HomeMy WebLinkAboutWPO201900053 Review Comments WPO VSMP 2019-12-13COUNTY 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 title:
Eco Village Charlottesville
Project file number:
WP02019-00053
Plan preparer:
Shimp Engineering Justin M. Shimp; Keane Rucker
Owner or rep.:
Ecovillage Holdings Inc.
Plan received date:
23 September 2019
(Rev. 1)
25 Oct 2019
Date of comments:
10 October 2019
(Rev. 1)
4 Dec 2019; rev. 13 Dec 2019 (response to 12/12 Meeting)
Reviewer:
WW Associates (J. Anderson, Rev. 1, )
Cc:
Tim Padalino, CDD /Planning
If text is grayscale, comments addressed with Rev. 1 New orfollow-up comments are included, and listed, below.
Additional follow-up comments a possibility, once plans revised.
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 ESOP, (3) a SWMP, and (4) any TMDL measures necessary. This project is subject to
approved SP201800056.
This SWPPP is disapproved, and the reasons are provided in the comments below.
1. Notice of general permit coverage (Rev. 1) Pending. Applicant (10/24/19): `Notice of general permit
coverage cannot be included until the land disturbance permit is issued. We add this document to the
SWPPP at the preconstruction meeting.'
2. Nature of the activity (use/development of the site, not the E&S controls). It should refer to redevelopment
of the site, number of units, parking, private roads, support structures and stormwater controls. The
narrative provided properly belongs in Section 4. (Rev. 1) Partially addressed. As follow-up: Minor edit —
Please revise description to reference 38 units.
3. Qualifications and contact information for qualified personnel (Rev. 1) Addressed. Applicant: `Qualified
personnel have not been selected yet, this will happen after the project is bid. A note stating this has been
added.'
4. Signed certification
5. Delegation of authority (Rev. 1) Withdrawn. NA at this time
6. The cover and site plan sheets state that 36 units will be constructed, although it appears that 38 units will
be constructed. Please revise wherever it appears.
7. Please include the WPO number above on the cover sheets of the plan, SWPPP and calculations.
8. Please note that additional comments may be generated based on the response to the comments provided.
New
9. Sec. 1, Reizistration Statement, p.2, Sec. III (A., B.), Offsite Support Activity Location Information: Revise.
If data unknown, please enter: Project requires offsite support; location information TBD (or similar).
10. Sec. 1, Registration Statement, p.2, Sec. IV, E —MS4: Enter: Albemarle County, since project within MS4.
Engineering Review Comments
Page 2 of 8
11. Sec. 1, Registration Statement, p.3, Sec. IV, F: Check }_es, since project is a common plan of development.
B. Stormwater Management Plan (SWMP)
VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a SWMP. This
plan is disapproved.
1. Show permanent drainage easement recording information on all parcels crossed by the Al-A-4 stormwater
conveyance piping and structures. 17-304.E. (Rev. 1) Persists. Applicant: `Noted, this is still being
obtained.'
2. Provide Albemarle County General Construction Notes for Stormwater Management Plans (three notes).
3. Provide buoyancy calculations for the sedimentation basin riser and the anti -floatation details.
4. Revise the principal spillway detail to show the base (see the previous question).
5. Provide calculations that demonstrate compliance with SP201800016, including hydrographs, routing
calculations and other necessary documentation that the proposed stormwater system is adequate to manage
the 25-year storm without downstream flooding. (Rev. 1) Partially addressed. As follow-up: See item 28.1.,
below. (Ref pg. 97 of .PDF document of 10/25/19 SWM Calculation Packet — Link 12L.)
New (Rev. 1)
6. C4, General: Provide, show, label VDOT GR-2 (guardrail) on south side of lower parking, consistent with
pending FSP comments, and recent Oak Hill Convenience Store review comments /discussion (unrelated
project).
7. C5: Building Lot/Str. 7A is partially within drainage easement. Revise structure /easement location.
8. C5: BMP D label (blue -circled text, image, below) is ambiguous. Please revise for clarity.
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BMP D: ADS BAYFILTER .
STORMTECH CHAMBERS
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AC AREA FROM BMPS A, / e,
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EXISTING AERMA 1
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9. C7, Stormwater Note 6. mentions BMP C, C1, C2 —there are just two biofilters; please revise for clarity.
