HomeMy WebLinkAboutFDP201600004 Study Floodplain Development Permit 2016-08-01
July 6, 2016
Mr. Alan Taylor
Brookhill Development, LLC
455 Second Street, SE
Suite 400
Charlottesville, Virginia 22903
TNT Project #: 330‐A1
Reference: Threatened and Endangered Freshwater Mussels Habitat Assessment, Brookhill,
Albemarle County, Virginia
Latitude: 38o 06’ 10” N, Longitude: 78o 26’ 59” W
Dear Mr. Taylor:
TNT Environmental, Inc. (TNT) is pleased to present this Threatened and Endangered Freshwater Mussels
Habitat Assessment for the above‐referenced project in general accordance with TNT Proposal Number
699, dated November 6, 2015. The potential for threatened and endangered species on and in the vicinity
of the project site was evaluated using available information and project reviews through the Virginia
Department of Conservation and Recreation (DCR), the Virginia Department of Game and Inland Fisheries
(DGIF), and the US. Fish and Wildlife Service (USFWS) Information, Planning, and Conservation System
(IPaC). During these reviews, two protected freshwater mussels were identified as having potential
habitat near or within the vicinity of the project, warranting habitat assessments for these species.
PROJECT SITE DESCRIPTION
The project site is approximately 277.497 acres and is located in the northeastern quadrant of the
intersection of Route 29 and Polo Grounds Road in Albemarle County, Virginia (Figure 1). The project site
is further identified by physical addresses 2571 and 2575 Seminole Trail and Albemarle County Parcel
ID#s: 04600‐00‐00‐01800, 04600‐00‐00‐018A0, and 04600‐00‐00‐01900. The terrain of the project site
consists gentle, moderate and steep slopes and is within the Rivanna River drainage basin (Figure 2). TNT
completed a wetland delineation on the project site in May 2015, which was confirmed during a
jurisdictional determination with the U.S. Army Corps of Engineers (NAO 2015‐02084, dated December 8,
2015). Based on the results of this delineation, approximately 12, 205 linear feet of perennial stream are
present onsite, all of which drain to the south towards the Rivanna River. Portions of the site have been
timbered and left fallow. Bottomland portions of the site are largely undisturbed with the exception of a
sanitary sewer line paralleling most of the length of perennial stream.
PROJECT BACKGROUND INFORMATION
Based on the threatened and endangered species database reviews, the green floater (Lasmigona
subviridis), a State‐listed threatened freshwater mussel, has been historically documented in the South
Rivanna River, located approximately one mile south of the project site. DCR has recommended a habitat
Brookhill Development, LLC
July 6, 2016
TNT Project #: 330‐A1
Page | 2
study to evaluation portions of the project site for habitat suitable to potentially sustain populations of
this species.
Based on the DGIF threatened and endangered species database review, the James spinymussel
(Pleurobema collina), a Federally‐listed and State‐listed endangered species, is noted as being observed
within Ivy Creek, located two miles southwest from the project area, as well as having potential habitat
within the South Fork Rivanna River located approximately ¼ mile south from the project area if suitable
habitat is present.
According to DCR, the green floaters’ preferred habitat includes pools and eddies with gravel and sand
bottoms of smaller rivers and creeks, or small to medium sized streams.
The James spinymussels’ preferred habitat includes perennial, free‐flowing streams with a variety of flow
regimes and water depths. It requires slow to moderate water current with clean sand and cobble bottom
sediments. The James spinymussel is found in a variety of substrates that are free from silt.
FIELD INVESTIGATION & METHODOLOGY
TNT ecologists, led by Mr. Avi Sareen – Certified Ecologist, conducted a pedestrian survey through the
onsite perennial streams to evaluate them for the presence/absence of suitable habitat to potentially
sustain populations of the green floater and/or the James spinymussel. The survey was conducted from
downstream to upstream in order to maximize instream visibility. Visual inspections were conducted by
two individuals by traversing each stream using alternating sine curves. The entirety of each perennial
stream was traversed from south to north through the project site.
