HomeMy WebLinkAboutWPO201400070 Review Comments WPO VSMP 2014-10-07�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(a),embargmail.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
(Rev. 1) 26 September 2014
Date of comments: 9 September 2014
(Rev. 1) 7 October 2014
Reviewer: John Anderson
A. VSMP: SWPPP and Pollution Prevention Plan (WP0201400070) — § 17 -405 (Rev. 1)
Comments not addressed — understand response is being prepared.
(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.virainia. goo /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 fallowing
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
Engineering Review Comments
Page 2 of 8
1. Include Albemarle County General Stormwater Notes. [ref ACDSM] (Rev. 1) Comment addressed.
2. Include Albemarle County General Construction Notes. [ACDSM] (Rev. 1) Comment addressed.
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. (Rev.
1) Comment addressed.
b. Short Version BMP computations .xIs 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. (Rev. 1) Comment partially addressed. As follow -up: short version BMP.xIs
(sheet C10.6) indicates compliance, but check figures. 0.3799Ac and 1.6164Ac values (inset box),
for example, have changed with addition of Filterra\s to entrance drive. Also, see Mitigation Plan
comments, section D., re replacing proposed entrance drive Filterra at inlet A2, with Filterra units
at inlets A3 and B3.
c. Include Short Version BMP (.xls data) on C10.6 as discussed 9/3. (Rev. 1) Comment addressed.
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.
(Rev. 1) Comment addressed; information removed.
e. Add Note to Ex. 15" plastic pipe, sheet C2.1: "Do not remove until storm line `D' installed."
(Rev. 1) Comment addressed.
f. Routings: revise FCCI post -front detention (3 -line) model input variables or plan sheet details, as
follows:
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. (Rev. 1)
Comment not addressed. On sheet C10.2 and 10.3, show length (L) dimension of the 3-
line underground detention system. Check L against HydroCAD model (C12.0) and `C'
line storm profile (C8.0). Revise profile /rerun model, if necessary. System length affects
volume and detention; it is critical information. It must be shown.
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.
(Rev. 1) Comment addressed, but as follow -up: With revision, change Manhole C3
detail label: 6" b4l& or conc. wall with PVC Outlet Pipe to read 8 " -10" concrete wall
with PVC Outlet Pipe. Furnish structural calculation to support 8" or 10" width. With
Engineering Review Comments
Page 3 of 8
wall supporting column of water 9.28' high, blocks or mortar joints are inappropriate.
This wall is detention system outlet control prone to saturation. Plan note calls for `an
additional 6 -8" thickness to the MH base,' similar and appropriate recognition of the
challenging nature of service conditions this internal wall will experience (detail / sheet
C8.0). This wall should be pre - manufactured, integrated with casting MH -C3. Furnish
reinforcement details or note reinforcement details are pending manufacturer's
recommendation (steel reinforcement — placement /size).
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). (Rev. 1) Comment
addressed.
iv. Also, revise INV label, 18" RCP, to 386.55' in section view (iv, above). (Rev. 1)
Comment addressed.
v. Furnish 3 -line (front) underground detention system volume calculations. It is unclear
how Avail. Storage =0.103 Ac. -ft is calculated. (Rev. 1) Comment not addressed; see,
f /i., above — furnish volume calculations. Volume is a critical design value.
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. (Rev. 1) Comment addressed; weir removed.
vii. Please confirm that S = - 0.2650 `/' double- check. [May be -0.16 ` /'] (Rev. 1)
Comment addressed.
viii. Re -run 2- and 10 -yr events; compare with pre - developed condition. (Rev. 1) Comment
addressed.
g. Routings: revise FCCI post -rear detention (4 -line) model input variables or plan sheet details, as
follows:
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. (Rev. 1) Comment not addressed;
HydroCAD lists rear detention system L = 121.3,' while `E' line storm profile lists L
= 137.33. On sheet C10.1 and 10.2, show length (L) dimension of the 4 -line underground
detention system. Check L against HydroCAD model (C12.0) and `E' line storm profile
(C8.2). Revise profile /rerun model, if necessary. System length affects volume and
detention; it is critical information. It must be shown.
ii. Furnish 4 -line (front) underground detention system volume calculations. It is unclear
how Avail. Storage =0.228 Ac. -ft is calculated. (Rev. 1) Comment not addressed; see,
g. /i., above — furnish volume calculations. Volume is a critical design value.
