HomeMy WebLinkAboutWPO200800083 Review Comments Stormwater Management Plan 2008-12-05ALg�,��
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COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project:
WPO- 2008 - 00083; SDP - 2008 - 00130; UVA Long Term Acute Care Hospital
Plan preparer:
Mrs. Ammy George; Timmons Group
Owner or rep.:
Kirtley Family Holdings and University of Virginia Health Services Foundation
Date received:
11 August 2008
(Rev. 1) 14 November 2008
(Rev. 2) 24 November 2008
Date of Comment:
11 September 2008
(Rev. 1) 20 November 2008
(Rev. 2) 5 December 2008
Engineer:
Phil Custer
The final site, ESC, and SWM plans for the UVA Long Term Acute Care Hospital have been reviewed.
Engineering review recommends approval to the final site plan. Engineering review approves the WPO
plan.
A. SDP - 2008 -00130 General Review Comments
1. These plans cannot be approved until the site and WPO plans for the Sieg maintenance parcel are
approved. At this time, approval has not been received for the Sieg maintenance site.
(Rev. 1) Comment remains unchanged.
(Rev. 2) The site plans should be approved simultaneously.
2. VDOT approval is required. At this time, VDOT approval has not yet been received.
(Rev. 1) At the time of this letter, approval from VDOT has not been given.
(Rev. 2) Comment has been addressed.
3. It appears the sanitary sewer lateral for the hospital was drawn through a proposed inlet.
(Rev. I) Comment has been addressed.
4. The parking calculations submitted in this site plan need to be approved by the Zoning
Administrator. After taking part in a meeting with Charlie Hurt, I understand that a separate study
will be submitted to the County.
(Rev. I) Comment has been addressed.
5. Please provide a 30ft access easement north of the loading dock for a possible future connection
from the Kirtley warehouse area. Please provide a construction easement on either side of the
access easement.
(Rev. I) Comment has been withdrawn.
B. SDP - 2008 -00130 Final Site Plan Comments
1. Please clearly reference each wall to a detail. In this set, there does not appear to be a detail for the
retaining /screening wall around the loading dock. (This wall and site plan doesn't appear to match
the ARB submittal.)
(Rev. 1) Please include the detail for this wall in the site plan set.
(Rev. 2) Comment has been addressed.
2. Safety railings are required on all retaining walls greater than 4ft in height.
(Rev. I) Comment has been addressed.
3. Please show a private sanitary sewer easement through the Northridge and Sieg properties for the
lateral from the Kirtley warehouse.
(Rev. I) Comment has been addressed.
4. A drainage easement is needed along the pipe system on the Korean Church property carrying
LTACH drainage. The width of the drainage easement must be computed using the equation
listed in the design manual. This drainage easement must be recorded with a deed of easement
before the site plan can be approved.
(Rev. I) Comment has been addressed.
5. Please show an access and parking easement over all spaces on the Northridge property and extend
this easement to the Sieg property line and the entrance onto Route 250.
(Rev. I) Comment has been addressed.
6. The existing entrances from Northridge and the private access easement must be called out as a
VDOT Standard entrance. If these entrances do not meet the VDOT standards, they must be
upgraded. It appears that the entrance of the private access easement (to the Korean Church,
Kirtley Warehouse, and ambulance drop off) does not meet the standard.
(Rev. 1) The entrance to the private access easement from Route 250 must have a VDOT standard
entrance specified. It does not appear that this culvert underneath the roadway should be
abandoned because of the roadside ditch.
(Rev. 2) Comment has been addressed.
7. Please show adequate sight distance on the site plan set from the two entrances.
(Rev. I) Comment has been addressed.
8. Please show the existing striped areas between the handicap spaces in the Northridge lot east of the
entrance to the proposed hospital.
(Rev. I) Comment has been addressed.
9. Curbing is required around the ambulance drop off area except at the entrance to the building.
(Rev. I) Comment has been addressed.
10. The maximum grade for parking/loading areas is 5 %.
(Rev. I) Comment has been addressed.
11. The curvilinear spaces on the southeast corner of the hospital appear to be narrower than 9ft.
(Rev. I) Comment has been addressed.
