NCS000548_Email RE Basins and Sampling_20210325

Gamble, Aana C
From: Wylie, Robert R <[e-mail]>
Sent: Thursday, March 25, 2021 11:00 AM
To: Gamble, Aana C
Subject: RE: [EXTERNAL] Basins Designed to Hold the 25-year 24-hour Storm
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Thanks Aana. I'll ask the project team to review this and get back to you.
From: Gamble, Aana C <[e-mail]>
Sent: Thursday, March 25, 2021 10:43 AM
To: Wylie, Robert R <[e-mail]>
Subject: [EXTERNAL] Basins Designed to Hold the 25-year 24-hour Storm
Good morning Robert,
Per our discussion on Tuesday, here is some additional information about basins designed to contain the 25-year, 24-
hour storm. The language from the permit in part D-4(c) is as follows:
Analytical monitoring is not required for the outlet of any basin or pond designed to contain the 25-year, 24-hour storm
without discharging, and that can regain capacity to hold such an event within five (5) days' time through means other
than discharge to surface waters.
In other words, the basin must be able to contain the 25-year, 24-hour storm without discharging through the outfall,
and then it must be able to contain an additional 25-year, 24-hour storm within 5 days of the first event, also without
discharging during that 5 days. For example, the basin could be pumped out or water could be reused in another
process, but it can't be discharged to surface water in order to make room for an additional 25-year, 24-hour storm.
Alternatively, it could just be a giant basin with the capacity to contain at least twice the rainfall that would be expected
in a 25-year, 24-hour storm.
I hope that makes sense! Please let me know if you have any additional questions. I will be working from home today so
email is better, but I should be in the office tomorrow and can be reached at the number below if you prefer a phone
conversation.
Thanks!
Aana Gamble
Environmental Specialist 11, Dam Safety
Division of Energy, Mineral and Land Resources
North Carolina Department of Environmental Quality
Phone: [phone]
Email: [e-mail]
Physical Address: 512 North Salisbury Street

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