HomeMy WebLinkAboutWPO201500037 Review Comments WPO VSMP 2015-09-16V77dGIN1P
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(cDshiW- 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
Date of comments: 21 Jul 2015
(Rev. 1) 16 Sep 2015
Reviewer: John Anderson
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 II 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 (Rev. 1) Withdrawn /review error.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 11 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.
[ ^ ttaehed 17 ^ County template/Rev. 1 • image deleted]
Engineering Review Comments
Page 2 of 6
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
disapproved for reasons provided in comments below. The stormwater management plan content requirements can be
found in County Code section 17 -403.
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 B 1.
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. ice: (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.
Engineering Review Comments
Page 3 of 6
Also: Please revise concrete footer detail, C15, so dimensions are easily readable.
Links (NC- PANA -MI):
1. http: / /www.bae. ncsu. edu/ stormwater/ PublicationFiles /LeveISpreaders2006.pdf
2. http: / /www.bae. ncsu. edu/ stormwater/ PublicationFiles/ LeveISpreaderDesign .Update2010.pdf
3. http:// www. elibrga. dep. state.pa.us /dsweb /Get/Document-
68013 /6.8.1 %20BMP %20Leve1 %20 Spreader.pdf
4. htt2:// www. vwrrc. vt. edu/ swc/ July2009UpdatesNA %20SWM %20BMP %2OSpec %202_SHEETFL
OW_vl.6 29Jun09 Pub %20Cmt %2ODraftReduced.pdf
5. httD: / /www.semcoL.orLy/reports /lid/index.html #236
Excerpts, links:
Link 1:
Link 2:
Link 3:
The minimum length of any level spreader should be
13 feet, and the maximum allowable length by DWQ
standards is 130 feet. A summary of the sizing guide-
lines for level spreader lip length is shown in Table 1.
Table 1. Laval Spreader Lip Sizing Guidelines
MAINTENANCE: DOS AND DON'TS
All stormwaier BMPs must receive regular main-
tenance to function as intended. Maintenance of
LS -VFSs involves mowing the VFS, removing trash
and debris, and removing sediment and solids from
the forebay and blind Swale_ Mowing should he
regular; preferably, the person responsible for mow-
ing should be aware that the LS -VFS is a BMP so
that he or she can detect problems early and perform
simple maintenance as needed. Avoid mowing dur-
ing wet conditions so that the VFS is not rutted by
wheels or blades_ Remove trash and debris every
six months using a wheelbarrow and shovel. Trash
and debris tend to collect in the splitter box, fore -
bay, and blind swale. Sediment in the diversion box,
forebay, and blind swales should be removed on
a yearly basis or after each 2 -year, 24 -hour event
Fertilizer should never be applied to the VFS, as this
will result in an export of nitrogen and phosphorus
from the BMP One exception to this rule would he
during initial vegetation establishment. Maintenance
requirements for LS -VFSs are detailed further in
NCDENR (2007a), Table 9-3.
Key lesion Elements
- Level spreaders must he level-
- Specific site condilions, such as topography, vegetative cover,
sell, and geologic conditions must he considered prior to design:
level spreaders are not applicable In areas with easily erod lb le
sells and/or little vegelallan.
- Level spreaders should safely diffuse at least the 10 -year storm
peak rate: bypassed Flows should be stabilized in a sufficient
manner-
- Length of level spreaders Is dependent on influent flow rate, pipe
diameter (it applicable): number and size of perforations (it
applicable), and downhill cover type.
- It Is always easier to keep flow distrlhuled than to redishlhule It
after It Is concentrated; mulllple outtallsRevel spreaders are
preferable to a single culfallltevel spreader.
Length of Level
Riparian Buffer
Rlpanan Buffer
Vegetation
Width )fU
tfi per 1 rfs of flaw)
Thick ground cover
For any width
13
Forested
50
65
Forested
100
s0
Forested
150
40
MAINTENANCE: DOS AND DON'TS
All stormwaier BMPs must receive regular main-
tenance to function as intended. Maintenance of
LS -VFSs involves mowing the VFS, removing trash
and debris, and removing sediment and solids from
the forebay and blind Swale_ Mowing should he
regular; preferably, the person responsible for mow-
ing should be aware that the LS -VFS is a BMP so
that he or she can detect problems early and perform
simple maintenance as needed. Avoid mowing dur-
ing wet conditions so that the VFS is not rutted by
wheels or blades_ Remove trash and debris every
six months using a wheelbarrow and shovel. Trash
and debris tend to collect in the splitter box, fore -
bay, and blind swale. Sediment in the diversion box,
forebay, and blind swales should be removed on
a yearly basis or after each 2 -year, 24 -hour event
Fertilizer should never be applied to the VFS, as this
will result in an export of nitrogen and phosphorus
from the BMP One exception to this rule would he
during initial vegetation establishment. Maintenance
requirements for LS -VFSs are detailed further in
NCDENR (2007a), Table 9-3.
