HomeMy WebLinkAboutWPO202000037 Review Comments WPO VSMP 2020-10-15� AI
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COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, Virginia 22902-4596
Phone (434) 296-5832 Fax (434) 972-4126
Project title:
Project file number:
Plan preparer:
Owner or rep.:
Plan received date:
(Rev. 1)
(Rev. 2)
Date of comments:
(Rev. 1)
(Rev. 2)
Reviewer:
VSMP Permit Plan Review
Galaxie Farm VSMP
Keane Rucker, Shimp Engineering [ keane a shimp-en ing eering.com ]
David S. or Anna Marie Witmer, 444 Rookwood Dr, Charlottesville, VA 22903
NSCROAGALLIFREYENTERPRISES. COM
2 Jul 2020
22 Sep 2020
14 Oct 2020
17 Aug 2020 (email, August 17, 2020 4:42 PM)
18 Aug 2020 (rev. /edited; this Memo)
7 Oct 2020
15 Oct 2020
John Anderson
County Code section 17-410 and Virginia Code §62.1-44.15:34 requires the VSMP authority to act on any
VSMP permit by issuing a project approval or denial. This project is denied for reasons listed, below. The
VSMP application content requirements can be found in County Code section 17-401.
A. Stormwater Pollution Prevention Plan (SWPPP)
The SWPPP content requirements can be found in County Code section 17-405. A SWPPP must contain
(1) a PPP, (2) an ESCP, (3) a SWMP, and (4) any TMDL measures necessary.
SWPPP: Provide. Please use SWPPP template, link: httys://www.albemarle.org/home/showdocument?id=166
(Rev.1, D Partially addressed. As follow-un: (Rev. 2) item 6, below:
1. Sec. 1, Registration Statement:
a. Cover:
i. Parcels under development appear to be 9, 15, please check /revise as needed.
ii. Please include reference to WP0202000037 in SWPPP title.
iii. Revise SWPPP title project name to match WPO Plan title.
b. Sec. IV.E: List Albemarle County since parcels under development are within Albemarle
County MS4.
C. Sec. IV.F: Check `yes' since Galaxie Farm is (itself) a common plan of development (vs.
single parcel without subdivision).
2. Sec. 4, ESC Plan: Include plan sheets, once review comments addressed.
3. Sec. 5, SWM Plan: Include plan sheets, once review comments addressed.
4. Sec. 6.A., PPP Exhibit — include in I I" x 17" Exhibit in SWPPP.
5. Sec, 6.E., Person: Name individual responsible for PPP prior to permit registration with DEQ.
6. New (Rev. 2)
a. Email to Vinny Pero, USACE (10/15/2020 10:41 AM) and follow-up tel. call to discuss
email (10:56AM, 10/15/20, USACE-Albemarle) support request:
i. At Sec. 5 /SWPPP, SWM Plan, provide USACE data sheet that states:
1. This project is subject to U.S. Army Corps of Engineers 2017
Nationwide Permit 18 (NWP-18) General Conditions (GCs). Email
coordination 9/3/20 between Applicant and Vinny Pero, USACE indicates
NWP-18 requirements apply and that project is non -reporting on basis of
4.5 CY fill [below OHW].
2. General Conditions may be found at document available at:
Engineering Review Comments
Page 2 of 12
https://www.nap.usace.army.mil/Portals/39/docs/re atory/publicnotices2017%20
Nationwide%o20Permit%20General%20Conditions.pdf .
3. [ Note: Also please see item 14 SWM Plan, Sec. C. below. ]
R. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17-404.
1. Provide PPP Exhibit (SWPPP Sec. 6A) that identifies preliminary location of (Rev. 1) Not addressed.
Applicant response (9/21/20 letter): `These items are included in the PPP.' As ollow-up: A graphic plan
/Exhibit was not included. Please provide an I I" x 17" exhibit at Sec. 6.A. of SWPPP to include: (Rev. 2)
Partially addressed. As follow-up:
a. Rain gauge
b. Portable sanitary facilities
c. Covered non -hazardous solid waste dumpster (Rev. 2) Persists; please revise Note beginning
`Contractor shall mark location of dumpsters and building materials...' to reference covered
dumpsters as this is a specific requirement of the 2019 CGP.
d. Concrete wash -out draining to trapping device (Rev. 2) Persists. PPP Exhibit ref. to Concrete
Operations may or may not indicate concrete wash -out station/s. Please explicitly identify
concrete wash out stations ( 1 or more).
e. Paved construction entrance w/ spray wash (Rev. 2) Please show trapping measure located
downslope of PCE /CE to collect vehicle spray wash ( to allow sediment to settle).
f Paint/Stucco /Solvent storage
g. Lined (10ml) on -site fuel storage containment sized for fuel volume + 10-yr storm event x 1.1
(Rev. 2) Persists.
It. New (Rev. 2)
i. Revise PPP Exhibit title to correspond with project (Galaxie Farm Subdivision).
ii. SWPPP at p. 58 includes phase II exhibit (streets constructed), Provide symbols and text,
notes or labels for each item listed above that ep rsists. For example: show PCE draining
to a depression (small trap, this is not a VESCH trap but small depression to collect CE
spray wash water.). Also, note specifying fuel storage containment sized adequate for
stored volume + 10-yr storm event, with impermeable liner.