FINDINGS & CONCLUSIONS
Based on TNT’s habitat assessment, no freshwater mussel species were observed in any of the onsite
perennial stream reaches.
The majority of the onsite perennial streams are underlain by bedrock. While some banks are stable with
rock, existing vegetation, root mats, etc., many of them are exposed, raw, and prone to erosion. Large
amounts of silt and sedimentation were observed throughout all stream reaches (including intermittent
and ephemeral) in riffles and pools, alike. Substrate sorting was moderate to weak due to the large
amount of sedimentation. Large, circular gravel deposits were observed mid‐channel, likely a result of
the lack of stream competency to effectively transport sediment.
Both mussel species in question prefer sorted substrate with a gravel or cobble bottom that contains
limited silt/sediment deposits. Given the site conditions encountered onsite, it is TNT’s opinion that
suitable habitat for both the James spinymussels and green floater is not present within the study area.
Brookhill Development, LLC
July 6, 2016
TNT Project #: 330‐A1
Page | 3
Despite the lack of suitable habitat for the green floater and James spinymussel, TNT concurs with DCR
and recommends the implementation of and strict adherence to applicable state and local erosion and
sediment control/stormwater management laws and regulations, to minimize adverse impacts to the
aquatic ecosystems as a result of the proposed activities.
TNT would like to thank you for the opportunity to provide you with this habitat assessment. We look
forward to assisting you further with this project and other environmental concerns you may have. If you
have any questions, please feel free to contact us at any time at (703) 466‐5123.
Sincerely,
TNT ENVIRONMENTAL, INC.
Avi M. Sareen, PWD, PWS, ISA‐CA
Principal/President
Avi@TNTenvironmentalinc.com
BROOKHILL PHOTOGRAPHIC LOG
TNT ENVIRONMENTAL, INC. JULY 2016
Photograph 1: View to the south showing a portion of perennial stream in the south‐central
portion of the site. Note the heavy sedimentation and mid‐channel deposition.
Photograph 2: View to the north showing typical substrate within the perennial stream in the
south‐central portion of the site.
BROOKHILL PHOTOGRAPHIC LOG
TNT ENVIRONMENTAL, INC. JULY 2016
Photograph 3: View to the north showing typical bench deposits within the perennial stream in
the south‐central portion of the site.
Photograph 4: View of a portion of riffle substrate within a portion of the perennial stream in
the south‐central portion of the site.
BROOKHILL PHOTOGRAPHIC LOG
TNT ENVIRONMENTAL, INC. JULY 2016
Photograph 5: View to the southwest showing a portion of perennial stream in the
northeastern portion of the site, near proposed Impact #9.
Photograph 6: View to the south showing a portion of perennial stream near the northern
property boundary at proposed Impact #10.
BROOKHILL PHOTOGRAPHIC LOG
TNT ENVIRONMENTAL, INC. JULY 2016
Photograph 7: View to the southeast showing a portion of perennial stream near proposed
Impact #12.
Photograph 8: View to the northwest showing a portion of perennial stream near proposed
Impact #13.
BROOKHILL PHOTOGRAPHIC LOG
TNT ENVIRONMENTAL, INC. JULY 2016
Photograph 9: View to the east showing a downstream view of the perennial stream at
proposed Impact #14 in the northwestern portion of the site.
Photograph 10: View to the south showing a portion of the perennial stream at proposed
Impact #1 in the southwestern portion of the site.
4IMWATERWAYS
CONSULTING, INC.
Ecological Restoration Design ^' Civil Engineering ^' Natural Resource Management
Hydrologic and Hydraulic Analysis
for
Brookhill
Prepared for Collins Engineering
December 18,2015
HYDROLOGY
The Brookhill project is located adjacent to the South Fork Rivanna River directly downstream of
the Route 29 Bridge. A small portion of the project is located within Zone AE of the FEMA Flood
Insurance Study(FIS)for Albemarle County and the City of Charlottesville (Map#:
51003CO280D). 100-year stream flows for this analysis use the specified values in Table 3 of the
FIS for the South Fork Rivanna River at the river's mouth. The 100-year flow at this location is
53,400 cubic feet per second.
