HomeMy WebLinkAboutWPO201500037 Approval - County 2015-12-04�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:
Chesterfield Landing —VSMP
Plan preparer:
Justin Shimp, Shimp Engineering, 201 E. Main St., Suite M, Charlottesville, VA
22902 [iustin(&shimp -en ing eering com; lauren(cDshimp- engineering.com ]
Owner or rep.:
Frank, Ann Jarman & Walter M Jarman Jr. & George Burton Jarman, 9 Hunters
Trail, Waynesboro, VA 22980 -6593
Plan received date:
19 Jun 2015
(Rev. 1)
21 Aug 2015
(Rev. 2)
18 Nov 2015
Date of comments:
21 Jul 2015
(Rev. 1)
16 Sep 2015
(Rev. 2)
4 Dec 2015 improved
Reviewer:
John Anderson
ENGINEERING comments approved with this or prior revisions.
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.
1. Sec. 1, Registration Statement: list construction activity operator tel., email, and check whether willing to
receive VGP correspondence electronically —check yes for quickest response. (Rev. 1) Addressed.
2. Show section 6 PPP measures on section 3, ESCP exhibit; for example: concrete washout, sanitary portable
facilities, dumpster, paint /solvent storage, on -site fueling, wash waters, vehicle and equipment washing.
Each must drain to downslope trapment. Portable sanitary facilities should have downslope SF; on -site
fueling/tank must have secondary containment (double -wall tank not sufficient); if shallow pit, then should
be lined with 10 ml liner, and sized to contain stored fuel volume plus 10 -yr storm event (5.6 in). —ref.
VAR 10 Part 11 A 4 (e) (Rev. 1) Addressed.
3. Sec. 5 —VaRRM .xls indicates C soils, but VRMM map shows A, B, B/D — please revise VRRM Map
Legend. Also, please transfer land use Ac. values liste on .xls to VRRM Map (6.86, 11.04, 3.67). VRRM
Map, incidentally, is excellent. (Rev. 1) Withdrawn /review error.
4. Sec. 5 — Revise per SWMP comment B_3. below. (Rev. 1) Addressed.
5. Sec. 6 Exhibit: show PPP measures listed in table on next 2 -pg of SWPPP. See item #2 above. (Rev. 1)
Addressed.
6. Sec. 8 — Designate qualified personnel, by name —ref. VAR10 Part II A 6. (Rev. 1) Addressed.
7. Sec. 12 — Inspection Log should include inspection frequency. There are no details on back of sheet.
General direction or inspector guidance is a minimal expectation for inspection logs. Explain or ref.
prohibited discharges; failed controls. Please revise for clarity, completeness. (Rev. 1) Addressed.
8. Update Sec. 4, ESCP, in response to comments. (Rev. 1) Addressed.
9. Sec. 6.17. —As supplement, include (image deleted Rev. 1): (Rev. 1) Addressed.
[ t4ae ed 17 ^ County template /Rev. 1 • image deleted]
Engineering Review Comments
Page 2 of 4
B. VSMP: SWPPP: Stormwater Management Plan (WPO201500037)
VSMP Regulation 9VAC25- 870 -108 requires the VSMP authority to approve or disapprove a SWMP. This plan is
improved.
1. File Floodplain Development Application. On Application, list I% base flood elevation at rear lot lines,
Lots 10 -15. Also, list BFE for ea. structures on these lots (604.3'- 608.1'). At a minimum, document lowest
structural floor elevation, including basement, relative to FEMA FIRM Zone `A' elevation. List on the four
blank lines reserved for description of development activity. —ref. CFR Title 44, §60.3 (b)(2), (b)(5)(i)
[Appendix E, NFIP Regulations] Provide hydrologic and hydraulic computations used to establish the base
flood elevations on each lot. (Rev. 1) Addressed. —Ref. FDP2015- 00007/Under review
2. FEMA FIRM — compare New MH -1 top elevation (583.5') with base flood elevation, 585' ±. Revise top of
MH elev. relative to base flood elevation. Ensure proposed sanitary line is protected against floodwater
intrusion, and damage due to floodwaters. —ref. 44CFR §60.3 (a)(4)(ii). (Rev. 1) Addressed.
