HomeMy WebLinkAboutWPO201200098 Review Comments Stormwater Management Plan 2013-04-08�pF A
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COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project: Estes Park
Plan preparer: Collins Engineering [293 -3719]
Owner or rep.: Estes Park LLC
Plan received date: Jan 22nd, 2013
Date of comments: April 8, 2013
Reviewer: Michelle Roberge
I have completed the engineering review for WP02012 -98. Please see below for the following comments.
A.Erosion Control Plan (WP0201200098)
1) An early grading application was submitted for this project. Please show the approved erosion
control measures on this plan. For example, the ST 2 was converted to a sediment basin. The
staging area was moved to be within the property and should be shown correctly on sheet 20.
Filtrexx diversions were added for the approved USACOE stream impact. CRS was provided
for the road to the site.
[Revision 11 Comment partially addressed. Please show the approved SB3 from the
early grading plan.
2) Please provide temporary diversions fills on both sides of road that crosses the proposed
culvert to direct water into sediment traps and to avoid runoff down the 2:1 slopes.
[Revision 11 Comment addressed.
3) Please remove the faircloth skimmers on plans, details and erosion control notes (sequence of
construction).
[Revision 11 Comment addressed.
4) Please revise the purpose section in the narrative to match what you are proposing. The note
currently discusses early grading.
[Revision 11 Comment addressed.
5) Please add a note in the erosion control section regarding the monthly meetings for Estes Park
developers and representatives of Forest Lakes Association. See the proffers on sheet 2. Also,
include the note that the developer will be responsible for removing the amount of
documented sediment from Arbor Lake.
[Revision 11 Comment addressed.
B.SWM Plan and Overlot Grading Plan
1) The approved zoning plan shows a 100' stream buffer near the proposed pond. See the attached
rezoning plan. Please provide a mitigation plan. I recommend along the stream, behind lots 47-
56 with a proposed buffer. I also recommend the area between the wetland and proposed pond.
Lastly, I recommend the area NW of pond near the outlet if the pond can be pulled back per
comment 4.
[Revision 11 Comment partially addressed. Please address the following:
Engineering Review Comments
Page 2 of 4
a)Please pay $150 for the mitigation fee.
b)The label .36 acres is incorrect and shall be revised to .26 acres.
c)Per 17 -322 C.3., the areas shall be bonded. Please provide an easement for the
mitigation areas.
d)Also, the county has set up a native plant database. Please change the note on sheet 27
to refer to database on http:// www .albemarle.ori!/nativeplants /.
2) The drainage areas should reflect the areas being developed. The existing areas north of site are
not being developed and do not need to be incorporated into the calcs. Please revise DA.
[Revision 1] Comment addressed.
3) The removal rate is approximately 54 %. However, the only areas being treated are in DA #I A,
which is about 70% of the site. 30% of the site is not being treated. Please address how you can
treat DA #113. One possible solution is to use a biofilter with a 65% removal rate to replace the
enhanced detention basin and propose additional BMP to treat lots 47 to 55.
Comment partially addressed. Please address the following:
a)Please provide an agreement from the Forest Lakes HOA to use existing pond to
remove the remainder of 6.87 lbs of pollutant. If an agreement is not attainable, one
recommendation as stated in previous letter dated April 8, 2013, is to provide a
biofilter, which has a target removal rate of 65 %.
b)Please reduce peak discharge from 15.87 cfs to 9.98 cfs for the EED to match 10 yr
predeveloped peak rate. [Section 17 -3141.
c)It also appears that 22,696 cf of water quality is not provided in the EED. Per VSMH
3.07 -5, please provide.
4) The location of the pond is close to the existing stream. Please pull back from stream. The
embankment can erode over time. If you decide to go with a biofilter instead, the size may be
reduced.
[Revision 1] Comment addressed.
5) Please show all details of SWM to scale.
[Revision 11 Comment addressed.
6) The grading for lot 14 -20 drains across 7 lots. One option is to provide a retaining wall south of
site and place yard inlet in the backyard. The second option is to grade outside property line,
but will require a construction permit.
[Revision 1] Comment partially addressed. Please provide a 20' drainage easement for
the swale.
7) It appears the backyards of lots 6 -12 will drain towards existing townhomes. Please address
how to capture the runoff and route to the proposed stormswer.
[Revision 11 Comment partially addressed. Please provide a 20' drainage easement for
the swale.
8) Please provide the mirror image of home on lot 11. That way the pipe can be perpendicular to
ST 14.
[Revision 1] Comment addressed.
9) Many stormsewer pipes are being shown as curved. For example, see between STR 8D and 8.
Please show all pipes as straight and not curved.
[Revision 1] Comment addressed.
Engineering Review Comments
Page 3 of 4
10) It appears that the garage elevation on lot 21 -23 are elevated less than 1' from the main
roadway. Please raise the the grades at least 1'.
[Revision 1] Comment addressed.
11) Please provide 20' drainage easement for yard drains behind lots 41 -43.
