HomeMy WebLinkAboutSUB201600092 Correspondence 2018-12-20 (3)Albemarle County
Service Authority
October 25, 2016
Mr. Brian Mitchell, P.E.
Townes Site Engineering
9850 Lori Road, Suite 201
Chesterfield, Virginia 23832
Re: North Pointe Subdivision Section 1
Dear Brian:
We have reviewed the plans entitled "North Pointe Subdivision Section 1
Road Plans" dated April 27, 2016, last revised October 7, 2016. The following
comments need to be addressed.
N/A has been written as a response for comments that no longer apply due to layout changes.
Renumbering has occurred for some MHs and most of the storm sewer system. These changes
have been noted throughout the comment letter where possible.
0hPP+ r._1
1. Flow acceptance will be required from the Rivanna Water and Sewer
Authority (RWSA) prior to final approval.
Noted.
2. We should discuss the results of the water model generated. The purpose
of the water model is to demonstrate that required fire flows and domestic
demands can be met under both the existing HGL of 805' and the future
HGL of 652'. In reviewing the items included for the water model in the
most recent submission, I have questions concerning the following items:
a. The hydraulic grade values exceed 900 feet for the existing
scenario.
b. The pressures for the 805' HGL scenario are in excess of 200 psi.
c. What is the required fire flow for this development?
d. Where did you apply the fire flow demand to the system to ensure
20 psi is maintained while meeting both the required fire flow and
domestic demands?
e. Hydraulic grade and pressure values appear higher than
anticipated with an HGL of 652'.
f. Water model must be sealed by a Professional Engineer.
Per discussion with ACSA prior to resubmittal, we are submitting the revised construction
plans without the updated water models so that the revised layout may be
reviewed/approved by ACSA and any necessary discussions can occur before the
water/fire flow models are updated.
Sheet C-3
1. Label the existing and future 16-inch ductile iron force mains.
Such labels have been shown in the middle of sheet C-3.
2. At the intersection north of the roundabout, be sure the cross has two 8-
inch diameter gate valves and two 12-inch diameter gate valves called
out.
Three 12" GVs and one 8" GVs are labeled on the existing tee North of the
roundabout. It was approved as a 12" cross with a reducer on one side to an 8"
line.
3. Show ARV on plan view along Northpointe Boulevard. This should be
located between the curb and sidewalk.
ARV has been added as requested.
Sheet C-3A
1. MH 12 has too many connections. Relocate the two laterals to the sewer
main.
One lateral has been removed to reduce the number of connections and the
layout has been revised such that the lateral enters the manhole at a 90
degree angle to the main lines.
2. Show ARV's on plan view along Northfork Place.
ARV's have been shown as requested.
3. Show gate valve at the blow -off at the end of Northfork Place.
Gate valve has been shown as requested.
Sheet C-3B
1. Show gate valve at the blow -off at the end of Northfork Place.
Gate valve has been shown as requested.
2. Provide sanitary sewer lateral for Lot 13.
Lateral has been provided as requested.
3. Relocate the water meter for Lot 17 to Northfork Court.
Due to lot and storm layout changes, the meter has remained as previously
shown - it seems that may be the most appropriate location given these
changes. Please review and let us know if you would still like it relocated.
3. Relocate the water meter for Lot 26 to Northfork Place.
Meter has been relocated as requested.
4. Relocate the fire hydrant along Northfork Court to the opposite side of Lot
8.
Fire hydrant has been relocated as requested.
6. Show ARV on plan view in front of Lot 31.
ARV has been shown as requested in from of what is now lot 37.
Sheet C-3C
1. Based on fixture counts for the clubhouse, a 1-inch meter will be required.
You should also review the flow requirements for the pool. The meter for
the clubhouse should be located between the curb and sidewalk along
Northpointe Boulevard. As long as the meter size remains 1-inch, a tee
and gate valve are not required for the service connection.
Meter has been upsized/relocated as requested and the tee/gate valve have
been removed.
2. Due to the excessive depth of MH 38A, you may want to consider
installing this lateral on the shallower line between MH's 36 and 38A if this
line can provide gravity service.
Lot 1 lateral and 4 laterals are now shown to be installed along MH 38 to MH
60 run (renumbering on manholes due to layout changes).
3. Review the feasibility of shifting the sanitary sewer between MH's 38 to 26
towards the road to increase the easement width. A 30' easement would
be preferable due to the depth of the sanitary sewer mains.
The sewer between MHs 38 and 37 has been shifter closer to NPB and the
depth shallowed up slightly.
4. At the intersection of Lewis and Clark and Northpointe, be sure the cross
has two 8-inch diameter gate valves and two 12-inch diameter gate valves
called out.
This has been corrected on the plan.
5. Provide additional inline gate valves at the tees serving the future parcels.
A valve has been provided after the tee at each future connection stub.
