HomeMy WebLinkAboutWPO201500047 Review Comments WPO VSMP 2015-09-02�pF A
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:
The Pants Project —VSMP
Plan preparer:
Justin Shimp, Shimp Engineering, 201 E. Main St.
Suite M, Charlottesville, VA 22902 fiustin(a,shimp -en ineering com]
Owner or rep.:
Grey Preservation Society LLC
P. O. Box 7143, Charlottesville, VA 22906
Plan received date:
16 Jul 2015
(Rev. 1)
25 Aug 2015
Date of comments:
6 Aug 2015
(Rev. 1)
2 Sep 2015 e- review
Reviewer:
John Anderson
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.
Coordinate single - family residence SWPPP (22- Apr -2015) with Geoff Elsie, Engineering Inspector (434.270 -3471)
B. VSMP: SWPPP: Stormwater Management Plan (WP0201500047)
VSMP Regulation 9VAC25- 870 -108 requires the VSMP authority to approve or disapprove a SWMP. This plan is
disapproved for reasons provided in comments below. The stormwater management plan content requirements can be
found in County Code section 17 -403.
Comment sections (SWPPP & VSMP SWMP) have been combined since, while we understand design
intent, site forces conceptual reconsideration. We believe conceptual redesign has potential to lessen
expense and yet provide adequate post - construction storm runoff control.
1. (Rev. 1) Withdrawn (visible, initial comments)
2. (Rev. 1) Withdrawn
3. Explain post - development drainage map abbreviations. While this map is carefully detailed, cannot
interpret `MGD'. Legend would be helpful. SF, IMP, AF, make sense —MGD? (Rev. 1) Addressed.
New (9/2/2015 5:03 AM /email)
1. Energy balance, can't follow — variables, where from ?? Tie Eq. variables to plan, or provide narrative and
direct calculations that explain.
Engineering Review Comments
Page 2 of 5
The Pants Project
Energy Balance Calculation
24 Hr 1 year Storm
Q _ 1. F, (Qp- * RVP-)
dea
RVdev
r1 (Qwooded + Rywooded)
'idav ?
R Vdev
2. 36" HDPE PIPE OUT, INV =674
&WM 900 AWAtr fJM
lib Ti* of D. 48'
�$PUWAr rANDPIPE
ELEV -683A
ELEw8a12n a.OWCE W5E =662.0
WET POND
I
36" HDPE 1 APCUXOiIr 1 - 1]
PIPE OUT j
INV =694.0 - I -II - I I _.w
3. Label principal spillway barrel (36" HDPE) length (100').
4. Provide Emergency spillway dimensions, profile view.
5. Show Emergency spillway contours, plan view.
6. Locate Emergency spillway in cut, not fill.
7. . (review error; shown)
8. Dimension culvert #3/ #4 outfall protection (riprap), plan view.
9. Provide VDOT End Section, Wet Pond outfall pipe, profile view.
10. Show and dimension Wet Pond outfall pipe OP (riprap), plan view.
11. Provide culvert #3 -wet pond cross section, similar to culvert #4 -wet pond cross - section.
12. Estimate stream buffer impact. Provide narrative analysis and details re. Mitigation. (please call if
questions)
13. With 6' of riser submerged, provide buoyancy calculations.
14. Provide concrete base/ embedment detail for riser, Also, 4. Above.
15. Specify 48" DIA riser material.
16. Provide detail for riser/barrel, suitable to guide construction.
17. Although listed elsewhere, include Area of disturbance =4.47 Ac. on C3.
18 Confirm site soils are hydrologic soil group `W. (review error', p. -29; 9 -Jul 2015 project report)
19. 6' X 6' weir, can't follow -12.0' top of dam.
f)ehCe RGUtins Insert OuHet OeVke$
41 Primary 676.00' 36.0" Round Culvert L= 100.6' Ke= OA00
Inlet) O�Slet !overt- 674.00' 1674.00' Sn OA31)0'1' Cc=0.900 n- OA13
P2 DR-R 1 682.00' 8.0 "Vert- orifice /Grate C= 0.600
A3 D.110e 1 683.00' 4$.0" Mrir. Riser C=0-600 Limited io weir flow aS low heads
nd Prim" 684.00' 6A' Wrw f16.4' breadth Rroad- Crested Rettangvlar Weir
20. Provide emergency spillway elevation.
21. Provide trash rack, 8" Vert. Orifice /Grate.
22. Provide trash rack, riser crest: Hanson or Alt -for example:
Clp-
2 -50
RVpfe
0.573
RVde„
0 -599
Q. (Eq- 1)
1913 .