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. (Rev.
1) Comment not addressed; please confirm that modeled weir length is unchanged.
Engineering Review Comments
Page 4 of 8
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'
(Rev. 1) Comment addressed.
v. Re -run 2- and 10 -yr events; compare with pre - developed condition. (Rev. 1) Comment
addressed.
h. Filterra project information Form, C9.1: explain what Target Treatment Rate 49% means. (Rev.
1) Comment partially addressed — revise value to 28% ( %RR, re- development, short version
BMP .xls /sheet C10.6)
4. MH E2, C8.2: include plan view showing VDOT storm inlet type DI -3A superimposed on MH. (Rev. 1)
Comment addressed.
5. MH C3, C8.0: include plan view showing VDOT storm inlet type DI -3A superimposed on MH. (Rev. 1)
Comment addressed.
6. All storm line outfall pipes are shown with end sections. Furnish end section typical detail for storm lines
outfalls. (Rev. 1) Comment addressed.
7. Show routing of roof runoff, sheet C10.2. 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 depthibedding. (Rev. 1)
Comment addressed.
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. (Rev. 1)
Comment deferred; comment remains a condition of WPO revision to accommodate site plan design
change.
9. If the 3- and 4 -line systems are manufactured (proprietary) systems, include written approval of the plan
from Mfr. (Rev. 1) Comment not addressed. Also, new item 41, below.
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. (Rev. 1) Comment addressed.
11. Confirm that 1 -6" PVC pipe through wall elevation = 392.62' is at correct elevation relative to INV out of
48" HDPE SWD pipe. Confirm and report length of 48" HDPE SWD pipe on `C' line storm profile. (Rev.
1) Comment partially addressed —Note underlined text. Please confirm and report L, 48" HDPE SWD
pipe on `C' line storm profile —see also 3..i., above.
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 (50.05cfs; > 98% efficiency) using
INT =6.50 (in). Information sent as email attachment to ACCD September 04, 2014 4:28 PM. (Rev. 1)
Comment partially addressed — Increase inlet length where significant disparity exists between required
(or P Effec.) length and design: inlets B2 and B3, for example. B2, in particular, initially 6.0' is now 2.5'
while required L = 10.4'. Please revise inlet L adequate relative to capacity (6.50 ") computations, C12.1.
13. Evaluate storm inlets using INT= 6.50 for capacity, INT= 4.00 for spread. (Rev. 1) Comment partially
addressed —ref. comment #12, above.
Engineering Review Comments
Page 5 of 8
14. Inlet C3: L= 2.5, INT= 4.00, Spread= 8.89: recommend longer inlet. (Rev. 1) Comment review
recommendation not accepted.
15. Inlet C6: L= 2.5, INT= 4.00, Spread= 7.81: recommend longer inlet. (Rev. 1) Comment review
recommendation not accepted.
16. Furnish inlet computations: capacity/spread, for E2, E3, E4, and E5. (Rev. 1) Comment partially
addressed. As follow -up, data furnished, but design length appears < required length. Also, 12, 13, above.
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. (Rev.
1) Comment addressed.
18. Sheet C 13.0: 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. (Rev. 1) Comment
addressed.
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. (Rev. 1) Comment
addressed.
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). (Rev. 1) Comment
addressed.
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).
(Rev. 1) Comment relates to final site plan/No revision required: ref. J. Anderson email sent Tue
9/16/2014 1:32 PM.
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 Layers column in Reinforcing Schedule rows of blocks, if this is what it
means. (Rev. 1) Comment relates to final site plan/No revision required: ref. email sent Tue 9/16/2014
1:32 PM.
23. Furnish embedment detail for handrail. S3 shows handrail in 57 stone. Provide detail for concrete
embedment sufficient to permanently anchor handrail. (Rev. 1) Comment relates to final site plan/No
revision required: ref. email sent Tue 9/16/2014 1:32 PM.
24. C11.0 —show off -site contours between property line and Shadwell Creek. (Rev. 1) Comment deferred;
comment remains a condition of WPO revision to accommodate site plan design change.
