HomeMy WebLinkAboutWPO200800004 Review Comments Erosion Control Plan 2008-08-22ALg�,��
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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:
SDP - 2008 - 00016, Martha Jefferson Final Site Plan
WPO- 2008 - 00004, Martha Jefferson SWM and Site ESC Plans
Plan preparer:
Mike Matthews, Matthews Dev. Company LLC fax 434.972.7769
Plan preparer:
Dan Knapp, Graef Anhalt, Scholemer & Assoc. fax 414.259.0037
Owner or rep.:
MJH Foundation [459 Locust Ave Charlottesville, VA 22902]
Date received:
29 January 2008 (plan signed date 23 January 2008)
(Rev. 1) 28 May 2008 (plan dated 23 May 2008)
(Rev. 2) 12 August 2008 (plan dated 8 August 2008)
Date of Comment:
14 March 2008
(Rev. 1) 23 July 2008
(Rev. 2) 22 August 2008
Engineer:
Phil Custer
The Final Site, SWM, and Site ESC plans for the Martha Jefferson Hospital project, received on 12
August 2008, have been reviewed. Engineering review can recommend approval to the site plan after the
following comments have been addressed.
A. General review comments:
1. The Will. .section from State Farm Boulevard to Peter Jefferson Parkway should be
made with this phase. The site plan should account for this work being done and include all of
the necessary amendments to the Outpatient Care Center parking lot.
(Rev. 1) Show proposed site work on OCC and MJHF office properties to match RKK's plan
on all sheets or provide a note referring to the RKK sheet sets where necessary. Comments
for the minor amendments will be given under separate letters.
(Rev. 2) Comment has been addressed.
Please submit a new ESC amendment fee of $150 for the review of the site ESC work. We
will consider the ESC measures needed during the site plan construction an amendment to
Phase II of the Mass Grading Plan.
(Rev. 1) Fee has been received.
3. Please provide on the plan Albemarle County's General notes for construction.
(Rev. 1) Comment has been addressed.
4. Engineering review understands that a revision to the amendment of the basin outlet structure
will be submitted at some point next week. On the amendment submitted on March 3rd, the
outlet pipe from the basin was reduced from a 48" pipe to a 42" pipe. Due to this change, the
open channel flow capacity of this outlet system reduces from -- 102cfs to - -71cfs (slope of
0.5 %). The peak release rate of the ten year storm of the previous riser structure was 80cfs.
This would have caused the pipes downstream not to operate under open channel flow for the
ten year storm which is a county requirement the applicant should be aware of during the
redesign of this system.
(Rev. 1) Comment has been addressed.
B. Site Plan review comments:
5. Please show sight distance triangles from the existing Peter Jefferson Outpatient Center and
the entrance to the parking lot across the Peter Jefferson Parkway from it. It appears a
dangerous entry condition could be created.
(Rev. I) Comment has been addressed.
6. Please overlay all sight distance triangles on the site plan grading sheets. Due to the grading
of the proposed roadways and adjacent slopes, some entrances may not have adequate sight
distance. For all entrances where sight distance may be questionable because of grading,
please provide a vertical sight distance analysis. For instance, from point G looking south, the
fill appears to block sight distance.
(Rev. l) My analysis shows that even without considering any landscaping, adequate sight
distance is not met in the following locations: from the main hospital entrance looking north
and from the entrance at Sta. 16 on PJP looking south. The sight distance from the entrance
at Sta. 24 on PJP looking north is also close to being inadequate. Please provide vertical
profiles of the sight lines mentioned above to prove that sight distance is available.
(Rev. 2) Comment has been addressed.
7. Please show sight distance easements on the layout and landscape sheets.
(Rev. l) Several of the sight lines from entrances will be obstructed by some of the on -site
landscaping (not street trees). Engineering review recommends amending the landscape plan
to provide a line of sight that is clearer.
(Rev. 2) Comment has been addressed.
8. Please provide a standard VDOT designation for all entrances onto a state route.
(Rev. l) Entrance designations are illegible.
(Rev. 2) Comment has been addressed.
9. Please provide a 40' landing of no greater than 4% at all entrances to a state route.
(Rev. l) The contour lines along Willis Road between the main entrance to the hospital and
the employee parking lot do not maintain their cross -slope to the curb. Please correct these
contour lines and pay particular attention to how it affects the entrances mentioned above.
Acceptable landings have been provided at all other entrances.
(Rev. 2) Comment has been addressed.
