Yeah, you ready? All right? Good morning
, ladies and gentlemen, I'm Alexis Karabot,
john Whitlock, I'm Katie gear and I'm dan brzezinski
And our mentor is Dennis Quinn. With Christopher consulting's
and our developers Madison homes. I'm gonna start off
with the location, the zoning ordinance and the slope
. Our location is in George mason boulevard in
Fairfax Virginia. Our developing goal was to have single
family detached homes. Uh Our site is located is
in Fairfax County, which is owed are one which
allows for one house per acre. This is not
what our developer wanted or what the com plant wanted
. So we? Re zoned to P. D
. H. Eight Which allows for a maximum eight
units per acre. Um This also had no setbacks
and area requirements and minimum minimal sight distance site,
25 green space was required as well as a 20
tree canopy within the 10 years. Uh development of
the site would be very easy because our slope is
very uh non existent and minimize grading is required.
Our current land use right now uh to the west
is green space into the east is a bus parking
lot. Our conceptual design. Our goal was to
as many plots Um as possible while making 25 green
streets and having a very pedestrian friendly environment. Our
first conceptual design had 46 lots and one access point
on George Mason Boulevard, which limits the disturbance of
traffic. Um We had to slow community speech,
which makes for a very pedestrian friendly environment and we
had limited off street parking. Our second conceptual design
had 55 plots to access of two points of access
uh which disturbed the traffic but utilized the space better
. Uh Again, we had slow community speeds and
lots of off street parking. Our next slide,
you're gonna see a progression of what we thought with
our project. Mhm mm. As you can see
in our progression the conceptual design stage and our final
decision picking our first conceptual design allowed us to have
a more green community, a better flow within the
community and less uh impact to current traffic. I'm
gonna pass it to john, he's gonna talk more
about the roads. Okay. As mentioned before,
there is one existing road that runs right through the
middle of our site and that's George mason boulevard.
The Fairfax County comprehension plan uh, desired one access
point. So we honored that in our design.
This is our site, if these are one thing
contours. So this barry is very flat and our
proposed roadway is on the right. We have harlequin
court on the left with the cold sack Christopher lane
on the right, and road street connects George mason
boulevard at one point um, we're use private roads
were designed for private roads to have a little more
flexibility in our road design. We maintain standards for
almost all of it except for really. The 50-foot
cold sack was just a little a little bit tight
and it's a little smaller than what beat up,
standardized. Uh we calculate our R. A.
D. T. To be about 400 which allows
for 15 mile per hour design speeds 28 ft right
away with 12 ft lanes and two ft curb and
gutter. This is our boat grading. Um This
is what the existing conditions, it's a little crowded
, but I want to show you that we,
the main thing we did was remove this dry swell
at the bottom of our site to make room for
our building pad and for some green space so close
up. But on on the right here is our
, is our boat rating and our main focus was
the building pads. And we held a high point
along the middle of the building pad, about two
ft above the proposed roadway to allow for drainage and
slope from either direction, about 20 to 1 on
this on towards the road, about 10 to 1
towards the back. And that was really the main
focus of milk ring and there wasn't too much else
to it. And the detailed rating was fine tuning
that bolt rating. And we held a constant elevation
for the finished floor, still two ft above the
proposed roadway, and then we have 5% grade sloping
for 10 ft out from the finished floor, which
equates to about half a foot drop over 10 ft
. And lastly, we added a sway on the
back to account for the drainage because this is a
long, hard look in court. We had a
large green space over here and there will be a
lot of stormwater to talk about and that's where we'll
go next with Katie. So I'm gonna talk a
little bit about the storm water here. You can
see our pre development watershed. You can see it's
mostly in one watershed heading to this low point down
here is marked by the green X. We use
the rational method and we used three different type of
concentration lines, all going to that one point to
find that our total pre development flow rate was 23
cubic feet per second. And here you can see
all of our post development watershed delineations, all also
flowing down to this final point and our total post
development watershed or flow rate was 29 cubic feet per
second. Here. You can see our proposed stormwater
lines which are sharing in the dark color. We
decided to tie into existing inlets on George mason boulevard
. There are seven of those as seen by the
darker blue. And we also chose to install 12
new inlets which are known by the lighter blue.
Those were placed in low points or before intersections to
prevent too much water from entering intersections or ponding on
the site. In order to make up for the
difference between the pre development and put post development flow
rates, we decided to install, install a detention
pond down here. Um This would have to be
about 0.17 acre feet, which is about 7500 cubic
feet. Um since there's an existing Swail in this
location, it made sense to place it here,
especially since all the water was drained from there.
So there didn't have to be a whole lot of
drastic grading changes made, since there is also an
existing outlet structure there as well. Also required by
Fairfax County are best management practices. So we looked
into what would be our best options and we ended
up settling with dry soils since they would reduce the
amount of water exiting the site as it flows through
. Now, I'm going to move into a little
bit about the erosion sediment control plants. We decided
to line most of the site with super steel fence
, which would prevent water from or dirt from floating
off of the site as grading is occurring in stockpiles
of soil are building up. We also put in
diversion dykes either to direct water towards a settlement basin
or sediment traps as well as to keep clean water
from coming in off of the site on the west
side. Um We have one sediment basin where the
uh detention pond and mentioned earlier would be going and
it's also construction entrances to prevent trucks from tracking dirt
on and off the site as they move as needed
, temporary seating will be installed up until final design
, which you can see here as we put in
the inlets that I discussed earlier, we would add
inlet protection and remove the sediment traps we had on
the east side, the sediment basin and the diversion
dykes leading to that sediment basins as well as the
super silt fence around the site would stay in place
until design is complete and then the sediment basin would
be turned into that detention pond. And now I'm
going to pass it over to dan. I'm gonna
talk a little bit about the wet utilities. You
can see we have both sewer and water, They're
in their own separate lanes in the roadways so that
we can meet the 10-foot horizontal An 18 ft or
18 excuse me, separation requirement. The sanitary line
proposed its own unique problem because our only existing tying
is up in the northwest corner here, which is
actually one of the highest point on the site.
We weren't able to gravity feed all of our sewage
to that point. So we had to do was
designed to bring all the sewage to the low point
on our site and then install the pump station,
which will bring all that sewage back up to the
top. The lines are eight PVC And are designed
to hold 68,000 gallons per day. The water system
we didn't have any problems with. There's an existing
six inch line up in the north here and a
12 inch line down here to the south, which
made it really easy for us to loop our water
lines together. Which is a requirement for Fairfax County
. This is an eight ductile iron pipe That supports
30,000 gallons per day for the residents and a 6700
gallons per minute fire flow requirement. Lastly, is
our cost. The final cost of our project was
$1.31 million. Some of the major cost for this
project Where the storm pipe, especially 24 storm pipe
near the outfall location. Uh huh. The PVC
for the sanitary, the doctor, iron pipe for
the water lines and then obviously roadways and driveways were
a huge cost for a development like this. And
does anybody have any questions? Great. Did you
have to consider any traffic control and crossing the road
? Yes. That's why we decided to go with
the first conceptual design with only one intersection. It
was like just about in between the two existing intersections
, and I actually got a chance to go look
at the site and I lived near there a couple
of summers ago, so I knew that it could
get a little crowded, especially um, with the
traffic in northern Virginia, but we figured it wouldn't
be a problem because it stayed away from most of
the existing term lines. Right. No questions asked
them. All right. Thank you.