10. C7, Stormwater Note `D'. Please renumber this, as Note 7.
11. C7, Offsite Areas: Identify offsite areas as pre -requisite to Grading Permit.
12. C8/C9: Label existing culverts under Rio Road E (X4, X3, X2, X1). Use light grayscale to indicate existing.
13. C13: Provide VDOT Anchoring detail. See VDOT Drainage Manual, 9.4.8.7 —image, below. Note caution
against corrugated pipe (if excessive abrasive bed load); slopes in excess of 16%; and flow velocities in
excess of 10f
ps. Revise design as needed. (Note: Storm profile Al-A5 is excessively steep).
Engineering Review Comments
Page 3 of 8
9.4.8.7 Maximum Grades
Slopes that incur uniform flow velocities in excess of 10 fps should be avoided because
of the potential for abrasion. Slopes in excess of 16% are not preferred because of the
need for anchor blocks. When anchor blocks are used, they should be installed at
every other pipe joint, as a minimum. (See Special Design Drawing No. A-73 and MA-
73 for Anchor Details for Concrete Pipe)
Corrugated pipe may be used on steep slopes in situations similar to those where
shoulder slot inlets are proposed. Corrugated pipe should not be used in areas where
the flow is expected to carry an abrasive bed load or that have PH and resistivity factors
beyond the ranges specified in the Allowable Pipe Type Table C in Standard PC-1 of
the VDOT Road and Bridge Standards. (See VDOT's Road and Bridge Standard PI-1,
for Anchor Details for Corrugated Pipe)
In steeper terrain, large elevation differences can be accommodated using drop
structures, otherwise known as "step down" manholes, to reduce the pipe gradient.
Rev. 7/14
Chapter 9-37 of 70
14. C13: Add SL-1 labels to Str. A4 and B5 (x 2) in profile views. Note alone is more likely to be overlooked.
15. C13: Str. A5A INV OUT is shown as 387.50 and 386.50 in separate profiles. Please reconcile.
16. C13: Str. C1 — INV IN < INV OUT. Check /revise.
17. C13: G1 - G2 profile — Eliminate 12" x 8" reducer, since Min. storm pipe DIA =12". (Rev. 12/13)
Withdrawn.
18. C13: B2 - F1 profile — Eliminate 12" x 8" reducer, since Min. storm pipe DIA =12". (Rev. 12/13)
Withdrawn.
19. C13: B2 - E3 profile — Provide MH at proposed 22-deg bend, and any location flow is proposed to change
direction other than within a MH (I1 - I3, for example). (Rev. 12/13) Withdrawn, per 12/12 discussion.
Also, item 26.h., below.
20. C13: Provide a E2 - E1 profile — Ref. Calc. report, pg. 57. (LD-229 Table)
21. C13: Revise E2 - E1 slope to 16% Max., else provide VDOT anchors.
22. C13: Revise 6" PVC storm pipe design per Min. pipe DIA comments, elsewhere. (Profile I2 - IA2) (Rev.
12/13) Withdrawn. Also, item 26.h., below.
23. C14: Provide biofilter floor dimensions. Label biofilter contours in detail plan views.
24. C15: Add flow lines to detail 1 internal to Isolator Row, StormTech chambers, Bayfilter, weir, bypass, etc.
Additional follow-up comments relating to this are possible.
25. C15: Consider /revise ADS Sheet 4 red text; examples: "The outlet invert needs to be lowered...," "The
Design Engineer must check..."
26. Provide standalone SWM Plan (1+ sheets). At present, there are only SWM details, no dedicated plan, or
comprehensive SWM plan (view). SWM Plan should include:
a. Drainage divides. While Calculation packet includes drainage divides, plan review requires
graphic drainage information on the plan. Copy /transfer p. 7 (of .PDF) of SWM Calc. Packet to
VSMP /WPO Plan. (Rev. 12/13) Withdrawn.
b. Show and label 1.26 Ac. Forest /Open Space Easement.
