WQ0035749_Correspondence_20160726

K" r,,Io_
Water Resources
ENVIRONMENTAL QUALITY
PAT MCCRORY
Govemor
DONALD R. VAN DER VAART
Secretary
S. JAY ZIMMERMAN
Director
July 26, 2016
ROBIN MAYCOCK, LSS — ENVIRONMENTAL OPERATIONS ENGINEER II
NORTH CAROLINA DEPARTMENT OF TRANSPORTATION
1558 MAIL SERVICE CENTER
RALEIGH, NORTH CAROLINA 27699
Dear Ms. Maycock:
Subject: Permit No. W00035749
Pilot Study Approval
Diamond Grinding /
Hydrodemolition
Residuals Management System
Statewide
The Division of Water Resources Non -Discharge Permitting Unit has reviewed your Pilot Study
for Diamond Grinding Slurry (DGS) to a Highway Shoulder (enclosed) received July 20, 2016. The pilot
study proposes to apply DGS directly from the grinding machine via a boom discharge to the highway
shoulder. The pilot study proposes four sites: a control that will not receive DGS; two primary sites (Sites
204C and 206D); and an alternate site located along the I-85 shoulder within the off -ramp at Exit 204.
Based on the pilot study and proposed site locations, I am approving your proposed pilot study in
accordance with General Statute 143-215.3(b).
Please note that adherence to the pilot study outline, and the requirements within Permit No.
WQ0035749 shall be met. The pilot study shall be documented as noted in the approved proposal, and a
summary provided to the Division at the conclusion of the study.
As noted in Condition IV.7. of Permit No. W00035749 issued June 3, 2014:
"The Permiee shall report by telephone to the appropriate Regional Office for the county in which
the project is located, as soon as possible, but in no case more than 24 hours or on the next working
day following the occurrence or first knowledge of the occurrence of any of the following:
a. Any occurrence with the land application program resulting in the land application of
significant amounts of wastes that are abnormal in quantity or characteristic.
b. Any failure of the land application program resulting in a release of material to surface waters.
c. Any time self -monitoring indicates the facility has gone out of compliance with its permit
limitations.
d. Any process unit failure, due to known or unknown reasons, rendering the land application
incapable of adequate operation.
e. Any spill or discharge from a vehicle or piping system during DGS/HOS transportation.
State of North Carolina I Environmental Quality I Water Resources I Water Quality Permitting I Non -Discharge Permitting
1617 Mail Service Center I Raleigh, North Carolina 27699-1617
919 807 6464

Ms. Robin Maycock, LSS
July 26, 2016
Page 2 of 2
Any emergency requiring immediate reporting (e.g., discharges to surface waters, imminent failure
of a storage structure, etc.) outside normal business hours shall be reported to the Division's
Emergency Response personnel at telephone number [phone], [phone], or (919)
733-3300.Persons reporting such occurrences by telephone shall also file a written report in letter
form within five days following first knowledge of the occurrence. This report shall outline the
actions taken or proposed to be taken to ensure that the problem does not recur."
If you need additional information concerning this letter, please contact me at [phone] or
nathaniel.thornburgtiCcr�ncderin gov.
Sincerely,
Nathaniel D. Thornburg, Supervisor
Division of Water Resources
cc: Asheville Regional Office, Water Quality Regional Operations Section (Electronic Copy)
Central Office, Water Quality Regional Operations Section (Electronic Copy)
Fayetteville Regional Office, Water Quality Regional Operations Section (Electronic Copy)
Mooresville Regional Office, Water Quality Regional Operations Section (Electronic Copy)
Raleigh Regional Office, Water Quality Regional Operations Section (Electronic Copy)
Washington Regional Office, Water Quality Regional Operations Section (Electronic Copy)
Wilmington Regional Office, Water Quality Regional Operations Section (Electronic Copy)
Winston-Salem Regional Office, Water Quality Regional Operations Section (Electronic Copy)
Rob Willcox, LSS — Willcox & Mahe Soil Solutions, PLLC (Electronic Copy)
Digital Permit Archive (Electronic Copy)
Central Files