12. Sidewalks abutting curbs must be 6ft in width, exclusive of curb, or a bumper block must be
provided.
(Rev. I) Comment has been addressed.
13. Engineering review maintains a policy of overland flow relief in case of inlet/drainage system
failure. It appears that spot elevation 20ft south of inlet 116 should be Ift lower and overland flow
relief will be achieved for all inlets.
(Rev. I) Comment has been addressed.
14. The applicant must provide a traffic generation and distribution summary for the site development.
The traffic impact analysis was not submitted with this application and must be submitted prior to
final approval. (PC condition #2)
(Rev. l) On sheet C4, please show the location of the traffic light pedestal. The proper striping on
Route 250 at the new lighted intersection should also be shown on this site plan.
(Rev. 2) Comment has been addressed.
15. The drainage profiles must include: a VDOT designation for each structure, throat length for each
curb inlet, and the grate type for each drop inlet (if applicable).
(Rev. l) Please specify the grate type for structures 408 and 508.
(Rev. 2) Comment has been addressed.
16. VDOT standard inlet shaping (IS -1) is required on all structures where the flow drop is 4ft or
greater (this includes drop from the surface to the bottom of the structure).
(Rev. I) Comment has been addressed.
17. VDOT standard safety slabs (SL -1) are required on all structures taller than 12ft. This requirement
also applies to the structures within the BMP system.
(Rev. 1) Safety slabs should not be specified on structures that do not require them. Note 2 on
sheet C1 addresses this comment. Please remove other callouts for SL -1 on the profiles.
(Rev. 2) Comment has been addressed.
18. Please provide an accurate profile of the downstream system from structure 100. This profile must
match all MS -19 calculations (see comment D2).
(Rev. I) Comment has been addressed.
19. Please accurately show what structure 200 will look like in the plan view. The detail does not
match what is shown in the plan view sheets. (Also, on sheet C5, the note for the detail of
structure 200 refers to the wrong sheet.)
(Rev. 1) Comment has been addressed.
20. Please provide a detail regarding how the stormfilter structure will be set on the existing inlet base.
Please clearly show how access will be maintained to the bottom of the structure.
(Rev. 1) Comment has been addressed.
21. Please provide drainage area maps for each structure including: drainage area lines, acreages,
hydrologic coefficient, time of concentration, and the structure labels.
(Rev. 1) Comment has been addressed.
22. Does the hospital have any other roof drain pipes exiting the building on the eastern half of the
building?
(Rev. 1) has been
C. WPO- 2008 -00083 Stormwater Management Plan Comments
i. w iacinty maintenance agreements will neea to oe recorded for both properties before the site
plan can be approved. Please submit these documents with fees directly to Pam Shifflett after
consulting the guidelines available on the county website.
(Rev. 1) Comment has not been addressed.
(Rev. 2) Comment has been addressed.
2. A letter from the manufacturer stating approval of the stormwater systems needs to be sent to the
county.
(Rev. l) Comment has not been addressed. A letter will be needed from the manufacturer of each
different swm facility.
(Rev. 2) Comment has been addressed.
3. Please extend the SWM easement over all BMP structures.
(Rev. 1) Comment has been addressed.
4. The pre - development drainage area map is not accurate. The drainage area lines should not run on
the property line.
(Rev. 1) Comment has been addressed.
5. Please adjust the grading to capture all of the parking lot and travelway around the two -story
building.
(Rev. 1) Comment has been addressed.
6. Please provide the standard county notes for SWM plans.
(Rev. l) Please include the notes in the SWM section of the set rather than next to the ESC
narrative.
(Rev. 2) Comment has not been addressed.
(Rev. 2) Comment has been addressed.
7. In the removal rate calculations, the applicant indicates that the project is located in the
development area when actually the entire site, except for the southern portion draining to the
roadside Swale, drains to a water supply reservoir.
(Rev. 1) Comment has been addressed.