c. Confirm Forest /Open Space Easement lies on hydrologic soil group type `A' soil. Also, ensure
1.26 Ac. Forest /Open Space Easement meets DEQ land cover guidance, April 2016, table, pgl2
/.PDF. Link:
httns://www. dea.vireinia. i!ov/Portals/O/DEO/Water/StormwaterManaaement/VRRM/GM 14-
2001%20Vir,ginia%20Runoff%20Reduction%20Method_V3.pdf
d. Provide and label public drainage easements for all storm pipes downstream of SWM Facilities,
Engineering Review Comments
Page 4of8
including individual raingardens, to the development property line. Ref. 14-431.A.1.
e. Show and label BMP D.
f. Show and label (1. - 38.) raingardens that will be built with individual lots, that will be bonded
with this WPO, and that are necessary (collectively and individually) for SWM quality compliance.
g. Provide plan sheet Note to identify raingarden area (SF) for facilities installed at Lots 18A-23A.
h. 6" of 8" DIA stofm pipe :s disallowed. Revise design. Revise LD-229 tables. (Rev. 12/13) As
follow-up: On this site given site constraints and design objectives, Min. 8" DIA HDPE is allowed
(Typically, with rare exception [other than Nyoplast® yard grate systems], a Min. 12" DIA is
required for storm lines in easement/s. See Drainage Plan checklist). 8" X 12" reducers will be
allowed since we anticipate no debris in HDPE raingarden collector lines. Most bends without
MH Str. are allowed, in this instance. Proposed T-connection should be reviewed, carefully. T-
connections are rarely (if ever) seen in gravity storm systems other than at a MH Str. Engineering
will evaluate revised T-connection, and encourages alternative design. Last: provide cleanouts at
terminal ends of raingarden collector lines, and intervals spaced not more than 150' apart.
i. Show and label two (2) Level 2 bioretention basins. (Rev. 12/13) Asfollow-up: Also, see item
26.k., below, for comparable level of VA DEQ Stormwater Design Specification No. 9
bioretention installation, inspection, and maintenance detail to include with VSMP /WPO plan.
j. Since retaining walls are proposed to the south side of the lower parking lot, shift Bayfilter
Treatment System and ADS Storm.Tech systems (incl Isolator Row) north and slightly west, to
avoid conflict with segmental block retaining wall anchoring geogrid, and to help preserve parking
during (eventual) future system replacement /maintenance, to maximum extent practical. (Rev.
12/13) As follow-up: Engineering continues to hold it is the long-term interest of development
residents if the stormwater management system shifts, as outlined, north and slightly west. Also,
County Engineer requests plan /profile detail of splitter /weir. Provide a manwav or observation
ports for both chambers of the StormTech system, if possible. At a minimum, provide manwav
access to flow splitter /weir structure, and ensure access is located outside of parking spaces.
k. CT Provide installation, inspection, and periodic maintenance Notes for raingardens; inspection
and periodic maintenance Notes for bioretention basins similar to Notes provided for Bayfilter
BMP. Ref. VA DEQ Stormwater Design Specification No. 9 (and Attached). (Rev. 12/13) As
follow-up: Please ensure Spec. 9, Sections 8.2, 8.3, 9.2 thru 9.4 for raingardens, transfer to plans,
and inform design. Note design specifications for raingardens, Table 9.2. Plans should identify
Level 1 or Level 2 design. Captions for details on C5, C6 should identify whether typ. detail is
Level 1 or Level 2. Include specification for media mix test. Above are specific Albemarle
County Engineer requests. Thirty-eight raingardens to be built with residences, likely by builders
not developer, on separately -owned private lots require initial care in design and installation, while
inspection and maintenance will be essential. Easements must provide private or public access to
inspect, repair, maintain or replace raingardens.
27. Revise all 6" — 8" HDPE or PVC storm pipe to 12" DIA Min. See drainage Plan checklist for plan
reviewers, pg. 2, Drainage computations, pipe computations, which reads: `For systems within drainage
easements, all proposed pipes are a minimum 15" in diameter.' (Rev. 12/13) Withdrawn. See item 26.h.,
above.
28. SWM Calculation Packet
a. Pg. 7: DA `A' and DA `B' raingarden CF is slightly inconsistent with C5 - C6 raingarden details.
