HomeMy WebLinkAboutWPO201700058 Review Comments WPO VSMP 2018-02-01COUNTY 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:
Date of comments:
Reviewer:
VSMP Permit plan review
Sparrow Hill
WP0201700058
Shimp Engineering
Judith S. Herring
July 21, 2017
Oct 13, 2017
Dec 11, 2017
Jan 22, 2018
Aug 31, 2017 (Rev. l)
Nov 16, 2017 (Rev.2)
Jan 11, 2018 (Rev.3)
Feb 1, 2018 (Rev.4)
David James (ext. 3273)
b ustin@shimp-engineering. com]
bu@erring@aol.com]
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 approved. The rationale is given in the
comments below. The application may be resubmitted for approval if all of the items below are satisfactorily
addressed. 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.
(Rev.2) There's impaired waters immediately downstream with a TMDL, H23R-02-BEN -
Lickinghole Creek. Include this report in swppp
http://www. deq.virginia. gov/FS2014/FactSheets.aspx?id=VAV-H23R_LKN01 A00&s1yle=1
(Rev.3) Change references of `Conservation Easement' to `SWM Forest and Open Space
Easement'. Make the changes in the WPO plan set as well.
(Rev.4) Addressed.
B. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17-404.
1. (Rev.3) Partially addressed. Show concrete cleanout location, wash rack, and fueling area.
(Rev.4) Addressed.
C. Stormwater Management Plan (SWMP)
VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a
SWMP. This plan is approved. The stormwater management plan content requirements can be
found in County Code section 17-403.
1. (Rev. l) Add the WPO number to title sheet.
(Rev.2) Addressed.
Engineering Review Comments
Page 2 of 9
2. (Rev. l) Sheet C3 — Show managed slopes & preserved slopes with hatching and symbols.
Response [Shimp Eng.]: Preserved slopes have been shown on all grading sheets. There are no
managed slopes on the site.
(Rev.2) Not completed. There are managed slopes in yellow according to County GIS. Show the
preserved/managed slopes as shown below.
(Rev.3) Provide an exhibit sheet (8'/z x 11" at 1:50 scale) of the surveyed topo of preserved
slopes with County GIS overlay so we can confirm accuracy and make determination.
(Rev.4) Addressed.
3. (Rev. l) Sheet C4 — Realign sanitary sewer outside buffer area. Sanitary sewer improvements are
allowed within a stream buffer with disturbance minimized.
Response [Shimp Eng.]: Per our meeting on Sept. 14, 2017, we are permitted to disturb buffer
and preserved slopes for public utility installation. The site layout dictates the current design...
(Rev.2) Acknowledged. I think you would need ACSA approval for the crossing. [18-30.7.4(b)]
the preserved slopes should be preserved to the maximum extent practicable consistent with the
intent and purpose of this overlay district.
(Rev.3) Plan can be anproved once ACSA approves alignment.
(Rev.4) Addressed. ACSA has notprovided any comments.
4. (Kev. l) Show all easements. Show proposed lot lines & ROW on all sheets.
(Rev.2) Area/s outside of property line to be shown in an easement that are to be disturbed
Correct boundary line / area information. Should match what's shown in County's GIS.
(Rev.3) Addressed.
5. (Rev. 1) Any facilities shown inside the stream buffer need to be relocated outside. Only outfall
from pipes can exist within a stream buffer where nessessary.
Response [Shimp Eng.]: Comment noted. Per our meeting Sept. 14, 2017 and County Code WPO
sec. 17-604 A (ii), we are permitted to disturb the landward 50' of the buffer. A mitigation plan
has been provided to offset the impacts of this disturbance.
(Rev.2) Not completed. Provide documentation report that shows where stream is
intermittent.
(Rev.3) Addressed.
6. (Rev. l) Areas of Forest/Open space to be protected as undisturbed space (outside limits of
disturbance) & shall be protected as such in agreements, deed of dedication, and platted within an
easement.
Response [Shimp Eng.]: We will draft copies of the SWM agreement and easement plats with the
next submittal.
(Rev.2) Acknowledged. According to the VRRM spreadsheet 12.6 ac offorest/open space will be
protected.
(Rev.3) Submit SWM Forest and Open Space easement deed & plat to be recorded. Change
labeling from `Conservation' to `Forest and Open Space'.
Response [Shimp Eng.]: Deed and plat shall be submitted with the final subdivision plat.
(Rev.4) Acknowledged.
7. (Rev. 1) Show SWM facility accesses. Easements must be provided over all access & facilities, to
accompany deeds & agreements (Design Manual, Sect. 5).
Response [Shimp Eng.]: Access to all facilities has been provided. See plans for locations and
easements. All access roads have a grade of 20% or less.
(Rev.2) Addressed.
8. (Rev. 1) Show drainage easements. Width should be calculated according to the equation below
from Design Manual:
Response [Shimp Eng.]: Comment noted. Pipes that required additional easement width have
been updated to proper width.
(Rev.2) Partially addressed. Show all of ditch 7 in an easement & other permanent ditches
(See comment 16).
Engineering Review Comments
Page 3 of 9
(Rev.3) Addressed.
9. 1) oiw�Luiauar elevations on all sheet where contours shown.
(Rev.2) Addressed.
10. (Rev. 1) Geotechnical report of soils required before the installation of infiltration facilities &
after final grading operations have be completed.
Response [Shimp Eng.]: Geotechnical report has been completed. 3 BMP's meet the criteria set
by the DEQ.
(Rev.2) Acknowledged. See comment 420 below.
(Rev.3) Add general construction notes for infiltration & testing procedure during
inspection (Sect. 8, 9.2).
(Rev.4) Addressed.
11. (Rev. l) Add note that installation of infiltration practices can begin only when all up -gradient
construction has been completed and pervious areas are stabilized.
(Rev.2) Addressed.
12. (Rev. 1) Increase size of text/linetype (i.e. roof drains). Provide standard list of symbols on the
cover, or C2.
(Rev.2) Addressed.
13. (Rev. 1) Connect storm str. G1 to A9.
(Rev.2) Addressed.
14. (Rev. 1) Outfall must discharge to a natural channel, or sheet flow.
Response [Shimp Eng.]: Outfalls now discharge to natural channels. Please see subdivision sheets
for greater detail. Channel adequacy analysis is not required because site complies with the
energy balance equation.
(Rev.2) Partially addressed. STR 4 and 10 outfall (2&4) does not appear to extend to a
natural channel. Sheet flow may re-channelize <100'.
(Rev.3) Addressed.
15. (Rev. 1) Show Tc flow path clearly& labeled. Show Tc, Coefficient, D.A. with drainage inlet
map.
Response [Shimp Eng.]: TC flow paths shown on pre- and post- development summary maps...
(Rev.2) Addressed.
16. (Rev. 1) Label all ditches; Provide ditch/swale cross-sections with dims & 2 -/10 -yr elev. Show
table/calcs for velocities & lining type.
Response [Shimp Eng.]: All ditches have been labeled. See updated calculation packet and ditch
detail for regulatory compliance.
(Rev.2) Partially addressed. Show for ditch at house/lot 22 & 6. For ditch 7 & 8 extend matting
further up. Consider grading out more behind house/lot 3 to divert more stormwater to STR A8A
or relocate a little further upstream.
(Rev.3) Show all permanent ditches/channels in the stormwater profiles sheets. Ditches 1 &
4A needs to be extended as well as easements to capture entire DA as shown on `Drainage
Area Map'.
(Rev.4) Addressed.
17. (Rev. 1) Show overall SWM drainage maps in plans & show flow arrows to inlets.
Response [Shimp Eng.]: See comment 15 above. We have drafted more legible drainage maps in
the calculation packet.
(Rev.2) Addressed.