Note: DEQ on all inspections immediately refers to the PPP Exhibit, and this Exhibit
guides DEQ site review. Albemarle cannot overstate the importance and value of an
accurate PPP Exhibit, from start of construction thra final stabilization /completion.
iii. Provide an initial PPP Exhibit showing all items listed above while site is in undeveloped
condition [ Exhibit provided shows advanced development, with streets already built. ]
[ Image immediately below is from county template at:
hfti)s://www.albemarle.org/home/showdocument?id=166
Section 6. Pollution Prevention Plan.
(reference County Code 17-404 and State Regulation 9VAC25-880-70 part II section A.4)
A. Plan showing pollution activities and prevention practices
Provide a reduced I I x 17 copv of a site plan on wh h all of the following activity locations are clearly
marked. Keep this plan up-to-date with ongo g site changes and inspections.)
C. Stormwater Management Plan (SWMP)
VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a SWMP.
This plan is disapproved for minor items (14, 15, 8.d.iv. below). The stormwater management plan content
requirements can be found in County Code section 17-403.
[ Note: Two item # Is are an error, but both items are addressed or NA. ]
Engineering Review Comments
Page 3 of 12
1. Any Forest and Open Space used in the VRRM worksheet as a Post -Development land cover will need to
be shown on the plans and labelled as'SWM Forest and Open Space'. The following note will need to be
placed on the plan:
"The SWM Forest and Open Space Easement is subject to the guidance set forth by DEQ in the Virginia
Stormwater Management Program. The areas will remain undisturbed in a natural, vegetated state, except
for activities as approved by the local program authority, such as forest management, control of invasive
species, replanting and revegetating, passive recreation (e.g., trails), and limited bush hogging to maintain
desired vegetative community (but no more than four times a year)." (Rev. 1) Addressed.
1. Pg. 1 and 2 of SWM calculation packet reference design intent to restore degraded sections of Cow Branch
to comply with 9VAC25-870-66(B) without submitting design for stream restoration. Plan appears to lack
any referential design data for riffle /run sections, sinuosity, stream bed, analysis of existing stream data, or
plan /profile information for proposed revised stream centerline or any in -stream structures required to
effect natural stream restoration. Albemarle has direct experience contracting with design and construction
firms to restore degraded streams, and anticipates revised SWM plan that furnishes requisite natural stream
design methodologies. Note: stream bank plantings alone are not natural stream restoration. FES /Water
Resources will be invited to review and comment on natural stream restoration elements of design. Note
on sheet C5: `Restore channel between culverts B and G per natural design standards in accordance with
9VAC25-870-66-B(2)' is a statement that references, requires and depends on design. (Rev. 1) NA
Applicant: `The storm system outfall location has been changed. This is due to several reasons, primarily
being that a revised routing which changes the location of POA 1 to be at the current point where local
runoff hits Cow Branch is easily achievable without having to perform channel restoration and without
major revision to the subdivision design. So for the current design, no restoration is proposed, and all
references to this have been removed from the plans.'
2. Additional comments possible, relative to item L, above. (Rev. 1) Acknowledged.
3. Revise per (related) preliminary plat or road plan review comments. (Rev. 1) Addressed. Applicant: `All
changes related to Road Plan & Prelim. Plat review comments are included in this submittal.'
4. Remove all portions of Lots 57, 58, 59 from 100' stream buffer (Also: Engineering preliminary plat and
road plan review comments). (Rev. 1) Addressed.
5. CS CT Show all portions of property. SSW comer of development does not appear to be visible on these,
and perhaps other sheets. A match -line inset of developed areas not yet shown is an acceptable approach.
(Rev. 1) Addressed.
6. C19
a. Show multiple inlets to single structure, graphically, for example: (Rev. 1) Addressed.
i. Str. E6
ii. Str. E7
b. Label MHs with 4' vertical interval between INV IN and MH floor to receive Y2" steel slab. (Rev.
1) Addressed.
c. Label Str, requiring VDOT SL-1 (safety slab, In. >12'). (Rev. 1) Addressed.
Revise Runoff Quality Narrative (p. 2 calc. packet) to reflect post -developed 2.80 Ac. Forest /Open space
land cover condition (p. 84). Also:
a. Final plat must include metes and bounds that establish 2.80 Ac. forest /open space easement
(Rev. 1, 2) Persists. Applicant: `Noted. We have already hired Roger W. Ray & Associates to
complete the final subdivision plat, they will prepare this using our AutoCAD linework as well as
Road & VSMP plans.'
b. Revise 0.58 Ac. SWM Forest /open space easement to exclude a portion proposed FOS easement
immediately east of sidewalk, and Lot 65. Galaxie Farm FICA, owner of Lot 65, and maintenance
crews cannot be expected to understand, appreciate or abide limits on maintenance of FOS area
proposed to approach within 1' of sidewalk. Engineering cannot approve west boundary of 0.58
Ac. FOS area, until revised to allow reasonable buffer for normal subdivision maintenance of open
space. In other words, HOA will bush hog areas adjacent to sidewalk more than 4 times per year;
and will likely maintain areas within 25' of sidewalk in lawn or turf condition. Revise, and adjust
VRRM and on -site SWM design and nutrient credit purchase proposals, as needed. (Rev. 1)
Addressed. Applicant: `Noted. Easement shifted 5' away from both ROW adjacent to sidewalk
Engineering Review Comments
Page 4 of 12
and from Lot 65. 5' gap between these areas will provide an adequate buffer for regular lawn
maintenance —this is plenty of width for an industrial riding lawnmower to pass in a stripe
alongside this area. ... A 25' wide buffer area is not necessary ... This revision has reduced the
FOS easement by 0.02 acres —this has been updated in the VRRM spreadsheet and throughout the
VSMP plans.'