Revise for consistency. Check SF v. CF descriptions.
b. Pa. 21: Compare 6" PVC Inv.=441.5' with C14 Biofilter C1 6" PVC Inv. =441'. Revise.
c. Pg. 21: Revise Pipe Out Inv. Elev. (table value), consistent with C14.
d. P�21: Compare 15" HDPE OUT vs. 12" HDPE OUT with C14 Biofilter C2. Revise.
e. Pg. 21: Check /revise table DA C-2 Pre-treatment Vol.
f. P�21: Biofilter bottom area (sf), 660 and 155, inconsistent with C14 profiles. Revise.
g. Pg. 22 thru 50: Relocate select material to plans. SWM Calc. Packet will not guide construction
installation, inspection, or periodic maintenance (an obscure location for this data). Transfer
Engineering Review Comments
Page 5 of 8
relevant data to plans. (Rev. 12/13) As follow-up: Not all 28-pg of material needs to transfer to the
plans. Consider range of material already included on C 15, refer to very useful descriptions on C7
for Bayfilter BMP (Installation, Inspection, Maintenance), and please ensure comparable data is
included for the ADS StormTech detention system. It is possible minimal additional BMP
installation, inspection or maintenance material now included in the Cale. packet should transfer.
h. Pg. 53-54: Transfer to plans. (Rev. 12/13) Withdrawn.
i. Piz. 55: Revise C2 and D2 throat length: C2, so no carryover across lower parking lot; D2 since
any carryover at this inlet is untreated, yet inlet is included in `treated' DA.
j. Pa. 55: Revise A5Z throat length so no carryover; project may not release carryover into Rio Road.
k. Piz. 57: Revise LD-229 table, as needed, to reflect revised Min. storm pipe DIA.
1. Piz. 97: Provide Additional Link 12L data (velocity for comparison with channel protection
requirements at 9VAC25-870-66.B.La. 2-yr. vel. (in pipe) Max. =20 s. Also, size riprap at
outfall near Meadow Creek. If riprap design is overlooked, please notify reviewer.
New (12/13/19 rev.)
29. Storm lines need not be centered within drainage easements.
30. Min. easement width for raingarden collector lines =10'.
31. Locate easements such that there is 2'-3' minimum clearance to any portion of a structure (footing, deck
support, etc.) In the future, current design participants /developer may be unavailable to mediate disputes
concerning right of access to repair or replace structures located within public drainage easements.
32. With revised design or storm line placement, please ensure minimum water line v. storm line horizontal
/vertical offset. Similarly, ensure minimum sanitary line v. storm line horizontal /vertical offset -clearance.
33. Curb for private street is required.
34. Revisit super -elevation in 70' R curve.
35. Ensure no drainage release to Rio Road E.
36. Curb cuts are an option; release of uncontained runoff across lower parking lot is not an option.
37. All easements downstream of raingardens are public drainage easements.
38. Consider effectiveness of pretreatment vis-a-vis proposed grade for private street, Road A (blue circle area;
image, blow).
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39
Engineering Review Comments
Page 6of8
Recommend continuous SWM Facility Easement fronting units 9A thru 16A, to provide casement access to
raingardens sandwiched between drives. Image, below (blue -circled area, left).
40. Propose `delineators' for geogrid /grass -pave fire -rescue access (Roads B, C, D) to limit vehicles operating
beyond stabilized geogrid. Image, above (blue -circled area, right /Typ.).
41. Albemarle recommends propose raingarden collector lines at (minimal) depth that still meets material
design specifications for minimum cover, and minimum slope.
42. Ensure all individual lot lines are shown, that lot lines continue to exterior property boundary, and provide a
complete boundary for each lot —this is not a request for platting, but to help ensure raingardens do not
cross lot lines. (Lots 213, 313, 413, for example.)
43. Raingarden for Lot 7A appears to be located on Lot 8A. This cannot be approved. SWM Facility for Lot
7A may be located in common, or open HOA space, but not another private residential lot.
44. Raingarden collector line for Lots IA, 2A (storm J2 — J1) appears to dead-end. Ensure these raingardens on
these lots connect with downstream treatment.
45. Include Construction Record Drawing (As -built) for VSMP (.PDF) on the plans; link:
hq://www.albemarle.orgLupload/imaaes/forms center/departments/Community Development/forms/En ineerin
g_and _WPO_Forms/WPO_VSMP_Construction _ Record_ Drawings Policy 23May2014.pdf
C. 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 disapproved, 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. Sheet C2 has overlapping labels, making them difficult to read. Please revise.
