HomeMy WebLinkAboutWPO201500087 Study 2018-11-21Hirschman Water & Environment, LLC
Stormwater Management • Environmental Training • Environmental Policy/Plannin
Memorandum
Date: November 21, 2018
To: Town Properties, LLC
Katurah Roell, Manager
From: David J. Hirschman
Hirschman Water & Environment, LLC
Re: Hollymead Town Center, Service Area C, SWM Facility 2
I inspected the aquatic bench of the subject pond on November 20, 2018. All of my observations relate
to the aquatic bench itself. There is a complementary plant community along the shoreline (above the
water line), but my focus is on the current status of the bench.
The original plan from 2004 listed the following species:
• Iris Pseudacorus (Yellow Flag Iris)
• Iris Virginia (Virginia Blue Flag)
• Nuphar Lutem (Spadderdock, Yellow Water -Lily)
• Scirpus Validus (Soft -Stem Bulrush)
Over time, a naturalized wetland plant community has developed on the bench. Of the original list, only
Scirpus Validus remains. The table below lists species found on the bench on the observation date of
11/20/18. The existing plant community is more diverse and locally -adapted to this type of aquatic
environment than the original list. Other observations include the following:
• The late fall vegetation was robust along the outer, or shallower, half of the bench (closest to
the shoreline). It is likely that the inner, or deeper, bench area may be too deep for many of the
local aquatic species that have colonized the bench or that were originally planted. Given that, I
believe the bench in its current state is fulfilling the objective of a well -vegetated aquatic bench.
• It is likely that additional species would be detected during the growing season. The list below
can be a starting point in terms of monitoring the plant community through time.
• 1 would recommend allowing the existing plant community to evolve and not remove species or
replant at this point in time. In terms of non-native or potentially invasive or aggressive species,
I would continue to monitor the Typha latifolia and the Pyrus pyraster (on the west side of the
pond). At present, there is not a need to remove these and/or replant other species, as they
have colonized part of the bench and are in balance with other species. The future concern
would be if they start to take over or crowd out the other species.
1107 Calhoun Street, Charlottesville, Virginia
P: (434)409-0993 • Email: daveRhirschmanwater.com • www.hirschmanwater.com
Hirschman Water & Environment, LLC
Stormwater Management • Environmental Training • Environmental Policy/Plannin
• Over time, a tree canopy will form as some of the trees and shrubs get larger. It may be
desirable in the future years to cut -back some of these species, at least in some areas, to allow
the herbaceous layer to continue to thrive.
There is one area along the western shoreline (closest to Deerwood) where it appears that the
landowner has cut the vegetation and maybe even applied herbicide. This is likely a landowner
education issue, and the landowner should be apprised of the importance of letting the aquatic
bench grow back in, which it will do on its own if left undistrubed. At this point, it would not be
beneficial to try to replant that area if it will continue to be distrubed. Also, as stated, the area
will recolonize on its own if given the opportunity to do so.
In summary, my key finding and recommendation is to let the existing plant communtiy continue to
evolve, as it constitutes a good and relatively diverse aquatic bench community. In the future, it may be
necessary to undertake some maintenance tasks to maintain a healthy plant community. At this point in
time, it is not necessary to remove or replant any of the species.
Hollymead Town Center, Service Area C, SWM Facility 2: Aquatic Bench Species Observed on
11/20/18
Scientific Name'
Common Name
Location Along Pond EdgeZ
Herbaceous
Carex lurida
Sallow Sedge
E
Cytisus scoparius
Scotch Broom — not native
IN
Schoenoplectus validus (D)
Soft -stem Bulrush
A
Scirpus cyperinus (D)
Woolgrass
A
Typha latifolia (D)
Cattail — hybrid of native
W
Trees & Shrubs
Acer rubrim
Red Maple
IN
Corpus sericea
Red -twig Dogwood
E
Ilex verticillata
Winterberry
W
Liquidambarstyraciflua
Sweet Gum
IN
Platanus occidentalis
American Sycamore
A, especially IN
Pyrus pyraster
Wild pear -- not native
W
Salix nigra (D)
Black willow
A
Ulmus americana
American Elm
W
'(D) denotes that the species is dominant, meaning widespread across the aquatic bench
'A = All around pond edge; E = eastern edge (Hollymead T.C. side); W = western edge (closest to
Deerwood); IN = pond inlet;
1107 Calhoun Street, Charlottesville, Virginia
P: (434)409-0993 • Email: daveRhirschmanwater.com • www.hirschmanwater.com