8. VSMP Plan SWM Calculation Packet
a. Pg. 1 —Revise ref. to POA A to POA 1, consistent with terminology elsewhere in packet. (Rev. 1)
Addressed.
b. Pg. 4 — 8 appear to be section dividers. Please align dividers with corresponding packet contents.
Relocate divider pages to sections of the calculation packet that follow /present listed information.
Otherwise, packet sections are indistinguishable with data difficult to locate, trace, or review.
(Rev. 1) Addressed.
c. Pg. 12 —Revise POA 2 label text color to black /similar, so readable. (Rev. 1) Addressed.
d. Pg. 13 v. Pg. 85: It is difficult to reconcile table values (p. 13) listing on- /offsite turf /impervious
areas that rout to BMP 1 (via Sir. F2) with VRMM.xls 4.60 Ac. /1.60 Ac. turf /impervious area
values (pg. 85, DA A) that route to Mfr. Treatment. Please clarify. Video -call may be helpful.
(Rev. 1) Partially addressed. Applicant: `Noted, this ... has been revisited and clarified. One
note —after additional review of upstream areas —we found that the Albemarle Health &
Rehabilitation Center (noted in the packet as MFA @Mill Creek) drains into a biofilter, which
drains into the Galaxie Stormtech BMP. In —2015, Shimp Engineering had completed the site
plan and as-builts for the MFA @Mill Creek design. Thus, to most accurately account for that
drainage area, we have imported the old HydroCAD design for MFA which includes this offsite
biofilter into our Predev and Postdev SWM analysis. In reviewing this old design, we found that
the MFA biofilter provides a 65% nutrient removal. So to account for this treatment, we only
accounted for the remaining untreated nutrient load in the VRRM spreadsheet. This was the
difference in total area (100%-65%=35%): so the equivalent of 35% of the MFA site is untreated
area which could be claimed as new treatable area in the VRRM spreadsheet. The physical design
of the BMP still incorporates the full MFA site area (refer to HydroCAD modelling) —but we have
now ensured this BMP does not "double -dip" nutrient removal. We also confirmed that there are
no other upstream BMP's which drain into the Galaxie Stormtech BMP. Thus, the VRMM
spreadsheet now accurately represents the treatment provided by the new BMP."
As follow-up: (Applicant response, letter): "
From WP0201200087 (MFA @Mill Creek) Calculations /undated -untitled (CV), p. 1 [ Image
removed with Rev. 2 comments]:
n P020 i /1/ 097 Calculations (Shi p E.._:_,.__:_,) on 21a 64 pg doe mv) .. n [ Image
removed with Rev 2 comments ]:
WP0201200087, Final Site Development Plan for Albemarle Health & Rehabilitation Center, C9,
Landscape Plan (Shimp Engineering) references an existing SWM easement at deed bk.-pg. 4425-
165. Instrument at 4425-165 is power of attorney. This power of attorney references a plat dated
August, 2013, revised October 9, 2013, but the plat is not attached, and if recorded, it is unclear
where. As follow-up: (Rev. 2) Addressed.
i. Since an upstream/offsite BMP is relied upon in calculations for Galaxie Farm, provide
accurate bk.-pg. reference to SWM easement for the biofilter at Albemarle Health &
Rehabilitation Center. (Rev. 2) Addressed. Applicant response (letter d. 10/13/20): `This
is actually DB 4425-325 and reference has been provided in plans (Sheet C9, "BMP
OFFSITE DRAINAGE NOTE") and in packet (Page 8, "Galaxie Farm Postdev Small
POA Drainage Map"). Copy of this Easement/BLA plat is included with this submittal.'
ii. images above from MFA project require some clarification, for example [ Images
removed with Rev. 2 comments 1:
1. There appear to be three paths for MFA downslope runoff, but this maybe in the
pre -developed and not post -developed condition. Engineering requests post-
Engineering Review Comments
Page 5 of 12
developed runoff drainage map downslope of MFA development. (Rev. 2)
Addressed. Applicant: `This map is the pre -developed map, post -developed
map is now included. This post-dev map shows the following areas drain to the
MFA Biofrlter. 257,689 sf total (5.91 ac), with 135,573 sf imp (3.11 ac). This
leaves 5.91-3.11=2.80 ac turf in the pond drainage area. So the calculated area
is 2.80ac turf, and 3.11 ac imp for the biofilter matches the drainage in the WPO
2012-87 calculations.' [ Image below,.88 /Cale. packet partial ]
GALAXIE FARM
:.„...o„...„E.o.E ......,.„.E.a,.. o�.„.ss..n+m POSTDEV SMALL
ti PDA DRAINAGE MAP
r:a� .,..o.,,.....n
M.voa
a .o
w.c.Tc.
o ro..
O38 4F �..c....,, ..a a..
