HomeMy WebLinkAboutWPO201500006 Review Comments WPO VSMP 2015-10-14�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 - Approved
Project: Fontana — Phase 4C, Section 1 & 2 (includes Cascadia Connector)
Plan preparer: Terra Engineering and Land Solutions, P.C.
Owner or rep.: Fontana Land Trust
Plan received date: 17 Feb 2015
(Rev. 1) 6 Oct 2015
Date of comments: 20 Mar 2015
(Rev. 1) 14 Oct 2015 — improved
Reviewer: John Anderson
A. Stormwater Pollution Prevention Plan
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.
Note: recommendation for text edit/text insert will be sent with plan review Approval e-mail transmittal.
1. Furnish SWPPP /PPP. A template and sample SWPPP will be sent. Please call if any questions.
(Rev. 1) Addressed.
Complete and sign General VPDES Permit Registration statement form. Ensure that Line 9, Area
to be disturbed includes Lot A/Cascadia Connector, 1.21 Ac.. Total —11.17 Ac. (C6.0, C6.1, C6.2)
(Rev. 1) Addressed.
3. Ensure that an individual is named responsible for SWPPP inspections. If contractor not selected,
individual may be owner /engineer. Inspection responsibility may be transferred at a later date.
(Rev. 1) Addressed.
B. VSMP: SWPPP: Stormwater Management Plan
VSMP Regulation 9VAC25- 870 -108 requires the VSMP authority to approve or disapprove a SWMP. This plan
is approved. Comments below addressed with plan revisions.
1. Note: request for revisions are relatively minor. (E -mail: ACCD -Terra Engineering 3/20/2015 9:35 AM)
2. At some point, please visit to retrieve and combine Maps /Appendices of Drainage Computations and SWM
Reports into a single report. Report d. 4 -Nov 14 and revised report 12 -Feb 2015 contain essential drainage
area maps that should be combined in final form, in a single report. Please wait until plan is nearly
approved, then arrange a time to visit (such that all comments are addressed).
3. To support review comments, please reference .PDF of DA Maps 11, 12, 13 —these maps do not require
revision, but .PDF is sent in support of comment 94, below.
4. Pre - /post 10 -year volumetric discharge (cfs) computations (ref .PDF /item #3, Rev. SWM report 12- Feb -15):
Engineering Review Comments
Page 2 of 4
a. SWM Report, p. E1: Cascadia Emergency Access Road/profile view (C3.4) shows L =158'. If use
30' FC/FC roadway width, 5' sidewalks, total surface width =40' Impervious area to each DI -3B
(Str. D7, D8) appears to be =0.072 Ac. Pg. E1 reports Area =0.058 Ac. Confirm 0.058 Ac. If
revise Area, please revise any dependent equations or design.
b. Pre - /post - developed 10 -yr discharge calculation for Lot A/Cascadia Connecctor is not immediately
clear. Review perspective: using DA maps 11 -13 and estimates of existing and developed ground
cover for mapped areas, together with Rational Method routing of areas bypassing treatment (Lot
120 /Lot A), there is apparent post - development Qlo increase, Lots A -120 = 1.0938 cfs (f). Report
Appx C, TR -20 Analysis, p. TR5 indicates 10 -yr attenuation (BELLUNO BIOFILTER) =12.52 cfs.
Report also states Total Attenuation required =10.83 cfs (p. TR5). Section 2 biofilter provides
attenuation surplus =1.69 cfs, a portion of which applies to Lot A/120 if post - developed runoff
increase discussed with comment appears reasonable. Please consider weighted runoff
coefficients /entire DA. At a minimum, furnish detailed pre- /post - developed 10 -yr runoff
calculations for Lots A and 120. Post - developed should include routed Lot A biofilter discharge
(SCS routing/Max. = 1.43cfs -p. E17), and areas of Lot 120 and Lot A whose slopes may be altered
or unaffected, whose post - developed runoff is not routed but releases without detention (Mod.
Rational Method, okay for this). Please call if any questions.
c. For b., REF. DA Maps 11, 12, 13. Also, consider comment review Qio estimates (Lot 120, Lot A)
based upon VSMH, Vol. 11, Table 4 -3, Rational Eq. Runoff Coefficients:
i. PRE, 10 -YR:
1. 0.324 Ac. Lot 120, "C" =0.45 (residential, lots of 17,000sq.ft.)