10. The curb callouts and details appear to be incorrect. The legend on all C200 sheets should be
modified as well.
a. CG -2 is standard curbing without a concrete gutter and it appears to be represented on
the C200 sheets as a solid line.
b. CG -7 is 4" tall mountable curbing and should not be used where it is shown. It appears
the applicant intended to use a CG -6 which is a 6" curb with a 2ft concrete gutter. This
curb appears to be represented by two lines of different thicknesses.
(Rev. I) Comment has been addressed.
11. Please note that the CG -6 curbing on the higher side of the curbed parking islands is not a
county requirement.
(Rev. I) This comment has been noted by the applicant.
12. Please show all necessary traffic control signs (stop, one -way, "do not enter ", etc.). It appears
that the logical place for these callouts should be on the layout sheets.
(Rev. 1) Please show stop signs at all site exits onto a public road. These are needed on the
site plan set in addition to the road plan set.
(Rev. 2) Comment has been addressed.
13. Sidewalks must be constructed with at least 4" of stone base and at least 4" of concrete of
3000psi at 28 day strength, or stronger. Please update the detail.
(Rev. I) Comment has been addressed.
14. The minimum width for all sidewalks is 5ft (exclusive of curb). All sidewalks adjacent to
parking spaces must be at least 6ft in width (exclusive of curb) or bumper blocks must be
provided. (See the diagram in the design manual for clarification.) [DM]
(Rev. 1) Please update detail to say 5ft sidewalk. Eight parking spaces on Sheet C331 will
need bumper blocks. Bumper blocks will be needed for the handicap parking areas where
there is no curb. Twelve spaces on sheet C332 will need bumper blocks because they are
adjacent to a sidewalk. On sheet C332, a curb will be required on the downhill side of the
handicap parking area. In other words, in this lot, the only area where the sidewalk can be
flush with the pavement is along the curvilinear spaces.
(Rev. 2) All areas curb changes required above has been provided on the latest plan.
However, because it appears no ADA access has been provided for the 16 handicap spaces
where a curb was placed, the building official cannot approve the current plan. The
applicant needs to provide handicap ramps at each hatched area (detail 101C800) or adjust
grading so no water drains to any sidewalk and allow the sidewalk to be flush with the
pavement as originally designed. Please contact me to discuss this comment.
15. All parking spaces must be protected by a curbed island of at least 3ft width. [DM]
(Rev. 1) Comment has been addressed.
16. Please dimension angled parking spaces so that they can be checked for compliance with
section 4.12.16c.3. The figure this section references can be found in the design manual.
(Rev. 1) Comment not addressed. The stall depth does not appear to be deep enough. With
one way travel and parking spaces at a 30 degree angle, the stall depth (from travelway to
curb) must be 20.1ft. This area will be in compliance with the code if the travelway is
reduced to no less than 16ft to increase the stall depth as needed. Please see the diagram in
the design manual and the table in section 18- 4.12.16. c. 3.
(Rev. 2) Comment has been addressed.
17. It appears that the wall on the southern tip of the building needs to be extended at least one
hundred feet to the parking lot corner.
(Rev. 1) Comment not addressed. The wall that needs to be extended is southeast of the
loading dock area. It appears the top would be 479 and it would travel southwest until it met
the grade in the corner of the loading dock area.
(Rev. 2) Comment has been addressed.
18. Please provide typical details for all proposed walls for this project.
(Rev. 1) Comment not addressed. Information regarding the attachment of handrail or
guardrail to each of the walls must be provided. Will guardrails be attached to the top
segment of the wall or a distance away from the back of wall? Engineering review is not
requiring each wall be fully designed. We are asking for these details on the site plan to
simplify the building permit review and zoning inspection processes.
(Rev. 2) Comment has been addressed.
19. All walls over 4ft in height will require a handrail. This should be included in the detail and
called out on the plans.
(Rev. 1) Please make it clearer on the plan which walls will require handrails and which
walls will require guardrails. See comment below.
(Rev. 2) Comment has been addressed.
20. Any wall adjacent to a travelway or parking area must include a guardrail on top of it. An
alternative solution would be to design and construct the wall to act as the guardrail.
(Rev. 1) It appears that all walls specify a guardrail when it is not required. The following
walls will require a guardrail: above the generator (the 42" extension is acceptable) and
close to the emergency drop off circle. All other locations appear to require handrails.
(Rev. 2) Comment has been addressed.
21. No travelway can be steeper than 10 %. It appears that the travelway to the loading dock area
exceeds this between the 479 and 480 contours. [4.12.17a]
(Rev. 1) Comment has been addressed.
22. Parking areas and travelways adjacent to parking areas cannot exceed a 5% slope. This has
occurred throughout the plan (measured between contour lines as well as between contour
lines and spot elevations). [4.12.15c]
(Rev. 1) Comment has been addressed.