T.
i
93 -
I ` ae
2. HydroCAD schematic above shows Galaxie residue apparently not receiving
MFA biofilter discharge, request clarification. (Rev. 2) Addressed. Applicant:
`Please refer to updated "Galaxie Farm Postdev Small PDA Drainage Map"
(page 8 of SWM Cale. Packet). In the HydroCAD schematic from WP02012-
87, the "Galaxie Residue" is a drainage area/subcatchment, not a destination.
This Galaxie Residue language stems from a BLA where part of TMP 91-12C -
owned by Galaxie LLC, was dedicated to the MFA property. That Residue is
now included in Subcatchment 2S. The destination is "Frazier" and refers to
TMP 91-12B -owned by the Fraziers. This "Frazier" destination is now shown
as Reach 6R'
iii. With WPO202000037, provide MFA post -developed turf and impervious area values that
drain to the biofilter and then to Galaxie Farm so we may compare with VRRM.xls for
Galaxie Farm. It is unclear without post -developed drainage map for MFA and tabular
(sf) data for turf /impervious areas that drain to the biofilter how to allocate additional
treatment (phosphorus reduction) to already -treated runoff that reaches Galaxie Farm
StormTech Mfr. system. Provide maps, tables, etc, that align with MFA post -developed
conditions (p. 17, Cale. packet) for comparison between MFA post -developed condition,
including MFA BMP, and Galaxie Farm VRRM.xls. (Rev. 2) Addressed. Applicant:
`After reviewing the packet, I realized I omitted a very important map: the Postdev BMP
Treatment Map" which explained the areas used in the VRRM spreadsheet. This is now
included in the SWM Quality Section. The map should be fairly self-explanatory. The
Engineering Review Comments
Page 6 of 12
WA areas are listed in the Post -Development Drainage Map in "Independent Reports"
section —MFA Biofilter Offsite Drainage Area. Additional notation was also added to the
"PostDev Small POA Drainage Map."'
iv. Revise EBE (p. 68 /Cale. booklet) reference to from pg. 31 to pg. 32 (RVpre). (Rev. 2)
Persists. Although comment response indicates ref is changed, p. 68 Calc. booklet and
p. 31/32, images, below:
Cale. booklet. o. 68
Energy Balance Equation Summary for POA 1
Galaxie Farm 24 Hr 1 year Storm Comparison:
Qenebped5 LF'(QplPce� bpm*RVPreDeveiopea)/RVoe.eiopea
Qdewbped5(OFOreg0 RVFore eWFIVoe.ebped
POA 1 Onsite Runoff: Past Orate Drainage Area = 9.39 ac
Opreeer<iwm = [18.14(De4e 3t) LF. = 0.8
RV�.,ebpd = (Page 31) M1ax 01.1,d = 4.91 cis
RVDerebpee = (pege 0)
POA 1 is in a natural channel prone to flooding. Runoff to this point is compliant with 9VAC25-870-66
C(2)b because the total runoff to this point is reduced by an amount exceeding the reduction required
by the entergy balance equation.
Site complies with 9VAC25-870-66-C 2 b because the 10- r peak runoff is reduced.
Energy Balance Equation Summary for POA 2
Galaxie Farm 24 Hr 1 year Storm Comparison:
Qde .ped5 I.F.'(QP,e.o bxdeRVP,e.oevebped)/RVoe.ebW
Qdevebped5 (OFurmted=RVF. axed)/RVoe.ebpw
POA 2 Onsite Runoff: Past Onslle Drainage Area = 12.69 ac
Qpredewiopm [19.66(Pass 3t) LF. = 0.8
RVF .ebpd (pge 31) Max Ode,.b .d = 6A1 eis
RVDe„eoped (page co)
PDA 1 is in a natural channel prone to flooding. Runoff to this point is compliant with 9VAC25-870-66
C(2)b because the total runoff to this point is reduced by an amount exceeding the reduction required
by the entergy balance equation.
She complies with 9VAC25-870-66-C 2 b because the 10- r peak runoff is reduced.
Balance
Galaxie Farm 24 Hr 1 year Storm Comparison:
Qdep014 I.F.'(QPrc-m. d'RVPr.ceeiopm)/RVWveiopd
Qd bped5 (Q,pa, a RVF..ed)/RVDe ebped
Entire Site Runoff: Post Onsite Drainage Area = 13.70 ac
Qp,eee„ebpm [A9.92(page 3l) LF. = 0.8
RVPre-Dnebpa (page 31) M ax Q..e = 5.67 cis
RVDbped (page W)
Engineering Review Comments
Page 7 of 12
Calc. booklet, D. 32, correct ref.
