HomeMy WebLinkAboutWPO201500015 Approval - County 2015-12-30COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, Virginia 22902-4596
Phone (434) 296-5832 Fax (434) 972-4126
Project title:
Project file number:
Plan preparer:
Owner or rep.:
Plan received date:
(Rev. 1)
Date of comments:
(Rev. 1)
Reviewers:
VSMP Permit Plan Review
Free State Run
WPO -2015-00015
Shimp Engineering, P.C.
Free State Partners, LLC
23 September 2015
19 November 2015
19 October 2015
30 December 2015
Justin Deel
County Code section 17-410 and Virginia Code §62.1-44.15:34 requires the VSMP authority to
act on any VSMP permit by issuing a project approval or denial. This project is approved. You
may contact Ana Kilmer (Albemarle County Department of Community Development) at ext.
3246 for further information on bonding procedures and maintenance agreements. The VSMP
application content requirements can be found in County Code section 17-401.
Note that this review letter includes reviews conducted by Justin Deel. It does not include
previous reviews conducted my Michelle Roberge. Review comments made by Ms. Roberge were
adequately addressed upon the 23 September resubmission or were otherwise included in the
below comments, which have all now been addressed.
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.
Provide an updated SWPPP document address these and all previous VSMP comments.
(Rev. 1) Comment addressed.
B. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17-404.
1. Include 11x17 PPP map with updated SWPPP.
(Rev. 1) Comment addressed.
C. Stormwater Management Plan (SWMP)
VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a
SWMP. This plan is approved. All comments in this letter and in previous letters appear to be
adequately addressed. The stormwater management plan content requirements can be found in
County Code section 17-403.
The purchase of credits will need to be approved by the County Attorney's Office. Please contact
Ana Kilmer akilmerkalbemarle.org for required information and documentation for credit
Engineering Review Comments
Page 2 of 4
purchases prior to finalizing the purchase.
(Rev. 1) Comment addressed.
2. The detention pipe is being filled completely to capacity during the 10 year storm, which will lead
to water backing up into the inlets. This should be avoided. The pipe may need to be resized.
Additionally, show that there is adequate over -land relief to avoid flooding the dwellings during
the 100 year storm. Is 1/10" precision required for the orifice?
(Rev. 1) Comment addressed.
3. The detention pipe detail on CSWM 2 shows outlet protection at the proposed grade; however, the
outfall pipe is well below. Please address.
(Rev. 1) Comment addressed.
4. Sheet CSWM 2 shows a "point of analysis" pointing to two different locations on the plan. Please
explain this. Also, it says the total flow during the 10 year storm is 17.13 cfs for these two
locations combined, yet you have nearly 40 cfs from the new 30" pipe alone. Does your
calculation include the piping of the offsite drainage through the new 30" pipe?
(Rev. 1) Comment addressed.
5. The detention pond is being proposed in the area was previously proposed to be a Bioretention
facility. Is the soil in this area suitable for both? Soil permeability should be confirmed to be
adequate for a detention pond. A clay liner may be necessary. Please address.
(Rev. 1) Comment addressed.
6. Provide geotechnical specifications. All dams require a clay core, show this in cross sections.
(Rev. 1) Comment addressed.
7. The detention pond calls for a pretreatment cell but you are not claiming any water quality credit
for this facility. Is this the sediment forebay? Please clarify.
(Rev. 1) Comment addressed.
8. The Bioretention facility shows rip -rap outlet protection going through the timber sediment
forebay wall, please address.
(Rev. 1) Comment addressed.
9. Facility embankment slopes should be no steeper than 3:1. Please adjust detention pond
embankment slopes.
(Rev. 1) Comment addressed.
10. Please remove the Bioretention facility, and all directly associated grading, from the adjacent home
lot.
(Rev. 1) Comment addressed.
11. Demonstrate adequate cover where the rip -rap channel crosses the proposed 30" pipe in fill
material. Can this be avoided?
(Rev. 1) Comment addressed.
12. According to the stormwater inlet computation table, structure MA intercepts 108 cfs. Is there
that much flow here? Please address.
(Rev. 1) Comment addressed.
13. Check the scales for the detention pond detail and cross-section. Are these reversed?
(Rev. 1) Comment addressed.
14. You've assumed that all your inlets will be 100% efficient. This seems a lofty assumption for
such a cramped site that relies on a detention pipe that will be filled to capacity during a 10 year
storm. Please address.
(Rev. 1) Comment addressed.
15. Why does drainage area #4 not include more of Freestate Road? Where is this drainage going?
(Rev. 1) Comment addressed.
Engineering Review Comments
Page 3 of 4
D. 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 approved. All comments in this letter and in previous letters appear to be adequately
addressed. The erosion control plan content requirements can be found in County Code section
17-402.
1. Please remove disturbances to preserved slopes. Show preserved slopes as they appear on the
County GIS overlay. Aerial topography will not warrant removal of preserved slope designations.
Per Section 30.7.4(b)(h) of the County Code; new topographic information should be based on
more accurate or better technical data demonstrating that slopes are less than twenty-five percent,
to the satisfaction of the County Engineer (emphasis added). The County Engineer requires either
a field survey, provided by a licensed Professional Survey, or convincing certified documentation
that the new aerial topographic source is more accurate than the existing steep slopes overlay
district topography.
(Rev. 1) Comment addressed. More accurate topographic information (to the satisfaction of the
County Engineer) has been presented demonstrating that the slopes in question are less than
twenty-five percent.
2. Please review and update your sequences of construction, Phases 1 & 2.
a. Provide more detail concerning the removal of sediment basin 2. How will this effectively
coincide with the installation of the detention system's outfall pipe?
b. The new 30" storm sewer pipe should be installed before the sediment basin 1 is installed.
Otherwise the basin should be sized to include drainage from the existing cross -drain.
c. It appears that the phase 2 sequence was not updated to reflect this resubmission as it calls
for the conversion of sediment basin 1 to a bio filter, and blocking structure E2 to prevent
sediment reaching the infiltration system. Do you mean E3 and the bio filter? Please
clarify.
(Rev. 1) Comment addressed.
3. Please re -include the grading plan. This is an essential element for E&SC/SWM review. The
E&SC Phase 2 sheet is not particularly clear.
(Rev. 1) Comment addressed.
4. The outlet protection for sediment basin 1 should be included in your limits of disturbance.
(Rev. 1) Comment addressed.
5. The limits of disturbance should also include all of the proposed improvements to and along Free
State Road. Please address.
(Rev. 1) Comment addressed.
6. The outlet protection for sediment basin 2 looks a little small and is very close to the property line.
Please provide calculations confirming this is adequate.
(Rev. 1) Comment addressed.
7. Please address why sediment basin 2 does not have an emergency spillway. It appears in your
calculations but is not shown on the plan.
(Rev. 1) Comment addressed.
8. Please show sediment basin drainage areas on plan, and provide details and profiles (to scale) for
each basin, showing both existing and proposed grades.
(Rev. 1) Comment addressed.
9. Phase 2 plan shows sediment basin 1 as detention pond. Please correct this as it will not be a
detention pond during the E&SC phases.
(Rev. 1) Comment addressed.
10. Provide sealed retaining walls plans.
(Rev. 1) Comment addressed.
Engineering Review Comments
Page 4 of 4
Engineering plan review staff are available from 2-4 PM on Thursdays, should you require a meeting 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;
hqp://www.albemarle.org/deptforms.asp?department--cdengmTo
File: WP0201500015 VSMP Review Rl.doc