HYDRAULICS
A HEC-RAS hydraulic model was developed to analyze impacts associated with grading within
the regulatory floodplain of the South Fork Rivanna River. The following model components
were used in this analysis.
Cross Sections
Cross Section locations were selected based on available topography and proposed project
grading(See Figure 1). Eleven cross sections were used to compare existing conditions to
proposed grading. Roughness values were set at 0.12 for within the channel and 0.06 for
overbank conditions, per Table 4 of the FIS.
Flows
The 100-year flow value of 53,400 cfs was used for the entire reach of the model. Upstream
boundary conditions were based on channel slope(Normal Depth). Downstream boundary
conditions used the Known Water Surface of 359.2'to match the FEMA water surface
profiles at that location.
RESULTS
The FEMA Flood Insurance Study states that regulatory base flood water surface elevation for
this portion of the South Fork Rivanna range from 358.7 to 360.2 feet(Floodway Data,Table 5 of
FIS,Cross Sections E, F, &G). The proposed grading within regulatory floodplain is mostly cut
with very minimal fill associated with widening of Polo Grounds Road to the north,and two new
connector roads for the Brookhill development. The results of this analysis show that there is no
rise in the regulatory 100-year flood elevations due to the proposed grading associated with this
project. HEC RAS flood profiles,cross sections,and output table have been provided in
Appendix A.
509A Swift St,Santa Cruz,CA 95060, Ph:831-421-9291 1/ 1020 SW Taylor St.,Ste 610,Portland,OR 97205, Ph:503-227-5979
[see-se trr wrR1dNaY ?a
OIOGs V7 tow V11,4
15 lei MOO -
'SNI�Nlllf1SN0�� *g3 � 10-31`01:14:17111-1)1001:19g.g
SAVM2i31VM iiis; 1
-Z
6
8
3
1
Or
P'
y 4"
@ 4f
i
Q
4
4IMWATERWAYS
CONSULTING, INC.
APPENDIX A
Ecological Restoration Design - Civil Engineering - Natural Resource Management
c
'o c
2 O
0 0
x
C O 1-1-1c c
r . — o p o
CLLI-
CL
a cn
C
0
_0
0
Ln
0
N
T
_
■
✓ 0
0
0
c
O _
U ■
X
W -
N
■
Ln
0
N •
1— _O
N c0 =
y
U
• c
C
C _n
'5 0
�2 N
V c
CL t
O U
c
a
o
T o
0
N
E -
as
0 •
L
o0
O
m O
0
-o
•
, , , , , , , , , , , , , , , , I I , , , I . , 0
cmcto
o N o
co co co co co co co co
(u)uoilenel3
a C a O O
C
N (p co tz
C7 U U U 0 (� 0 U U U 0
c• o W �j W o o c o w W w a o
0 LL c Co 0-
(n D_ d T a d
as J LL c fn co
cn 3 C7 $ ° „ a c. 2 c
cn
CO
-N -O
V
O
O
o
O
O
U U
W LX o
o
N (V
0
LI116.16)1_
-o
co
0 X Q v) -0
O X _
0 - E 0-
-o o "- o
01 - io
C - C C/)
CZ al
0- C -o
co
a— _ _c -
2 _0 o 0
m m _
0
-o
v
o • II
-
= N 0
-o
- N
I / 1 i i iii11111i , 111 / IIIIIIIIIIIIIII 0 i I i I i i i I I 1 p i f I 1 i i 1 I 1 i „ o
O O O O O O o O O O O O O O
O O) co N- (o U co a0 n (o (f) m• c")
co M M 0) 0) 0) 0) M 0) 0) M 0) 0)
(u)uollen013 (u)uollenel3
o = c o CI) o
0,15 k k 13 C 0 \ 0 j k j ti
\
0 0 0 0
13 C
\ C. ) W E 0 C 0 \ x j . 0
�§ , o . e. .�e0_ & 4a_ c,e& .2 ea
j J 2 « ' Q j ,_ J 2 2 ' Q
J G c e L J «
\ \ 03 J % 2 §
a m k 0 ]
00
_2 _E
11\11.1111118144111116418.1 _
_% �\
0
k �\ / /
_.III)
CV
lliliga)
0
_a
E _0 =
Es k
O0, Om
-0
/2 \$
a. ¥ a_ F.
