HomeMy WebLinkAboutWPO201500009 Review Comments WPO VSMP 2015-08-30�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 — Amendment Application review
Project:
Faith Christian Center International
Project File Number:
WP02015 -00009
Plan preparer:
Brian Smith; Brian P. Smith, PE, Civil Engineering [4835 Three Chopt Road,
Troy, VA 22974 — bl2sl2enembargmail.com]
Owner or rep.:
Faith Christian Center International, Inc - Pastor Wayne Frye
[pastorkfccintl.org; P. O. Box 2306, Charlottesville, VA 22902]
Plan received date:
24 Feb 2015
(Rev. 1)
12 Aug 2015
Date of comments:
8 Apr 2015
(Rev. 1)
30 Aug 2015
Reviewer:
John Anderson
Note— VSMP Application requests to amend SWM plan under WP0201400070, per VAR10 Part 1113. 1. VPDES
Permit VAR IOG420 approved 12/10/14 remains valid through June 30, 2019. When approved, SWM Plan under
WP0201500009 will replace SWM Plan approval under WP020100070, which will then be void.
*As follow -up — Plan title sheet: Title: Revise "VSMP — WP0201400070" to read "VSMP — WP02015- 00009 ".
VSMP — WP0201400070 was approved 11/11/14. WP02015 -00009 is file # assigned Amendment to
WP0201400070. WP02015 -00009 does not require bond recalculation.
A. VSMP: SWPPP and Pollution Prevention Plan (WP0201400070/WP0201500009) — §17-405
The SWPPP content requirements can be found in County Code section 17 -405. A SWPPP must contain (1)
a PPP, (2) an ESCP, (3) a SWMP, and (4) any TMDL measures necessary.
SWPPP as constituted under 17 -405 is unchanged. SWPPP as defined under VAR10 is revised
with act of Application requesting design revision for specific elements of prior- approved SWM
Plan (WP0201400070). —see Sec. B., below /SWM Plan comments.
B. VSMP: SWPPP: Stormwater Management Plan (WP0201500009)
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.
1. Include sheet L5.2, which appears to be missing. (Rev. 1) Addressed.
2. Revise sheet L5.2: Account for increased buffer impact: WP0201400070, 46,638 sf; WP0201500009,
49,341 sf. —Also, Sec. D., item 92, below. (Rev. 1) Addressed. Also, D. #2, below.
Engineering Review Comments
Page 2 of 4
Ase follow-up: Sheet L5.2 — Mitigation Plant list appears to contain higher quantities than necessary. 128
Mitigation units requires 128 canopy trees, 128 understory trees, and 128 small shrubs. Revise at your
discretion.
Ref text/Option 1:
Option 1 — Mitigate through new plantings and permanent protection as given
below. New plantings must be in the stream buffer area. Applicant has choice of
planting one of the following:
a. For every 400 square foot unit or fraction thereof, plant one (1) canopy tree
measuring 1 V2" — 2" caliper or a large evergreen 6 feet in height, one (1)
understory tree measuring 3/s" — 1 'W caliper or one evergreen 4 feet in height.
and one (1) small shrub 15" — 18" in height.
b. For every acre or fraction thereof, plant 1,214 hardwood and/or pine seedlings
on approximately 6'X6' centers without tree tubes and mats.
c. For every acre or fraction thereof, plant 610 hardwood and/or pine seedlings
on approximately 8'X8' centers with tree tubes and mats.
3. Note: VSMP SWM Plan review does not include review of Retaining Wall. Engineering will comment on
revised retaining wall design when submitted with revised site plans. (Rachel Falkenstein, Lead Reviewer)
4. Sheet C7.1: Compare L = 119.41, `Front' Parking Lot Detention with `C' Line Storm Profile dimensions:
56.58' and 68.83'. These values total 125.41' without even considering 6' DIA Manhole. Revise to show
consistent length for `C' Line storm detention system, with endpoints clearly discernible, across plan sheets.
(Rev. 1) Partially addressed — see Rev. 1 follow -up comment, item #8, below.