[Revision 11 Comment addressed.
12) Please provide a 15' drainage easement for yard drains behind lots 44 -46.
[Revision 1] Comment addressed, but I recommend to reduce pipe slope. Typically we
ask for 20' easements to provide a 10' equipment landing. Since this 20' is not possible, I
recommend to reduce pipe slope.
13) Please provide the 498 contour for lots 41 -43.
[Revision 1] Comment addressed.
14) The area behind lots 34 -35 and lots 44 -46 drain towards the homes. There is also a low spot in
between 45 -46 and no YD is provided. I recommend to revise grading to show a swale behind
these lots to direct runoff to STR 68.
[Revision 1] Comment addressed.
15) Please revise grading behind lot 59 to drain away from house. Also fix the contour 504 behind
lot 65 since it overlaps with the proposed 502 if you follow the existing contour line.
[Revision 1] Comment addressed.
16) Please provide a pedestrian guardrail on both sides of Decatur Drive where there is a proposed
culvert or revise the slope to 3:1.
[Revision 1] Comment addressed.
17) The portion of the Regent Street was proffered to be constructed to 51' ROW. This will require
a temporary construction permit.
[Revision 1] Comment addressed.
18) Please provide calcs for the stormsewer for the 10 year storm to show actual amount captured
into each inlet and into the pipes. The SWM assumes full capture.
[Revision 1] Comment addressed.
19) Lots 56 -57 and 33 -34 are critical areas that need to be looked at for ponding. Please provide
analysis of the area assuming the pipes are clogged 50% to see the ponding area.
[Revision 1] Comment addressed.
20) [New Comment] Please revise pipe STR -19 to be 18 ".
21) [New Comment] It appears the 516 contour on Burgundy Lane should not be a closed
contour within the road. Please tie to correct contour.
22) [New Comment] Reduce the pipe slopes for YD A -B to STR 20 and YD C -D to STR 14 -B.
The 10' drainage easement shall satisfy the minimum depth for trenches from equation
below.
Engineering Review Comments
Page 4 of 4
EASENIEN'T R"TDTH = DIANtETER + 2' r 2 IH -5') + 10' i'0' '.4QV_
23) [New Comment] Please state the grass for the water quality swale. I recommend using
native plants from the Albemarle County database. Also, please show type of undrain
system as stated in VSMH 3.13 -13.
24) [New Comment] I am concerned about the potential erosion between lots 20 and 21. I
recommend extending the pipe south, and possibly near the 100' stream buffer and up
to ACOE permitted areas.
Sincerely,
Michelle Roberge
File: E1 rp,esc,swm,fsp_GEB_template.doc
�pF A
vt�r�1Q
COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project:
Plan preparer:
Owner or rep.:
Plan received date:
Plan received date
for Engineering review:
Date of comments:
Reviewer:
Estes Park
Collins Engineering [293 -3719]
Estes Park LLC
Jan 22nd, 2013
April 3rd, 2013
April 8, 2013
Michelle Roberge
I have completed the engineering review for WP02012 -98. Please see below for the following comments.
A. Erosion Control Plan (WP0201200098)
1) An early grading application was submitted for this project. Please show the approved erosion
control measures on this plan. For example, the ST 2 was converted to a sediment basin. The
staging area was moved to be within the property and should be shown correctly on sheet 20.
Filtrexx diversions were added for the approved USACOE stream impact. CRS was provided
for the road to the site.
2) Please provide temporary diversions fills on both sides of road that crosses the proposed
culvert to direct water into sediment traps and to avoid runoff down the 2:1 slopes.
3) Please remove the faircloth skimmers on plans, details and erosion control notes (sequence of
construction).
4) Please revise the purpose section in the narrative to match what you are proposing. The note
currently discusses early grading.
5) Please add a note in the erosion control section regarding the monthly meetings for Estes Park
developers and representatives of Forest Lakes Association. See the proffers on sheet 2. Also,
include the note that the developer will be responsible for removing the amount of
documented sediment from Arbor Lake.
B. SWM Plan and Overlot Grading Plan
1) The approved zoning plan shows a 100' stream buffer near the proposed pond. See the attached
rezoning plan. Please provide a mitigation plan. I recommend along the stream, behind lots 47-
56 with a proposed buffer. I also recommend the area between the wetland and proposed pond.
Lastly, I recommend the area NW of pond near the outlet if the pond can be pulled back per
comment 4.
2) The drainage areas should reflect the areas being developed. The existing areas north of site are
not being developed and do not need to be incorporated into the calcs. Please revise DA.
3) The removal rate is approximately 54 %. However, the only areas being treated are in DA #I A,
which is about 70% of the site. 30% of the site is not being treated. Please address how you can
treat DA #1B. One possible solution is to use a biofilter with a 65% removal rate to replace the
enhanced detention basin and propose additional BMP to treat lots 47 to 55.