2. Sheet C2 does not show all of the disturbed area (omits the sanitary sewer and stormwater piping offsite).
Please revise. (Rev. 1) Addressed. As follow-up: Please show full extent of storm pipe conveyance
between Rio Road E and Meadow Creek, ESC, Phase 2, C9 (see C2 /Matchline, which shows pipe to
creek). Show Phase 2 ESC measures required to install this stormwater pipe.
3. Sheet C7 Offsite Areas narrative appears to have a typo. Please clarify. (Rev. 1) Addressed. As follow-up:
Engineering Review Comments
Page 7 of 8
Please revise offsite narrative, if offsite locations identified. At a minimum, by preconstruction meeting and
prerequisite to issuance of a Grading permit, provide offsite information to Albemarle County. Provide an
offsite ESC plan, if required, or an Agreement in lieu of a plan. Again, offsite borrow /waste site
information is required prior to Grading Permit issuance.
4. Sheet C8: Note on Sheet C2 states that driveways are to remain until Phase 2 of construction. This sheet
(Phase 1) shows the sediment basin in conflict with the driveway. Revise to correct conflict.
5. Detail references on Sheet C8 appear to refer to incorrect detail or sheet numbers. Please revise.
6. Sheet C8 appears to have a stray SF symbol SW of Agnes Road. Clarify or delete.
7. Sequence of Construction does not mention the Stormtech system construction. Please include the detention
basin in the sequence of construction.
New (Rev. 1)
8. C8: DD is shown outside Limits of Disturbance (LOD). Show inside LOD, or expand LOD.
9. C8: Phase 1 ESC shows proposed grading and utility (storm) system A that is to occur in Phase 2. Revise
Phase 1 to remove Phase 2 grading and utilities (storm pipe).
10. C9: Legend shows LOD. Show LOD on plan view using legend line -type.
11. C9: SB primary riser and portion of principal spillway pipe are not visible; please show, consistent with C8.
12. C 10: Show Phase 3 LOD on plan sheet.
13. C10: Provide soil stabilization blanket (VESCH Std. & Spec. 3.36) between Rio Road E and retaining walls
at lower parking, ESC, Phase 3.
D. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17-404. This plan is disapproved, for
the reasons provided below.
1. If fueling will occur onsite, provide location and address it in the plan.
2. On the Phase 2 sheet, only 10 feet of width between the dike and edge of pavement is provided to the
dumpster, portaj ohns and rinse supply area. The extent of the RWD is not provided. Please clarify whether
that section of DD is RWD and that service trucks will not damage the dike. (Rev. 1) Addressed.
Applicant: `Note added to direct that RWD be properly maintained.'
3. Table in section C:
a. Show the location of the leakproof container for concrete washout.
b. Show dewatering sites on the plan, and relationship to E&S and/or PPP measures.
c. Show material delivery areas on the plans.
d. Solid waste disposal area is downslope of hill; stormwater from this location bypasses all
stormwater BMPs. Please show protection of the site from upland runoff and PPP measures for
leakage and spills.
e. Vehicle washing area(s) not shown on the plans. If the activity will occur, show on the plans how
the wash water will be handled. Detail for "Paved Wash Rack" (Sheet C11) shows wash water
draining to trapping device. Therefore, provide a trapping device in the vicinity of the construction
entrance. (Rev. 1) Addressed. Applicant: `Due to the slopes and the nature of the cut in this area,
we cannot provide a sediment trap. However, we have added a note provide a trapping device and
for wash rack runoff to be pumped into the sediment basin.'
f. Show a contractor laydown/storage area on the plan. (Rev. 1) Partially addressed. As follow-up:
PPP exhibit may show relic Phase 2 stockpile labels; please check /remove unintentional labels.
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 Review Comments
Page 8 of 8
Engineering plan review staff arc available from 2-4 PM on Thursdays, should you rcquirc a mccting 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 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;
hlW://www.albemarle.org/dgptfonns.asp?departinent--cdengUo
WPO201900053 Ecovillage 120419revl-rev121319