18. (Rev. l) Sheet C 12 — Callout ditches/swales, OP going to a natural channel / sheet flow. How does
amount of drainage get to BMP F? Show 100' stream buffer not shown. Change note about
groundcover, specify type to be used, as final stabilization measure. BMP E OP should run
parallel with pipe parallel with channel.
Response [Shimp Eng.]: C12 (now sheet C16) Comment noted. Outlet condition labels added.
Drainage to BMP F will be routed by roof drains and ditches. 100' buffer shown. Groundcover
Engineering Review Comments
Page 4 of 9
note updated. BMP E outlet updated.
(Rev.2) Addressed.
19. (Rev. 1) Sheet C14 — Show all utility crossings, anchors required for pipes over 16% slope.
(Rev.2) PaY*;Qnx• Q4dressed. Show all drainage connections to structures in profiles.
(Rev.3) Addressed.
20. (Rev. l) Infiltration Trenches — Show for each facility: geographic coordinates, impervious areas
treated, level of design used, types of pretreatments used, max. depth & surface area calcs, depth
of cover, hydraulic head, the 1 -yr 24 -hr storm RR volume infiltrates in 36-48 hours, if back up
underdrain needed?, soil tests (1-2 per practice), mets 200' down -gradient slope requirements,
ave. slope of CDA is <15%, bottom of facilities are flat 0% slope. Show `permeable' filter fabric
on trench sides. Observation wells every 50 feet. Provide specific material & min/max
dimensions for fabrication/installation (Sect. 6.9).
A minimum vertical distance of 2 feet must be provided between the bottom of the infiltration
practice and the seasonal high water table or bedrock layer.
Response [Shimp Eng.]: Infiltration trenches have been updated to have consistent labelling. We
will include coordinates with final submittal. Impervious area treated is shown on the maps and
BMP...
(Rev.2) Based on the soil's report dated Oct. 6 it appears that only BMP D & E may meet
infiltration rates. BMP's A & B soil's show poor permeability, BMP's C is too close to bedrock,
and BMP F currently has low infiltration rate. Are there at least two forms of pre-treatment? How
much imperious area is going to each BMP? See 6.1 on Design infiltration rates. See Table 8.4
for recommended design solutions.
(Rev.3) BMP B does not meet the recommended CDA<2 acre & close to 100% impervious.
Show the three forms of pretreatments used in the plan details. Show that the design
storms will infiltrate within 48 hours.
Rename BMPs A -F to underground detention (UD), except BMP B Infiltration.
BMP B —1. Remove infiltration from pretreatment pipe/area. 2. Model pretreatment pipe
separately from BMP B. Show velocities do not scour. 3. Provide maintenance
requirements, confined space certification, etc. 4. Add MH at outlet before the
pretreatment weir W -B2. 5. Move inlet of 15" HDPE pipe away from weir to prevent short
circuiting & resuspension (turbulence) of sediment at weir W -B2. 6. Provide detail/specs on
filter fabric installation. 7. Provide certification from pipe manufacturer that holes from
the filter fabric fasteners (bolts/screws) will not rust and that screwing into pipe will not
affect the long term warranty/performance of pipe.
(Rev.4) Addressed.
21. (Rev. 1) Provide SWF maintenance requirements on the plan.
(Rev.3) Partially addressed. Add controls/notes regarding protection of area until stabilized.
Provide maintenance requirements for the underground pretreatment device, including
maintainance/replacement of filter fabric and confined space entry.
Provide approximate cost of yearly maintenance.
Add/change under `Maintenance Activity' column: "Clean out accumulated
sediments/debris from the infiltration facility."
(Rev.4) Addressed.
22. (Rev. 1) Provide purchase of nutrient credits, contact Ana Kilmer.
Response [Shimp Eng.]: Nutrient credit details will be coordinated when we have the final design
number.
(Rev.2) Not completed. Proof of purchase required before VSMP plan approval.
(Rev.3) The spreadsheet indicates you now meet/exceed phosphorous load requirements
with the infiltration BMP proposed, thus the purchase of nutrient credits is not required.
(Rev.4) Addressed.
23. (Rev. 1) Road access lots need easements.
Engineering Review Comments
Page 5 of 9
(Rev.2) Addressed.
24. (Rev. l) A maintenance agreement will be needed for walls. Walls/grading outside of preserved
slopes. Walls details with safety fences.
Response [Shimp Eng.]: Comment noted. Walls are standard Eagle Bay segmental block
retaining walls. To avoid redundant design, we are requesting that the VSMP be approved
without wall details...
(Rev.2) Not competed. The retaining wall design will have to be approved before the VSMP
plan can be approved. The design should be included on both plans.
(Rev.3) Acknowledged.
25. (Rev.2) The construction area of BMP D appears to be both in preserved slopes, and in the WPO
stream buffer. While it may meet 17-604(A) requirement with a mitigation plan it may not meet
requirements under 18-30.7.4(b) by right and may require a special use permit.
(Rev.3) Will be confirmed/determined with exhibit sheet.
(Rev.4) Addressed.
26. (Rev.2) VRRM for quality compliance - Drainage Areas for B, C & F do not match what's
shown on the BMP Drainage Map.
(Rev.3) DA tab sheet data for BMP B has been removed, please include.
(Rev.4) Addressed.
27. (Rev.2) Sheet C17 - Correct the invert on BMP C & elevation on weir plate. Correct elevations
on weir plate BMP A. BMP D elevation.
(Rev.3) Addressed.
28. (Rev.2) Sheet C'1 R - Correct BMP F weir elevations. Correct the profile view for STM C-C1A.
(Rev.3) Addressed.
29. (Rev.3) Provlue pre -development flow rate (cfs) at each point of discharge to meet Channel
Protection criteria.
(Rev.4) Addressed.
30. (Rev.3) Sheet C5 -1. Move inlet STR 131A (invert out) to upper end of pretreatment section.
2. Add access MH at end of pretreatment section (before Weir Plate W -B2).
(Rev.4) Addressed.
31. (Rev.3) Sheet C17 -1. Fix the details of BMP B etc. with the comments of #20/29 above. 2.
Fix the excavation elevations. 3. Fix the cut off text (detail VC17).
(Rev.4) Addressed.
32. (Rev.3) Page 20 (SWM calculation packet) - The invert elevation should be 615.0' (double
check/correct). The exfiltration rate can not include the pretreatment area of filter fabric
(correct). Suggest modeling pretreatment area separately from infiltration area.
(Rev.4) Addressed.
33. (Rev.3) VRRM spreadsheet - Total disturbed area increase by a tenth, but land cover areas
increased significantly (comparing this versus last review of VRRM spreadsheet, double
check). Where does that 0.03ac under C Soils forest/open space come from (pre/post
development) ?
(Rev.4) Addressed.
34. (Rev.4) The nve. veloeity (18.5fps) going into BI%W C from pipe C is quite abrasive and MR
blow-out thefilter- fabr-ie. Same for- 91%W A 16.8f s ave. veloeity
35 (Rev.4) On the ilr.,:..age m of the inlets, ..lease providevalues TOC and valuess ., well.
36. (Rev.4) For eneh POA provide the DA & CN on the Post Dev map.
37. (Rei.A) ALRR i Corr eet the r-ainfairaepths (in) should be 3.05"for-,�� 9" for- ' yr -
?35» f 40yr- n the Runoff Vol,,.... and C -N tab.
f f
storage,? double ebeek) on sheet C18.
while the plans propose n 1590ef storage
-$k-.
Engineering Review Comments
Page 6 of 9
D. Mitigation Plan (MP)
The mitigation plan requirements can be found in County Code Chapter 17-406.
1. (Rev. 1) The fee was not paid for the review of this plan (17-208).
(Rev.2) Addressed.
2. (Rev.2) Show 100 -yr floodplain with callout.
(Rev.3) Addressed.
3. (Rev.2) Show critical slopes. Show sewer/drainage easements those that should not have
troac
(Rev.3) Acknowledged.
