HomeMy WebLinkAboutWPO201400070 Review Comments WPO VSMP 2014-09-09�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
Project: Faith Christian Center International — Initial Site Plan
Plan preparer: Brian Smith; Brian P. Smith, PE, Civil Engineering [4835 Three Chopt Road,
Troy, VA 22974 — b]2spe(dembargmail.com]
Owner or rep.: Faith Christian Center International, Inc - Pastor Wayne Frye [P. O. Box 2306,
Charlottesville, VA 22902]
Plan received date: 13 August 2014
Date of comments: 9 September 2014
Reviewer: John Anderson
A. VSMP: SWPPP and Pollution Prevention Plan (WP0201400070) — § 17 -405
(The Virginia stormwater management program, stormwater pollution prevention plan application
and documents
1. SWPPP/PPP, 1- and 3 -p. documents dated August 11, 2014, require revision:
a. Include a plan drawing of site that identifies each area or item referenced in items i. -vi.,
including: vehicle fueling, chemical storage, sanitary waste facilities, and rental bin for
construction waste. None of these facilities may be located upslope of streams or inlets,
without intercepting containment
b. Attach 22 -p. VAR10 to SWPPP. Although SWPPP explains that General Permit is
attached, it was not. Link to GP:
htW: / /www.deq.virginia. goy/programs/ water / stormwatermanagement /vsmppermits /constr
uction eg neralpermit.aspx
c. If you elect not to use EPA SWPPP template, it may be helpful to review it: it is valuable
guide to inspection schedules, pollution prevention narratives, signature blocks, etc.
d. PPP, Part III G: ii, iii, iv, v, vi, vii do not specify how measures will be accomplished.
They are too general to be useful — please revise PPP.
e. Furnish Certifications Statement exactly as follows:
Certification. Any person signing a document under Part III K 1 or 2 shall make the following
certification:
"I certify under penalty of law that I have read and understand this document and that this document
and all attachments were prepared in accordance with a system designed to assure that qualified
personnel properly gathered and evaluated the information submitted. Based on my inquiry of the
person or persons who manage the system, or those persons directly responsible for gathering the
information, the information submitted is, to the best of my knowledge and belief, true, accurate, and
complete. I am aware that there are significant penalties for submitting false information, including the
possibility of fine and imprisonment for knowing violations."
B. VSMP: SWPPP: Stormwater Management Plan ((WP0201400070) — §17-401
1. Include Albemarle County General Stormwater Notes. [ref ACDSM]
2. Include Albemarle County General Construction Notes. [ACDSM]
Engineering Review Comments
Page 2 of 5
3. Calculations /Drainage Areas/HydroCAD
a. Sheet C 11.0 — pre - development DA listed = 7.1702 acres. Sheet 11.1 — post - development
uncontrolled area (hatched area not routed through detention) listed = 4.9304 acres. Sheet 12.0,
post - developed front detention (routed/controlled) listed =0.773 acres; post - developed rear
detention (routed/controlled) listed =1.279 acres. Post - developed figures above, if added, =
6.9824 acres. Please account for the difference: 7.1702 — 6.9824 = 0.1878 acres. Also, please
apply hatching to area not routed (simple oversight). This may help reconcile discrepancy.
b. Short Version BMP computations .xls sent as .pdf dated 5- Sep -14 (attachment to email) reveals
slight area imbalance. BMP post - developed impervious areas (well access, pavement, sidewalks,
buildings) total 2.096 acres. Even if all areas routed to underground storage are impervious, the
total area routed to underground systems =2.052 acres. Please account for the difference: 0.044
acres (1937 sf). A roof structure at rear of church may or may not be routed; this area is 7 -8' x
80', or 640sff.
c. Include Short Version BMP (.xls data) on C10.6 as discussed 9/3.
d. Plan title sheet proposed land coverage and BMP post - developed areas for pavement, sidewalks,
and open space do not match — reconcile values. Make adjustments revised values may require.
e. Add Note to Ex. 15" plastic pipe, sheet C2.1: "Do not remove until storm line `D' installed."
i Routings: revise FCCI post -front detention (3 -line) model input variables or plan sheet details, as
follows:
i. Storage: 48.0" D x 119.4'L, but `C' Line storm profile shows a 56.58' detention system
section, C4 MH (6' dia ?), and a 68.83' detention system section. Total L = 131.41'.