PREDEV ONSITE
PREDEV ONSITE FOR EBE Type 1/ 24-hr i-YR Rainfall=3.04"
Prepared by Shimp Engineering, P.C. Printed 9/21/2020
Hw1roCAD®9.10 srn 07054 02011 HvdroCAD Software Solutions LLC Paoe2
Time spsn.5.00.48.00 hrs, dt.0.05 hrs, 861 points
Runoff by SCS TR-20 method, 11H=SCS
Reach routing by Stor-IndaTrans method - Pond routing by Stor-Ind method
Subcatchment 1S: ONSITE TO POA I Rumff Area-10.450 ac 5.07%Impervious Runoff Depth=0.74"
Tc=17.5 min CN=70 Runoff=6.14 cls 0.641 al
Link 10L: POA 1 Inflow=6.14 s 0.641 al
Primary-�.1 0.641 al
`�
Subcatchment ll S: ONSITE TO POA 2 Runoff Area=1.980 ac 3.54%Impervious Ru R .69"
Tc=12.9min CN=69 Runoff= Weis 0.11 f
Link 13L: POA 2 Inflow.k66 cis 0.756 of
Primary- ti6 cls 0.756 a1
�i
Subcatchment 145: ONSITE TO POA3 Runoff Area-1.270 ac 0.00%Impervious - 7 Bpib=0.29"
Tc.11.2 min CN=SB Runoff= Ids 0 of
Link 15L: POA 3 (COW BRANCH) Inflow=%..92 cis 0.786 a
Pri.ary-9112 cis 0.786 at
TOM Runoff ArM=13.700 ac Runoff Volume = 0.786af Average Runoff Ih=0.69"
95.62% Pervious = 13.100 ac 4.38 % Impervious = 0.600 ac
Cale. booklet, n. 31, incorrect ref.
iS
ONSITE TOb'\\O\A 1 11$
�J ONSITE O POA 2
10L 141S
PCIA 1 13L ONSITE Tq/ POA 3
� 1b
POA2 15L
POA 3 (COW
Su Z4 L nk
Engineering Review Comments
Page 8 of 12
e. Pg. 81: this table is difficult to evaluate, please:
i. POA 3 (Entire site runoff) 10-year Q pre/post <10cfs, while POA 1 and POA 2 onsite
runoff 10-year Q pre/post are orders of magnitude higher. Please clarify. (Rev. 1)
Addressed. Applicant: `Clarified with narrative.'
ii. For every Q 1-yr, 10-yr value in any table on pg.-8 1, please list corresponding
HydroCAD letter descriptor and pg. 4. Additional comments possible, once correlation
provided. Albemarle commends sophistication, elegance, detail, and accuracy of design,
but cannot trace it with ease to the point we are able (yet) to confirm compliance with
9VAC25-870-66. (Rev. 1) Addressed. Applicant: `Notation has been clarified.'
iii. Section of Cow branch between POA 1 and POA 2 proposed to be restored assumes
certain channel capacity /ability to absorb additional Q 1-year post -developed flow
(12.00cfs). Provide natural method stream design for this section of Cow Branch that
proves the point, computationally. (Rev. 1) Addressed. Applicant: `Design has been
revised so that this is now not needed.'
iv. Storm pipe capacity (LD-229): Ensure flow does not exceed storm pipe capacity. Also,
please ref. Engineering preliminary plat and road plan review comments re. pipe
capacity. (Rev. 1) Addressed. Applicant: `This has been accomplished with recent
revisions.'
9. C5 includes label `slopes surveyed <25%'. Submit survey for Engineering review. (Rev. 1) Addressed.
Applicant: `All Preserved Slopes disturbance removed.'
10. Revise grayscale text across all plan sheets to print black, rather than grayscale. It is difficult to review and
recognize labels, notes, dimensions, etc. (Rev. 1) Addressed.
11. Revise C8 and C20 , and elsewhere as needed, StormTech stone invert elevations for consistency, for
example, bottom of stone is given in labels, notes or table on these sheets as: 474.00, 474,75, 475.00, (Rev.
1) Addressed,
12. C20
a. Revise to resolve weir /stair 2 conflict. (Rev. 1) Addressed.
b. Detail 3: show 6" solid PVC underdrain to Str. E6 in plan view (C7) and in pipe profile, C 19.
(Rev. 1) Addressed. Applicant: `Design revised to route 6" PVC into Str. E6Z after weir. 6"
PVC shown in details and profiles. Main BMP outlet profile (E6-E6Z) copied onto C20 for ease
of reference.'
c. Supplement Stormtech BMP profile with SWM facility overall L x W dimensions in plan views
(to aid review, construction inspection, As -built review, and bond estimate -reduction -release).
(Rev. 1) Addressed.
d. Weir E3 details:
i. Label weir plate thickness. If weir plate is precast, indicate with label. (Rev. 1)
Addressed.
ii. Provide 18" x 30" trash rack detail. (Rev. 1) Withdrawn. Applicant: `Trash rack
removed. Rationale:
1. A trash rack is unnecessary for an opening this large as debris large enough to
obscure or clog this orifice is unlikely to float, and unlikely to enter the BMP
anyway.
2. With the exception of large storms, most debris will be intentionally caught in
the Isolator Row (that is its function). Regular debris is not anticipated around
the weir/orifice.
3. Even with debris, a trash rack would cause more of a maintenance burden, as it
could hinder debris such as grass clippings, leaves, small branches from passing
through this orifice, and trap it in the manhole whereas without a trash rack it
could pass through. The above -mentioned debris would not prevent a
downstream nuisance, as the larger downstream storm sewer has more cross -
sectional area than the orifice.
Engineering Review Comments
Page 9 of 12
4. Additional space for maintenance activity in the manhole will provide better
benefit to the function of the BMP than a trash rack.
Thus, these considerations dictate that trash rack be removed from this orifice.'
iii. Resolve ladder /trash rack conflicts, if any. (Rev. 1) Addressed. Applicant:
`Ladder/trash rack conflicts removed. See response to d.ii, above.'
iv. Labels ref. E7Z and E7, which is confusing. Revise to reference single structure. (Rev.