4. (Rev.2) Label Sq -ft of preserved forest/open space & mitigation areas on map. Note: Areas
of mitigation outside buffer can't count towards VRRM nutrient reduction.
(Rev.3) Addressed. double check
5. (Rev.2) All concentrated discharges needs to be treated or extended to adequate channel.
(Rev.3) Addressed.
6. (Rev.3) Callout Area H (not shown).
(Rev.4) Addressed.
7. (Rev.3) Obtain floodplain development permit for sewer line work in the floodplain prior to
(Rev.4) Addressed.
8. (Rev.4) Sheet C9/CII Show tree proteetion around all Forest/Open Spnee arens.
9. (Rev.4) Sheet CII Aeeording to enleuintions 1,395 har-dwood/pine seedlings wFe required,
option e. [89,220/(8x8-64)- 1,394.061.
E. 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 approved. The erosion control plan content requirements can be found in County
Code section 17-402.
1. (Kev. l) Limits of disturbance to be shown outside of preserved slopes. No
grading/tunneling/trenching can occur in tree protected areas (18-30.6.3).
Response [Shimp Eng.]: The LOD have been updated. They are now outside preserved slopes.
(Rev.2) See comment #2 above.
(Rev.3) Addressed.
2. (Rev. 1) Provideap ved wash rack and construction entrance (Design Manual, Sect. 3).
(Rev.2) Addressed.
3. (Rev. l) Show any staging area and stockpile locations.
Response [Shimp Eng.]: Staging/stockpile areas shown.
(Rev.2) Not addressed.
(Rev.3) Addressed.
4. (Rev. 1) Show contour elevations on all sheets where contours shown.
(Rev.2) Addressed.
5. (Rev. 1) Proposed slopes greater than 3:1 to have low maintenance (not grass) ground cover
specified on plan (Design Manual, sect. 8A). List approved ground cover type.
Response [Shimp Eng.]: Groundcover type added to mitigation plan sheet cl 1. Additional notes
added to plans.
(Rev.2) Partially addressed. Show areas on E&SC phase IL The low maintenance is to be
used as a final stabilization measure.
(Rev.3) Addressed.
6. (Rev. l) Show proposed lot lines & ROW on all sheets.
Response [Shimp Eng.]: Lot lines and ROW shown on all sheets.
Engineering Review Comments
Page 7 of 9
(Rev.2) Area/s outside of property line to be shown in an easement that are to be disturber
Correct existing boundary line / area information. Should match what's shown on County
GIS.
(Rev.3) Addressed.
7. (Rev. l) Show tree protection symbols & callout.
Response [Shimp Eng.]: Tree protection symbols and details shown.
(Rev.2) Partially addressed. Show tree protection, safety fence & other symbols in legend.
Tree protection should be in place before any land clearing; Show on phase 1 of E&SC
sheet C9.
(Rev.3) Addressed.
(Rev.4) Sheet C9/CII Show tree proteetion around all Forest/Open Spnee nrens.
8. (Rev. l) Show arrows indicating location or extent of E&SC practice (as needed).
(Rev.2) Double check.
9. (Rev. 1) Show phasing for ESCs.
Response [Shimp Eng.]: Phasing shown on the same sheet as the E&SC practices for
clarification.
(Rev.2) Show phasing (line) on sheet C 10.
Response [Shimp Eng.]: E&S Phasing is no longer proposed, linework and notation has been
removed.
(Rev.3) Acknowledged.
10. (Rev. l) Apply surface roughening (SR) and temp. slope drains (TSD) for slope protection where
soil erosion is a problem.
(Rev.2) Addressed.
11. (Rev. 1) Provide baffle for sediment traps to prevent shortcutting of storm runoff.
(Rev.2) Addressed.
12. (Rev. l) Sheet C5 — Show OP for sediment basin.
(Rev.2) Addressed.
13. (Rev. 1) Sheet C9 — Show SF detail. IP detail, also provide detail for gutter buddy. Change
"Stone" CE to "Paved" CE.
(Rev.2) Addressed.
14. (Rev. 1) Sheet C10 — Show side & embankment slope info. for SB detail. Show SF detail for drop
inlet protection.
Response [Shimp Eng.]: Embankment info shown on what is now C14. Side slope is 2:1. Drop
inlet protection was chosen as wire mesh and gravel because of the steepness of the slopes on the
site before and after grading. This can be revised at reviewers recommendation.
(Rev.2) Not completed. Show the embankment side slopes at 2:1 (max) in the detail. Show
cutoff trench for the fill embankment. The downstream end of the embankment shows 1:1
grade and should be 3:1 overall. (DEQ, Spec 3.14).
Engineering Review Comments
Page 8 of 9
Constructed top of embankment
Settled top of embankment
Emergency spillway
Assumed phreatic line 4H:1V
Riser \
structure
60
of embankment Anti—seep collars
75
�RCP — .4
barrel
4' mlm— outlet
protection
cut off
trench
Figure A.3. Profile Along Centerline ojPrincoal SPiRlray
(Rev.3) Addressed.
15. (Rev. 1) Any construction activities outside property line to be shown in an easement.
Response [Shimp Eng.]: Comment noted, no construction is proposed outside the property line
and retaining wall location that may have caused outside disturbance has been removed.
(Rev.2) Acknowledged. See above comments.
(Rev.3) Addressed.
16. (Rev.3) Sheet C10 — Add CIP for culvertls instead of IP. Add SF around stockpile location.
Show concrete cleanout and detail.
(Rev.4) Addressed.
47. (Rev.4) Sediment tr-ap 3 appears to have 4.54 side slopes and should be 24. The exeavated
area eanhave 44 slope (42 max). ESCH93.43
18. (Rev.4) Sheet CIO Add SF along slopes.
The VSMP permit application and all plans may be resubmitted for approval when all comments have
been satisfactorily addressed. For re -submittals please provide 2 copies of the complete permit package
with a completed application form.
Engineering plan review staff are available from 2-4 PM on Thursdays, should you require a meeting to
discuss this review.
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. 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.
Engineering Review Comments
Page 9 of 9
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;
http: //www. albemarle. org/deptforms. asp?department=cdengwVo
File: Sparrow Hill VSMP WPO201700058 - 11-2017 rev(4).doex
Er
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:
Date of comments:
Reviewer:
VSMP Permit plan review
Sparrow Hill
WP0201700058
Shimp Engineering
Judith S. Herring
July 21, 2017
Oct 13, 2017
Dec 11, 2017
Aug 31, 2017 (Rev. l)
Nov 16, 2017 (Rev.2)
Jan 11, 2018 (Rev. 3)
David James (ext. 3273)
[j ustin@shimp-engineering. com]
[ju@erring@aol.com]
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 application may be resubmitted for approval if all of the items below are satisfactorily
addressed. 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.
1. (Rev.2) There's impaired waters immediately downstream with a TMDL, H23R-02-BEN -
Lickinghole Creek. Include this report in swppp
htti)://www.decl.vir2inia.2ov/FS2014/FactSheets.asl)x?id=VAV-H23R LKN01A00&style=l
(Rev.3) Change references of `Conservation Easement' to `SWM Forest and Open Space
Easement'. Make the changes in the WPO plan set as well.
B. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17-404.
1. (Rev. 3) Partially addressed. Show concrete cleanout location, wash rack, and fueling area.
C. Stormwater Management Plan (SWMP)
VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a
SWMP. This plan is not approved, and the reasons are provided in the comments below. The
stormwater management plan content requirements can be found in County Code section 17-403.
1. (Rev. l) Add the WPO number to title sheet.
(Rev.2) Addressed.
2. (Rev. 1) Sheet C3 — Show managed slopes & preserved slopes with hatching and symbols.
Response [Skimp Eng]: Preserved slopes have been shown on all grading sheets. There are no
managed slopes on the site.
