HomeMy WebLinkAboutWPO202000037 Review Comments WPO VSMP 2020-08-18� 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
VSMP Permit Plan Review
Project title: Galaxie Farm VSMP
Project file number: WPO202000037
Plan preparer: Keane Rucker, Shimp Engineering [ keane a shimp-en ing eering.com ]
Owner or rep.: David S. or Anna Marie Witmer, 444 Rookwood Dr, Charlottesville, VA 22903
NSCROAGALLIFREYENTERPRISES. COM
Plan received date: 2 Jul 2020
Date of comments: 17 Aug 2020 (email, August 17, 2020 4:42 PM)
18 Aug 2020 (rev. /edited; this Memo)
Reviewer: 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. The rationale is given in the
comments 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: httos://www.albemarle.orgJhome/showdocument?id=166
B. 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:
a. Rain gauge
b. Portable sanitary facilities
c. Covered non -hazardous solid waste dumpster
d. Concrete wash -out draining to trapping device
e. Paved construction entrance w/ spray wash
f. Paint /Stucco /Solvent storage
g. Lined (10nd) on -site fuel storage containment sized for fuel volume + 10-yr storm event x 1
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 reasons listed, below. The stormwater management plan content requirements
can be found in County Code section 17-403.
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)."
Engineering Review Comments
Page 2 of 8
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 f imishes 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.
2. Additional comments possible, relative to item L, above.
3. Revise per (related) preliminary plat or road plan review comments.
4. Remove all portions of Lots 57, 58, 59 from 100' stream buffer (Also: Engineering preliminary plat and
road plan review comments).
5. C5C7: Show all portions of property. SSW corner 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.
6. C19
a. Show multiple inlets to single structure, graphically, for example:
i. Str. E6
ii. Str. E7
b. Label MHs with 4' vertical interval between [WIN and MH floor to receive %:" steel slab.
c. Label Str. requiring VDOT SL-1 (safety slab, ht. >12').
7. 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
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 HOA, 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.
8. VSMP Plan SWM Calculation Packet
a. Pg. 1—Revise ref. to POA A to POA 1, consistent with terminology elsewhere in packet.
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.
c. Pg. 12 —Revise POA 2 label text color to black /similar, so readable.
d. Pg. 13 v. Pg. 85: It is difficult to reconcile table values (p. 13) listing on- /offsite turf /impervious
areas that rout to BMW 1 (via Str. 172) 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.
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.
ii. For every Q 1-yr, 10-yr value in any table on pg: 81, please list corresponding
HydroCAD letter descriptor and pg. #. 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.
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
Engineering Review Comments
Page 3 of 8
(12.00cfs). Provide natural method stream design for this section of Cow Branch that
proves the point, computationally.
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.
9. C5 includes label `slopes surveyed <25%'. Submit survey for Engineering review.
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.
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.
12. C20
a. Revise to resolve weir /stair 2 conflict
b. Detail 3: show 6" solid PVC underdrain to Str. E6 in plan view (C7) and in pipe profile, C19.
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).
d. Weir E3 details:
i. Label weir plate thickness. If weir plat is precast, indicate with label.
ii. Provide 18" x 30" trash rack detail.
iii. Resolve ladder /trash rack conflicts, if any.
iv. Labels ref. EV and E7, which is confusing. Revise to reference single structure.
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: https: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 StreamStats. Were this not the case, review would request design revision.
a. Stream stats, Attached, Q25,1, Culvert A (DA, 0.23 Mi.2)=310cfs
Compare USGS with calc. report, p. 93, Q25, Culvert A=202.5cfs
b. Cate. report, culvert A, 133.2 Ac. ( p. 93, calc. report)
Engineering Review Comments
Page 4 of 8
Culvert A
A E L
133.2 Ac 927.5 ft 4440 ft
0.208 sq mi 0.84 mi
Southern Piedmont Regression Equations
Storm
I Multiple -Parameter
Drainage -Area -Only
Q2
21.6A0.881E0310L-0423
48.5 cfs
122(A)
45.0 cfs
Q10
38.8A0.848E0.379L-0.430
147.1 cfs
33S(A)0596
131.5 cfs
Q25
54.8A0.852E0.392L-0.463
227.0 cfs
504(A)0.se2
202.5 ds
Q50
74.3A0.860E0.390L-0.495
301.5 cfs
661(A)0.5'0
270.2 cfs
Q100
101A0.869E0.382L-0.529
384.8 cfs
849(A)" 59
353.1 ds
c. On-line Manning pipe flow calculator: Dom', n =0.012, slope=0.0533, 0.95 capacity: 386cfs*
* A single line pipe cute., but dbl. line is proposed —Also: exit _ corresponding with V2 x Q2,,
(or V2 x 57.2cfs) � ( % of full depth =0.1905)
Link: http://www.hawsedc.com/en9caics/Manning-Pipe-Flow.i)hp
d.
Stream stats, Attached, Q25-y,., Culvert B (DA, 0.51 Mi.2)=512cfs
Compare USGS with calc. report, p. 93, Q25, Culvert B=347.9cfs
.q
J.,
e. Cale. report, culvert B, 338.1 Ac. ( p. 93, calc. report)
Engineering Review Comments
Page 5 of 8
EL
A E L
ey
338.1 Ac 927.5 ft 6411 ft
0.528 sq mi 1.21 mi
Southern Piedmont Regression Equations
Storm
Multiple -Parameter
Drainage -Area -Only
Q2
21.61E0.310L0.423
94.3 cfs
122(A)
81.4 cfs
Q10
38.8Aa848E0.379L-0.430
276.8 cfs
335(A)0.596
229.0 cfs
Q28
54.8A0.852E0.392L-0.463
423.5 cfs
504(1
347.9 dS WM
Q50
743Ao.860E0.390L0.495
560.0 cfs
661(A)0,570
459.4 cfs
Q100
lolAO-869E0382L0529
711.9 cfs
849(A)u559
594.3 cfs
f On-line Manning pipe flow calculator: D=5', n=0.012, slope=0.0344, 0.95 capacity: 5623efs*
* A single line pipe calc., but dbl. line is proposed —Also: exit _ corresponding with V2 x Q2_yr
(or V2 x 83.1 cfs) � ( % of full depth =0.1906)
g. About StreamStats...