1) Addressed,
13. This item does not request revision but notes that USGS StreamStats peak flow (a regression methodology)
predicts significantly higher peak flow than the Southern Piedmont Rural Regression Equation
methodology referenced in the calculation packet (Link: httl)s:Hstreamstats.usgs.gov/ss/ )
An online pipe capacity calculator appears to indicate dbl. line culverts A and B have capacity for peak
flow predicted by USGS Stream Stats. Were this not the case, review would request design revision. (Rev.
1) Withdrawn. Applicant: `Noted, the USGS StreamStats website is a useful resource, we appreciate you
sharing it. Since Southern Piedmont Rural Regression Method is a standard accepted by VDOT for
computing peak runoff, and since it produces similar computation results as the HydroCAD peak flow,
(added to packet), we will not replace the contents of the packet, but appreciate the additional redundancy
in calculation.' [series of StreamStats or submittal images removed with Rev. 1 comments ]
a. Stream stats, Attached, Q25-Y1, Culvert A (DA, 0.23 Mi.2)=310cfs
r,.....PUO USGS With ,..a,..o..,... P. oa Q25, Culvert A=202.5efs
b. Cale. report, culvert A, 133.2 Ae.r p. o
C. On-line Manning Dipe flow calculator: D=4', n=0.012, slope=0.0533, 0.95 capacity: 386efs*
* A single line pipe talc., but dbl. line is proposed —Also: exit Vel2-Y, corresponding with Y2 x QzY,
(or Y: x 57.2efs) =17.1 fps ( % of full depth =0.1905)
Link: http://www.hawsedc.com/en2cales/Manning-Pipe-Flow.1hp
d. Stream stats, Attached, Q25-Y1_, Culvert B (DA, 0.51 Mi.2)=512efs
Compare USGS with calc. report, p. 93, Q25, Culvert B=347.9cfs
e. Cale. report, culvert B, 338.1 Ac. r p. °
f. On-line Manning pipe flow calculator: D=5', n=0.012, slope=0.0344, 0.95 capacity: 562.3efs*
* A single line pipe calc., but dbl. line is proposed —Also: exit Vel2-y, corresponding with Yz x QzY,
(or Yz x 83.1cfs)=15.93fps ( % of full depth =0.1906)
g.
14. New (Rev. 2)
a. Email to Vinny Pero, USACE (10/15/2020 10:41 AM) and follow-up tel. call to discuss email
(10:56AM, 10/15/20, USACE-Albemarle) support request:
b. Add C 1 Notes that read:
i. This project is subject to U.S. Army Corps of Engineers 2017 Nationwide Permit 18
(NWP-18) General Conditions (GCs). Email coordination 9/3/20 between Applicant and
Vinny Pero, USACE indicates NWP-18 requirements apply and that project is non -
reporting on basis of 4.5 CY fill [below OHW].
ii. General Nationwide Permit Conditions may be found at document available at:
https://www.nap.upace.gnny.mil/Portals/39/docs/re atorypublicnotices/2Ol7%20Nationwide%2
OPermit%20General%20Conditions.odf .
c. Note: USACE Nationwide Permit General Conditions (document) is attached to this Engineering
VSMP /WPO plan review (is transmitted to Applicant and developer).
15. New: Revise VSMP /WPO plan title to include WPO202000037.
D. Erosion and Sediment Control Plan (ESCP)
Virginia Code §62.1-44.15:55 requires the VESCP authority to approve or disapprove an ESCP. This plan
Pan be is approved once email with (and plan sent to) USACE are shared with Albemarle (items 8, 9,
below). (Rev. 2) Addressed. Also, see item 14 SWM Plan, Sec. C. above.
C10-C13
a. Revise LOD to show no disturbance within stream buffer, except minimal grading needed to
construct stream crossings ( x 2) or to install drainage structures, or pipes. Disturbance within
Engineering Review Comments
Page 10 of 12
stream buffer is constrained by ordinance, and LOD shown appears to exceed minimal required
disturbance within the stream buffer. (Rev. 1) Addressed. Applicant: `LOD slightly revised to be
as small as possible within the stream buffer area. LOD may appear excessive on some sheets due
to the disturbance required to remove the existing Galaxie Farm Lane pavement, as well as to
allow enough room to install Cow Branch culverts and riprap. The best graphical description
which dictates the LOD required is shown on C10 — Phase 1B.'
2. C5 or CT On either sheet, dimension riprap at all pipe outfalls (L x W x D). Labels are helpful, but
additional detail is needed for review, bond estimate, construction inspection, etc. (Rev. 1) Addressed.
C7 C8C8
3. Provide additional proposed contour labels. (Rev. 1) Addressed.
4. Wherever proposed lot grading falls toward a street (Road Bl or D, for example) provide collection behind
curbing (yard inlets, for example) to convey runoff into piped storm conveyance. As -built grading does not
admit lot runoff to cross back of curb to gutter. Recall, for example, multiple low areas behind curb during
recent bond inspection at Riverside Village. Design is theoretical, but for cross -lot runoff to actually reach
in -street storm lines, provision must be made for runoff to cross beneath curb to reach the in -street system.
