HomeMy WebLinkAboutC.054.93011_1348Robertson: The intent of the ordinance was to deal with the water quality issues and to prevent
some of the problems we had before. Iredell County gets many benefits from having a good,
clean lake. Because of the lake, streams, and the Catawba River, Iredell County is known for
its good quality of life, and there's much value in having clean water sources. Lake property has
high property values, and many parts of the county obtain their drinking water from Lake
Norman. Long term, many governmental entities will be held accountable for the quality of
water or the degradation of the water sources. We have a vested interest in making sure we
don't muck up our water because of irresponsible or shoddy construction. I've built two homes
on the lake. The first was built wrong with a little silt fence on a very steep lot. The builder met
the letter of the law, but not the intent. All of the topsoil from my lot washed into the lake. The
lot for my next house was not as steep, but two silt fences were installed. The lot was seeded
multiple times. We did not remove the first silt fence until there was a stand of grass
established. We didn't remove the second one until a year later. The plant life in the
designated buffer zone wasn't disturbed either. There is a right way and a wrong way. I was
fortunate with the last house. It was done right. You refer to 10 year and 25 year storms. For
clarification, when you talk about stormwater runoff as resulting from precipitation of an intensity
that is expected to be equal or exceeded on average once every x number of years, is that a
peak for how many inches per hour for one hour? Is it inches of rainfall over the course of a
day? What is the time unit?
Selquist: There are tables where you could find this information. You can get the information
from NOAA (National Oceanic and Atmospheric Administration) to calculate the runoff. As far
as to whether it's a 24-hour period, I believe it's a 24-hour period, but there are tables for this.
Robertson: The standards need to be easily understood. On the buffer zone, the ordinance
states that most of the silting has to occur within 25% of the buffer zone. Can you clarify this —
how big the buffer zone would need to be?
Selquist: This will vary and be dependent upon the area's size that is adjacent. Also, it would
depend upon the slope as far as the velocity of the water. What it is stating is that within the
first 25% of that total buffer zone, all the sediment coming off the exposed area needs to fall out
of the water flow. Basically, if you had a 100 -acre buffer, and the sediment was coming down, it
would have to be filtered out in the first 25 feet. You could make a calculation that if 25 feet
were required, then you would need a 100 -foot buffer.
Robertson: Calculations would have to occur on large-scale projects as opposed to small lots if
there was a fairly steep slope and a high clay -soil content. Then, a greater buffer might be
needed as opposed to a flat property with soil that didn't have as much clay.
Selquist: Yes, calculations would be determined on a case -try -case basis.
Robertson: On page nine, Section (b), pertaining to angles, will the staff be measuring these or
using the county's GIS topographic maps?
Selquist: The angles would be dependent upon the type of soil in the area. There would be a
determination on how steep the slopes could be for that soil type. We would look at the slopes
— it would be on a case-by-case basis dependent upon the soil type.
Robertson: On page ten, Section (d), pertaining to the plan's contents, are these by state and
federal laws? You didn't come up with the requirements for maximum velocity. Most of these
came from state and federal laws. Is this correct?
Selquist: Yes. These were taken right out of the state regulations
Robertson: On page thirteen, Section (f), pertaining to stormwater runoff and "measures to
control the velocity to the point of discharge so as to minimize accelerated erosion of the site
and increased sedimentation of the stream." What does minimize mean as opposed to just
reducing? I'm concerned about what is a threshold with this section. Are we asking them to
show intent, or how do you know when someone has accomplished this?
Selquist: As far as the word "minimize," I would read this to be that it needs to be controlled
down to the threshold levels as far as particle size coming off that slope and there are some
standards within the ordinance that address this. You would have to reduce the velocity so that
you could maintain the threshold requirements for the different size particulate matter.
Robertson: To minimize and accelerate erosion down to the threshold.
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