23. The direction of flow change in a drainage structure cannot be less than 90 degrees.
(Rev. 1) Comment has been changed. All structures with a flow change of sharper than 90
degrees has a significant change in elevation between inverts.
24. Drainage cannot run across or back up on the compactor pad.
(Rev. 1) Comment has been addressed.
25. Please design and show adequate channels from the curb cuts in the northern parking lot down
to the sediment forebay. Engineering review recommends a grouted riprap channel along the
3:1 slopes.
(Rev. 1) Comment has been addressed.
26. A 3:1 slope is mislabeled as a 4:1 slope on sheet C235.
(Rev. 1) Comment has been addressed.
27. The radius from Willis Dr. into the northern parking lot appears to be mislabeled.
(Rev. 1) Comment has been addressed.
28. Please show the linear storm sewer pipes of the proposed VDOT roadways and their respective
easements on the hospital property. The pipes are shown as being curved in the site plan set.
Easements must be sized according to the equation in the Design Manual.
(Rev. 1) Radial pipes are allowed per VDOT standard. The drainage easements should be
designated separate from the utility easements and marked "dedicated to public use ". It
appears some of pipes are not at the correct widths as specified in the design manual (Width
= 10' + pipe diameter + 2' + 2' *(depth - 5'), minimum 20' easement). For instance, the pipe
from the riser should be much larger than the 20ft minimum. The easement should also be
extended to cover the outlet protection stone. Another pipe requiring a larger easement
would be from 6 -35 to 6 -30. In addition, the pipe from 1575 State Farm Blvd. should have its
easement centered and extended to the new system through the hospital parcel.
(Rev. 1) The easement on the outlet system from the riser does not have the correct
easement width. All other easements appear to be correct.
29. Site runoff cannot drain into public streets. This appears to occur at the entrance from the
loading dock area onto PJP and from the hospital's main entrance on Willis Drive. Inlets must
provide 100% site runoff capture at entrances.
(Rev. 1) Comment not addressed. Inlets 3A and 3B are undersized to capture 100% of the
flow draining to them. Input values longitudinal slope, road cross slope, and gutter slope
appear to be incorrect. Please see comment 42. No inlets have been placed to prevent water
from entering Willis Drive from the hospital's main entrance.
(Rev. 2) Comment has been addressed.
30. Please provide inlet shaping (VDOT IS -1) on all inlets or structures where flow drops 4ft or
greater. This includes the drop from the surface to the base of the structure in addition to from
an incoming pipe.
(Rev. 1) Comment has been addressed.
31. Engineering review maintains a policy that in case of inlet failure, site grading should allow
for overland flow relief. Please modify grading so the building will not flood with inlet
failure.
(Rev. 1) Comment has been addressed.
32. Please show all drainage easements on the landscape plans. Easements should be sized per the
design manual and are only needed on pipes carrying water from VDOT ROW or water from
offsite adjacent parcels. No trees will be allowed in these drainage easements.
(Rev. 1) Please remove trees from drainage easement along the northeast edge of the pond.
(Rev. 2) Comment has been addressed.
33. Please provide an inlet drainage area map so that the inlet and pipe calculations can be
confirmed. The drainage map should include the following:
a. limits of all areas draining to proposed structures, existing structures, or channels
b. acreage of each drainage area as used in computations
c. hydrologic coefficient for each drainage area as used in computations
d. time of concentration for each drainage area as used in computations
e. destination structure labeled in each drainage area
(Rev. 1) Drainage area lines are not accurate and may result in undersized inlets. Drainage
area lines are not perpendicular to contours. As an example, the contour lines in the
drainage area to inlet 10 run perpendicular to the travelway. If the parking lot was graded as
shown, the majority of this runoff would pass through the entrance and into inlet 5D.
Similarly, most of the runoff in inlet 8B's watershed will enter 8A with the current site
grading.
(Rev. 2) Comment has been addressed.
34. The minimum allowable time of concentration for an inlet is five, not ten, minutes. Please
update drainage system design.
(Rev. 1) Comment has been addressed.
35. In the pipe information table, please provide the hydrologic data (CA, time of concentration,
intensity, and peak flow) for the watershed to the pipe as well as the pipe's calculated capacity.
We recommend using the format of Table 8 of the Design Manual.
(Rev. I) Comment has been addressed.
36. Please specify the length of all DI -2AA inlets.
(Rev. 1) Comment has been addressed.
