19940599 Ver 1_Complete File_19950616

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Signed
N.C. Dept. of Environment, Health, lan\(d?) Natural Resources
V?rY

State of North Carolina
Department of Environment,
Health and Natural Resources
Division of Environmental Management
Ja mes B. Hunt, Jr., G ove mor
Jonathan & Howes, Secretary
A. Preston Howard, Jr., P.E., Director
June 16, 1995
Mr. Larry F. Baldwin
Land Management Group, Inc.
Post Office Box 2522
Wilmington, NC 28402
Dear Mr. Baldwin:
M1.9NA
A&14
CD F= F4
FILE COPY
Thank you for the opportunity to review and comment on the wetland enhancement-
mitigation plans for the Lowes tract in Carteret County (DEM #94599). This project is
unique because a wetland will be used to receive and treat stormwater runoff from the roof
and concrete aprons. The salient ecological issues are the quality of stormwater runoff, and
how the additional quantity and quality of water will affect the vegetation, hydrology and
water quality of the wetland. We believe our suggestions for monitoring will address these
concerns without an extensive effort.
Water Quality Monitoring
The quality of water leaving the roof and aprons, and entering and leaving the
wetland should be assessed. We recommend that water quality leaving the roof and aprons
be assessed during the early stages of selected storms. Water should be analyzed for total
phosphorus, total nitrogen, nitrate+nitrite-nitrogen, total Kjeldahl-nitrogen, total
phosphorus, soluble phosphorus, temperature, pH, conductivity, copper, zinc, and oil and
grease. Sampling should occur during one storm during March-June, and another storm
July-September.
We believe this protocol will address water quality concerns of water leaving the
project and entering the wetland. However, this protocol fails to address whether the
wetland is assimilating any pollutants (i.e. is the'wetland performing the functions of a
stormwater retention basin). The parameters listed above should be analyzed for water
entering and leaving the wetland site during peak, moderate and low flows that are
associated with the selected storms.
Monitoring should occur for three years. Water quality analyses must be performed
at a laboratory certified by the Division of Environmental Management.
Wetland Vegetation and Hydrology Monitoring
In addition to water quality concerns, monitoring should address how the additional
quantity and quality of water affect the wetland. Since wetlands are defined using
hydrology, soils and vegetation these components should be assessed or monitored.
Soils
The soil types of the site should be identified and described in the field. Are the
types present at the site the same as those identified in the soil manual for the county?
Environmental Sciences Branch 4401 Reedy Creek Road Raleigh, North Carolina 27607
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Ve2etation
The plan submitted states that "data to be recorded should include all vegetative
types and quantity sufficient enough to attain a representative percentage of vegetative
species present." It is not clear if all species within the 0.1 acre plot will be identified and
whether density and cover will be measured. A 0.1 acre plot is an appropriate size to
sample trees (dbh > 10 cm [4 in]), but is too large for shrubs and herbs. However,
reducing the size to sample herbs and shrubs will most likely position the sample plot too
close to the monitoring well used as the center of the 0.1 acre plot. A monitoring well used
to locate the center of a permanent plot has a disadvantage of attracting people. This results
in disturbing the vegetation near the well.
We recommend using three 0.05 acre plots for the 1.5 acre site. (This density of
sample plots is consistent with Corps of Engineer guidelines for monitoring bottomland
hardwood forest restorations.) Sample plots should be placed in a stratified random
manner, depending on the homogeneity of soils and vegetation and desired placement of
monitoring wells. All woody stems greater than 10 cm in diameter at breast height (dbh)
should be identified, counted and the dbh measured. The two monitoring wells may be
used as the centers for two of the plots. Since there are few trees present on the site, the
composition of shrubs and herbs also should be determined. However, the areas around
the monitoring wells should not be used as a sample site.
There are a variety of methods that can be used to determine the composition of
shrubs. One acceptable method would be to use belt transects (e.g. 2 x 10 m). All woody
stems less than 10 cm dbh and greater that 1 m in height could be identified and a visual
estimate of cover provided. The plots could be positioned 10 m along a known compass
direction from the monitoring wells.
We recognize that a quantitative measure of herbaceous plants is time consuming
and species composition changes throughout,the growing season. Therefore, we suggest
walking through the site, identifying as many plants as you can, and providing a visual
estimate of dominance or cover.
Vegetation should be assessed once each year during July or August.
Hydrology
Biannual sampling is not frequent enough to characterize ground and surface water
levels. Therefore we recommend using at least one continuous monitoring well for the first
year. After the first year, water levels in at least two wells should be noted during site
visits. The stratigraphy of the site where the monitoring wells are installed should be
described.
We believe our suggestions address the ecological concerns with a minimum of
effort and expense. However, since the monitoring plan is not complete we are willing to
assist in the development of a final plan. Please call if you have any questions.
Sincerely,
R. Nom
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