-% / •— - §
a al
E c
as as 0
E - �2
-co= 0 . -
2 o § -o
03 _ 03 (0
_0
_0
et
-0
N
0 111 o
0 0 0 0 0 0 0 0 0 0 0 0 0 ~ '0 ^ '0 0
CD 7 a 0 CO CD $ q CO 7 > 0 CO R A q
Uppna UpRenes
E 0) E 0) E c0)
---a
7 2 \ t 7 7 2 7 ) 2
c o § o a o c o 3 % o 0
2 E / j E 0 2 O ) Q.
eu \ - `%'a ��'% $ �� °%®Q '�®\
U. c e m LL C « ' _
J § C 2 L § 2 §
\ \ ) .- « \ o d «
I a c ]o 0
_o cv0
\ 1111.51.110ftiftekam _
V
- 0 -\
w W
o -
7 _ 7
ON. 0C
oX - 02 -
0_ E LI ¥
I �0 ) — -0 $
C _ c _ co
ƒ ƒ
/ /
CO 11_ 03 -
-0 -§
, , , , , , , , o . TIP, , . 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
7 Q 0 m CD ¥ @ ¥ m m % CD m $ §
UpRBAe UuBAa
5
E3 = c ° 'v E c c c V
v R
0 U U ca 0 ° ° cd
�j C7 U �j U C7
c o w W w o o c o w W w a o
1 a ❑.•, ■a Ga d .a ❑i•' ■a•ll
J LL c fA 05
U) 3 m a cn U g c
U m m U m
o o
N M
00
O N
O
N
U U
111 w
N
c..7.1.
T
- o
_o
0
N
O
e to
cn
O X 0 X
2
d - -
° T o c
r _
ca
iC
C c (n
a -03 al
a -
0
0
0
Yo Y
It i
m - m 22 O
O
O
-O -
to
O
-O
to
, , . , , , . . , , , , . , , , , , , , . , , to , wei . ,al o
O O o O O O 000000000
N O c0 f0 N
a a CO M CO M 7 O m M Cr..; (aM M M
(u)uoi;enei3 (u)uoilenal3
c O co of 0
"C 'C C -0 'C C C
E5 °
C7 U U U .-
at
D C7 0 U 8 U 0
C o lL ul tL o 0 C o W Lues W o 0
mea` ❑ . •� .a �n � .a` ' ❑ , •� .aOa
J ,- LL C (n is J r LL C CO
co
d fn c 0 O CO d cn `O f0 o Y
co 3 m m in 3 CD m 3°
m O m O
_0 _0
■
wass
cO
M M
Mgill"li.gi
O
U co U M
cO
W W
N N -
o 0 o
'5 N 5 N
CD M CD N
O x 0 X
0_ E d r
— N 0 - _0 0
c+ N l0
NC0
cu 03
CL CL
_
O _ p
LE La - r
CO 2
1.? _ m
0 0
_O p
O p
O o
-N -O
0
O OO O O O O O O O O O O O
No co co et N O m co I-- co N et co
et et co co M co 7 co M M co co M co
(u)uollen013 (11)UOQBn0l3
C
C
O fd C o
0 U (}
c w o w W a o
4n. ❑ . • ' •ao
•d
a c N - ro
o
(/) U m 2 c
3 � m
0
o
M
.111.11111111411.11"1211
O _o
U
X
N
o
N
0 r
O-X
/L
-p
O
N
fa
0
_ p
o
O
L
m
0
_o
0
-o
O CO tpp N
V M M M
(u)uopnal3
N_ N_ 0_ _0 COO 8 O N N N Un CO CO M M CO M N N M CO
O O 0 0 O 0 0 0 0 0 O O O O O O
V O O O O 0 O O O O O O C O O O O O O 0 O O O
O
LL QOpp
t O (D N N N O - N 0 CO0N n CO N N N CO CO CO N O 0
UN() CO CO CO0COMCO N. N.