5. Sheet C8.0: Revise Channel #1 detail to show 12" min depth consistent with C10.4 (`1 -FOOT DEEP')
(Rev. 1) Addressed.
6. Sheet C8.1: Recommend revise slope of 34.43' 24" RCP (Storm DI) between D2 and outlet to limit height
of Storm D2 to <12'. Alternatively, provide safety slab for Storm D2 (ht. = 12.23'). (Rev. 1) Addressed.
As follow -up 8.1 — "D" Line storm profile — Recommend drop /lower (elevation of) safety slab such that
distance from safety slab to floor of MH is less. Note VDOT SL -1 Note 1, text below.
NOTES,
1. THE STANDARD SAFETY SLAB (SL -1) IS TO BE USED ONLY WHEN SPECIFIED IN THE PLANS
ON THE DRAINAGE SUMMARY SHEET AND /OR THE DRAINAGE DESCRIPTION. FOR MANHOLES,
JUNCTION BOXES, AND DROP INLETS WITH HEIGHTS GREATER THAN 12 FEET, THE SPACING OF
ADJACENT SAFETY SLABS SHALL BE 8' TO 12' WITH NO SAFETY SLAB LOCATED WITHIN 6 FEET
OF THE TOP OR BOTTOM OF THE STRUCTURE. SAFETY SLABS SHALL NOT BE LOCATED BELOW
ANY INLET PIPE OF 30" DIAMETER OR GREATER.
7. Sheet C8.2 /Channel table, Channel #1, Entrance: Revise detail to show D =12" Min, since Qto Depth =8.5 ".
(Rev. 1) Addressed.
8. Sheet 8.2: A,13, C Line SWD Profiles, use dash (oval /circle) to represent Tee end sections. Ref. `E' Line
storm profile (this plan sheet), as example. Revise each profile to show L consistent with 112.00' L shown
on C10.2, or revise C10.2 L, consistent with C8.2. Note: C8.0, `C' Line storm profile lengths (56.58/68.83)
are inconsistent with both C8.2 and 10.2 — please revise for consistency. (9.29' difference: C10.2, C8.2)
(Rev. 1) Partially addressed. Ase follow-up: C8.0 vs. C10.3: sheets 10.2 and 10.3 plan view of `C' Line
storm profile = 119.41'. C8.0 profile: 74.83 + 62.58 X119.41. Revise profile dimensions as necessary.
Sheet 7.1: Plan view, SW detention control MH E3: revise outline of VDOT DI -3A, to reflect DI -3C (detail
belo w; Rev. 1— detail deleted) (Rev. 1) Addressed.
Engineering Review Comments
Page 3 of 4
10. C10.2/C12.0: Provide design/spot Elevations at Church Entrance to ensure drainage to Filterra units #1, #6
to avoid ponding which may occur without precise elevations. Include schematic arrows. (Ifnag°, below;
Rev. 1, image deleted.) (Rev. 1) Addressed.
11. Sheet C10.6 /C11.1: Revise SHORT VERSION BMP COMPUTATIONS values. Decrease 1.9391 ac. value by
0.1979 ac., since areas (Ac. slightly less than) A2 /B2 route to Filterra units #9, #10 (0.0748, 0.1231 Ac) and
should be excluded from 0.3907 ac. pavement value /C11.1. Report Tot. AREA = 1.7412 acres. Then,
1.5484/1.7412=0.89. Then, 0.74 X 0.89=0.66. Then 0.66 > 0.25. (Rev. 1) Addressed.
12. C11.1: Revise hatching to include (stair /phased) areas at NE corner of Church; these areas are not routed
through detention. (images, below/ Rev. 1 -image deleted). (Rev. 1) Addressed.
