UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y REGIO N VII I

9 99 18th STREET - SUITE 600 DENVER, COLORADO 80202-2466

INITIAL POLLUTION REPORT Midvale Slag OU2 Abandoned Well s

27020

SF FIL E NUMBER

I . HEADIN G

Date: Subj ect: From: T o:

POLREP No.

10/10/96 Midvale Slag NPL Sit e (OU2 ) Abandoned Well s Mike Zimmerman, OSC /Yy\oL4 Anne Spencer, EPA Headquarters Emergency Response INITIAL POLREP #1

71UTD081834277 CERCLA UDEQ Notified

07/26/96

10/3/96 N /A

I I . BACKGROUN D

Site No. : . CERCLIS No: Response Authority: Stat e Notification : Action Memorandum: Start Date: Completion Date:

III . SIT E INFORMATIO N

A. Incident Category

Time-Critical , NPL

B. Sit e Description

1. Sit e Description ' ' j

T he entire Midvale Slag site consists of about 530

acres; OU2 covers about 200 acres of the Site . A smelter

operated on OU2 from 1897 until 1958. lOver the years, it

changed from a copper to a lead smelting facility , producing

gold/lead/silver bullion from sulfide ores. Five wells were

installed on OU2 in 1936 in the Deep Principal Aquifer for

the purpose of supplyin g water to the smelter. During the

demolition of the smelter in 1960, the surface casings of

the wells were damaged and several of the well heads were

covered with demolition materials. It appears that the

wells remained in an unprotected condition for many years,

Printed on Recycled Paper
making it likel y that surface water and windblown smelter

 • I ; ; waste materials entered the casings.

2. Description of Threat

As a result of damaged/deteriorated surface casing of 5 wells on the OU2 site, surface water and windblown smelter

waste materials have entered the wells , and they now show

elevated concentrations of several metals , especiall y barium

and cadmium. Since there are abundant concentrations of

lead, arsenic, copper, silver, chromium, and zinc in the

slag, dross, and baghouse dust found on the Site from

previous smelter operations, it is possible that addition metals could migrate into the wells in the future. Because

these wells may be acting as conduits for contamination to

the underlying aquifer, they will be abandoned and plugged.

C. Sit e Evaluation Results

During the EE/CA field investigation in 1993, the surface

casings for these 5 former water-supply wells were located. Two

of the wells were sampled and showed elevated concentrations

greater than the Maximum Contaminant Level (MCL) for total and

dissolved barium and cadmium. These elevated concentrations

might be accounted for by surface water infiltratio n due to

severely deteriorated well casings at the surface.

I V . RESPONSE INFORMATION

A. Situatio n

1. Current Situatio n

On October 3, 1996, the EPA ERGS Contractor mobilized

to the Sit e to begin the pluggin g and abandonment of the

five (5) wells. The well stems on the nine (9) monitoring

well s will be removed and the well s will be plugged and

abandoned. When this is completed it will remove a conduit

for contamination and an obstacle to future remediation.

2. Next Steps

T he Contractor plans to complete the pluggin g and

abandonment of the wells within 3 weeks.

V. COST INFORMATION

Since this is the initial POLREP, costs are stil l minimal.
POLREP FILE GENERATION

(to be submitted by OSC with initial Polrep)

Site Name: Nl t OO & US "SiUVCg - A^ ft-H Oo 64€O ^^ <JLS>

City/County/State: M

SSZD #0. I/ CASENO.

Polreps Dist. List

1. Program Dir., Doug Side, T. Leaders: Jim Knoy, Steve Hawthorn,

Luke Chavez (rotating)

2. RA, DRA, ARAships

3. ERD - Headquarters ATTN: Director (5202G)

4. Region Response Team Members (via fax - 19 members)

5. 8OC ATTN: Rich Lathrop

6. Legal Depart (ENF) ATTN: Oots-vM^ A\^5HJ>Q. , ttS-\c -

7. osc: M,u<e

8. EPS

9. Adm. Records Coordinator

10. State Program

Director/Manager \4 g ^T G 0.^^ ^ O

Address "3. U

11. National Pollution Fund Center: Y 01

12. Ann Spencer HQ/EPA 703/603-9116