22001 2nd Quarterly Vacuum Reading Letter Report 20220307

2nd Quarterly Post-Occupancy Vacuum Readings Letter Report
South Graham Tower
Brownfields Project No.: 22001-18-060
ECS Project No.: 49:13566
March 7, 2022

1

March 7, 2022

Mr. Bill Schmithorst
NC Department of Environmental Quality
Division of Waste Management
Brownfields Program

Reference: 2nd Quarterly Post-Occupancy Vacuum Readings Letter Report
South Graham Tower
401 South Graham Street
Charlotte, Mecklenburg County, North Carolina
Brownfields Project No. 22001-18-060
ECS Project No. 49:13566

Dear Mr. Schmithorst:

ECS Southeast, LLP (ECS) has completed the Second Post-Occupancy Vacuum Readings Letter Report for the
above referenced site. These readings were collected in accordance with the Vapor Intrusion Mitigation
System Design Submittal, dated July 3, 2019, and prepared by S&ME, Inc., which was approved by the North
Carolina Department of Environmental Quality (NCDEQ) Division of Waste Management (DWM) – North
Carolina Brownfields Program (NCBP) in an August 7, 2019, email; and as discussed in ECS’ Post
Construction/Pre-Occupancy Sampling Report dated September 13, 2021.

On November 30 and December 17, 2021, and January 26, 2022, ECS personnel collected vacuum readings
at the measuring points MP-3 through MP-15. The readings are presented on the attached Table 1. As
can be seen, the readings collected are greater than the minimum vacuum reading threshold of 0.016
inches of water, with the exception of the readings collected from measuring point MP-13 which were all
below the threshold.

It should be noted that MP-13 is located in the area where construction activities and repairs were
conducted, and it appears that MP-13 was damaged and is no longer a reliable vacuum measuring point.
Additionally, in S&ME’s Vapor Intrusion Mitigation System Repair and Blower Replacement letter, dated
August 2, 2021, S&ME stated, “Based on the vacuum readings of the other points, we [S&ME] conclude
that the system is operating properly, and that Monitoring Point 13 is obstructed and is not registering
actual vacuum being imposes at the sample location”. According to the letter from S&ME, it appears that
even though this monitoring point is damaged, it does not affect the validity of the remaining measuring
points or the Vapor Intrusion Mitigation System.

ECS will continue to collect monthly vacuum readings at the site in accordance with the approved Vapor
Intrusion Mitigation System Design Submittal, and will submit an additional letter report updating the status
of the vacuum readings following the April 2022 measuring event.

Table 1
Monthly Post-Occupancy Vapor Mitigation System Vaccum Readings
MLK and Graham Tower
401 South Graham Street
Charlotte, Mecklenburg County, North Carolina
ECS Project No.: 49:13566
Sample Point ID Measurement Date Vacuum Measurement
(in H2O)
08/17/21 0.169
09/09/21 0.135
10/14/21 0.124
11/30/21 0.143
12/17/21 0.132
01/26/22 0.131
08/17/21 0.185
09/09/21 0.168
10/14/21 0.146
11/30/21 0.160
12/17/21 0.162
01/26/22 0.145
08/17/21 2.207
09/09/21 2.171
10/14/21 2.187
11/30/21 2.308
12/17/21 2.272
01/26/22 2.268
08/17/21 0.119
09/09/21 0.125
10/14/21 0.123
11/30/21 0.086
12/17/21 0.102
01/26/22 0.079
08/17/21 0.201
09/09/21 0.176
10/14/21 0.161
11/30/21 0.170
12/17/21 0.174
01/26/22 0.166
08/17/21 0.903
09/09/21 0.848
10/14/21 0.795
11/30/21 0.802
12/17/21 0.786
01/26/22 0.781
08/17/21 0.202
09/09/21 0.176
10/14/21 0.157
11/30/21 0.159
12/17/21 0.172
01/26/22 0.159
MP-9
MP-8
MP-7
MP-6
MP-5
MP-4
MP-3
Table 1
Monthly Post-Occupancy Vapor Mitigation System Vaccum Readings
MLK and Graham Tower
401 South Graham Street
Charlotte, Mecklenburg County, North Carolina
ECS Project No.: 49:13566
Sample Point ID Measurement Date Vacuum Measurement
(in H2O)
08/17/21 0.483
09/09/21 0.443
10/14/21 0.414
11/30/21 0.417
12/17/21 0.417
01/26/22 0.387
08/17/21 0.155
09/09/21 0.119
10/14/21 0.157
11/30/21 0.054
12/17/21 0.080
01/26/22 0.024
08/17/21 0.169
09/09/21 0.126
10/14/21 0.157
11/30/21 0.022
12/17/21 0.079
01/26/22 0.030
08/17/21 0.011
09/09/21 0.003
10/14/21 0.002
11/30/21 0.003
12/17/21 0.011
01/26/22 0.002
08/17/21 0.151
09/09/21 0.122
10/14/21 0.153
11/30/21 0.024
12/17/21 0.066
01/26/22 0.085
08/17/21 0.149
09/09/21 0.118
10/14/21 0.151
11/30/21 0.033
12/17/21 0.074
01/26/22 0.025
Notes:
in H20 = inches of water
NC = Not Collected
Values in RED indicate readings below 0.016" WC threshold
MP-10
MP-15
MP-14
MP-13
MP-12
MP-11