13. Note: Although calculations support design, eliminating Filterra units and associated inlets forces 0.4974
Ac. to Filterra #1 and 0.3300 Ac. to unit #2. Spread, inlet E3, increases from 8.88' to 11.73' and 10 -yr Q,
from 2.616 cfs to 4.930 cfs (int = 6.5 "). Rear parking SW quality control depends on 2 Filterra units rather
than 5. An 8' DI -3C (E3) replaces initial inlet design: 2.5' DI -3A (E2). Eliminating 3 Filterra units invites
uncertainty should remaining units or DI -3C experience performance issues. More units rather than less
and additional points of connection between paved surface and rear stormwater detention provide inherent
reliability (seen in initial design). Additional units on south and east sides of the rear parking lot would help
ensure system reliability, and are recommended but are not required. (Rev. 1) Recommendation not
accepted.
14. Strongly recommend consider future expansion, and revise rear SW detention capacity to accommodate
Q2 /Qlo routing under phased future expansion scenarios. May require only modest additional length. (Rev.
1) Addressed. -Also, item #15, below.
15. Strongly recommend: In addition to changes outlined in #11, above, recommend revise SHORT VERSION BMP
COMPUTATIONS, C10.6, to include future impervious surface runoff from Phase 2 construction. Additional
future construction is not exempt from the VSMP since part of a common plan of development (Church).
This means water quality requirements apply to future expansion. Design will be evaluated against Part IIB
technical criteria (9VAC25- 870 -65, VaRRM .xls). The SHORT VERSION BMP COMPUTATIONS .xls (now
discontinued, but useful in this case/Part IIC) may be revised to include walks, roof, stairs, or paved
impervious areas to show future quality compliance. For example, if estimate 6,000 SF future impervious
area, current design may cover future expansion. Math (see #11, above): Report Tot. AREA = 1.7412 acres
+ 6,000 sf, or 1.8789 acres. Then, 1.5484/1.88 =0.82. Then, 0.74 X 0.82 =0.61. Then 0.61 > 0.25. (Rev.
1) Addressed. / Applicant response (Dr. W. Frye, email, June 08, 2015 12:42 PM): "There will be no Phase
2. The playground, walk and stairs will be included in Phase 1. Yes, the SW computations accounted for
the playground, walk and stairs."
16. New: Sheet 7.1: Section/Plan view, Stormwater Detention Control MH E3 includes Note: trash racks for the
lower 34" pipes, but then also: 2 -4" PVC pipes and 1 -3" PVC pipe. Reconcile. Also: In section view is
this label: 14" PVC pipe (Elev. 400.37). View appears to show two orifices. Please revise.
C. VSMP: SWPPP: Erosion Control Plan (WP0201400070) - § 17 -402
Virginia Code §62.1- 44.15:55 requires the VESCP authority to approve or disapprove an ESCP. This plan is approved, ref.
comment, below. The erosion control plan content requirements can be found in County Code section 17 -402.
1. Design unchanged from initial ESCP, WP0201400070/lnitial remains approved.
Engineering Review Comments
Page 4 of 4
D. VSMP: Mitigation Plan (WP0201500009) §17-406
1. Restore sheet L5.2. —Also, item # B.1. above. (Rev. 1) Addressed.
2. Stream buffer impact has increased from 46,638 sf to 49,341, or 2,703 sf. Mitigation at 2 X impact =5,406
sf. Propose Mitigation for additional impact. A suitable proposal would be to restore 2 of 3 Filterra units
eliminated with revised design for the rear parking lot, with additional (inlet) connection to rear detention
system. Development lies within 150 ft. of Shadwell Creek. Stream water quality and mitigating elements
of design are a priority. Please note that if two Filterra units are restored, 4 smaller units could be used; that
is, units 1 and 2 would be smaller, and additional units may be relatively small. This alleviates concern
relating to system performance or SWM compliance issues. —Items # B.2./13., above. (Rev. 1)
Withdrawn — ref. email, JA to Dr. W. Frye, 6/8/2015 10:40 AM.
The VSMP permit Amendment application and plans may be resubmitted for approval when all comments have been
satisfactorily addressed. Please provide 2 copies of the complete permit package with a completed application form.
Engineering plan review staff is available 2 -4 PM on Thursdays, should you require a meeting to discuss this review.
Plan reviewer is available at 434.296 -5832 -0069 should you have any questions.
File: WP0201500009 FCCI 083015 revl