2. 0.155 Ac. Lot A/Lot 120, "C" =0.45
3. 0.153 Ac. Lot A, "C" =0.30, forest
4. 0.27 Ac. Lot A, "C" = 0.30
5. ...then, using "C" weighted = .3797, DA =0.902 Ac., Mod. Rational routing:
PRE 10 -YR = 2.2829 cfs
ii. POST, 10 -YR (1. - 3., bypass - no detention):
1. 0.324 Ac. Lot 120, "C" =0.45 (residential, lots of 17,000sq.ft.)
2. 0.155 Ac. Lot A/Lot 120, "C" =0.45
3. 0.153 Ac. Lot A, "C" =0.50, shoulder /ditch areas (vs. 0.7 steep grass slopes)
4. And TR -20 Lot A/Cascadia pond routing /detention =1.43 cfs
5. ...then, using "C" weighted = .4621, DA =0.632 Ac., Mod. Rational routing:
bypass = 1.9467 cfs; TOTAL (Lot A, Lot 120) = 3.3767 cfs (1.43cfs + 1.9467cfs)
iii. Review Estimate, Lots A and 120: POST, 10 -YR> PRE 10 -YR. DIFF. = 1.0938 cfs increase.
5. SWM Report, p. TR3 makes reference to private, planted biofilter, and public composite area hydrographs
(# 2, 3, 1, respectively) which is confusing since these areas total 5.44 Ac. 4 hydrographs for 5.44 Ac. Area
(Summary for Pond 9P: Belluno Pond; 2 -, 10 -, 25 -, 100 -yr) are included with 12- Feb -15 SWM report, but
no hydrographs labeled 1, 2, 3 or hydrographs for areas < 5.44 Ac. appear in revised SWM Report. Clarify.
6. Appendix E relates to the Cascadia Emergency Connector, but 9 -Mar, Mr. Nichols explained the Connector
will not be built as shown on plans. Please affirm if intent is to build as shown. If not, please confirm.
7. C5.3 -Show 22.5° bend, Lot A biofilter outfall pipe.
C. VSMP: SWPPP: Erosion Control Plan
Virginia Code §62.1- 44.15:55 requires the VESCP authority to approve or disapprove an ESCP. This plan is
approved. Comments below addressed with plan revisions.
Engineering Review Comments
Page 3 of 4
1. 03.0/3.4/3.6/4.0 -Show grading, relocated driveway, Ex. Lot 118, if property owner consents.
2. C3.5 - Remove sheet.
3. C6.0 -This sheet provides an overall view of initial ESC, but as work on the Connector advances,
the trap at the N end of Lot A must be removed. Furnish sequence of construction for the
Connector, notes, drawings, etc, for ESC measures once the trap is removed.
4. C6.0 - Furnish temporary diversion dike (or detail for backer berm) E of 38 LF 10" HDPE pipe, to
ensure runoff capture from grading E of drainage divide (ref. proposed contours in this area, C4.0).
5. C6.0 -Re -label sediment trap ST -1 as ST -3 (there is a second ST -1).
6. C6.2 -Label floor dimensions, SB -I
7. C6.2 -SB -1: side slope design max. =2:1 per VESCH Spec. 3.14, Temp Sediment Basin,
Embankment Cross - Section. C6.6 indicates sufficient volume, but please revise floor dimensions
to accommodate 2:1 slopes. Floor area will decrease. Dimensions shown are restored with
conversion to biofilter.
8. C6.3 - Revise BOFILTER CONSTRUCTION NOTES to reference 2:1 to 1:1 sideslope conversion
(sediment basin side slopes, 2:1, Max. - item #7, above).
9. C6.7 - Delete pea gravel drain since 10 -m1 plastic barrier /s impermeable.
10. C6.7 - Revise Sediment Basin Note 1, bottom Elev., to read 574.33'.
11. C6.7 - Sediment Basin detail: Show permanent 20" orifice (bio- filter).
12. C6.7 - Sediment Basin detail: Revise to show 2:1 sideslopes, Max.
13. C6.7 -Temp Sediment Trap Design Table: Revise title, Trap 3.
14. C6.6/6.7 - Revise Temp Sediment Trap tables to include top embankment width, and trap bottom
Elev.
15. C6.6 - Compare sediment basin data volumes (cy) against TR -20 storage values (p. TRI8 -21);
Elev. 581.00' for example: 1707.4cy (46,100cf /C6.6) vs. 36,200 cf (TR -20 summary data).
Revise basin data if necessary.
16. C6.6 - Sediment basin data: Complete collar data fields. REF. VESCH, Plate 3.14 -12. If z =2, Ls =
27.9'. Design appears to require 2 collars @ 3.75' X 3.75' or 1 @ 5.25' X 5.25' (for example).
