

3.78'

5.03'

11.96'

16.54'

17.78'

10.69'

12.22'

14.74'

16.29'

21.10'

Sources: Esri, HERE, DeLorme, USGS, Intermap, INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), MapmyIndia,NGCC, © OpenStreetMap contributors, and the GIS User Community

LegendCurrent Soil Gas WellProposed Soil Gas Well

# Vaper PinRecovery WellMonitor WellProposed VP Install1,000 to 10,000 ug/l Total VOCs100 to 1,000 ug/l Total VOCs>1 to 100 ug/l Total VOCs

ACO Facility

DATUM - NAD83PROJECTION: MICHIGAN GEOREFAERIAL PHOTO SOURCE: ESRIData sourced from Quantum Environmental, Inc.

®

0 250 500125 Feet

1 inch = 225 feet

FIGURE 1CREATION DATE: SEPTEMBER 2018

ACO Site- GroundwaterContamination Plume

Site ID- 4700013PUTNAM TOWNSHIP, LIVINGSTON COUNTY

T1N R4E SECTION 23

SITE MAPPHASE 1: VIAP

Remediation and Redevelopment Division

Groundwater FlowApproximately SW