Revise profile or input value (I 19.4'L) so they are consistent with one another.
ii. Primary routing, 18" RCP invert listed = 392.72'. This invert was changed; true inv
= 386.55'. Ref. `C' Line storm profile, and revise model input consistent with profile.
iii. Since INV 18" RCP pipe outfall at stormwater detention control MH is 386.55', please
revise section view to show invert of 18" RCP accurately (C8.0).
iv. Also, revise INV label, 18" RCP, to 386.55' in section view (iv, above).
v. Furnish 3 -line (front) underground detention system volume calculations. It is unclear
how Avail. Storage =0.103 Ac. -ft is calculated.
vi. 9/3, we discussed need to shift 6" block or concrete wall that serves as outlet control,
MHC3, to the left, closer to the 18" pipe. Please ensure that after shifting this wall to the
left (within the MH) that the 2' long rectangular weir is still 2' in length. If it is not,
please revise model input.
vii. Please confirm that S = - 0.2650 `P — double- check. [May be -0.16 `P]
viii. Re -run 2- and 10 -yr events; compare with pre - developed condition.
Engineering Review Comments
Page 3 of 5
g. Routings: revise FCCI post -rear detention (4 -line) model input variables or plan sheet details, as
follows:
i. Storage: 60.0" D X 126.3'L, but `E' Line storm profile shows 137.33' L. Revise profile
(or 126.3'L), consistent with one another.
ii. Furnish 4 -line (front) underground detention system volume calculations. It is unclear
how Avail. Storage =0.228 Ac. -ft is calculated.
iii. 9/3, we discussed need to shift 6" block or concrete wall that serves as outlet control,
MHE2, to the left, closer to the 18" pipe. Please ensure that after shifting wall (within the
MH) that the modeled weir length, 6', remains unchanged. I anticipate this wall, acting as
weir control, will be less than 6' in length. Revise weir model input, if necessary.
iv. Adjust Elev., 34" PVC pipes through wall (low -flow orifice), MH E2, C8.2, to 387.48',
since 388.17' - .005 X 137.33' = 387.48'. With change, revise device #s 2, 3, 4 to 387.48'
v. Re -run 2- and 10 -yr events; compare with pre - developed condition.
h. Filterra project information Form, C9.1: explain what Target Treatment Rate 49% means.
4. MH E2, C8.2: include plan view showing VDOT storm inlet type DI -3A superimposed on MH.
5. MH C3, C8.0: include plan view showing VDOT storm inlet type DI -3A superimposed on MH.
6. All storm line outfall pipes are shown with end sections. Furnish end section typical detail for storm lines
outfalls.
7. Show routing of roof runoff, sheet C 10.2. Roof runoff is directed to underground storage, but this is not
shown, except at point of entry to MH E2; furnish detail for roof drains, including depth/bedding.
8. 3 -line and 4 -line detention systems are split in plan views across sheets C10.2/10.3 (3 -line) and C10.1 /10.2
(4- line). Furnish plan views at 1" = 20' or larger scale; show each system in its entirety.
9. If the 3- and 4 -line systems are manufactured (proprietary) systems, include written approval of the plan
from Mfr.
10. Furnish trash racks over the three 4" and one 6" through wall pipes in Control MH E2 and MH C3; furnish
trash rack detail.
11. Confirm that 1 -6" PVC pipe through wall elevation = 392.62' is at correct elevation relative to 1W out of
48" HDPE SWD pipe. Confirm and report length of 48" HDPE SWD pipe on `C' line storm profile.
12. For storm inlets: include inlet design information (type, length, %efficiency, spread, carryover) on plans —
for inlets A2, A3, select inlet length to ensure little to no carryover ( <0.05cfs; > 98% efficiency) using
INT =6.50 (in). Information sent as email attachment to ACCD September 04, 2014 4:28 PM.
13. Evaluate storm inlets using INT= 6.50 for capacity, INT= 4.00 for spread.
14. Inlet C3: L= 2.5, INT= 4.00, Spread= 8.89: recommend longer inlet.
15. Inlet C6: L= 2.5, INT= 4.00, Spread= 7.81: recommend longer inlet.
Engineering Review Comments
Page 4 of 5
16. Furnish inlet computations: capacity/spread, for E2, E3, E4, and E5.
17. Revise Post - development Drainage Area Map, C11.1: narrow drainage projection flanked with two arrows
to NW of retaining wall at N end of the site can be removed since all off -site drainage at this location either
passes under the site (`F' line) or is skirts the N end of the wall, skirts pavement, and is not collected.