(Rev.2) Not completed. There are managed slopes in yellow according to County GIS. Show the
Engineering Review Comments
Page 2 of 8
preserved/managed slopes as shown below.
(Rev.3) Provide an exhibit sheet (8 V2 x 11" at 1:50 scale) of the surveyed topo of preserved
slopes with County GIS overlay so we can confirm accuracy and make determination.
(Rev. 1) Sheet C4 — Realign sanitary sewer outside buffer area. Sanitary sewer improvements are
allowed within a stream buffer with disturbance minimized.
Response [Shimp Eng]: Per our meeting on Sept. 14, 2017, we are permitted to disturb buffer
and preserved slopes for public utility installation. The site layout dictates the current design...
(Rev.2) Acknowledged. I think you would need ACSA approval for the crossing. [ 18-30.7.4(b)]
the preserved slopes should be preserved to the maximum extent practicable consistent with the
intent and purpose of this overlay district.
(Rev.3) Plan can be approved once ACSA approves alignment.
(Rev. l) Show all easements. Show proposed lot lines & ROW on all sheets.
(Rev.2) Area/s outside of property line to be shown in an easement that are to be disturbed
Correct boundary line / area information. Should match what's shown in County's GIS.
(Rev.3) Addressed.
(Rev. 1) Any facilities shown inside the stream buffer need to be relocated outside. Only outfall
from pipes can exist within a stream buffer where nessessary.
Response [Shimp Eng]: Comment noted. Per our meeting Sept. 14, 2017 and County Code WPO
sec. 17-604 A (ii), we are permitted to disturb the landward 50' of the buffer. A mitigation plan
has been provided to offset the impacts of this disturbance.
(Rev.2) Not completed. Provide documentation report that shows where stream is
intermittent.
(Rev.3) Addressed.
(Rev. 1) Areas of Forest/Open space to be protected as undisturbed space (outside limits of
disturbance) & shall be protected as such in agreements, deed of dedication, and platted within an
easement.
Response [Shimp Eng]: We will draft copies of the SWM agreement and easement plats with the
next submittal.
(Rev.2) Acknowledged. According to the VRRM spreadsheet 12.6 ac offorest/open space will be
protected.
(Rev.3) Submit SWM Forest and Open Space easement deed & plat to be recorded. Change
labeling from `Conservation' to `Forest and Open Space'.
7. (Rev. 1) Show SWM facility accesses. Easements must be provided over all access & facilities, to
accompany deeds & agreements (Design Manual, Sect. 5).
Response [Shimp Eng]: Access to all facilities has been provided. See plans for locations and
easements. All access roads have a grade of 20% or less.
(Rev.2) Addressed.
8. (Rev. 1) Show drainage easements. Width should be calculated according to the equation below
from Design Manual:
Response [Shimp Eng]: Comment noted. Pipes that required additional easement width have
been updated to proper width.
(Rev.2) Partially addressed. Show all of ditch 7 in an easement & other permanent ditches
(See comment 16).
(Rev.3) Addressed.
9. (Rev. l) Show contour elevations on all sheet where contours shown.
(Rev.2) Addressed.
10. (Rev. 1) Geotechnical report of soils required before the installation of infiltration facilities &
after final grading operations have be completed.
Response [Shimp Eng]: Geotechnical report has been completed. 3 BMP's meet the criteria set
by the DEQ.
(Rev.2) Acknowledged. See comment #20 below.
Engineering Review Comments
Page 3 of 8
(Rev.3) Add general construction notes for infiltration & testing procedure during
inspection (Sect. 8, 9.2).
11. (Rev. l) Add note that installation of infiltration practices can begin only when all up -gradient
construction has been completed and pervious areas are stabilized.
(Rev.2) Addressed.
12. (Rev. 1) Increase size of text/linetype (i.e. roof drains). Provide standard list of symbols on the
cover, or C2.
(Rev.2) Addressed.
13. (Rev. 1) Connect storm str. G1 to A9.
(Rev.2) Addressed.
14. (Rev. 1) Outfall must discharge to a natural channel, or sheet flow.
Response [Shimp Eng.]: Outfalls now discharge to natural channels. Please see subdivision sheets
for greater detail. Channel adequacy analysis is not required because site complies with the
energy balance equation.
(Rev.2) Partially addressed. STR 4 and 10 outfall (2&4) does not appear to extend to a
natural channel. Sheet flow may re-channelize <100'.
(Rev.3) Addressed.
15. (Rev. l) Show 1 c 11ow path clearly& labeled. Show Tc, Coefficient, D.A. with drainage inlet
map.
Response [Shimp Eng.]: TC flow paths shown on pre- and post- development summary maps...
(Rev.2) Addressed.
16. (Rev. 1) Label all ditches; Provide ditch/swale cross-sections with dims & 2 -/10 -yr elev. Show
table/calcs for velocities & lining type.
Response [Shimp Eng.]: All ditches have been labeled. See updated calculation packet and ditch
detail for regulatory compliance.
(Rev.2) Partially addressed. Show for ditch at house/lot 22 & 6. For ditch 7 & 8 extend matting
further up. Consider grading out more behind house/lot 3 to divert more stormwater to STR A8A
or relocate a little further upstream.
(Rev.3) Show all permanent ditches/channels in the stormwater profiles sheets. Ditches 1 &
4A needs to be extended as well as easements to capture entire DA as shown on `Drainage
Area Map'.
17. (Rev. l) Show overall SWM drainage maps in plans & show flow arrows to inlets.
Response [Shimp Eng.]: See comment 15 above. We have drafted more legible drainage maps in
the calculation packet.
(Rev.2) Addressed.
18. (Rev. l) Sheet C 12 — Callout ditches/swales, OP going to a natural channel / sheet flow. How does
amount of drainage get to BMP F? Show 100' stream buffer not shown. Change note about
groundcover, specify type to be used, as final stabilization measure. BMP E OP should run
parallel with pipe parallel with channel.
Response [Shimp Eng.]: C12 (now sheet C16) Comment noted. Outlet condition labels added.
Drainage to BMP F will be routed by roof drains and ditches. 100' buffer shown. Groundcover
note updated. BMP E outlet updated.
(Rev.2) Addressed.
19. (Rev. 1) Sheet C14 — Show all utility crossings, anchors required for pipes over 16% slope.
(Rev.2) Partially addressed. Show all drainage connections to structures in profiles.
(Rev.3) Addressed.
20. (Rev. l) Infiltration Trenches — Show for each facility: geographic coordinates, impervious areas
treated, level of design used, types of pretreatments used, max. depth & surface area calcs, depth
of cover, hydraulic head, the 1 -yr 24 -hr storm RR volume infiltrates in 36-48 hours, if back up
underdrain needed?, soil tests (1-2 per practice), mets 200' down -gradient slope requirements,
ave. slope of CDA is <15%, bottom of facilities are flat 0% slope. Show `permeable' filter fabric
Engineering Review Comments
Page 4 of 8
on trench sides. Observation wells every 50 feet. Provide specific material & min/max
dimensions for fabrication/installation (Sect. 6.9).
A minimum vertical distance of 2 feet must be provided between the bottom of the infiltration
practice and the seasonal high water table or bedrock layer.
Response [Shimp Eng]: Infiltration trenches have been updated to have consistent labelling. We
will include coordinates with final submittal. Impervious area treated is shown on the maps and
BMP...
(Rev.2) Based on the soil's report dated Oct. 6 it appears that only BMP D & E may meet
infiltration rates. BMP's A & B soil's show poor permeability, BMP's C is too close to bedrock,
and BMP F currently has low infiltration rate. Are there at least two forms of pre-treatment? How
much imperious area is going to each BMP? See 6.1 on Design infiltration rates. See Table 8.4
for recommended design solutions.
(Rev.3) BMP B does not meet the recommended CDA<2 acre & close to 100% impervious.