Process:
After approval, plans will need to be bonded. The bonding process is begun by submitting a bond estimate request
form and fee (complete) 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.
Engineering Review Comments
Page 4 of 4
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. (Reviewer will confirm whether tree cutting depends on Final Plat approval, Phase 4C /Sec. 1 & 2.) 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;
hllp://www.albemarle.orgJdeptforms.asp?departinent--cdengno
�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: Fontana — Phase 4C, Section 1 & 2 (includes Cascadia Connector)
Plan preparer: Terra Engineering and Land Solutions, P.C.
Owner or rep.: Fontana Land Trust
Plan received date: 17 Feb 2015
Date of comments: 20 Mar 2015
Reviewer: John Anderson
A. Stormwater Pollution Prevention Plan
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. Furnish SWPPP/PPP. A template and sample SWPPP will be sent. Please call if any questions.
2. Complete and sign General VPDES Permit Registration statement form. Ensure that Line 9, Area
to be disturbed includes Lot A/Cascadia Connector, 1.21 Ac.. Total =11.17 Ac. (C6.0, C6.1, C6.2)
3. Ensure that an individual is named responsible for SWPPP inspections. If contractor not selected,
individual may be owner /engineer. Inspection responsibility may be transferred at a later date.
B. VSMP: SWPPP: Stormwater Management Plan
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. Note: request for revisions are relatively minor. (E -mail: ACCD -Terra Engineering 3/20/2015 9:35 AM)
2. At some point, please visit to retrieve and combine Maps /Appendices of Drainage Computations and SWM
Reports into a single report. Report d. 4 -Nov 14 and revised report 12 -Feb 2015 contain essential drainage
area maps that should be combined in final form, in a single report. Please wait until plan is nearly
approved, then arrange a time to visit (such that all comments are addressed).
3. To support review comments, please reference .PDF of DA Maps 11, 12, 13 —these maps do not require
revision, but .PDF is sent in support of comment #4, below.
4. Pre - /post 10 -year volumetric discharge (cfs) computations (ref .PDF /item #3, Rev. SWM report 12- Feb -15):
a. SWM Report, p. El: Cascadia Emergency Access Road/profile view (C3.4) shows L =158'. If use
30' FC/FC roadway width, 5' sidewalks, total surface width =40' Impervious area to each 13I -313
(Str. D7, 138) appears to be =0.072 Ac. Pg. E1 reports Area =0.058 Ac. Confirm 0.058 Ac. If
revise Area, please revise any dependent equations or design.
Engineering Review Comments
Page 2 of 4
b. Pre - /post - developed 10 -yr discharge calculation for Lot A/Cascadia Connecctor is not immediately
clear. Review perspective: using DA maps 11 -13 and estimates of existing and developed ground
cover for mapped areas, together with Rational Method routing of areas bypassing treatment (Lot
120 /Lot A), there is apparent post - development Qlo increase, Lots A -120 = 1.0938 cfs (f). Report
Appx C, TR -20 Analysis, p. TR5 indicates 10 -yr attenuation (BELLUNO BIOFILTER) =12.52 cfs.
Report also states Total Attenuation required =10.83 cfs (p. TR5). Section 2 biofilter provides
attenuation surplus =1.69 cfs, a portion of which applies to Lot A/120 if post - developed runoff
increase discussed with comment appears reasonable. Please consider weighted runoff
coefficients /entire DA. At a minimum, furnish detailed pre- /post - developed 10 -yr runoff
calculations for Lots A and 120. Post - developed should include routed Lot A biofilter discharge
(SCS routing/Max. =1.43 cfs -p. E17), and areas of Lot 120 and Lot A whose slopes may be altered
or unaffected, whose post - developed runoff is not routed but releases without detention (Mod.
Rational Method, okay for this). Please call if any questions.
c. For b., REF. DA Maps 11, 12, 13. Also, consider comment review Qlo estimates (Lot 120, Lot A)
based upon VSMH, Vol. II, Table 4 -3, Rational Eq. Runoff Coefficients:
i. PRE, 10 -YR:
1. 0.324 Ac. Lot 120, "C" =0.45 (residential, lots of 17,000sq.ft.)
2. 0.155 Ac. Lot A/Lot 120, "C" =0.45
3. 0.153 Ac. Lot A, "C" =0.30, forest
4. 0.27 Ac. Lot A, "C" = 0.30
5. ...then, using "C" weighted = .3797, DA =0.902 Ac., Mod. Rational routing:
PRE 10 -YR = 2.2829 cfs
ii. POST, 10 -YR (1. - 3., bypass - no detention):
1. 0.324 Ac. Lot 120, "C" =0.45 (residential, lots of 17,000sq.ft.)