37. Safety slabs (VDOT SL -1) are required on all structures greater than 12ft in depth.
(Rev. 1) Safety slabs do not appear to be called out on the plan. A note similar to note 5
regarding IS-1 would suffice.
(Rev. 2) Comment has been addressed.
38. Engineering review does not recommend providing riprapped sumps in the base of manholes.
We recommend either grouting the riprap sump or providing inlet shaping.
(Rev. I) Comment has been addressed.
39. The type of inlet for structures 3C, 3D, and 4C are not called out on sheet C530.
(Rev. 1) Comment has been addressed.
40. Please callout an end section for the outfall of the 36" pipe into the eastern sediment forebay.
(Rev. 1) End section callout has been included in the road plan set. Though, the pipe is
labeled as 36" but the end section is listed as 30 ".
(Rev. 2) Comment has been addressed.
41. Please provide scour protection at all outlets. Calculations for the dimensions of the scour
protection should be included in the plan set.
(Rev. I) Comment has been addressed. Calculations were provided in the road plan.
42. Please provide spread calculations for all curb inlets and where curbing is used to convey flow
to an inlet. All spreads must be below loft for the 4in/hr storm. We recommend using Tables
6 and 7 of the Design Manual.
(Rev. 1) Comment not addressed. The curb inlet calculations do not seem to be accurate. For
instance, the cross and longitudinal slopes for inlets 3A and 3B are switched. Also, if VDOT
standard CG -6 is used, the gutter slope (Sw) is always 0.0833 ft /ft. Engineering review
recommends using VDOT LD -204 (Appendix 9B -1 of the VDOT drainage manual).
(Rev. 2) Please note in the calculations and the plan and profile sheets that IN -3A and IN-
3B are DI -2B, not 2A. Please double check other inlets to assure this small oversight was
not repeated.
43. Due to site grading, channels are created in the pavement in some parking lots. Please provide
spread calculations for each of those channels using a storm intensity of 4in/hr. No spread can
be larger than IOft. Please also note that no concentrated flow greater than Icfs can exist in
the travelway.
(Rev. 1) Channels exist in the pavement and spread calculations should be provided. Please
provide channel calculations for the channels draining to inlets 6,7,8,14B, and 21A. Parking
islands should not disrupt flow to the inlets. This layout with be difficult to work out correctly
in the field. The islands should be eliminated or an inlet should be placed on the uphill side.
(Rev. 2) The inlet arrangement is satisfactory.
44. Many of the pipe systems and segments are not shown in profile.
(Rev. 1) Please make sure the storm sewer system that is shown in profile in both the road
plans and site plans match. With this review, a few discrepancies were found.
(Rev. 2) Comment not addressed. Please recheck the storm drain system from MH -18 to
the outlet.
45. Additional comments may be forthcoming on the next submittal due to required changes.
a. (Rev. 1) Please provide a sidewalk on the south side of parking lot J and on the
east side of parking lot B. [18- 32.7.2.8]
(Rev. 2) The minor amendment to TMP 78 -71 mentions that some spaces for
that lot are accounted for in this hospital lot. Please connect the spaces in the
lot to the building entrance.
b. (Rev. 1) Low maintenance groundcover is required on all slopes steeper than 3:1.
Please show this on the landscape plan.
(Rev. 2) Please remove "or grass seed mix "from the groundcover note on all
landscape sheets. If a specific planting is not specified on the plan, please
provide a note stating that the low maintenance groundcover needs to be
approved by Albemarle County Engineering review before installation.
c. (Rev. 1) The minimum slope on a storm drain is 0.5 %. [DM]
(Rev. 2) Comment has been addressed.
d. (Rev. 1) Pipes A and D need to connect to the storm drain at an accessible
structure.
(Rev. 2) Comment has been addressed.
C. SWM review comments:
46. Detention compliance could not be reviewed at this time because of the changes to the riser
structure discussed on the meeting held on Thursday, March 13`". Detention comments will be
given after the amended riser structure information is submitted as a revision to phase I of the
mass grading plan.
(Rev. 1) Comment has been addressed.
47. Please provide access to both forebays.
(Rev. 1) Comment has been addressed.
48. Please provide the Albemarle County Stormwater Management notes.
(Rev. 1) Comment has been addressed.
49. Please provide baffles to create a longer flow path from the southern sediment forebay.
(Rev. 1) Comment has been addressed.
50. Please provide sediment forebay sizing calculations. Forebays must be sized for a 0.25 inch of
rain over all impervious areas of each forebay watersheds.
(Rev. 1) Comment has been addressed.