(O I^O I( M O) N. N. ai CC) M M 0 N N CO N
• ^
N. Na
N N N N M (O N M M CO
H8
1f) CO 0) N CO (0 a 0) Of C) 1f) V N 0 0 0 0
U) 0) '- co O R N pp m 0) I7 N C) 0 p0 N O V- N M to
• fD N
(N� (n n O O O LO (f.M�� jr,' N. N. (00 (O 0 co O (�(0 �Q 7
2 ^ N (D (0 aO OD 0/ O) N N N OND M CO CO R ' () ^V N.
LL 0)
coOco co co (_n an m N LO N ON) ONN
) O) COMOMD (CO (MO CMO CMO
L MM N N (U N N N ,- .- 4. 4. O O O O O O O O O O
U
0
N Of N O 0) O) a 7 CO CO 0 0 N N CO OD 0 0
� o5 88 8 0 88 88 88 00 ss os so
0 E O 0 0 0 0 0 O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
x "00 00 00 00 00 00 00 00 00 00 00
W
(0 N CO (0 N N 0 0p 0) Cr) N N 0) 0) UO LLD CO CO N N
• V V ^ N 0 0 CO CO ^ 3 M M M MN N N N N N N N
2 O O O O Oi 0) Oi O) 0) O) O) 0) O) 0) O) 0) Oi 0) O) Oi T 0i
W CD CO CO CD CO UO 1O N UO (f) LO ID UO (L) (f) (C) N (f) LII (O (0 tO
E.M M CO CO CO CO CO M CO CO CO CO CO CO CO CO M CO M CO CO CO
U
W
CO CO
N Uri tri
av fD D 0 fO
aNNCO NNN. `- CO CO () (7 CO CO CO CO CO N
,1 O O 0) 0) 0i 0) O 0i 0) 0) 0) W Oi 0) 0i 0) O Oi 0) 0) O O
W (D co N u-) N W LII U) O In If)
U(i N N N (0 N IO (D O (0 UID
X M M M MLO
CO CO CO CO CO M M M CO CO M CO M M M M M
`
0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 S O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O O
W N N N N NN N N N N N N N N N N N N N N N N
. M M M 8 M co M co M M M M CO CO CO CO CO CO CO CO CO M
U M M ('�1 M M CO CO CO M CO CO CO M CO M M M CO CO M M
_
2
O O O O O O O O O O O O O O O O O O O O O O
O O O O O O O O O O O O O O O O O O O O O O
2 o o O O O O O O O O O d O O O O o o O O O O
.o �C O O O O aO O O aO O O O aO O aO O O (0 O O O O O
1- -60, 0,0 M m fh (�� N f") N f�7 M (h C�7 fh Off') N lO (ND COM (MD UCO COC
0 `-'N UO Un tO IO UO UO U) UO IO UO Un uD U) UO (O
UL
a e En En 2' En 2'
En 2' 2' 2 PaA w m mo .a m g� � � 6a 0go � w a8 0 -
dw0p� d3 d3 3 d
�
pw 0 w a. w O. it a..... w
w
t
U
(C
cc
C O
5 a`
Lc a s a s 0 a a s a s a s a s a s a s U. a a s
LL }}t�b
m
FF
(p� (� UO CCpp pppp cu � � �
7 V' (O M O M N N
g
U
W