Note: Pg. 13 of Cale. packet makes clear that offsite runoff (via multiple TOC pathways /Sir. F2) reaches
BMP 1. Design must ensure these runoff pathways exist (as designed) in the post -developed (As -built)
condition. (Rev. 1) Withdrawn. Applicant: `We appreciate Engineering's concern for ensuring the goals of
the plan translate to effectiveness in the field, however if poor grading or unfinished lot delivery causes
issues that prevent runoff from following plan design, these items must be corrected in the field. If as -built
inspections require regrading to achieve design objectives, then that must be accomplished.... Additional
conveyance will not be provided behind curbs since this would be redundant infrastructure with undue cost
burden for both initial construction and long-term maintenance. Also, the VDOT road calculations show
that the existing road infrastructure can readily achieve the drainage objectives of this plan.' Engineering
accepts and appreciates (these) well -reasoned points.
5. C9: Project Description Notes:
a. Note 1: Owner /developer submits application for and obtains an approved plan, unless contractor
is a licensed surveyor, or professional engineer. (Rev. 1) Addressed.
b. Note 2: revise to read `Installation of temporary erosion and sediment...' (Rev. 1) Addressed.
c. Ref. comments for CIO — C 13, and revise C9 sequence notes, as needed. (Rev. 1) Addressed.
C10
6. Label STI, ST2 weir outfall dimensions (L x L). (Rev. 1) Addressed.
7. Provide demolition Note/s, Phase IA. (Ex. building, Ex. drive: TBR) (Rev. 1) Addressed. Applicant:
"`Demo" leader notes added.'
8. Coordinate with USACE for permit coverage (work in a live stream, cofferdam, structure installation,
stream impact /loss of stream reach). Provide evidence of USACE NW permit issuance. (Rev. 1) May
Persist. Applicant: `Per attached email with Vinny Pero at USACE, this project falls under nonreporting
Nationwide Permit 18.' As follow-up: Please send email with Vinny Pero to reviewer (was not attached).
9. Estimate /report live stream reach loss (LF). (Rev. 1) Partially addressed. Similar to item not attached,
please send plans sent to Vinny Pero to reviewer. Anticipate loss of live stream reach: 1451f. [Applicant:
`We have attached the plans that were sent to Vinny which calculates the loss and fill within the stream.
Loss of live stream reach: 145sf'] (Rev. 2) Addressed. Correspondence with USACE included with SE
email to Albemarle (K. Rucker to J. Anderson, 10/14/2020 6:28 PM).
10. Provide notes, details re. Ex. well abandonment. Provide copy of coordination with VDOT on topic of well
abandonment within future VDOT ROW (Road A). (Rev. 1) Addressed.
11. Provide ESC Legend: Line -type symbols /meaning can be discerned, but legend is needed for clarity, for
stream diversion, DD, RWD, SF, tree protection, etc. (Rev. 1) Addressed.
12. Provide Note or revise Phase IA sequence to eliminate apparent STI — Ex. driveway conflict. (Rev. 1)
Addressed,
13. Revise sequence Note 6 (phase 1B) to reference Road A, rather than Road 1. (Rev. 1) Addressed,
14. Revise sequence Note 5 (phase IA) to reference culverts A and B. (Rev. 1) Addressed.
Engineering Review Comments
Page 11 of 12
15. Revise sequence Note 6 (phase 1B) to reference culverts A and B. (Rev. 1) Addressed.
16. Remove storm line D from Phase IA AB unless installed with Phase 1. (Rev. 1) Addressed,
17. If storm line D is installed with Phase 1, show ST2 in storm line D profile. (Rev. 1) Addressed.
C11
18. Label Rt. 20. (Rev. 1) Addressed.
19. Provide ESC legend. (Rev. 1) Addressed.
20. Remove storm line D unless installed with Phase 2. (Rev. 1) Addressed.
C12
21. Provide SF (DID, or similar) behind upslope curb to protect surface of roads A, B, C, D from silt /sediment
deposition. (Rev. 1) Addressed.
22. PCE at Rt. 20 may be removed, once Road A is paved. (Rev. 1) Addressed,
23. Show relocated stone /paved construction entrances at points construction vehicles may leave paved
development road surface and enter graded earth areas. (Rev. 1) Addressed.
24. Label SB riprap outfall dimensions in this, or other view (L x W). (Rev. 1) Addressed,
25. Provide temporary rock -lined SCC upslope of and parallel with FD that receives runoff from DD and DV
shown along south edge of parcel, south of Road C. Momentum and volume of sediment -laden runoff
exiting DV for FD will likely cause recurrent erosion issues unless rock -lined SCC conveys runoff to SB.
(Rev. 1) Addressed.
26. If runoff from partially -stabilized graded slopes is meant to sheet across Road A to reach the SB, this
cannot be approved. Once Road A curb and gutter is installed, sediment -laden runoff that reaches the base -
asphalt surface of Road A will be confined by C&G. Revise ESC Phase 3 so runoff from all areas intended
to be controlled by the sediment basin, reaches the SB. Ensure curb inlets, once constructed, are protected
adequately during all phases of construction. (Rev. 1) Addressed. Applicant: `Runoff is not intended to
flow across street, error in linework has been corrected.'
C13
27. Revise proposed permanent DV along south edge of development to underground piped storm conveyance.
Also, ref. Engineering review comments on road plan, and preliminary plat. (Rev. 1) Addressed.