Sheet C-7
1. Insulate water main where it crossing above the pedestrian culvert.
A noted has been added specifying that the waterline shall be insulated above
the pedestrian culvert.
Sheet C-7A
1. Show tee and gate valves for the stub -out serving the property across
from the basketball courts.
N/A
2. Insulate water main where it crossing above the pedestrian culvert.
A noted has been added specifying that the waterline shall be insulated above
the pedestrian culvert.
Sheet C-7C
1. Show water main crossing downstream of STIR 31.
Watermain crossing has been shown downstream of what is now structure 41.
Sheet C-7D
1. Revise pipe diameter to 6-inch for water main crossing between STR's
178-180.
N/A.
2. Revise pipe diameter to 6-inch for water main crossing between STR's
187-182.
Crossing has been revised between what are now STRs 171-151.
.qhPPt ('.-7F
1. Review the need to lower the storm sewer between STR's 53A and 53 to
accommodate the water service.
N/A.
2. Show sanitary sewer crossing between STR's 172 and 170.
Sanitary crossing has been shown between what are now STRs 177-179.
Sheet C-7F
1. Revise pipe diameter to 6-inch
140-116.
Revised— now STRs 169-147.
2. Revise pipe diameter to 6-inch
134-112.
Revised —now STRs 161-143.
3. Revise pipe diameter to 6-inch
106-108.
Revised — now STRs 159-139.
for water main crossing between STR's
for water main crossing between STR's
for water main crossing between STR's
Sheet C-7K
1 . Sanitary sewer main downstream of MH 1 needs to be ductile iron due to
the depth. This should also be modified on the Middle Entrance Plans.
Also review the length and slope of this pipe segment.
Sewer man material has been changed as requested. The length and slope
are based on the pipe extending from the existing stub to the edge of the
manhole (not the center).
2. Sewer main between 6 and 5A must be ductile iron since it is inside a
casing pipe. ShoW casing pipe on the sewer profile.
Sewer material has been changed to DI and the casing pipe shown on the
profile — now MHs 7-6.
.qhPPt r._71
1. Eliminate the profile for sewer between 5 and 5A as it is already shown on
Sheet C-71K.
Duplicate profiles have been eliminated.
3. Indicate the required compaction in fill areas.
Notes have been added to the profiles indicating required compaction in fill
areas.
4. Note the minimum cover over the sanitary sewer main near MH 10.
This run (now MHs 17-9) has been deepened.
Sheet C-7M
1. Indicate the required compaction in fill areas.
Notes have been added to the profiles indicating required compaction in fill.
2. Increase the slope between MH's 30 and 31. There appears to be
sufficient fall on the upstream and downstream pipes to avoid being at a
minimum slope.
N/A
3. Increase the slope between MH's 28 and 29. There appears to be
sufficient fall on the upstream and downstream pipes to avoid being at a
minimum slope.
N/A
5. Extend the casing pipe between MH's 25 and 26 10' past the sidewalk.
The casing pipe for the run under NPB (now MHs 28-27) has been extended
past the sidewalk on either side.
Sheet C-7N
1. Revise invert in for MH 48 to 502. Adjust pipe slope accordingly and
revise pipe material to ductile iron due to depth.
N/A
Show water main stub -out downstream of MH 47.
Stub out for water main has been shown downstream of what is now MH 48.
2. Revise invert in for MH 29A to 465 and adjust pipe slope accordingly.
N/A
3. Provide MH Stationing for MH's 51 and 52.
MH stationing has been provided as requested.
5. Increase the pipe slope between MH's 51 and 52.
N/A
Sheet C-70
1. Revise invert in for MH 42 to 489 and adjust pipe slope accordingly.
Invert for what is now MH 44 has been revised to 488.13.
2. Revise invert in for MH 37 to an elevation between 465 and 465.5 and
adjust pipe slopes for the next three sewer runs accordingly. I do not see
any reason to have minimum slope through these sections.
Inverts for MH 37 and downstream sewer runs have been revised to run at
greater than minimum slope.
3. Provide pipe material for sewer main between MH's 53A to 26. Based on
depth, ductile iron pipe should be used.
N/A
Sheet C-7P
1. Indicate the required compaction in fill areas.
Notes have been added to the profiles indicating required compaction in fill
areas.
2. Sanitary sewer main downstream of MH 55A needs to be ductile iron due
to the depth.
Applicable sewer main has been changed to Dl.
3. Sewer main between 54 and 55 must be ductile iron since it is inside a
casing pipe.
Applicable sewer main has been changed to DI.
Sheet C-10
1. Ensure that all street tress and light poles are a minimum of 10' from
ACSA utilities.
See revised street tree and lighting plan on C-10.
Sheet C-118
1. Eliminate this sheet from the ACSA submittal.
This sheet has been removed from the ACSA submittal.
If you have any questions concerning this review, feel free to call me at
(434) 977-4511, Ext. 114.
Sincerely,
Jeremy M. Lynn, P.E.
Senior Civil Engineer