Show the three forms of pretreatments used in the plan details. Show that the design
storms will infiltrate within 48 hours.
Rename BMPs A -F to underground detention (UD), except BMP B Infiltration.
BMP B —1. Remove infiltration from pretreatment pipe/area. 2. Model pretreatment pipe
separately from BMP B. Show velocities do not scour. 3. Provide maintenance
requirements, confined space certification, etc. 4. Add MH at outlet before the
pretreatment weir W-132. 5. Move inlet of 15" HDPE pipe away from weir to prevent short
circuiting & resuspension (turbulence) of sediment at weir W-132. 6. Provide detail/specs on
filter fabric installation. 7. Provide certification from pipe manufacturer that holes from
the filter fabric fasteners (bolts/screws) will not rust and that screwing into pipe will not
affect the long term warranty/performance of pipe.
21. (Rev. 1) Provide SWF maintenance requirements on the plan.
(Rev.3) Partially addressed. Add controls/notes regarding protection of area until stabilized.
Provide maintenance requirements for the underground pretreatment device, including
maintainance/replacement of filter fabric and confined space entry.
Provide approximate cost of yearly maintenance.
Add/change under `Maintenance Activity' column: "Clean out accumulated
sediments/debris from the infiltration facility."
22. (Rev. 1) Provide purchase of nutrient credits, contact Ana Kilmer.
Response [Shimp Eng]: Nutrient credit details will be coordinated when we have the final design
number.
(Rev.2) Not completed. Proof of purchase required before VSMP plan approval.
(Rev.3) The spreadsheet indicates you now meet/exceed phosphorous load requirements
with the infiltration BMP proposed, thus the purchase of nutrient credits is not required.
23. (Rev. 1) Road access lots need easements.
(Rev.2) Addressed.
24. (Rev. 1) A maintenance agreement will be needed for walls. Walls/grading outside of preserved
slopes. Walls details with safety fences.
Response [Shimp Eng]: Comment noted. Walls are standard Eagle Bay segmental block
retaining walls. To avoid redundant design, we are requesting that the VSMP be approved
without wall details...
(Rev.2) Not competed. The retaining wall design will have to be approved before the VSMP
plan can be approved. The design should be included on both plans.
(Rev.3) Acknowledged.
25. (Rev.2) The construction area of BMP D appears to be both in preserved slopes, and in the WPO
stream buffer. While it may meet 17-604(A) requirement with a mitigation plan it may not meet
requirements under 18-30.7.4(b) by right and may require a special use permit.
(Rev.3) Will be confirmed/determined with exhibit sheet.
Engineering Review Comments
Page 5 of 8
26. (Rev.2) VRRM for quality compliance - Drainage Areas for B, C & F do not match what's
shown on the BMP Drainage Map.
(Rev.3) DA tab sheet data for BMP B has been removed, please include.
Correct elevations
on weir plate BMP A. BMP D elevation.
(Rev.3) Addressed.
C 18 - Correct BMP F weir elevations. Correct the profile view for STM C -C lA.
(Rev.3) Addressed.
29. Provide pre -development flow rate (cfs) at each point of discharge to meet Channel
Protection criteria.
30. Sheet C5 -1. Move inlet STR 131A (invert out) to upper end of pretreatment section. 2. Add
access MH at end of pretreatment section (before Weir Plate W-132).
31. Sheet C17 -1. Fix the details of BMP B etc. with the comments of #20/29 above. 2. Fix the
excavation elevations. 3. Fix the cut off text (detail 4/C17).
32. Page 20 (SWM calculation packet) - The invert elevation should be 615.0' (double
check/correct). The exfiltration rate can not include the pretreatment area of filter fabric
(correct). Suggest modeling pretreatment area separately from infiltration area.
33. (Rev.3) VRRM spreadsheet - Total disturbed area increase by a tenth, but land cover areas
increased significantly (comparing this versus last review of VRRM spreadsheet, double
check). Where does that 0.03ac under C Soils forest/open space come from (pre/post
development) ?
D. Mitigation Plan (MP)
The mitigation plan requirements can be found in County Code Chapter 17-406.
1. (Rev. 1) The fee was not paid for the review of this plan (17-208).
(Rev.2) Addressed.
2. (Rev.2) Show 100 -yr floodplain with callout.
(Rev.3) Addressed.
J. (Rev.2) Show critical slopes. Show sewer/drainage easements those that should not have
trees.
(Rev.3) Acknowledged.
4. (Rev.2) Label Sq -ft of preserved forest/open space & mitigation areas on map. Note: Areas
of mitigation outside buffer can't count towards VRRM nutrient reduction.
(Rev.3) Addressed. double check
area aiscnarges needs to be treated or extended to adequate channel.
(Rev.3) Addressed.
6. (Rev.3) Callout Area H (not shown).
7. (Rev.3) Obtain floodplain development permit for sewer line work in the floodplain prior to
disturbance.
E. 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 not approved, and the reasons are provided in the comments below. The erosion
control plan content requirements can be found in County Code section 17-402.
1. (Rev. 1) Limits of distur0ance to be shown outside of preserved slopes. No
grading/tunneling/trenching can occur in tree protected areas (18-30.6.3).
Response [Shimp Eng.]: The LOD have been updated. They are now outside preserved slopes.
(Rev.2) See comment #2 above.
(Rev.3) Addressed.
Engineering Review Comments
Page 6 of 8
2. (Rev. 1) Provide paved wash rack and construction entrance (Design Manual, Sect. 3).
(Rev.2) Addressed.
3. (Rev. l) Show any staging area and stockpile locations.
Response [Shimp Eng.]: Staging/stockpile areas shown.
(Rev.2) Not addressed.
(Rev.3) Addressed.
4. (Rev. l) Show contour elevations on all sheets where contours shown.
(Rev.2) Addressed.
5. (Rev. 1) Proposed slopes greater than 3:1 to have low maintenance (not grass) ground cover
specified on plan (Design Manual, sect. 8A). List approved ground cover type.
Response [Shimp Eng.]: Groundcover type added to mitigation plan sheet cl 1. Additional notes
added to plans.
(Rev.2) Partially addressed. Show areas on E&SC phase IL The low maintenance is to be
used as a final stabilization measure.
(Rev.3) Addressed.
6. (Rev. l) Show proposed lot lines & ROW on all sheets.
Response [Shimp Eng.]: Lot lines and ROW shown on all sheets.
(Rev.2) Area/s outside of property line to be shown in an easement that are to be disturbed
Correct existing boundary line / area information. Should match what's shown on County
GIS.
(Rev.3) Addressed.
7. (Rev. l) Show tree protection symbols & callout.
Response [Shimp Eng.]: Tree protection symbols and details shown.
(Rev.2) Partially addressed. Show tree protection, safety fence & other symbols in legend.
Tree protection should be in place before any land clearing; Show on phase 1 of E&SC
sheet C9.
(Rev.3) Addressed.
8. (Rev. l) Show arrows indicating location or extent of E&SC practice (as needed).
(Rev.2) Double check.
9. (Rev. 1) Show phasing for ESCs.
Response [Shimp Eng]: Phasing shown on the same sheet as the E&SC practices for
clarification.
(Rev.2) Show phasing (line) on sheet C10.
Response [Shimp Eng]: E&S Phasing is no longer proposed, linework and notation has been
removed.
(Rev.3) Acknowledged.
10. (Rev. 1) Apply surface roughening (SR) and temp. slope drains (TSD) for slope protection where
soil erosion is a problem.
(Rev.2) Addressed.
11. (Rev. l) Provide baffle for sediment traps to prevent shortcutting of storm runoff.
(Rev.2) Addressed.
12. (Rev. 1) Sheet C5 - Show OP for sediment basin.
(Rev.2) Addressed.
