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City of Alexandria, Virginia
KING, STRAND, AND UNION STREETS
Park & Recreation Commission
NOVEMBER 15, 2012
Daily High Tides for 2012
3
-1
0
1
2
3
4
5
21-Jan
24-Jan
27-Jan
30-Jan
2-Feb
5-Feb
8-Feb
11-Feb
14-Feb
17-Feb
20-Feb
23-Feb
26-Feb
29-Feb
3-M
ar
6-M
ar
9-M
ar
12-M
ar
15-M
ar
18-M
ar
21-M
ar
24-M
ar
27-M
ar
30-M
ar
2-Apr
5-Apr
8-Apr
11-Apr
14-Apr
17-Apr
20-Apr
23-Apr
26-Apr
29-Apr
2-M
ay
5-M
ay
8-M
ay
11-M
ay
14-M
ay
17-M
ay
20-M
ay
23-M
ay
26-M
ay
29-M
ay
1-Jun
4-Jun
7-Jun
10-Jun
13-Jun
16-Jun
19-Jun
22-Jun
25-Jun
28-Jun
1-Jul
4-Jul
7-Jul
10-Jul
13-Jul
16-Jul
19-Jul
22-Jul
25-Jul
28-Jul
31-Jul
3-Aug
6-Aug
9-Aug
12-Aug
15-Aug
18-Aug
21-Aug
24-Aug
27-Aug
30-Aug
2-Sep
5-Sep
8-Sep
11-Sep
14-Sep
17-Sep
20-Sep
23-Sep
26-Sep
29-Sep
2-Oct
5-Oct
8-Oct
11-Oct
14-Oct
17-Oct
20-Oct
23-Oct
26-Oct
29-Oct
1-Nov
4-Nov
7-Nov
Daily High-High Tide Elevations (NAVD88)Jan 21 thru Nov 7, 2012
DATE/TIME
Max of ELEV
What causes the flooding?
• Some flooding is caused by
rainfall
- However -
• Most of the flooding is caused
by tidal backups through the
storm sewers on Strand, King
and Union Streets
4
5
• Substantially reduce
nuisance flooding
raising the elevation of
storm inlets
• Minimize impacts to
private properties
• Minimize cost
June 6th , 2012 @ 10:00 am
• The existing lowest point is along Strand Street at Elevation 1.45’
• Low points along King Street between Elevation 2.6’ and 2.8’
6
• Potomac River water surface elevations
• Elevations of existing building entrances
• Minimum slopes required for drainage
• Road and sidewalk design standards
• ADA compliance
• Cost
7
• Relocates the low point from Strand Street to King Street
• Raises lowest storm inlet opening from 1.45’ to 2.66’ (Alt.1) or 3.22’ (Alt.2)
• Annual projected flood days will be reduced from 303 to 61 (Alt.1) or 13 (Alt.2)
• Impacts to properties:
• Mai Thai (remove internal ramp) (Alt.2 only)
• Stairwell (possibly reconstruct stairs and entrance) (Alt.2 only)
• Re-Grade Portion of Boat Club Parking Lot
• Cost estimate: $925,000, (Alt.1) or $1,150,000 (Alt.2)
8
Depth of Flood Events
17
Approximate Annual Average Flood Depths
For Existing Roadway Elevations
Depth
Greater
Than
Strand Street
(Elev. 1.45)
King Street
(Elev. 2.43)
King & Union Street
(Elev. 3.22)
6" 223 30 7
1' 100 7 2
1.5' 30 2 <1
2.0' 7 <1 <1
2.5' 2 <1 <1
• With Alternative 1:
• Average of less than 1 incident of flooding per year at Strand Street
• Flood incidents on King Street will be shallower by 3”
• With Alternative 2:
• Average of less than 1 incident of flooding per year at Strand Street
and King Street