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Upper Park Cistern Overflow and Lower Park Storm Water Runoff, Dec 24, 2020
4:34 PM. Big storm predicted and flash flood warning for Christmas Eve. [ARLnow: Flash Flood Watch Issued for Arlington, D.C. Area] Light rain fell during the day. Storm water sheeting off newly expanded parking lot, but no noticeable storm water flow in discharge gully by 4:34 PM.
4:34 PM. Big storm predicted and flash flood warning for Christmas Eve. [ARLnow: Flash Flood Watch Issued for Arlington, D.C. Area] Light rain fell during the day. Storm water sheeting off newly expanded parking lot, but no noticeable storm water flow in discharge gully by 4:34 PM.
Heavier band of clouds observed to west at 4:32 PM. Subsequent check of weather radar shows heavy rain band moving eastwards at 4:15 PM. At 4:35 PM, heavy band of rain reaching Upton Hill.
Heavier band of clouds observed to west at 4:32 PM. Subsequent check of weather radar shows heavy rain band moving eastwards at 4:15 PM. At 4:35 PM, heavy band of rain reaching Upton Hill.
4:42 PM. Ground observations show rain growing heavier around 4:42 PM. Heavier storm water flow off newly expanded parking lot and sediment off excavated hillside.
4:42 PM. Ground observations show rain growing heavier around 4:42 PM. Heavier storm water flow off newly expanded parking lot and sediment off excavated hillside.
4:46 PM. A few minutes later, storm water run off begins to sluice down discharge gully.
4:46 PM. A few minutes later, storm water run off begins to sluice down discharge gully.
4:48 PM. Steady flow of storm water runoff.
4:48 PM. Steady flow of storm water runoff.
4:49 PM. Large, steady flow.
4:49 PM. Large, steady flow.
Storm water runoff enters the forest through and next to the akibia overgrown area described in the 2007 Natural Resources inventory.
Storm water runoff enters the forest through and next to the akibia overgrown area described in the 2007 Natural Resources inventory.
Over the years, one gully eroded by storm water run off from the old parking lot, apparently took out the hiking path necessitating the construction of wooden bridge.
Over the years, one gully eroded by storm water run off from the old parking lot, apparently took out the hiking path necessitating the construction of wooden bridge.
For another eroded gully, NOVA Parks apparently put in a plastic drainage pipe to sluice the storm water under the path where it is eroding a gully further into the forest on the way to the sensitive wetlands in the RPA in the NE corner of the park.
For another eroded gully, NOVA Parks apparently put in a plastic drainage pipe to sluice the storm water under the path where it is eroding a gully further into the forest on the way to the sensitive wetlands in the RPA in the NE corner of the park.
4:54 PM. Meanwhile, storm water runoff flowing down access road and from playground construction area flows down bike path and its shoulder.
4:54 PM. Meanwhile, storm water runoff flowing down access road and from playground construction area flows down bike path and its shoulder.
On north side of bike path there is a shallow culvert and NOVA Parks installed a plastic drain pipe so the water with its sediment can flow under the bike path directly into the RPA, eroding a gully in the forest floor.
On north side of bike path there is a shallow culvert and NOVA Parks installed a plastic drain pipe so the water with its sediment can flow under the bike path directly into the RPA, eroding a gully in the forest floor.
Arlington County's 2007 Natural Resource Inventory of Upton Hill Regional Park highlighted the danger storm water flows posed to the sensitive wetlands in the NE corner of the park:
Arlington County's 2007 Natural Resource Inventory of Upton Hill Regional Park highlighted the danger storm water flows posed to the sensitive wetlands in the NE corner of the park:
In two areas, uncontrolled storm water flow threatens the integrity of the wetland. From the southeast, originating from the neighborhood at the top of slope [Longfellow Street], storm water sheetflow enters the park and flows by gravity down a series of drainage ravines, some of which appear to have been created by storm water flow. During periods of high water flow (thunderstorms), an increased volume of water flowing at high intensity is compounding the problem by downcutting the ravines. To the west of the wetland, storm water enters the wetland head from the paved service road, open playground area, and from the newly constructed outboard berm along the paved commuter trail. During high rain events, it was observed that a high volume of silt-laden water (orange color) was flowing directly into the top of the wetland. Without some form of remediation, the clean, cobble and sand covered stream beds downstream are in danger of being irreparably covered with successive layers of silt.
It seems little or nothing was done in the last 13 years to mitigate these threats to the wetlands.
It seems little or nothing was done in the last 13 years to mitigate these threats to the wetlands.
In 2007, no particular erosion was noted from the storm water run off from the parking lot in the upper park:
In 2007, no particular erosion was noted from the storm water run off from the parking lot in the upper park:
UH-2: Near the crest of the hill on the old park road, is a small artificial depression that collects storm-water runoff from the adjacent parking lot. This small basin probably provides some contribution to the ground-water budget of the adjacent headwaters where the wetlands are located. A corrugated pipe acts as the outlet and extends east under the old road for about 90-100 feet, to discharge in a bank of rip rap and old brush piles near the head of the slope (UH-2A). No erosion associated with the outlet was noted. Weathered gravel embedded in orange brown loam is visible in several bare spots in this general area. The gravel ranges up to cobble size, consists entirely of siliceous rocks, and has the characteristically pitted, polished surfaces associated with long, intense weathering.
Seemingly, the storm water run off danger from the parking lot was not great 13 years ago, but grew over time and now continues.
Seemingly, the storm water run off danger from the parking lot was not great 13 years ago, but grew over time and now continues.
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