13. (Rev. 1) Sheet C9 - Show SF detail. IP detail, also provide detail for gutter buddy. Change
"Stone" CE to "Paved" CE.
(Rev.2) Addressed.
14. (Rev. 1) Sheet C10 - Show side & embankment slope info. for SB detail. Show SF detail for drop
inlet protection.
Response [Shimp Eng.]: Embankment info shown on what is now C14. Side slope is 2:1. Drop
inlet protection was chosen as wire mesh and gravel because of the steepness of the slopes on the
site before and after grading. This can be revised at reviewers recommendation.
Engineering Review Comments
Page 7 of 8
(Rev.2) Not completed. Show the embankment side slopes at 2:1 (max) in the detail. Show
cutoff trench for the fill embankment. The downstream end of the embankment shows 1:1
end should be 3:1 overall. DEQ, Spec 3.14).
Constructed top of embankment
\\- Settled top of embankment
Emergency spillway
Frew Assumed phreatic line 4H:1V
*Uchre
60
Of embonkmart Andi—seep collars
A
tgmel
4' rnln. �OuUet
protection
Cut off
trench
fixure.1-3. Pro/ilr.11uiiyCenterline of Prin,'ipal.Spilhra r.
(Rev.3) Addressed.
15. (Rev. 1) Any construction acuviues outsiue property line to be shown in an easement.
Response [Shimp Eng.]: Comment noted, no construction is proposed outside the property line
and retaining wall location that may have caused outside disturbance has been removed.
(Rev.2) Acknowledged. See above comments.
(Rev.3) Addressed.
16. (Rev.3) Sheet C10 — Add CIP for culvert/s instead of IP. Add SF around stockpile location.
Show concrete cleanout and detail.
The VSMP permit application and all plans may be resubmitted for approval when all comments have
been satisfactorily addressed. For re -submittals please provide 2 copies of the complete permit package
with a completed application form.
Engineering plan review staff are available from 2-4 PM on Thursdays, should you require a meeting to
discuss this review.
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. 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
Engineering Review Comments
Page 8 of 8
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;
http://www.albemarle.org/deptforms.asp?department--cdengno
File: Sparrow Hill VSMP WPO201700058 - 11-2017 rev(3).docx
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:
Date of comments:
Reviewer
VSMP Permit plan review
Sparrow Hill
WPO201700058
Shimp Engineering
Judith S. Herring
July 21, 2017
Oct 13, 2017
Aug 31, 2017 (Rev. l)
Nov 16, 2017 (Rev.2)
David James (ext. 3273)
b ustin@shimp-engineering. com]
bu@erring@aol.com]
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 application may be resubmitted for approval if all of the items below are satisfactorily
addressed. 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.
1. (Rev.2) There's impaired waters immediately downstream with a TMDL, H23R-02-BEN -
Lickinghole Creek. Include this report in swppp
http://www.deq.virginia.gov/FS2014/FactSheets.aspx?id=VAV-H23R LKNOlA00&style=l
B. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17-404.
(Submit a PPP satisfying requirements of section 17-404)
C. Stormwater Management Plan (SWMP)
VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a
SWMP. This plan is not approved, and the reasons are provided in the comments below. The
stormwater management plan content requirements can be found in County Code section 17-403.
1. (Rev.l) Add the WPO number to title sheet.
(Rev.2) Addressed.
2. (Rev. l) Sheet C3 — Show managed slopes & preserved slopes with hatching and symbols.
Response [Shimp Eng]: Preserved slopes have been shown on all grading sheets. There are no
managed slopes on the site.
(Rev.2) Not completed. There are managed slopes in yellow according to County GIS. Show
the preserved/managed slopes as shown below.
Engineering Review Comments
Page 2 of 7
(Rev. l) Sheet C4 — Realign sanitary sewer outside buffer area. Sanitary sewer improvements are
allowed within a stream buffer with disturbance minimized.
Response [Shimp Eng]: Per our meeting on Sept. 14, 2017, we are permitted to disturb buffer
and preserved slopes for public utility installation. The site layout dictates the current design...
(Rev.2) Acknowledged. I think you would need ACSA approval for the crossing. [18-30.7.4(b)]
the preserved slopes should be preserved to the maximum extent practicable consistent with the
intent and purpose of this overlay district
(Rev. l) Show all easements. Show proposed lot lines & ROW on all sheets.
(Rev.2) Area/s outside of property line to be shown in an easement that are to be disturbed
Correct boundary line / area information. Should match what's shown in County's GIS.
(Rev. l) Any facilities shown inside the stream buffer need to be relocated outside. Only outfall
from pipes can exist within a stream buffer where nessessary.
Response [Shimp Eng]: Comment noted. Per our meeting Sept. 14, 2017 and County Code WPO
sec. 17-604 A (ii), we are permitted to disturb the landward 50' of the buffer. A mitigation plan
has been provided to offset the impacts of this disturbance.
(Rev.2) Not completed. Provide documentation report that shows where stream is
intermittent.
(Rev. l) Areas of Forest/Open space to be protected as undisturbed space (outside limits of
disturbance) & shall be protected as such in agreements, deed of dedication, and platted within an
easement.
Response [Shimp Eng]: We will draft copies of the SWM agreement and easement plats with the
next submittal.
(Rev.2) Acknowledged. According to the VRRM spreadsheet 12.6 ac offorest/open space will
be protected
v SWM facility accesses. Easements must be provided overall access &
facilities, to accompany deeds & agreements (Design Manual, Sect. 5).
Response [Shimp Eng]: Access to all facilities has been provided. See plans for locations and
easements. All access roads have a grade of 20% or less.
(Rev.2) Addressed.
(Rev. l) Show drainage easements. Width should be calculated according to the equation below
from Design Manual:
Response [Shimp Eng]: Comment noted. Pipes that required additional easement width have
been updated to proper width.
(Rev.2) Partially addressed. Show all of ditch 7 in an easement & other permanent ditches
Engineering Review Comments
Page 3 of 7
(See comment 16).
9. (Rev.1) Show contour elevations on all sheet where contours shown.
(Rev.2) Addressed.
10. (Rev. l) Geotechnical report of soils required before the installation of infiltration facilities &
after final grading operations have be completed.
Response [Shimp Eng]: Geotechnical report has been completed. 3 BMP's meet the criteria set
by the DEQ.
(Rev.2) Acknowledged. See comment #20 below.
11. (Rev.1) Add note that installation of infiltration practices can begin only when all up -
gradient enngtr»ction has been completed and pervious areas are stabilized.
(Rev.2) Addressed.
12. (Rev.1) Increase size of text/linetype (i.e. roof drains). Provide standard list of symbols on
the cover, or C2.
(Rev.2) Addressed.
13. (Rev.1) Connect storm str. G1 to A9.
(Rev.2) Addressed.
14. (Rev. l) Outfall must discharge to a natural channel, or sheet flow.
Response [Shimp Eng]: Outfalls now discharge to natural channels. Please see subdivision sheets
for greater detail. Channel adequacy analysis is not required because site complies with the
energy balance equation.
(Rev.2) Partially addressed. STR 4 and 10 outfall (2&4) does not appear to extend to a
natural channel. Sheet flow may re-channelize <100'.
15. (Rev.1) Show Tc flow path clearly& labeled. Show Tc, Coefficient, D.A. with drainage inlet
map.
Response [Shimp Eng]: TC flow paths shown on pre- and post- development summary maps...
(Rev.2) Addressed.
16. (Rev. l) Label all ditches; Provide ditch/swale cross-sections with dims & 2 -/10 -yr elev. Show
table/calcs for velocities & lining type.
Response [Shimp Eng]: All ditches have been labeled. See updated calculation packet and ditch
detail for regulatory compliance.
(Rev.2) Partially addressed. Show for ditch at house/lot 22 & 6. For ditch 7 & 8 extend
matting further up. Consider grading out more behind house/lot 3 to divert more
stormwater to STR A8A or relocate a little further upstream.