Applicant: `Noted, DV will be replaced with piped system during phase 4. Shown on C 13.'
28. Provide sequence /narrative /symbols /linework for coffered work area required to construct Road F. (Rev.
1) NA. Applicant: `Since Road F was removed this is no longer required.'
29. Provide PCE at Int. Road F and Rt. 20, whether it is intended to be used or not. It will likely be used as a
site entrance, despite design intent. Albemarle County inspector may, at his discretion, not require a paved
construction entrance at this location, but Road F is to be paved, so a paved CE is appropriate. (Rev. 1) NA.
Applicant: `Since Road F was removed this is no longer required. Ex. Avinity fire access road cannot be
used for construction (since it is offsite property), so none will be provided for this either.'
30. Provide SF, diversion, etc, to protect surface of road E, once constructed, until upslope DA is stabilized.
(Rev. 1) Addressed. Applicant: `Silt fence will be sufficient, and is now provided.'
31. Include narrative sequence (Note 9), symbols, measures that outline/describe stream channel restoration
activities in adequate detail, and offer adequate stream protection during this phase of the project. (Rev. 1)
Addressed. Applicant: `Stream channel restoration no longer proposed.'
E. Mitigation Plan
32. C17, Mitigation Plan:
a. Please provide source of Mitigation Option A (channel restoration) requirements. Although used
in the past, Crozet Court subdivision, for example, reviewer needs to identify source of this option.
(Rev. 1) Addressed. Applicant: `This came from an old Albemarle County E&S guidance
document, however channel restoration is no longer proposed.'
b. Math: Since only 1.32 Ac. of unforested buffer appears available for mitigation plantings, the
proposed 1600 bare root seedlings at 1,210 stems /Ac. ( planted 6' x 6' OC) appears to represent a
Engineering Review Comments
Page 12 of 12
maximum, but (related to a., above) were this not the case, the 2:1 plantings : area of buffer impact
ratio would apply to 1.26 Ac. area disturbed within stream buffer. Table narrative on C 17 credits
1 LF channel restoration as offset for 100sf disturbed buffer. Again, reviewer not familiar with
source of channel restoration buffer impact offset credit. Also, please note that 1,210 seedlings
option (Option C, Table B, DCR Riparian Buffers Guidance Manual, p. 95) requires applicant to
enter into a 5-year maintenance and performance guarantee, which will also stipulate minimal
survival required after two growing seasons of 600 plants per Ac. Provide 5-year maintenance and
performance guarantee as condition of VSMP /WPO plan approval. (Rev. 1, D Partially persists.
Applicant: `Math updated to reflect strategy revision. DCR source listed. 5-yr maintenance and
performance guarantee noted (guarantee documents will be handled by Nicole Scro). Additional
notes added.'
c. Provide planting pattern ( 6' OC). (Rev. 1) Addressed.
d. Provide list /table of proposed mitigation plant species (type /count) from Albemarle County
Approved planting list (to be evaluated by Water Resources staff). (Rev. 1) Addressed.
e. Channel Restoration Instructions is inadequate. Also, see comments elsewhere. Natural stream
restoration design is required for plan approval to support 9VAC25-870-66 compliance. (Rev. 1)
NA. Applicant: `Stream channel restoration no longer proposed.'
The VSMP permit application, plans, and calculation packet may be resubmitted for approval when all comments
have been satisfactorily addressed. Please submit items digitally with a completed application form.
Process;
After approval, plans will need to be bonded. The bonding process is begun by submitting a bond estimate request
form and fee to the Department of Community Development [bond estimate is in process]. One of the plan
reviewers will prepare check [Shimp Engineering] estimates and check parcel and easement information based on
the approved plans. The County's Management Analyst will prepare bond agreement forms, which will need to be
completed by the owner and submitted along with cash, certificates or sureties for the amounts specified. The
agreements will need to be approved and signed by the County Attorney and County Engineer. This may take 2-4
weeks to obtain all the correct signatures and forms.
Stormwater Management Facilities Maintenance agreements will also need to be completed and recorded. The
County's Management Analyst or other staff will prepare the forms and check for ownership and signature
information. The completed forms will need to be submitted along with court recording fees.
After bonding and agreements are complete, county staff will need to enter project information in a DEQ database
for state application processing. DEQ will review the application information based on local VSMP authority
approval. At this time, the DEQ portion of the application fees will need to be paid directly to the state. For fastest
processing, this is done electronically with the emalls provided on the application. DEQ should notify applicants
with instructions on how to pay fees. When DEQ approves the application, they will issue a permit coverage letter.
This should be copied to the county.
After DEQ coverage is issued, via the coverage letter, the County can hold a pre -construction conference.
Applicants will need to complete the request for a pre -construction conference form, and pay the remainder of the
application fee. The form identifies the contractor and responsible land disturber, and the fee remaining to be paid.
This will be checked by county staff, and upon approval, a pre -construction conference will be scheduled with the
County inspector. At the pre -construction conference, should everything proceed satisfactorily, a joint VSMP and
grading permit will be issued by the County so that work may begin.
County forms can be found on the county website forms center under engineering;
hops: //www.albemarle. org[govemment/community-development/aoly-for/engineering—applications
WP0202000037 Galaxie Farm subdiv 101520rev2