HomeMy WebLinkAboutSUB200500352 Assessment - Environmental 2006-02-01County of Albemarle
Department of Community Development
Memorandum
To:
Jack Kelsey
From:
Tamara Jo Ambler
Division:
Planning
Date:
February 1, 2006
Subject: Review of water resources on SUB 2005 -0352 — Inglecress Lot 15 Family Division
TMP 60G -15
Jack,
On January 31, 2006 I field reviewed the water resources on the above parcel. My involvement was due to a request
from a concerned citizen for the County to verify whether or not an intermittent stream is present on this parcel. Because
this parcel lies within a water supply watershed, the presence of an intermittent stream would invoke the County's stream
buffer requirements. As shown in Figure 1 below, the land within the parcel does contain a topographic feature that
could point to the existence of a stream. The 7.5" series 1:24,000 USGS maps do not indicate a stream (either
intermittent or perennial) at this location. The County's Design Standards Manual allows for the field delineation of
intermittent streams if they have a drainage area of at least 5 acres and have defined streambeds and streambanks where
the bed and channel materials are distinct from the surrounding valley or swale.
FIGURE 1
Lot 15
It must be noted that significant removal of trees, shrubs, and other vegetation had taken place within the swale. This
disturbance likely altered the condition of the bed and channel materials, and conclusions from this field review are based
upon the current conditions.
The drainage area of the topographic feature at the southern border of the parcel is approximately 13.5 acres. The
streambed and banks of the feature were reviewed, starting just north of the parcel on Lot 40, where an 18 -inch culvert
directs runoff under Inglecress Drive to the feature. As seen in Figure 2, there is no evidence of defined bed or banks
immediately upstream of Inglecress Drive on Lot 40. Figure 3 shows that immediately downstream of Inglecress Drive
on Lot 15, at the outfall of the 18 -inch pipe more distinct banks begin to appear.
However, an inspection of the substrate material (channel bed) at the outfall area of the 18 -inch pipe did not reveal a
distinct difference from the surrounding area. Figures 4 and 5 show that a significant amount of leaf litter was present,
and below the leaf litter the soil appeared similar in nature to the surrounding soil.
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Figure 5 — Bed material not distinct from surround area
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As the swale progresses midway through the parcel the banks cannot be distinguished, as shown in Figures 6 and 7.
Again, significant remove of trees and woody vegetation is evident in this area, and this disturbance may have altered the
appearance. However, there was no evidence of significant earthwork such as grading or filling.
Figure 6 — View further down the swale where banks become less distinct
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Figure 7 — View looking back IM the parcel, where banks cannot be distinguished
Continuing further down through the parcel distinct banks again appear, but bed materials still appear similar to the
surrounding area, as shown in Figure 8.
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Figure 8 — View further down the swale, where banks become distinct again
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Nearing the southern border of the parcel, a substantial amount of brush and tree debris (apparently generated from
the removal of trees and woody vegetation along the swale) has been piled within the swale, preventing a field
review of the swale. See Figure 9. Immediately downstream of the brush pile, banks are more distinct, and the bed
material begins to become differentiated from the surround material, as shown in Figure 10. At this point a slight
flow was observed. Further downstream, beyond the southern boundary of Lot 15, a spring was observed
contributing flow to this swale, and from that point downstream the channel materials become significantly different
than the surrounding area.
Figure 9 — Brush piled in swale
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of Lot 15
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In conclusion, although the vegetation along the swale has been removed and the area has been disturbed, I did not find
sufficient evidence to consider the swale contained within Lot 15 an intermittent stream, based upon the criteria
established in the County's Design Standards Manual. At the southern boundary of the parcel where spring flow was
observed and the bed materials become distinct from the surrounding area, it appears that an intermittent stream does
exist.
Please advise if you have any questions regarding this field report.
Sincerely,
Tamara
Cc: Bill Fritz
David Benish