51. Please provide a typical 10'x10' planting detail for the aquatic bench for bonding purposes.
The aquatic bench should have at least 3 species of plant. Please provide this planting plan in
the SWM section of the plan set.
(Rev. 1) Comment has been addressed.
52. Please include the entire updated outlet system on sheet C511.
(Rev. 1) The pipe from the riser is labeled as a 0.005 ft /ft slope.
(Rev. 2) Comment has been addressed.
53. In the Water Compliance Table in the SWM calculations package, one of the cell states that
7560cy of Water Quality Volume is provided. This is not correct. 7560cy is the volume of
the pond. The WQv of a Type III Retention Basin is the pond volume divided by four. In this
case, the provided WQv is 1890cy. This does not leave much treatment volume available for
future development. In other words, as currently designed, the pond can only treat 28.1 acres
of impervious surfaces; after this land development project, 27.3 acres or impervious surface
will be draining to the basin.
If the treatment volume of this pond is to be designed for future development projects, it
would be best to provide in these calculations a conservative estimate of future development
and show those areas on a new SWM facility drainage map. Future land development projects
will be required to provide as -built information on the pond if it is to be used for SWM after
its construction.
(Rev. 1) Stormwater quality calculations are adequate for this site. Any development in the
future of this approved plan must meet the SWM requirements at the time of the submittal. If
the existing pond is to be used, as -built information will be required.
(Rev. 2) Comment has been addressed.
54. Additional comments may be forthcoming on the next submittal due to required changes.
(Rev. I) No future SWM comments appear to be needed.
D. Site ESC review comments:
55. Please include all necessary sheets that were approved on Phase I and Phase H of the mass
grading plan in this set. The intention of this ESC amendment should be to replace the
existing approved plan (Phase II). The stream restoration sheets do not have to be included in
this set, but the stream channel work should be referred to in all ESC sheets.
(Rev. 1) The Phase H ESC plan sheets need to be updated to match the approved Phase II
ESC plan including the construction trailer area. Any adjustment to the construction trailer
area from the approved plan should meet all requirements listed by the Zoning Administrator,
Amelia McCulley, in her July 14th email to Mike Matthews.
(Rev. 2) Comment has been addressed.
56. Please include on all erosion and sediment control sheets, all previous measures needed to
protect the disturbed areas. For instance, it is conceivable that all basins and sediment traps
(and their associated diversions) from earlier phases will be needed throughout the latest
phases of the plan. Phase 11 -A should show all required measures from Phase 1. Phase 11 -B
should show all required measures from both Phase I and Phase II -A, and so on.
(Rev. 1) The Phase II ESC plan sheets need to be updated to match the approved Phase II
ESC plan including the construction trailer area. Any adjustment to the construction trailer
area from the approved plan should meet all requirements listed by the Zoning Administrator,
Amelia McCulley, in her July 14th email to Mike Matthews.
(Rev. 2) Comment has been addressed.
57. Please provide MS -19 analysis of the downstream stormsewer network for subarea 30.
(Rev. I) Comment has been addressed.
58. Silt fence is not an adequate protection measure for the excavated spoil area. It appears that
the silt fence will receive direct channel flow from the access path's roadside ditches. It
appears that either constructing a new sediment trap in the roadside ditch or extending a
diversion from the sediment basin being constructed in phase 11 would be an appropriate
measure.
(Rev. I) Comment has been addressed.
59. Please provide temporary and permanent seeding callouts in the appropriate places.
(Rev. I) Comment has been addressed.
60. Please expand limits of disturbance lines to include the slopes, sediment trapping measures,
and stream restoration of the previous phases. It is likely that routine maintenance and
additional slope stabilization will be required of these areas through this phase of the project.
(Rev. I) Comment has been addressed.
61. Additional comments may be forthcoming on the next submittal due to required changes.
a. (Rev. 1) Please provide ESC measures for the work on TMP's 78 -71 and 78 -311
shown in the minor amendment packages. The limits of disturbance lines should
also be adjusted.
(Rev. 2) Comment not addressed.
b. (Rev. 1) Please provide a detailed staging and construction area on the plan.
(Rev. 2) The trailer schematic plans shown on ESC -270 and C805 should
match the trailer plan on ESC -300.
Also, please note that if a CO is applied for without the entire building and site
completed, an amendment to the site plan will be necessary showing adequate
parking with an amendment to the construction and staging area. Also, if the
Peter Jefferson Parkway is accepted by VDOT, the construction yard will need
to be pulled back 50ft from the ROW. [18- 5.1.19.21
Please contact me at (434)296 -5832 ext. 3072 should you have any questions.
File: E3_fsp, esc, swm_PBC_Martha Jefferson