Engineering Review Comments
Page 2 of 2
4) The location of the pond is close to the existing stream. Please pull back from stream. The
embankment can erode over time. If you decide to go with a biofilter instead, the size may be
reduced.
5) Please show all details of SWM to scale.
6) The grading for lot 14 -20 drains across 7 lots. One option is to provide a retaining wall south of
site and place yard inlet in the backyard. The second option is to grade outside property line,
but will require a construction permit.
7) It appears the backyards of lots 6 -12 will drain towards existing townhomes. Please address
how to capture the runoff and route to the proposed stormswer.
8) Please provide the mirror image of home on lot 11. That way the pipe can be perpendicular to
ST 14.
9) Many stormsewer pipes are being shown as curved. For example, see between STR 8D and 8.
Please show all pipes as straight and not curved.
10) It appears that the garage elevation on lot 21 -23 are elevated less than 1' from the main
roadway. Please raise the the grades at least 1'.
11) Please provide 20' drainage easement for yard drains behind lots 41 -43.
12) Please provide a 15' drainage easement for yard drains behind lots 44 -46.
13) Please provide the 498 contour for lots 41 -43.
14) The area behind lots 34 -35 and lots 44 -46 drain towards the homes. There is also a low spot in
between 45 -46 and no YD is provided. I recommend to revise grading to show a swale behind
these lots to direct runoff to STR 68.
15) Please revise grading behind lot 59 to drain away from house. Also fix the contour 504 behind
lot 65 since it overlaps with the proposed 502 if you follow the existing contour line.
16) Please provide a pedestrian guardrail on both sides of Decatur Drive where there is a proposed
culvert or revise the slope to 3:1.
17) The portion of the Regent Street was proffered to be constructed to 51' ROW. This will require
a temporary construction permit.
18) Please provide calcs for the stormsewer for the 10 year storm to show actual amount captured
into each inlet and into the pipes. The SWM assumes full capture.
19) Lots 56 -57 and 33 -34 are critical areas that need to be looked at for ponding. Please provide
analysis of the area assuming the pipes are clogged 50% to see the ponding area.
Sincerely,
r&wr-
Michelle Roberge
File: E1_ rp,csc,swm,fsp_GEB_tcmplatc.doc
�pF A
vt�r�1Q
COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project: Estes Park
Plan preparer: Collins Engineering [293 -3719]
Owner or rep.: Estes Park LLC
Plan received date: 28 Jun 2013
Date of comments: 10 Jul 2013
Reviewer: Michelle Roberge
I have completed the engineering review for WP02012 -98 and SUB2013 -35. Please see below for the
following comments. The plans aforementioned will be approved on the conditions set forth below.
A.Erosion Control Plan & SWM (WP0201200098)
1) The grading for lot 14 -20 drains across 7 lots. One option is to provide a retaining wall south of
site and place yard inlet in the backyard. The second option is to grade outside property line,
but will require a construction permit.
[Revision 1] Comment partially addressed. Please show a 20' drainage easement for the
swale.
2) It appears the backyards of lots 6 -12 will drain towards existing townhomes. Please address
how to capture the runoff and route to the proposed stormswer.
[Revision 1] Comment partially addressed. Please show a 20' drainage easement for the
swale.
3) Per 17 -322 C.3., the mitigation areas shall be bonded. Please show the easement for the
mitigation areas.
B.Road Plan (SUB201300035)
1) Please show the revised landscaping reviewed by Megan on July 8, 2013.
2) Please address all of VDOT's comments. Also, install 20 mph advisory signs at recommended
locations.
Sincerely,
r&T-
Michelle Roberge
�pF A
vt�r�1Q
COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project:
Plan preparer:
Owner or rep.:
Plan received date:
Date of comments:
Reviewer:
Estes Park
Collins Engineering [293 -3719]
Estes Park LLC
21 Dec 2012
7 Feb 2013
Michelle Roberge
A. Erosion Control Plan (WP0201200098)
1. Move the construction entrance within the property boundary and label as CE. Please provide
easements and the construction road stabilization (CRS) symbol for the construction road off- site.
2. Please add a note in the Erosion Control Notes & Narrative in between comment 7 & 8 stating that
the county E &S inspector will need to give approval to begin phase 2 only after completing phase
1 and all erosion control measures are stabilized.
3. The contributing drainage area for SB 2 is only 1.19 acres. I recommend changing it to a sediment
trap since the maximum allowable contributing area for a sediment trap is 3 acres.
4. Please change sediment trap 2 to a sediment basin. Once Road A is in place, ST3 will not be able
to capture the delineated drainage area on plans and should be routed to ST2. This will increase
the drainage area to ST2 and therefore needs to be changed to a sediment basin.
5. In phase 2, describe how you will control the outflow from the basin north of site as you are
grading in between lot 34 & lot 35 and up to the completion of the project. It is unrealistic to show
this outflow area to the diversion dike as undisturbed.
Sincerely,
Michelle Roberge
File: E1_rp,esc,swm,fsp_GEB _ template.doc