3. Remove and eliminate conveyance channels (SCC) from stream buffer. SCCs are not listed as a structure,
improvement or activity which may be allowed in a stream buffer by program authority (ref. 17- 604A. -F.).
Beyond this, proposed conveyance structures essentially skirt channel protection requirements (9VAC25 -
870-66.B.) by introducing 500' and 225' ± v -notch stone channels (SCC 2, 15' wide; SCC B1, 12% SCC
C1, 12') across floodplain/floodway /stream buffer to Lickinghole Creek. This design may be non - erosive,
but without these channels, true 24" DIA storm line discharge is: OUTFALL Cl: 12.18 cfs /6.4fps; ouTFALL
Bl: 16.42 cfs /6.8 fps. Design must comply with 9VAC25- 870- 66.B.3. Points of discharge release to
protected stream buffer /floodplain. Provide energy balance equations at discharge outfalls: C1 and B1.
From a practical standpoint, erosion control and stormwater management should be provided before
discharging to the stream buffer area. (The erosion control downhill of the fill slope for the lots appears
difficult to protect without pulling back or collecting water with diversions.) This approach stands a better
chance of preserving the buffer, and making use of its filtering benefits. (Rev. 1) Addressed.
4. Restore on -site SWM facilities shown (in concept form) on Approved preliminary plat [Wayland's Ridge].
Ref. image : (image deleted /Rev. 1) Addressed - Applicant response (4 -Aug 2015 Letter): "The
stormwater plan as currently submitted provides measures to comply with all DEQ regulations." As follow-
up: Please provide standalone SWM plan sheet, titled SWM plan. —Also, see email sent 9/15/2015 11:48
AM: " —a plan sheet with: site - specific ELS details; plan view of 6.86 Ac. forest /open space; BMP Spec. #2
design details; Spec. #2 construction /maintenance detail (text /verbatim; cut /paste); SWM Narrative." In
addition: provide narrative for ELS Maintenance (Link 2, below, suggests maintenance).
5. Sheet 3, hatch or otherwise delineate 9,650 SF and 6,536 SF `buildable' space in open space 2 and 3.
Please consider impact, if any, on VaRRM .xls. (Rev. 1) Addressed.
6. Provide documentation of purchase of nutrient credits: (Rev. 1) Partially Addressed. As follow -up:
SWPPP Sec. 5 states " Stormwater shall be discharged in the east through level spreaders to ensure sheet
flow." And: "Flood protection: stormwater shall be discharged to manmade stormwater conveyance systems
that confine the 10 -yr 24 -hr storm within the system." The system is a network of subdivision inlets and
pipes. Where systems end (B1, C1), though these points are coincident with limits of analysis, no defined
channels and distances of 360' and 260'± separate system discharge points from Lickinghole Creek.
Compliance with 9VAC25- 870 -66 should rely on Energy balance (floodplain is a natural stormwater
conveyance system), or, alternatively, convert pipe system concentrated flow to sheet flow. If water
quantity compliance relies on sheet flow, compare LD -229 storm drain computations (Tot Flow /cfs) with
ELS design criteria (Spec. #2/ Table 2.2): Length of ELS Lip = 13 lin. ft. per each 1 cfs of inflow if area has
90% cover. LD -229 cfs rates do not match ELS length provided. 16.42 cfs and 12.18 cfs require lengths
= 213.5' and 158', respectively. Provide 13 lin. ft. / 1 cfs of inflow, while observing 100' max. Length
(Link 4). In August, we discussed this, Justin explained design would be altered to reflect relationship
between flow (Qlo /cfs) and length, in recognition of a practical upper limit. Let's discuss 17 -Sep to avoid
iterative revisions. (Rev. 2) Addressed.
Also: Please revise concrete footer detail, C15, so dimensions are easily readable. (Rev. 2) Addressed.