,be 3trmm5Yla bite page pmnezin tna nwtemi e¢cnptlmults, program. a ru," manual. Mssnprlunz
prgall . eelarlans pl WyIn [nsazte ills aneEmmBan 9nrlAlrs. andeatiars as use plena applllday. and
In,, lnlplmadon, the usefz manual al»un be.1. by docked on ine Help fnk on. tali ocRare. Vserssaould
read rneuze,, manual More allempeng to— aappareit.
traducing pmNees cantatas of whanic slarrobow statistics for law argued zirn by smv Ing rep ez9on epuatlons The
regression "'whiny were developeotn ougna press, Xnwn sh he.onallhad, lm, wNrni nrolves use N uadezzion
nalyzls In relate streanflpw catlelo, ,.led Is, a srau dselledstreamppgez lusually vamina and le Wiln
Maactensal—rasured for IN, Rreamgagex py laracheiSG¢ measured by AreamAare a,e enterer l nb l he
rezull,hs equations m duch estimates of the rebound my sutiztirs In ungegM rile:. The regression equations
generally we¢ der eldpee separatN, bl each state hostile rohsnaring agreements Eelwem the larks no state
agencies as a rerun, the achrob cna that are avmlade Ia a given state vary based an an statislica the stale
agencies need I« regmalervi Nanning. or other wfWses and and sNenmg a stare of bl—btln the user
hadface the srmNFegional Info tab andve eexubes the areamndw, suhsics that can Ce estimated using
in II my Issues with
for the
mistae also aesnited anyspec mnrnoNluy oral
III o peens wha usingndamsaras Pe eat MMIemeshnks to related raperts.andnlbemihesme
cddpdming agencies Ind supponm srennalata �mmelt.manod.
The map hall indicates the status of necessary and oral4 Green Notes are available way mu functionally
purple stela It.. balm definition, and mcreadyg basin donefthencs, but estimates of now surnitica from
regression equations are not aenlabla nine rims ere au mny an development. Yellow states are notlmplammted
because no omen agency has agreed to partner with the uSGs to cavn Implementatlm rests.
0
AK Hl PR -VI
Bards
O Fully implemented
Delineation and basin characteristics only
Engineering Review Comments
Page 6 of 8
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
is disapproved for reasons listed, below. The erosion control plan content requirements can be found in
County Code section 17-402.
1. 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
stream buffer is constrained by ordinance, and LOD shown appears to exceed minimal required
disturbance within the stream buffer.
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.
C7C8
3. Provide additional proposed contour labels.
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 Calc. packet makes clear that offsite runoff (via multiple TOC pathways /Str. 172) reaches
BMP 1. Design must ensure these runoff pathways exist (as designed) in the post -developed (As -built)
condition.
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.
b. Note 2: revise to read `Installation of temporary erosion and sediment...'
c. Ref. comments for CIO — C 13, and revise C9 sequence notes, as needed.
C10
6. Label STI, ST2 weir outfall dimensions (L x L).
7. Provide demolition Note/s, Phase IA. (Ex. building, Ex. drive: TBR)
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.
9. Estimate /report live stream reach loss (LF).
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).
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.
12. Provide Note or revise Phase IA sequence to eliminate apparent STI — Ex. driveway conflict.
13. Revise sequence Note 6 (phase 1B) to reference Road A, rather than Road 1.
14. Revise sequence Note 5 (phase IA) to reference culverts A and B.
15. Revise sequence Note 6 (phase 1B) to reference culverts A and B.
16. Remove storm line D from Phase IA /113 unless installed with Phase 1.
17. If storm line D is installed with Phase 1, show ST2 in storm line D profile.
C11
18. Label Rt. 20.
19. Provide ESC legend.
20. Remove storm line D unless installed with Phase 2.
C12
Engineering Review Comments
Page 7 of 8
21. Provide SF (DD, or similar) behind upslope curb to protect surface of roads A, B, C, D from silt /sediment
deposition.
22. PCE at Rt. 20 may be removed, once Road A is paved.
23. Show relocated stone /paved construction entrances at points construction vehicles may leave paved
development road surface and enter graded earth areas.
24. Label SB riprap outfall dimensions in this, or other view (L x W).
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.
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.
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.
28. Provide sequence /narrative /symbols Ainework for coffered work area required to construct Road F.
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.
30. Provide SF, diversion, etc. to protect surface of road E, once constructed, until upslope DA is stabilized.
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.
E. Mitigation Plan
32. C 17. 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.
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
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 C17 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.
c. Provide planting pattern ( 6' OC).
d. Provide list /table of proposed mitigation plant species (type /count) from Albemarle County
Approved planting list (to be evaluated by Water Resources staff).
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.
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;
Engineering Review Comments
Page 8 of 8
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. One of the plan reviewers will prepare 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 emails 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,
httos://www.albemarle. ore/eovemment/community-develODment/aDDIv-for/engineerirre-aDD] ications
WP0202000037 Gataxie Fame subdiv 081720_rev 081820