Key lesion Elements
- Level spreaders must he level-
- Specific site condilions, such as topography, vegetative cover,
sell, and geologic conditions must he considered prior to design:
level spreaders are not applicable In areas with easily erod lb le
sells and/or little vegelallan.
- Level spreaders should safely diffuse at least the 10 -year storm
peak rate: bypassed Flows should be stabilized in a sufficient
manner-
- Length of level spreaders Is dependent on influent flow rate, pipe
diameter (it applicable): number and size of perforations (it
applicable), and downhill cover type.
- It Is always easier to keep flow distrlhuled than to redishlhule It
after It Is concentrated; mulllple outtallsRevel spreaders are
preferable to a single culfallltevel spreader.
Link 4:
Link 5:
Engineering Review Comments
Page 4 of 6
w The length of the level spreader is 13 feet per every 1 cubic foot per second (cfs) of
inflow for discharges across a grass filter strip, and 40 to 65 feet of level spreader length
is needed for each 1 cfs of inflow when the spreader discharges to a foresi buffer (see
Hathaway and Hunt, 2006)_ The minimum level spreader length is 10 feet and the
maximum is 100 feet
8. The length of level spreaders is primarily a function
of the calculated influent flow rate. The level
spreader should be long enough to freely discharge
the desired flow rate. At a minimum, the desired
flow rate should be that resulting from a 10 -year
design storm. This flow rate should be safely
diffused without the threat of failure (i.e., creation
of erosion, gullies, or rills). Diffusion of the storms
greater than the 10 -year storm is possible only if
space permits. Generally, level spreaders should
have a minimum length of 10 feet and a maximum
length of 200 feet.
9. Conventional level spreaders designed to diffuse all
flow rates should be sized based on the following:
o For grass or thick ground cover vegetation:
■ 13 linear feet of level spreader for every one
cubic feet per second (cfs)
7. 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."
C. VSMP: SWPPP: Erosion Control Plan (WPO201500037)
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 elev. 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.
Engineering Review Comments
Page 5 of 6
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). —GIS image
Engineering plan review staff are available from 2 -4 PM on Thursdays. Meeting is scheduled for 17 -Sep 2015.
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
Engineering Review Comments
Page 6 of 6
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;
http://www.albemarle.oriz/deptforms.asp?del2arttnent--cdengMo
Thank you - 434.296 -5832 —0069
File: WPO201500037 Chesterfield Landmg_VSMP 091615 revl
�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 fiustin(&shimp -en ing eering 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
Date of comments: 21 Jul 2015
Reviewer: John Anderson
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.
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 1IA4(e)
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.
4. Sec. 5 — Revise per SWMP comment B_3. below
5. Sec. 6 Exhibit: show PPP measures listed in table on next 2 -pg of SWPPP. See item #2 above.
6. Sec. 8 — Designate qualified personnel, by name —ref. VAR 10 Part II A 6.
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.
8. Update Sec. 4, ESCP, in response to comments
9. Sec. 6.F. —As supplement, include:
Engineering Review Comments
Page 2 of 5
7.0 Spill Prevention & Response
Most spills can be cleaned up foltm irg manufacture, specifications. Arsorbent:o I dry, sealable containers. plastic
bags, and shovels/brooms are suggested mir111-ium spill respcnse items that shau.d be ava.lable at this Incaticn.
1st Priority: Protect all people
2nd Priority Protect equipment and property
3rd Priority: Protect the environment
1. Check for hazards (flammable material, noxious fumes, cause of spill) — if flammable liquid, turn off engines
and nearty electrical equipment. If serious hazards are present leave the area and call 911. LARGE
SPILLS ARE ! IKELY TO PRESENT HAZARD.