Q., (Eq. 2)
2.391
2. 36" HDPE PIPE OUT, INV =674
&WM 900 AWAtr fJM
lib Ti* of D. 48'
�$PUWAr rANDPIPE
ELEV -683A
ELEw8a12n a.OWCE W5E =662.0
WET POND
I
36" HDPE 1 APCUXOiIr 1 - 1]
PIPE OUT j
INV =694.0 - I -II - I I _.w
3. Label principal spillway barrel (36" HDPE) length (100').
4. Provide Emergency spillway dimensions, profile view.
5. Show Emergency spillway contours, plan view.
6. Locate Emergency spillway in cut, not fill.
7. . (review error; shown)
8. Dimension culvert #3/ #4 outfall protection (riprap), plan view.
9. Provide VDOT End Section, Wet Pond outfall pipe, profile view.
10. Show and dimension Wet Pond outfall pipe OP (riprap), plan view.
11. Provide culvert #3 -wet pond cross section, similar to culvert #4 -wet pond cross - section.
12. Estimate stream buffer impact. Provide narrative analysis and details re. Mitigation. (please call if
questions)
13. With 6' of riser submerged, provide buoyancy calculations.
14. Provide concrete base/ embedment detail for riser, Also, 4. Above.
15. Specify 48" DIA riser material.
16. Provide detail for riser/barrel, suitable to guide construction.
17. Although listed elsewhere, include Area of disturbance =4.47 Ac. on C3.
18 Confirm site soils are hydrologic soil group `W. (review error', p. -29; 9 -Jul 2015 project report)
19. 6' X 6' weir, can't follow -12.0' top of dam.
f)ehCe RGUtins Insert OuHet OeVke$
41 Primary 676.00' 36.0" Round Culvert L= 100.6' Ke= OA00
Inlet) O�Slet !overt- 674.00' 1674.00' Sn OA31)0'1' Cc=0.900 n- OA13
P2 DR-R 1 682.00' 8.0 "Vert- orifice /Grate C= 0.600
A3 D.110e 1 683.00' 4$.0" Mrir. Riser C=0-600 Limited io weir flow aS low heads
nd Prim" 684.00' 6A' Wrw f16.4' breadth Rroad- Crested Rettangvlar Weir
20. Provide emergency spillway elevation.
21. Provide trash rack, 8" Vert. Orifice /Grate.
22. Provide trash rack, riser crest: Hanson or Alt -for example:
Engineering Review Comments
Page 3 of 5
StarmRoxI
ROUND SERIES TRASH FLACK
f.CtK WM MAWC Lr
SrµpNaC 44 iNRi MaN sL+ami
DMEIMOrrS IN INEMA
vrsitY:+w n..nw:,v
w+.c.ou„oa,c
PLAN ME VIEW
swfflltaTM Wuwd Series for C01MIM h4ntwk
.%a ML
IErD1
uai
red
l cr,% a.
17% ... ui,
nfs_ i uk
-n v
a.c to
e — .M
�n3c ]t
sT. a-
Iran
41
si-
6f0
1
a
PlssdcSoNtI110 , kv-
N►H IMW14. ir vA i�w
tssrtrri. r. w►d.ww, VA UM
dta>u -n'.w.
i�VA+� *WrsarulwYr
JL
fwr!�i
CONCRIM STFAXRInt a111eirMGi1{
INSUaF amuenxiE DIEM ICK
CUMDESTRNCTURE04MM M
Ar+I.MI A 01710"
CRIMtnAZ. FM oVUBLwo
OP
IE MaWOR7bf PLAT4
puC
orew rr.
A"vr.