8. The county maintains the current policy of the state by giving proposed stormfilters a removal rate
of 50 %. The application of the stormfilters in drainage area 2 is satisfactory due to the low
removal rate. However, it seems in drainage area 1 more quality treatment will be required. In
addition to the larger stormfilters (sized for 1 ") shown in the plan, the applicant should provide
more water quality treatment in drainage area 1. Possible solutions include: providing a biofilter
above the detention system used to treat the roof runoff, providing an appropriately sized
cistern /rainwater harvesting system, or pervious paving in the travelway and parking areas around
the 2 -story building. The county will not accept the BMP as designed especially when such a high
removal rate is required.
(Rev. 1) Comment has been addressed.
9. A trash screening system should be provided in structure 106 before entering the detention system.
(Rev. 1) Comment no longer applicable.
10. Three inches is the smallest orifice allowed in the county. Please adjust the detail and routing.
(Rev. 1) Comment no longer applicable.
It. Please supply a detail showing the profile of the detention system specifically showing how access
from the surface is provided into the 1Oft pipe. The calculations indicate that the system will be
placed at an odd slope and this should be shown in this detail.
(Rev. 1) Comment no longer applicable.
12. The pipe from the 96" volume manhole is called out as 15" in the site specific detail but is 3" in
the Contech detail.
(Rev. 1) Comment no longer applicable.
13. In the calculations, there is a 1.5 inch orifice assumed at the bottom of plate in the facility, but the
detail does not show this. In order to provide the water quality treatment, it appears this orifice
should be removed.
(Rev. 1) Comment no longer applicable.
14. Were the routings performed assuming an empty structure? If so, what is the estimate drawdown
time for the stormfilter system? If the drawdown time is too long, the system should be routed
with some of the water quality volume still present in the system.
(Rev. 1) Comment no longer applicable.
15. Please provide calculations showing that the volume below the orifices in the structure is greater
than or equal to the water quality volume.
(Rev. 1) Comment no longer applicable.
16. Please provide spot elevations on the plan showing that the access path is flat. (It appears that
there will be a 649 plateau between the building and the edge of the detention facility.)
(Rev. 1) Comment has been addressed.
17. A SWM bond has not been computed at this time. The bond will be computed once the plans are
approved.
(Rev. 1) Comment remains unchanged.
(Rev. 2) The SWM portion of the WPO bond will be forthcoming.
The SWM systems on site have been modified since the last submittal. The following are new
comments based on the latest design of the SWM system.
18. (Rev. 1) The raintank does not appear to be large enough. The routing for the 10 -year critical
duration storm I performed (as well as the Basinflow routing provided at the end of the SWM
report) uses the spillway.
(Rev. 2) Comment has been addressed.
19. (Rev. 1) Pipes entering the raintank system should be located as close to the top of the facility as
possible. This may require lowering of the raintank so that structure 401A enters as high as
possible.
(Rev. 2) Comment has been addressed.
20. (Rev. 1) Please show the location of the inspection ports for the raintank in plan view.
(Rev. 2) Comment has been addressed.
21. (Rev. 1) Please provide a detail on sheet C22 of the CMP detention system in profile. Please be
sure to specify access ladders into the pipe as well as into the Contech system that are equivalent
to VDOT Standard ST -1. The equivalent of VDOT standard SL -1 should also be provided in both
structures. Please also detail the access risers into the 8ft pipe. The risers must meet all
applicable OSHA standards.
(Rev. 2) Comment has been addressed.
22. (Rev. 1) Please provide a detail regarding the connections between the RCP pipes and the metal
detention facility.
(Rev. 2) Comment has been addressed.
23. (Rev. 1) The weir length in the CMP pipe routing is shown as 4ft but the detail shows aft.
(Rev. 2) Comment has been addressed.
D. WPO- 2008 -00083 Erosion and Sediment Control Plan Comments
I . Lj mr- appiwant intends to use "super silt fence ", a variance is needed from the program authority
because the method is not listed in the VESCH. Please submit a letter requesting this variance
including reasons why the measure is proposed and a fee of $760.
(Rev. 1) Please remove all references to Super Silt Fence from the narrative.
(Rev. 2) Comment has been addressed.
