NC0023965_staff comments_20070508

ID
,object: mixing zones
From: Toya Fields <[e-mail]>
Date: Tue, 08 May 2007 16:41:38 -0400
To: Agyeman Adupoku <[e-mail]>
CC: Susan Wilson <[e-mail]>
Hey Agyeman,
This questionaire is geared more towards mixing zones, but we ask the same type of
questions for any model. Look at the sections on "plume characterization" and "plume
impacts". If this is a tidal discharge, we really need to get a good idea of what
the plume "looks" like. The plume will have a certain shape and there will be
variations in concentration through that shape.
The model Wilmington provided gives you effluent concentrations (where? it isn't
clear) at certain time periods during the tide. But what is their reference point?
Were they giving dilution at the outfall? Perhaps they were, but we also want to
know: where does the discharge plume go? Does it accumulate in a certain physical
area? Does the concentration of effluent increase over time as a result of
accumulation? Their analysis leaves a lot of questions unanswered. We need for them
to "characterize the plume". We're concerned about the accumulation (and transport)
of toxicants.
Just some thoughts. Lemme know if you need anything.
Susan- cc'ing you in case you need this info for your talk with Marshall.
Toya
Toya Fields - toya.fields®ncmail.net
Environmental Engineer I
Western NPDES Program
Division of Water Quality
Tel: [phone] x 551
Fax: [phone]
Mixing Zone notes2.doc
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