Rst<
23. Sum DA 2,3,4,5 =32.21 Ac. Compare with:
Summary for Pond SP: Level 2 Wet Pond
Inflow Area = 93A 19 ac, aW% kopervious, Inflow O plh a 0.22- for iyr ewnl
inflow = 2 -67 cfs @ 12 -23 he$, Vetume= DAW aI
outflow s 0.52 ch @ 115.950s, Volume= 0.812 at, Attenv 81 %, Lop 283.5 mm
Primary + 0.52 ch @ 15.95 Ixs, Volume, 0.412 A
Powroa try Star• fed method, ikm# Spin= 0,o}•24.w Mry, t1t = 0.4E hri
Ptak flew MAT lid 16.95 hr; Surf.Arear 23,189 sf Storager 9,560 cf
Plug -Flaw detention time= 251.2 min calculated for 0A11 of gF.9% of in%wl
Censer -of -Mass del. tome= 1.28.8 min j 1,106,0- 977.11
Vafume Inver AMail.5torage Storage OescrunFan
+11 882 -00 84,955 cf Custom 5taee Oslo iPrf~kj Listed below ftcslrl
24. Impervious Area to pond =0.43 Ac., compare with image above.
25. `100.00% Pervious Area' descriptor, DA 2,3,4,5 /report —a value carried to the hundredths, is inaccurate.
Explain or revise.
26. Is forebay =684' a WSE? Will this Elev. equalize with wet pond 682' WSE?
T_., _ -em .
M5E�29
NET POND —
- — art art Rim � Y iYi IK
rmrm r�n.ea.i:
27. Please confirm that 24" DIA culvert #3 and 36" DIA culvert #4 will convey the 25 -yr storm event without
overtopping driveway.
28. Please explain 4.35 Ac. site data Land Cover vs. 4.47 Ac. disturbance. VaRRM .xls site data must at least
=Area of disturbance.
29. Provide SWM Facility single - vehicle parking (Access) for Alb. County periodic inspection.
30. Provide SWM Facility Easements.
31. Discuss SWM in project description, C2.
32. Provide Narrative, description, Notes, and sequence that correlate wet pond construction with project
development generally, and sheet C2 ESC sequence, specifically.
33. Provide ESC perimeter measures to limit offsite impacts during wet pond construction.
New (not included with email):
Engineering Review Comments
Page 4of5
34. Provide wetland plant species quantities as supplement to Design Specification No. 13 Tables 13.4/13.3, C7
(aid bonding).
35. Provide L X W plan view dimension for each forebay and wet pond to aid construction and earthwork
estimate (bonding).
36. Provide anti -seep collar design for principal spillway (100' L pipe outfall).
37. From Table 2.2, Filter strip design criteria VA DEQ Stormwater Design Specification No. 2:
Length of ELS 6 U = 13 lin.ft. per
each 1 ifs of inflow (13 11 n.ft_ min;
130 Ini.ft. max.)
Revise ELS design. Compare design criteria with Darken residence Modified LD -268 values, p. 30, 9 -Jul
SWM report.
C. VSMP: SWPPP: Erosion Control Plan (WPO201500047)
Virginia Code §62.1- 44.15:55 requires the VESCP authority to approve or disapprove an ESOP. This plan is disapproved
for reasons provided in comments below. The erosion control plan content requirements can be found in County Code
section 17 -402.
1. C3 — Label ditch sections to correspond with Stormwater Management Report Modified LD -268 ditch
labeling convention. (Rev. 1) Not Addressed.
2. LD -268 table —Add note to make protective lining design intent clear. (Rev. 1) Not Addressed.
3. C4 — Provide stockpile silt fence. (Rev. 1) Not Addressed.
Engineering plan review staff are available from 2 -4 PM on Thursdays, should you require a meeting to discuss this
review. Plan review staff are also available at 434 - 296 -5832 (- x3069) should you have questions.
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 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 request a pre - construction conference by completing a 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.
Engineering Review Comments
Page 5 of 5
County forms can be found on the county website forms center under engineering;
http : / /www.albemarle.org/deptforms .asp ?department--cdengwTo
Thank you - 434.296 -5832 —x3069
File: WPO201500047_Pants Project VSMP_090215revl