2. 0.155 Ac. Lot A/Lot 120, "C" =0.45
3. 0.153 Ac. Lot A, "C" =0.50, shoulder /ditch areas (vs. 0.7 steep grass slopes)
4. And TR -20 Lot A/Cascadia pond routing /detention =1.43 cfs
5. ...then, using "C" weighted = .4621, DA =0.632 Ac., Mod. Rational routing:
bypass = 1.9467 cfs; TOTAL (Lot A, Lot 120) = 3.3767 cfs (1.43cfs + 1.9467cfs)
iii. Review Estimate, Lots A and 120: POST, 10 -YR> PRE 10 -YR. DIFF. = 1.0938 cfs increase.
5. SWM Report, p. TR3 makes reference to private, planted biofilter, and public composite area hydrographs
(# 2, 3, 1, respectively) which is confusing since these areas total 5.44 Ac. 4 hydrographs for 5.44 Ac. Area
(Summary for Pond 9P: Belluno Pond; 2 -, 10 -, 25 -, 100 -yr) are included with 12- Feb -15 SWM report, but
no hydrographs labeled 1, 2, 3 or hydrographs for areas < 5.44 Ac. appear in revised SWM Report. Clarify.
6. Appendix E relates to the Cascadia Emergency Connector, but 9 -Mar, Mr. Nichols explained the Connector
will not be built as shown on plans. Please affirm if intent is to build as shown. If not, please confirm.
7. C5.3 -Show 22.5° bend, Lot A biofilter outfall pipe.
C. VSMP: SWPPP: Erosion Control Plan
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. C3.0/3.4/3.6/4.0 -Show grading, relocated driveway, Ex. Lot 118, if property owner consents.
2. C3.5 - Remove sheet.
Engineering Review Comments
Page 3 of 4
3. C6.0 -This sheet provides an overall view of initial ESC, but as work on the Connector advances,
the trap at the N end of Lot A must be removed. Furnish sequence of construction for the
Connector, notes, drawings, etc, for ESC measures once the trap is removed.
4. C6.0 - Furnish temporary diversion dike (or detail for backer berm) E of 38 LF 10" HDPE pipe, to
ensure runoff capture from grading E of drainage divide (ref. proposed contours in this area, C4.0).
5. C6.0 -Re -label sediment trap ST -1 as ST -3 (there is a second ST -1).
6. C6.2 -Label floor dimensions, SB -1
7. C6.2 -SB -1: side slope design max. =2:1 per VESCH Spec. 3.14, Temp Sediment Basin,
Embankment Cross - Section. C6.6 indicates sufficient volume, but please revise floor dimensions
to accommodate 2:1 slopes. Floor area will decrease. Dimensions shown are restored with
conversion to biofllter.
8. C6.3 - Revise BOFILTER CONSTRUCTION NOTES to reference 2:1 to 1:1 sideslope conversion
(sediment basin side slopes, 2:1, Max. - item #7, above).
9. C6.7 - Delete pea gravel drain since 10 -m1 plastic barrier /s impermeable.
10. C6.7 - Revise Sediment Basin Note 1, bottom Elev., to read 574.33'.
11. C6.7 - Sediment Basin detail: Show permanent 20" orifice (bio- filter).
12. C6.7 - Sediment Basin detail: Revise to show 2:1 sideslopes, Max.
13. C6.7 -Temp Sediment Trap Design Table: Revise title, Trap 3.
14. C6.6/6.7 - Revise Temp Sediment Trap tables to include top embankment width, and trap bottom
Elev.
15. C6.6 - Compare sediment basin data volumes (cy) against TR -20 storage values (p. TR18 -21);
Elev. 581.00' for example: 1707.4cy (46,100cf /C6.6) vs. 36,200 cf (TR -20 summary data).
Revise basin data if necessary.
16. C6.6 - Sediment basin data: Complete collar data fields. REF. VESCH, Plate 3.14 -12. If z =2, Ls =
27.9'. Design appears to require 2 collars @ 3.75' X 3.75' or 1 @ 5.25' X 5.25' (for example).
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 plan review staff is available 2 -4 PM on Thursdays, should you require a meeting to discuss this review.
Plan reviewer is available at 434.296 -5832 -0069 should you have any questions.
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.
Engineering Review Comments
Page 4 of 4
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;
hllp://www.albemarle.org/deptforms.asp?dej2artinent--cdengno
File: WP0201500006- Fontana4C, sect 1,2 VSMP.doc