HomeMy WebLinkAboutSDP200800100 Review Comments Major Amendment, Final Site Plan 2009-01-12*-&A
County of Albemarle
Department of Community Development
Memorandum
To: Summer Frederick, Current Development Project Planner
From: Phil Custer, Current Development engineering review
Date: 12 January 2009
Subject: Moore's Creek Sanitary Sewer Treatment Facility Major Site Plan Amendment
(SDP- 2008 - 00100)
The site plan amendment for the Moore's Creek Sanitary Sewer Treatment Facility has been reviewed.
The following comments are provided.
Before approval of this amendment is granted, a WPO (Water Protection Ordinance) plan
will need to be submitted and approved by engineering review. Currently, an application
has not been submitted.
It appears that there are some ESC measures shown on the site plan. Engineering review
will provide brief comments on the ESC scheme at the end of this memo. Also, it appears
water quality will need to be provided treating the new impervious area of tertiary filters
and UV disinfection facility on sheet C12 as well as chemical filling station area.
The SWM plan should analyze which areas of development will require stormwater
quality treatment by using the Modified Simple BMP spreadsheet. A detention waiver has
been granted by the county engineer.
(Rev. ])An application for an ESC, SWM, and mitigation plan has been received by
engineering. Review comments will be given in a separate letter.
2. The applicant should show the stream buffer lines on all sheets. The stream buffer is
100ft from the top of each of streambank of Moore's Creek. Disturbance of the stream
buffer will be allowed per 17- 321.1, but a mitigation plan must be submitted and approved
during the WPO plan review. Mitigation plan requirements can be found in the county
design manual available online.
(Rev. I) Please refer to WPO comment letter.
3. The Bulk Chemical Storage facility in the floodplain will require a Special Use Permit for
fill in the floodplain. An application for this permit is available online. The storage of the
chemicals will be allowed in this building if they located at least Ift above the 100 -year
flood elevation. [18 -30.3]
(Rev. I) Comment has been addressed.
4. Please provide the FEMA map number and date on the plan. The 20 scale sheets should
also show the FEMA floodplain. [DM]
(Rev. I) Comment has been addressed.
5. Please provide existing topography on all 20 scale sheets. In areas being developed, there
is no existing topography.
(Rev. I) Comment has been addressed.
6. Please show all critical slopes on the plan. A waiver of critical slope disturbance will be
required.
(Rev. I) A waiver for the disturbance of critical slopes is not needed.
Current Development
Engineering Review Comments
Page 2 of 3
7. Please show safety railing for any wall over 4ft in height. [DM]
(Rev. 1) A retaining wall exists between the UV disinfection facility and the tertiary filters.
(Rev. 2) Comment has been addressed.
8. Provide a typical detail for all walls. Please include any safety railings on this detail as
well. [DM]
(Rev. 1) A retaining wall exists between the UV disinfection facility and the tertiary filters.
(Rev. 2) Comment has been addressed.
9. Curbing is required on both sides of the travelway on sheet C12. [18- 4.12.15]
(Rev. I) Comment has been addressed.
10. A waiver of the travelway width will need to be given by the Zoning Administrator.
Engineering review supports the approval of this wavier. [18- 4.12.16]
(Rev. I) A waiver of the travelway standard has been given.
11. Profiles are required in the sheet set for all new stormwater pipes. The profiles should
include all of the requirements listed in the checklist in the design manual. Please note
that the four foot drop specified in the IS -1 requirement includes drops from grates to
invert out elevation.
a. (Rev. 1) Not all pipe systems appear in profile. The sheets are missing profiles
for pipes CD21 -CB19, CB6 -CB3, and CB7 -CB2.
(Rev. 2) Comment has been addressed.
b. (Rev. ])For each structure, please provide a standard VDOT designation (MH -1,
DI -1, DI -3, etc.). All inlets in parking areas must be VDOT standard inlets.
(Rev. 2) Comment has been addressed.
c. (Rev. 1) Inlet shaping has not been provided where necessary.
(Rev. 2) Comment has not been addressed. VDOT IS-] must be provided on all
inlets where a drop of Oft exists in the structure, including the drop from the
grate at the surface. This requirement can be covered with a standard note on
the profile sheets stating that VDOT IS-] is required on all drainage structures
unless otherwise noted.
d. (Rev. 1) Please specify the throat length and grate type for each inlet.
(Rev. 2) Comment has been addressed.
12. There seems to be a discrepancy between the sheet C12 and the calculation summary table
for pipe 5 -4. Also, please note that none of the structures in this set are labeled.
(Rev. I) Comment has been addressed.
13. Inlet capacity calculations do not appear to provided.
(Rev. 1) In the calculations, what does "sweep" mean under inlet length?
(Rev. 2) Comment has been addressed.
14. Please provide drainage area maps for each drainage structure with acreages, hydrologic
coefficients, destination structures, and time of concentrations labeled.
(Rev. 1) The northern drainage area map should designate the drainage areas.
(Rev. 2) The table on the main road drainage area map does not seem to correspond
with the inlet designations on the map. Please clarify.
The following comments regard the ESC measures shown on the site plan amendment. A full review will
be completed once an application and all other WPO plan requirements are received.
1. Please show limits of disturbance lines. [DM]
2. Please provide construction entrances to disturbed areas. [DM]
3. Silt fence cannot run across contour lines. On sheet C13, please provide a silt trap at the
low point with diversion dikes running east and west where the silt fence was called out.
[DM]
Current Development
Engineering Review Comments
Page 3 of 3
4. A narrative should be provided. [VESCH]
5. Please show soil stockpile areas where necessary. [DM]
(Rev. I) Comments regarding ESC will be given in the WPO letter.
File: E1_fmj_PBC_sdp200800100