HomeMy WebLinkAboutSUB200500206 Review Comments 2006-02-01County of Albemarle
Department of Community Development
Memorandum
To:
Jack Kelsey
From:
Tamara Jo Ambler
Division:
Planning
Date:
February 1, 2006
Subject:
Water Resources and Associated Buffers — Echols Subdivision Phase 2
Jack,
On January 31, 2006 I performed a field review of the water resources associated with Phase 2 of the Echols
Subdivision. The preliminary subdivision plat (SUB 2004 - 00333) was approved 1/4/2005, and the final
subdivision plat (SUB 2005- 00206) was approved 11/23/05. I have attached copies of both plats for your
reference. Phase 1 of the subdivision involves the construction of a roadway and the creation of 21 lots within
several parcels. Phase 2 of the subdivision involves the construction of a roadway and the creation of 6 additional
lots within a single parcel. In addition to the attached plats, Figure 1 illustrates the parcels associated with Phases 1
and 2 respectively.
My involvement was initiated through the receipt of a citizen complaint regarding possible disturbance to the stream
buffer associated with ongoing construction of Phase 1 of the project. In performing file research to respond to the
complaint, I noted that stream buffers were delineated on Phase 1 at Ivy Creek and a portion of an intermittent
tributary to Ivy Creek (labeled intermittent stream #3 in Figure 2). Both Ivy Creek and the intermittent stream #3
are identified on the 7.5" 1:24,000 series USGS maps. However, I noted that no buffer was delineated along the
upper portion of intermittent stream #3 adjacent to Phase 2. In addition, I noted topographic features within the
parcel associated with Phase 2 that were not identified as streams on the USGS maps, but could be delineated as
intermittent streams in accordance with the County's Design Standards Manual. 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. Field review of both features in the field showed that both do indeed meet the criteria for
intermittent streams, and therefore a 100 -foot vegetative buffer must be maintained on both sides of these streams.
The streams are labeled as intermittent streams #1 and #2 in Figure 2.
The following information outlines my findings in the field that resulted in my determination regarding streams #1
and #2. Intermittent stream #1 has a drainage area well over 50 acres, and clearly exhibits characteristics of bed and
banks, with the bed material different from the surrounding area. These characteristics persist along the entire reach
of the stream where Phase 2 of the Echols Subdivision is proposed (see Figures 3, 4, and 5). The Stormwater
Management plan for the development shows that this stream will be crossed by the subdivision roadway near its
confluence with intermittent stream #2.
reach of intermittent stream #1
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4 Downstream reach of intermittent stream #1, near confluence with intermittent stream #2
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Figure 5 — Downstream reach of intermittent stream #1, looking downstream to confluence with intermittent
stream #2
Intermittent stream #2 has a drainage area well over 30 acres and exhibits characteristics of bed and banks, with the
bed material different from the surrounding area. Although a smaller stream channel, these characteristics also
persist along the entire reach of the stream where Phase 2 of the Echols Subdivision is proposed (see Figures 6 and
7). In addition, the subdivision plat indicates that Lot 23 contains a significant portion of the stream.
►termittent stream #1
As would be expected, beyond the confluence of the two intermittent streams, the characteristics indicating that an
intermittent stream is present become more pronounced, and persist to the confluence with Ivy Creek (see Figures 8
and 9). The Stormwater Management plan shows a proposed drainage easement along the area, with a level
spreader to be installed at the ultimate confluence with Ivy Creek.
Figure 8 — Downstream of confluence of intermittent streams #1 and #2
In conclusion, the two intermittent streams described above require protection through the County's stream buffer
requirements. Undisturbed vegetative buffers must be maintained for 100 - horizontal feet on each side of both
streams. These buffers need to be illustrated correctly on the subdivision plat. Lot configurations must coincide
with these requirements and all buildable areas must be shown outside the buffer. Where the buffer is proposed to
be crossed by the roadway, mitigation for that buffer encroachment must be performed, which will require the
submittal and approval of a stream buffer mitigation plan. In addition, any instream work will require proper
authorization from federal and state regulatory agencies through the issuance of water quality permits. Prior to the
commencement of construction activities on Phase 2, these issues need to be addressed and resolved.
If you have any questions about this report, please advise.
Cc: Bill Fritz
David Benish