25. NOTES: (Rev. 1) Notes a, b, d relate to final site plan/No response required:
a. VDOT advises pavement design, C7.0, for entrance, drive, and parking, maybe inadequate if ADT
=685. Please check and revise (2" SM -9.5A; 8 "- VDOT #21A base stone with prime on site).
Engineering Review Comments
Page 6 of 8
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 133, C2, C4) is unfamiliar —what does it mean? (Rev.
1) Comment not addressed; please explain abbreviation: F & C.
d. VDH approval of on -site sewerage system is required prior to final site plan approval.
New
1. Identify manufacturer of 3 -line and 4 -line underground detention systems, if prefabricated.
Furnish Mfr installation notes and system details.
2. C8.0 — Stormwater detention control MH C3, section view — Furnish material/construction details
between top of manhole and pavement/grade.
3. C8.0 — All structures with a depth of 12' or greater shall have safety slabs in accordance with
standard SL -1 as found in the 2008 Road and Bridge Standards (VDOT). MH C3 appears to
require safety slab. Link:
http: / /www.extranet.vdot. state. va.us /LocDes /Electronic %20Pubs /Standards /TOC l OO.pdf
A
SECTION A -A
SECTION B -B
N07ES.
1. SAND— SL -1, MP,Y.CLE SAFETY SUM, IS REDNIREC AR PMT OF THE CRWWAGE
OF— FOR M CLER, BO %FS M'1 DROR WLEIR WITH HEI.TS GREATER
.IUNCT10N
TWN 12 FEET, THE SPACING OF ADJACENT SAFETY SLABS SHALL BE 3' TO 12'WITH
OTTRISICAFTURE SLAB LOCATED SW1uTLLNNOTF FE L-TED FETEW - N�EM OF TOF
SO" DimEr ER - GREATER_
2. TIE CORT -H—C Tx[ SIRHGTHRE
SEE CAST PLACE DRAWINGS
11 TIE 1 IR N 111T EE 11F
Ix
FOR FURTHER DETAILS
3. ACCESS CPENINGS ARE TO BE STAGGERED FROM ONE SIDE OF STRUCTLRE TO THE
OTHER WHERE APPLICABLE- STEPS AFE TO BE STAGGERED ACCORDINGLY,
D. C-C TYP,
A- SAFETY SLAB MAY BE CAST- Ix-P.ACE Ex .... AST_ CAOT-IN-PLA{{ CONCRETE 10 BE
GLASS A] 13000 P _ PREGASI TE BE Aa IADFD P 1 FE- DRECIG
STEEL TO BE IN ACCIXiDAWF WITH .Na Ii01 M]I.
S. ACCESS CPCNINGS MAY BE 30" D�E`FA Oa 30" SCUM WHEN STIMISTURE WIDTH IS
LESS THAN 30" THE ACCESS OPE-1 SHALL BE RECTANGIAM ISTRIJCTBRE WIDTH BY
37 LOW).
TYPICAL PRECAST UNIT
FOR DROP INLETS, MANHOLES AND JUNCTION BOXES
I ARCRA DEPARTMENT OF TRANSPORTATION
4. All structures with a depth of 4' or greater shall have steps in accordance with standard ST -1 as found in
the 2008 Road and Bridge Standards (VDOT). Furnish detail, notes, and provide steps as required, str. C3,
C4, C5, etc. Link: http:// www. extranet .vdot.state.va.us/LocDes/ Electronic %20Pubs /Standards /TOC100.pdf
4ews,�
wry
30• 94 � R
TYPICAL SECTION
OINAHUEACTURER•SV DE-NG H
NO.6 GALVANIZED STEEL STEP
Engineering Review Comments
Page 7 of 8
N4, DR., 60, REIKOBCNO ROO ENCASED IH
& CORR05CN RESISTANT RU ®ER OR OTHER
MATERIAL APPROVED 8Y THE ENCNEER_
IUINENW N MAY VARY WITH MMJUFAOTUNER'S
DESIGN,
7MpRENOS. RE95TPNT
p! REINFORCING ROD
L SECTION
! W—UH OF 3" EU6EOHENT
:P
STANDARD STEP
VIRGINIA DEPMTIENT OF TRANSPORTATION
NOTES=
/TO SORILCR ATEROVENLESSI IN ALL HOTTED ON ME RLMS,�
STR Er— wwL PROTRUDE we FR04 INSIDE FACE BF
MAbdUE STEP WMNG TO HE 15" C-C,
STEPS SHAD WITHSTMO A MINIMUM FORCE OF NO POUIOS ME
E %TENDED H/" FROM THE FACE OF THE SUPPORT_
STEPS PRE TO BE VERTICALLY &ENETI AND —FORMALY SPREE
FOR THE ENTIRE DEPTH OF MY STRUCTURE.