17. (Rev.1) Show overall SWM drainage maps in plans & show flow arrows to inlets.
Response [Shimp Eng]: See comment 15 above. We have drafted more legible drainage maps in
the calculation packet.
(Rev.2) Addressed.
18. (Rev.1) Sheet C12 - Callout ditches/swales, OP going to a natural channel / sheet flow. How
does amount of drainage get to BMP F? Show 100' stream buffer not shown. Change note
about groundcover, specify type to be used, as final stabilization measure. BMP E OP
should run parallel with pipe parallel with channel.
Response [Shimp Eng]: C12 (now sheet C16) Comment noted. Outlet condition labels added.
Drainage to BMP F will be routed by roof drains and ditches. 100' buffer shown. Groundcover
note updated. BMP E outlet updated.
(Rev.2) Addressed.
19. (Rev. l) Sheet C 14 - Show all utility crossings, anchors required for pipes over 16% slope.
(Rev.2) Partially addressed. Show all drainage connections to structures in profiles.
20. (Rev. l) Infiltration Trenches - Show for each facility: geographic coordinates, impervious areas
treated, level of design used, types of pretreatments used, max. depth & surface area calcs, depth
of cover, hydraulic head, the 1 -yr 24 -hr storm RR volume infiltrates in 36-48 hours, if back up
underdram needed?, soil tests (1-2 per practice), mets 200' down -gradient slope requirements,
Engineering Review Comments
Page 4 of 7
ave. slope of CDA is <15%, bottom of facilities are flat 0% slope. Show `permeable' filter fabric
on trench sides. Observation wells every 50 feet. Provide specific material & min/max
dimensions for fabrication/installation (Sect. 6.9).
A minimum vertical distance of 2 feet must be provided between the bottom of the infiltration
practice and the seasonal high water table or bedrock layer.
Response [Shimp Eng]: Infiltration trenches have been updated to have consistent labelling. We
will include coordinates with final submittal. Impervious area treated is shown on the maps and
BMP...
(Rev.2) Based on the soil's report dated Oct. 6 it appears that only BMP D & E may meet
infiltration rates. BMP's A & B soil's show poor permeability, BMP's C is too close to
bedrock, and BMP F currently has low infiltration rate. Are there at least two forms of pre-
treatment? How much imperious area is going to each BMP? See 6.1 on Design infiltration
rates. See Table 8.4 for recommended design solutions.
r manitcumice requn•e,ncnts on uie plan.
(Rev.2) Addressed.
22. (Rev. l) Provide purchase of nutrient credits, contact Ana Kilmer.
Response [Shimp Eng]: Nutrient credit details will be coordinated when we have the final design
number.
(Rev.2) Not completed. Proof of purchase required before VSMP plan approval.
.vks necu easements.
(Rev.2) Addressed.
24. (Rev. l) A maintenance agreement will be needed for walls. Walls/grading outside of preserved
slopes. Walls details with safety fences.
Response [Shimp Eng]: Comment noted. Walls are standard Eagle Bay segmental block
retaining walls. To avoid redundant design, we are requesting that the VSMP be approved
without wall details...
(Rev.2) Not competed. The retaining wall design will have to be approved before the VSMP
plan can be approved. The design should be included on both plans.
25. (Rev.2) The construction area of BMP D appears to be both in preserved slopes, and in the
WPO stream buffer. While it may meet 17-604(A) requirement with a mitigation plan it
may not meet requirements under 18-30.7.4(b) by right and may require a special use
permit.
26. (Rev.2) VRRM for quality compliance — Drainage Areas for B, C & F do not match what's
shown on the BMP Drainage Map.
27. (Rev.2) Sheet C17 — Correct the invert on BMP C & elevation on weir plate. Correct
elevations on weir plate BMP A. BMP D elevation.
28. (Rev.2) Sheet C18 — Correct BMP F weir elevations. Correct the profile view for STM C -
CIA.
D. Mitigation Plan (MP)
The mitigation plan requirements can be found in County Code Chapter 17-406.
1. (Rev. l) Th- fee was not paid for the review of this plan (17-208).
(Rev.2) Addressed.
2. (Rev.2) Show 100 -yr floodplain with callout.
3. (Rev.2) Show critical slopes. Show sewer/drainage easements those that should not have
trees.
4. (Rev.2) Label Sq -ft of preserved forest/open space & mitigation areas on map. Note: Areas
of mitigation outside buffer can't count towards VRRM nutrient reduction.
5. (Rev.2) All concentrated discharges needs to be treated or extended to adequate channel.
Engineering Review Comments
Page 5 of 7
E. 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 not approved, and the reasons are provided in the comments below. The erosion
control plan content requirements can be found in County Code section 17-402.
1. (Rev. l) Limits of disturbance to be shown outside of preserved slopes. No
grading/tunneling/trenching can occur in tree protected areas (18-30.6.3).
Response [Shimp Eng]: The LOD have been updated. They are now outside preserved slopes.
(Rev.2) See comment #2 above.
2. (Rev.1) Provide paved wash rack and construction entrance (Design Manual, Sect. 3).
(Rev.2) Addressed.
3. (Rev. l) Show any staging area and stockpile locations.
Response [Shimp Eng]: Staging/stockpile areas shown.
(Rev.2) Not addressed.
4. (Rev.1) Show contour elevations on all sheets where contours shown.
(Rev.2) Addressed.
5. (Rev. l) Proposed slopes greater than 3:1 to have low maintenance (not grass) ground cover
specified on plan (Design Manual, sect. 8A). List approved ground cover type.
Response [Shimp Eng]: Groundcover type added to mitigation plan sheet cl 1. Additional notes
added to plans.
(Rev.2) Partially addressed. Show areas on E&SC phase 11. The low maintenance is to be
used as a final stabilization measure.
6. (Rev. l) Show proposed lot lines & ROW on all sheets.
Response [Shimp Eng]: Lot lines and ROW shown on all sheets.
(Rev.2) Area/s outside of property line to be shown in an easement that are to be disturbed
Correct existing boundary line / area information. Should match what's shown on County
GIS.
7. (Rev. l) Show tree protection symbols & callout.
Response [Shimp Eng]: Tree protection symbols and details shown.
(Rev.2) Partially addressed. Show tree protection, safety fence & other symbols in legend.
Tree protection should be in place before any land clearing; Show on phase 1 of E&SC
sheet C9.
8. (Rev. l) Show arrows indicating location or extent of E&SC practice (as needed).
(Rev.2) Double check.
9. (Rev. l) Show phasing for ESCs.
Response [Shimp Eng]: Phasing shown on the same sheet as the E&SC practices for
clarification.
(Rev.2) Show phasing (line) on sheet C10.
10. (Rev.1) Apply surf. oughening (SR) and temp. slope drains (TSD) for slope protection
where soil erosion is a problem.
(Rev.2) Addressed.
11. (Rev.1) Provide baffle for sediment traps to prevent shortcutting of storm runoff.
(Rev.2) Addressed.
12. (Rev.1) Sheet C5 - Show OP for sediment basin.
(Rev.2) Addressed.
13. (Rev.1) Sheet C9 - Show SF detail. IP detail, also provide detail for gutter buddy. Change
"Stone" CE to "Paved" CE.
(Rev.2) Addressed.
14. (Rev. l) Sheet C 10 - Show side & embankment slope info. for SB detail. Show SF detail for drop
inlet protection.
Response [Shimp Eng]: Embankment info shown on what is now C14. Side slope is 2:1. Drop
Engineering Review Comments
Page 6 of 7
inlet protection was chosen as wire mesh and gravel because of the steepness of the slopes on the
site before and after grading. This can be revised at reviewers recommendation.