2. In initial phase of site disturbance, the ESC measures proposed in the southwest corner of the site
are not adequate. Silt fence cannot treat concentrated discharge. Please provide a sediment trap
with diversion dikes in this area. It seems that locating a trap close to the existing parking lot
(where the handicap spaces and concrete plaza will be) would work for ESC control until the
storm drain is installed.
(Rev. 1) Please make the following changes to the sediment trap:
a. Please extend the berm (at elevation 648) 100ft to the north
b. The slope of the dry storage must be 2:1 or flatter.
c. The bottom of trap dimension shown in the spreadsheet does not appear to be accurate.
(Rev. 2) Comment has been addressed.
3. The adequate channel analysis of downstream system is not as detailed as the county requires.
Please provide an analysis as described in the latest edition (8/18/08) of the design manual (page 7
of 42). Each segment of the downstream network should be checked. The analysis should stop
once the development is I% of the watershed as stated in Virginia ESC law.
(Rev. I) The applicants have agreed to detain as much as reasonably practicable in lieu of
providing a downstream adequate channel.
4. Will this plan require fill from off -site or need to dispose of excess soil? If so, please include a
statement in the narrative under "Off -site areas" referencing that.
(Rev. I) Comment has been addressed.
5. All construction and site improvement need to be shown within the limits of disturbance.
(Rev. 1) Construction limits cannot encroach on existing critical slopes there were not shown as
being disturbed during the preliminary site plan without approval from the Planning Commission.
Critical slope disturbance to install the detention pipe north of the hospital will be considered
exempt.
(Rev. 2) Comment has been addressed.
6. Please provide on the plan symbols for dust control, temporary seeding, and permanent seeding.
(Rev. 1) Please add a DC symbol to the phase 77 plan.
(Rev. 2) Comment has been addressed.
7. The construction entrance must drain to a sediment trap or basin. The construction entrance
should also not be placed in a location that requires significant grading and tree removal.
Engineering review recommends using the existing pavement already on site. I do not understand
the construction entrance note on sheet C14 because existing pavement is not proposed to be used
as the CE.
(Rev. 1) Please provide a construction entrance on the Phase II sheet. Also, the construction
entrance during the initial stage of construction can be located on the existing pavement 50ft west
of the trap at the safety fence.
(Rev. 2) Comment has been addressed.
8. Please provide a soil stockpile location on the plan. [DM]
(Rev. 1) Comment not addressed.
(Rev. 2) Comment has been addressed.
9. Please provide a staging and parking area. Please also describe how the parking demand for the
Northridge site will be managed with the construction traffic and construction workers parking
demand and the loss of parking spaces in the Northridge lot. It appears that the lot on the Sieg
property may need to be constructed first.
(Rev. 1) Please provide the response to this comment as a note on the plan.
(Rev. 2) Comment has been addressed.
10. Inlet protection is missing from a few inlets in the area of the construction activities.
(Rev. I) Comment has been addressed.
11. Phase II of the ESC plan appears to be missing many ESC measures that should remain in place
from the Phase I plan.
(Rev. I) Comment has been addressed.
12. Please specify in the construction sequence when and how the detention system will be installed
while the site is disturbed. Is there any way to take the system offline until the site is deemed
stabilized? Otherwise, the surface inlets may have to be sealed until site stabilization.
(Rev. 1) It appears from the construction sequence that the detention systems will be online and
will accept some sediment laden runoff. Please add to step 3 in Phase II that both detention
systems will be cleaned out (for the stormtank, the facility will need to be hydrovaced) to the
satisfaction of the stormwater and ESC inspectors.
(Rev. 2) Comment has been addressed.
13. An ESC bond has not been computed at this time. The bond will be computed once the plans are
approved.
(Rev. 1) Comment remains unchanged.
(Rev. 2) The ESC portion of the WPO bond will be forthcoming.
14. (Rev. 1) In the construction sequence, the fiery fencing, and tree
protection fencing steps should occur before steps 2 and 3. Please remove comment #4 in Phase
II. It does not appear to apply.
(Rev. 2) Comment has been addressed.
File: E3_fsp swm esc_PBC_wpo0800083- sdp0800130 UVA LTACH.doc