I'd a <e Sure ±lie spill area is safe to enter and that it does not pose an immediate threat to health or safety of
ary oerson.
Stop the spill source.
Call co- workers and supervisor for assistance and to make them aware of the spill and potential dangers.
If possible, stop spi I f•om entering drains (use absorbent or other material as necessary).
Stop spill from spreacing (use absorbent or other material)
If spilled material has entered a sto•n- seder conta,_: bc,calitr s storm water department.
Clean up spilled material according to manufacturer specirications, for Liquid spills use absorbent materials
and do not flush area with water.
Properly dispose of cleaning materials and used absorbent material according to manufacturer
specifications.
Emergency Contacts:
Normal Working Hours
DEQ Blue Ridge Regional Office (Roanoke)
540 - 562 -6706
DEQ Blue Ridge Regional Office (Lynchburg)
434 -:532 -=120
DEQ Northern Regional Office
703 -=33 -3800
DEQ Piedmont Regional Off ce
804 -=27 -=020
DEQ Southwest Regio ial Of=ice
27'•- 676 -L800
DEQ Tidewater Regional Office
757- 518 -2000
DEQ Valley Regional Office
540 -574 -7800
Nights, Holidays & Weekends
VA Dept. of Emergency Management
804- 674 -2400
24 Hour Reporting Service
Local Contacts
Local Fire Department
Insert Telephone Number
Local Police Department
Insert Telephone Number
[Attached 17 -p. County template]
B. VSMP: SWPPP: Stormwater Management Plan (WP0201500037)
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. File Floodplain Development Application. On Application, list 1% 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.
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).
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-
Engineering Review Comments
Page 3 of 5
870- 66.B.) by introducing 500' and 225' f v -notch stone channels (SCC 2, 15' wide; SCC B1, 12'; SCC
Cl, 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
B1: 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.
4. Restore on -site SWM facilities shown (in concept form) on Approved preliminary plat. Ref image below:
_�- i
1 � � rz �-•� �
�l
s
1
IiA
✓' �U \__\��i es+µ. "� 1 1 _— —'+� j�` �'_j�G 1 �� r� Bra'- -
~' sw
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.
6. Provide documentation of purchase of nutrient credits:
E. Documentation of the applicant's acquisition of nutrient credits shall be provided to the VSMP authority and
the Department in a certification from the credit provider documenting the number of phosphorus nutrient
credits acquired and the associated ratio of nitrogen nutrient credits at the credit - generating entity. Until the
effective date of regulations establishing application fees in accordance with § 62.1- 44.19:20, the credit
provider shall pay the Department a water quality enhancement fee equal to six percent of the amount paid by
the applicant for the credits. Such fee shall be deposited into the Virginia Stormwater Management Fund
established by § 62.1 - 94.15:29.
7. 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.
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 disapproved
for reasons provided in comments below. The erosion control plan content requirements can be found in County Code
section 17 -402.
1. Sediment basin design data sheet —dry storage, item 8: crest of riser 585.0' elev. does not match crest of
riser elev. 581.4', p. 2, data sheet. Reconcile.
2. SB design data sheet, p. 2, design high water elev. 587' does not match 586.6' high water elevation, ESCP,
sheet 20. Reconcile.
3. Sheet 20, SB detail —label principal (crest of riser) elev.; label dewatering device elevation.
Engineering Review Comments
Page 4of5
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.
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.
6. SB — Provide armored emergency spillway, provide dimensions.
7. Two sheets C4 may be misprint, please renumber as necessary.
D. VSMP: Mitigation Plan
The mitigation plan requirements can be found in County Code section 17 -406.
No structure, improvement, or activity is allowed in stream buffer except connection with existing sanitary
sewer easement.
2. Estimate /report and label Area (SF) of stream buffer impact associated with sanitary connection, #1 above.
3. Provide mitigation for sanitary sewer line connection impact at 2:1 ratio.
Engineering plan review staff are available from 2 -4 PM on Thursdays, should you require a meeting to discuss this
review. Plan review staff are also available at 434 - 296 -5832 (- x3069) should you have questions.
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;
http://www.albemarle.org/deptfonns.asp?department--cdengmTo
Engineering Review Comments
Page 5 of 5
Thank you - 434.296 -5832 —0069
File: WPO201500037_Chesterfield Landing_VSMP_072115geb