(Rev.2) Not completed. Show the embankment side slopes at 2:1 (max) in the detail. Show
cutoff trench for the fill embankment. The downstream end of the embankment shows 1:1
rade and should be 3:1 overall. (DEQ, Spec 3.14).
PlgwreA-3. Profile Along Centerline of Principal Spilfwap
15. (Rev. l) Any construction activities outside property line to be shown in an easement.
Response [Shimp Eng]: Comment noted, no construction is proposed outside the property line
and retaining wall location that may have caused outside disturbance has been removed.
(Rev.2) Acknowledged. See above comments.
The VSMP permit application and all plans may be resubmitted for approval when all comments have
been satisfactorily addressed. For re -submittals please provide 2 copies of the complete permit package
with a completed application form.
Engineering plan review staff are available from 2-4 PM on Thursdays, should you require a meeting to
discuss this review.
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. 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
Constructed top of embankment
Settled top of embankment
Emergency spillway
Assumed phreatic line 4H:1V
structure
60
22' of embankment Anti—seep colors
A
�R
4' mtn.—
borml '11-�putlet
protection
cut oN
trench
PlgwreA-3. Profile Along Centerline of Principal Spilfwap
15. (Rev. l) Any construction activities outside property line to be shown in an easement.
Response [Shimp Eng]: Comment noted, no construction is proposed outside the property line
and retaining wall location that may have caused outside disturbance has been removed.
(Rev.2) Acknowledged. See above comments.
The VSMP permit application and all plans may be resubmitted for approval when all comments have
been satisfactorily addressed. For re -submittals please provide 2 copies of the complete permit package
with a completed application form.
Engineering plan review staff are available from 2-4 PM on Thursdays, should you require a meeting to
discuss this review.
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. 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
Engineering Review Comments
Page 7 of 7
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;
http : //www. albemarle. org/deptforms. asp?department=cdengwVo
File: Sparrow Hill VSMP WPO201700058 - 11-2017 rev(2).doex
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:
Date of comments:
Reviewer:
VSMP Permit plan review
Sparrow Hill
WP0201700058
Shimp Engineering
Judith S. Herring
July 21, 2017
Aug 31, 2017
David James (ext. 3273)
Dustin@shimp-engineering. com]
bujuherring@aol.com]
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 application may be resubmitted for approval if all of the items below are satisfactorily
addressed. 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.
(Submit a SWPPP satisfying the requirements of section 17-405)
B. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17-404.
(Submit a PPP satisfying requirements of section 17-404)
C. Stormwater Management Plan (SWMP)
VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a
SWMP. This plan is not approved, and the reasons are provided in the comments below. The
stormwater management plan content requirements can be found in County Code section 17-403.
1. Add the WPO number to title sheet.
2. Sheet C3 — Show managed slopes & preserved slopes with hatching and symbols.
3. Sheet C4 — Realign sanitary sewer outside buffer area. Sanitary sewer improvements are
allowed within a stream buffer with disturbance minimized.
4. Show all easements. Show proposed lot lines & ROW on all sheets.
5. Any facilities shown inside the stream buffer need to be relocated outside. Only outfall from
pipes can exist within a stream buffer where nessessary.
6. Areas of Forest/Open space to be protected as undisturbed space (outside limits of
disturbance) & shall be protected as such in agreements, deed of dedication, and platted
within an easement.
7. Show SWM facility accesses. Easements must be provided over all access & facilities, to
accompany deeds & agreements (Design Manual, Sect. 5).
8. Show drainage easements. Width should be calculated according to the equation below
from Design Manual:
Engineering Review Comments
Page 2 of 4
LASfi DENT IVLI]7H = DULI.11 R r , # c&5' w r lV V, Nuti_r
9. Show contour elevations on all sheet where contours shown.
10. Geotechnical report of soils required before the installation of infiltration facilities & after
final grading operations have be completed.
11. Add note that installation of infiltration practices can begin only when all up -gradient
construction has been completed and pervious areas are stabilized.
12. Increase size of text/linetype (i.e. roof drains). Provide standard list of symbols on the cover,
or C2.
13. Connect storm str. G1 to A9.
14. Outfall must discharge to a natural channel, or sheet flow.
15. Show Tc flow path clearly& labeled. Show Tc, Coefficient, D.A. with drainage inlet map.
16. Label all ditches; Provide ditch/swale cross-sections with dims & 2 -/10 -yr elev. Show
table/calcs for velocities & lining type.
17. Show overall SWM drainage maps in plans & show flow arrows to inlets.
18. Sheet C12 — Callout ditches/swales, OP going to a natural channel / sheet flow. How does
amount of drainage get to BMP F? Show 100' stream buffer not shown. Change note about
groundcover, specify type to be used, as final stabilization measure. BMP E OP should run
parallel with pipe parallel with channel.
19. Sheet C14 — Show all utility crossings, anchors required for pipes over 16% slope.
20. Infiltration Trenches — Show for each facility: geographic coordinates, impervious areas
treated, level of design used, types of pretreatments used, max. depth & surface area calcs,
depth of cover, hydraulic head, the 1 -yr 24 -hr storm RR volume infiltrates in 36-48 hours, if
back up underdrain needed?, soil tests (1-2 per practice), mets 200' down -gradient slope
requirements, ave. slope of CDA is <15%, bottom of facilities are flat 0% slope. Show
`permeable' filter fabric on trench sides. Observation wells every 50 feet. Provide specific
material & min/max dimensions for fabrication/installation (Sect. 6.9).
A minimum vertical distance of 2 feet must be provided between the bottom of the
infiltration practice and the seasonal high water table or bedrock layer.
21. Provide SWF maintenance requirements on the plan.
22. Provide purchase of nutrient credits, contact Ana Kilmer.
23. Road access lots need easements.
24. A maintenance agreement will be needed for walls. Walls/grading outside of preserved
slopes. Walls details with safety fences.
Engineering Review Comments
Page 3 of 4
D. Mitigation Plan (MP)
The mitigation plan requirements can be found in County Code Chapter 17-406.
1. The fee was not paid for the review of this plan (17-208).
E. 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 not approved, and the reasons are provided in the comments below. The erosion
control plan content requirements can be found in County Code section 17-402.
1. Limits of disturbance to be shown outside of preserved slopes. No
grading/tunneling/trenching can occur in tree protected areas (18-30.6.3).
2. Provide paved wash rack and construction entrance (Design Manual, Sect. 3).
3. Show any staging area and stockpile locations.
4. Show contour elevations on all sheets where contours shown.
5. Proposed slopes greater than 3:1 to have low maintenance (not grass) ground cover
specified on plan (Design Manual, sect. 8A). List approved ground cover type.
6. Show proposed lot lines & ROW on all sheets.
7. Show tree protection symbols & callout.
8. Show arrows indicating location or extent of E&SC practice (as needed).
9. Show phasing for ESCs.
10. Apply surface roughening (SR) and temp. slope drains (TSD) for slope protection where soil
erosion is a problem.
11. Provide baffle for sediment traps to prevent shortcutting of storm runoff.
12. Sheet C5 — Show OP for sediment basin.
13. Sheet C9 — Show SF detail. IP detail, also provide detail for gutter buddy. Change "Stone"
CE to "Paved" CE.
14. Sheet C10 — Show side & embankment slope info. for SB detail. Show SF detail for drop
inlet protection.
15. Any construction activities outside property line to be shown in an easement.
The VSMP permit application and all plans may be resubmitted for approval when all comments have
been satisfactorily addressed. For re -submittals please provide 2 copies of the complete permit package
with a completed application form.
Engineering plan review staff are available from 2-4 PM on Thursdays, should you require a meeting to
discuss this review.
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. 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.
Engineering Review Comments
Page 4 of 4
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;
hllp://www.albemarle.ora/deptforms.asp?department=cdeng3Uo
File: Sparrow Hill VSMP WPO201700058 - 8-2017 rev(1).docx