Engineering Review Comments
Page 3 of 4
Links (NC- PA- VA -MI): [(Rev. 2) Links removed; visible with prior comments]
For 6.86 Ac. forest, post - developed site land cover, provide and show preservation or conservation
easements. While stream buffer ordinance should protect forest or open space within developments, it does
not, and is insufficient assurance of preservation. Show easements on sheets C4, C5. Also, aerial
photography indicates much of this stream buffer does not have forest, so that would need to be established.
(Rev. 1) Partially Addressed. As follow -up: Applicant response noted; we are grateful for copy of DEQ
2013 Stormwater Management Handbook, Table 12. 1, which appears to support comment: "All areas that
will be considered forest/open space for stormwater purposes must have documentation that prescribes that
the area will remain in a natural, vegetated state. Appropriate documentation includes: subdivision
covenants and restrictions, deeded operation and maintenance agreements and plans, parcel of common
ownership with maintenance plan, third -party protective easement, within public right -of -way or easement
with maintenance plan, or other documentation approved by the local program authority." (Rev. 2)
Addressed. 12 Nov 2015 Applicant comment response letter: "The developer will provide a permanent
deed restriction to be held by Albemarle County or the Thomas Jefferson Conservation District."
C. VSMP: SWPPP: Erosion Control Plan (WP0201500037)
Virginia Code §62.1- 44.15:55 requires the VESCP authority to approve or disapprove an ESCP. This plan is approved.
1. Sediment basin design data sheet —dry storage, item 8: crest of riser 585.0' elev. does not match crest of
riser cicv. 581.4', p. 2, data sheet. Reconcile. (Rev. 1) Addressed.
2. SB design data sheet, p. 2, design high water elev. 587' does not match 586.6' high water elevation, ESCP,
sheet 20. Reconcile. (Rev. 1) Addressed.
3. Sheet 20, SB detail —label principal (crest of riser) elev.; label dewatering device elevation. (Rev. 1)
Addressed.
4. Sheet 16, Narrative, Phase 3 Include text that Lots 1, 14, 15 may not be graded until all areas draining to
sediment trap and sediment basin are stabilized. (Rev. 1) Addressed.
5. Sheet 16, Narrative and Plan must direct that paved CE will remain at Phase 1 PCE location until all but
remnant grading remains at intersection Rte. 240 and Watervale Drive. A RWD will likely fail with harsh
consequence for Rte. 240. Phase 1 PCE must remain active until mass /fine grading for Watervale Drive are
all but complete. Plan and VSMP application will not be approved unless plan and narrative impose and
clarify this condition via sequence of construction note. (Rev. 1) Addressed.
6. SB — Provide armored emergency spillway, provide dimensions. (Rev. 1) Addressed.
7. Two sheets C4 may be misprint, please renumber as necessary. (Rev. 1) Addressed.
D. VSMP: Mitigation Plan
The mitigation plan requirements can be found in County Code section 17 -406.
1. No structure, improvement, or activity is allowed in stream buffer except connection with existing sanitary
sewer easement. (Rev. 1) Addressed.
2. Estimate /report and label Area (SF) of stream buffer impact associated with sanitary connection, #1 above.
(Rev. 1) Addressed.
3. Provide mitigation for sanitary sewer line connection impact at 2:1 ratio. (Rev. 1) Addressed. Applicant
response that per 17 -60213, the installation of sewer lines for dedication to ACSA or RWSA is exempt from
duties to manage a stream buffer is accurate (appreciate reference). As follow -up: Please provide mitigation
for permanent SWM BMP (ELS / 2280sf, 2600 sf). SWM facilities are not listed as an eligible structure,
improvement, or activity within stream buffers (17 -604). (Rev. 2) Addressed. [Rev. 2 /image
removed]
Engineering Review Comments
Page 4 of 4
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.
County forms can be found on the county website forms center under engineering;
htt2://www.albemarle.org/deptforms.asp?departrnent--cdengMo
Thank you
File: WP0201500037_Chesterfield Landing_VSMP 120415 rev2_Approv