IN PRECAST UNITS STEPS MAY BE LAST N PLACE. MCRTARED
INTO HOLES PROVIDED BY THE FABNIWTDR, OR DRIVEN.
KX- 4ATErarls IN FROM THOSE SnO- MAY PESO SE USED PRO'nOEO THEY 1EET
THE MINIMUM RENREEENTS SHOWN HEREON AND THE
ASTN B22I. ALLOY 5005 -T5.
THAT PORTION OF THE STEP ENCASED IN MASONRY SHKL BE
F E®W KUn EFOEROu h- INUM b r dNO OATGCORIG IOEU
SPECFCAnN C- C- 00a9A
5. C8.2 — Stormwater detention control manhole E2 — Revise Note: "SWD Control Manhole 6'
Diameter or Manufact. Recommendation." Obtain Mfr. recommendation, specify MH DIA/size.
6. C8.2 — Stormwater detention control manhole E2, Section view —Show steps; ref. New #4, above.
7. C11.1 Post- development uncontrolled land coverage: Revise 0.3799 Ac pavement value.
8. C12.0 — Stormwater Detention Summary —rear detention, 2 -yr Q =2.32 cfs; revise calculations and
4 -line system design, if Q post - development >Q pre-development-
C. VSMP: SWPPP: Erosion Control Plan (WP0201400070) — §17 -402
1. Specify landscaping vegetation hardier than grass for proposed slopes > 3:1. [Ref ACDSM 8.A.2] (Rev. 1)
Comment addressed —ref. Table 3.32D, sheet C10.5.
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."
(Rev. 1) Comment addressed.
3. Show tree protection (TP) on sheets C10.1, C10.2, C10.3, and C10.4. (Rev. 1) Comment addressed.
4. Revise ESC symbol legend, CIO. 1, to specify type vegetative ground cover on slopes steeper than 3:1.
(Rev. 1) Comment partially addressed — please include ref. to Table 3.32D, C10.5, in symbol legend.
5. Confirm that 3' wide LOD strip shown on sheet C 10.3 is ditch witching, or low- impact activity. 3' LOD is
otherwise unrealistic. (Rev. 1) Comment partially addressed — narrow LOD eliminated, not increased;
please confirm design intent. No disturbance may occur beyond LOD.
6. Between C103 and C10.4 a portion of LOD disappears; please show LOD continuing from C103 to CIOA
(Rev. 1) Comment addressed.
Engineering Review Comments
Page 8 of 8
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).
(Rev. 1) Comment addressed; ref. level spreader at outfalls El, F1.
8. Show inlet protection at church Entrance culvert pipe. (Rev. 1) Comment addressed.
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. (Rev. 1) Comment partially addressed —As discussed (and
as Stream Buffer Mitigation Program Notes, L5.2, explain), inclusion of alternative water quality measures
will be acceptable in meeting the balance of mitigation requirements. "An area of roughly 51,200 SF within
the WPO buffer is considered suitable for mitigation plantings" (L5.2); "limits of stream buffer disturbance
= 46,638 SF," C14.0. Two points: revise inlets B2, B3 (entrance drive) to have adequate length relative to
capacity computations (items 12, 13, above). Furnish Filterra units at inlets A3 and B3, the entrance drive
inlets which experience substantially higher flow than inlet B2. Filterra unit proposed at inlet B2 may be
removed. Filterra units at A3 and B3 are requisite to mitigation plan approval.
Please feel free to call 434.296- 5832 —ext 3069 to discuss this project.
File: WP0201400070 -FCCI- 100714 -.- 1