RECEIVED/NCDEWDWR
Pilot Study for DGS Application to a Highway Shoulde JUL 20 1016
NonOsaho%e
Submitted to NC DOT on 6/29/16 PermRling Un"
The `Pilot Study on DGS Application to a Highway Shoulder' will involve applying
diamond grinding slurry (DGS) to a length of shoulder along I85 and then monitoring the runoff
discharge from the shoulder to document changes in water quality of the runoff. I am proposing
that the study will take place on the southbound shoulder of I85 between the off and on ramps of
one of the exits. Monitoring at an exit provides several advantages including relatively easy and
safe access to the I85 shoulder, mostly hydrologically isolated shoulders (runoff from areas other
than the shoulder should be minimal thereby removing extraneous variables), and storm drains in
the ditch to provide monitoring locations. Vegetation on the shoulder was mostly Bahiagrass and
other volunteer plants with occasional patches of centipede. Analysis of 3 soil samples collected
from the shoulder of I85 documented a soil pH of 5.9, which corresponded to a recommended
lime application rate of 0.5 ton/ac for growing tall fescue. This lime application rate corresponds
to a target pH of 6.2; however, the pH range for growing bahiagrass, fescue, and bermudagrass is
6.0 to 6.5 and NCSU showed that a soil pH=7 did not significantly reduce the growth of these
grasses, so there is a margin of safety associated with this recommended application rate.
In order to document changes in runoff water quality associated with the DGS application
directing from the grinding machine, the runoff from three reaches of shoulder will need to be
monitored simultaneously. Two of the reaches will be existing shoulder with one without DGS
application (control) and one with DGS application. The third reach will have DGS application
after a cultivator -like tillage tool (leaves 4-5 channels parallel to the highway) is run on the
shoulder.
Water quality monitoring will include continuous rainfall and discharge/runoff
measurement as well as the collection of samples of runoff. An automated sampler will be used
at each monitoring station along with an associated raingage, a runoff measuring device such as a
weir or flume, and an in -situ water quality sensor such as a sonde. Samples will be analyzed for
total suspended solids (TSS), total phosphorus (TP), calcium (Ca), magnesium (Mg) and lead
(Pb), while the sondes will measure pH, conductivity, and temperature in the runoff. Previous
research on runoff from DGS application areas found that these water quality parameters were of
primary concern. Rainfall and runoff will be monitored for 10-15 storms (maximum of 3
months) to provide the data needed for a statistical comparison between the water quality data of
the three stations.
Photodocumentation of vegetation in application areas will be conducted. Also,
vegetation from two to three small plots (1-2 ftz) in the application and no application shoulder
areas will be harvested, dried, and weighed to document the growth of vegetation. Soil samples
will be collected near the end of the monitoring to document changes in soil.
APPROVED
North Carolina Environmental
Managernent Commission
Division of VVater Resources
Date J u �.� 2t, 20 ' c.
Permit # t,�Qoo 11 7�+1—

Pilot Study of Direct Discharge of Concrete Grinding Residuals to Roadside Shoulders
Submitted July 19, 2016
Timeline: Much of the timeline is dependent on the diamond grinding operation, but below is an
estimate:
Task
Period
Select 2 DGS application sites
6/30/16 to 7/14/16
Instrument 3 sites (includes control)
7/15/16 to 7/30/16
Pre-DGS application monitoring
7/30/16 to 8/15/16
Cultivation & DGS application
8/15/16 to 8/30/16 or when applied)
Post-DGS application monitoring
8/30/16 to 9/30/16
Sample soil and vegetation
9/30/16 to 10/10/16
Data analysis and reporting
8/15/16 to 10/31/16
Site Selection:
The control (no DGS application) site will be on the shoulder of the northbound lane of I85 at
exit 204A or B as presented at the 6/29/16 meeting. Two sites along the southbound lanes of I85
have been selected for application of DGS as part of the pilot study with a third selected as an
alternate. Initially the first (Site 209D) was to be located within the on ramp from Poplar Creek
Road to I85 at exit 209. However, the pH of 3 soil samples was 7.9, so this site is not
recommended. Hence, site 204C was selected (fig. 1). This site is between the off ramp and I85
as such it has a relatively narrow shoulder at the start of the off ramp, but then expands into a
wider than normal grassed shoulder near the storm drain inlet. The soil pH was 5.3 and thus
application of DGS would be recommended. I suggest using the cultivator at this site.
Figure 1. Pilot monitoring Site 204C.

The second site (Site 206D) is located along the shoulder of southbound I85 within the on ramp
from US 158 at exit 206. This section of shoulder is slightly steeper than that of Site204C, but of
similar width. The soil pH was 5.7 which is similar to site 204C in that DGS application to
correct soil acidity would be recommended.
N'igure 2. Pilot monitoring Site 206D.
The third or alternate site is located along the I85 shoulder within the off ramp at exit 204. This
is an excellent site for monitoring; however, the drainage angles away from the shoulder at the
downstream end thereby providing a much greater grass buffer between the shoulder and the
drainage swale (fig 1.).