18. Sheet C13.0: As discussed 9/3, minor correction required DA D5: slope of 186' section is 13.9 %; please
revise. Also, please check and revise values which may depend on revised slope.
19. Sheet C13.0/Minor correction: DA D4: slope of 59' section is 22% since vertical interval is 13' (415 -402);
revise. Also, please check and revise values which may depend on revised slope.
20. Sheet C11.1/Minor correction: FCCI post uncontrolled 2- and 10 -yr event tables. Revise velocity of 74',
45.9% slope shallow concentrated flow. Ref. VESCH, Plate 5 -2 (vel. >10fps).
21. Retaining Wall: Transfer profiles with details of geosynthetic reinforcement for varying wall heights from
DMWPV report to plans. Insert a new sheet (S4), if necessary, to accommodate profiles. Transfer profiles
only, not design calculations. Report is untitled, d. 4/30/14. Transfer profiles on pages: 8, 15, 22, 28, 34
(43 -pg FCCI geotechnical retaining wall design calculations attached to email: Sep -04, 2014 9:49 AM).
22. Typical wall section and Reinforcing Schedule, plan sheet S3, conflict with every report profile schematic
except p. -34; profiles show Miragrid 3XT at a different location relative to lowest row of blocks. Schedule
on S3 is confusing. Label No. of Lam column in Reinforcing Schedule rows of blocks, if this is what it
means.
23. Furnish embedment detail for handrail. S3 shows handrail in 57 stone. Provide detail for concrete
embedment sufficient to permanently anchor handrail.
24. C11.0 —show off -site contours between property line and Shadwell Creek.
25. NOTES:
a. VDOT advises pavement design, C7.0, for entrance, drive, and parking, may be inadequate if ADT
=685. Please check and revise (2" SM -9.5A; 8 "- VDOT #21A base stone with prime on site).
b. ACCD notes Stephen D. Barber's view that `F' line storm profile, which proposes to penetrate all
layers of geogrid at F5 and F4 (DI -7 Type 1 inlets), is appropriate. Engineering expresses concern
with design, especially at F4, a ninety- degree outside corner (sta. 288).
c. F & C label (storm F2, storm MHF3, storm D3, C2, C4) is unfamiliar —what does it mean?
d. VDH approval of on -site sewerage system is required prior to final site plan approval.
C. VSMP: SWPPP: Erosion Control Plan (WPO201400070) — §17-402
1. Specify landscaping vegetation hardier than grass for proposed slopes > 3:1. [Ref ACDSM 8.A.2]
2. Revise General Project Instruction g. to include "...and will be removed only when a satisfactory stand of
permanent grass is present and only with Albemarle County erosion control or VSMP inspector approval."
3. Show tree protection (TP) on sheets C10.1, C10.2, C10.3, and C10.4.
Engineering Review Comments
Page 5 of 5
4. Revise ESC symbol legend, C10.1, to specify type vegetative ground cover on slopes steeper than 3:1.
5. Confirm that 3' wide LOD strip shown on sheet C10.3 is ditch witching, or low- impact activity. 3' LOD is
otherwise unrealistic.
6. Between C10.3 and C10.4 a portion of LOD disappears; please show LOD continuing from C10.3 to C10.4
7. C11.0 — Acquire drainage easements for storm line outfalls A, B, C, D, E, and F, to Shadwell Creek.
Easements would cross adjacent property. If storm line outfalls correspond with existing drainage patterns
or features, easements are not required. Plans should show or state this. If storm lines A, B, C, D, E, and F
discharge to areas that have not seen shallow or concentrated flow, MS -19 applies. If discharge establishes
new drainage patterns beyond existing depressions or swales, then easements or calming measures that limit
concentrated (pipe outfall) flow to 0.0 - 0.5 fps are required, per MS -19 (level spreaders, for example).
8. Show inlet protection at church Entrance culvert pipe.
D. VSMP: Mitigation Plan (WP0201400070) — §17-406
2. Provide Mitigation Plan —ref. ACDSM planting options attached to email sent September 03, 2014 8:48.
Limits of stream buffer disturbance are shown on C14.0: area estimated = 40,912.42sf. Delineate 81,825sf
area (2:1 offset) to be replanted as mitigation. Note: Area will be included in the Thomas Jefferson Soil and
Water Conservation District (TJSWCD) Easement Program, or recordation of a permanent maintenance
agreement and escrow to run with the land.
Please feel free to call 434.296- 5832 —ext 3069 to discuss this project.
File: WP0201400070 -FCCI- 090914