01589340 - Rognel Heights Storm Sewer at Baltimore, Md.

Location - Lat. 39° 17' 59", long. 76° 41' 26", Baltimore City, on left wingwall of culvert at downstream side of storm sewer outfall on Seminole Avenue, 0.3 miles upstream from Dead Run, 0.6 miles southeast of Leakin Park, 1.5 miles southwest of Walbrook.

Gaging station may be reached from intersection of Edmondson Avenue and Hilton Parkway as follows:

Parking, on street

Follow Edmondson Avenue westbound past Hilton Parkway, turn right onto Wildwood Parkway. Follow Wildwood Parkway for approximately 0.4 miles, turn left onto Rokeby Road. Follow Rokeby Road for approximately 0.5 miles. Bear right at split in road onto Seminole Avenue. Follow Seminole Avenue approximately 0.2 miles, park van on right side of road at first storm sewer drain. Walk across grass berm to cut path in brush at edge of woods. Follow path down embankment to gage on left wingwall of concrete culvert. See map for route to gage.

Establishment - November 25, 1998.

Drainage Area - 0.03 square mile (19.26 acres; delineation based on Baltimore City DPW sewer plans).

Datum of Gage - Approximately 318 feet above National Geodetic Vertical Datum of 1929 (NGVD), based on Baltimore City DPW sewer plans and USGS 7.5 minute topographic maps.

Culvert and sensor line, looking upstream

Gage - 2 ft. by 2 ft. by 1 ft. galvanized, rainproof electrical pull box mounted to top of left downstream wingwall of culvert. Probe cable is protected by 2.5 inch PVC pipe. Pipe is capped at outlet to prevent debris and rodents from entering pipe.

Pertinent elevations:	Gage Height (feet)
Invert of pipe just upstream of probe	0.0
Top of pipe (inside diameter)	3.5

Equipment shelf

Equipment - ISCO 4150 Area/Velocity Meter (5 minute measurement interval), with standard probe (area velocity sensor) mounted to circular ISCO mounting rings at outfall of 42-inch concrete storm sewer pipe.

History

1. No other gages have been operated on this stream.

Vertical Controls

[BM = Bench Mark; RM = Reference Mark; RP = Reference Point]

Looking upstream from gage Looking downstream

Channel - Channel is a 42-inch concrete sewer pipe that is straight for about 61 feet above the outfall.

Control

Control - Low stage control is the concrete pipe. PVC pipe that houses probe cable will affect low flows up to a stage of approximately 0.25 ft., gage datum. Medium and high stage control is the pipe outlet. At extreme high stages, the concrete invert outside the pipe will become the control. Some minor backwater detected from small amounts of debris catching on PVC pipe. Pipe outlet was patched and reformed with hydraulic cement and quikrete on March 29-30, 1999. A small, rectangular section of sheet metal was set into the form at the pipe outlet and protrudes approximately 0.5 ft. out from the pipe outlet. The sheet metal section contracts low flows at the outlet for volumetric discharge measurements.

Volumetric measurement

Discharge Measurements - For gage heights less than 0.13 ft., measurements can be made volumetrically at the outfall. For gage heights of 0.13 ft. to 0.25 ft., wading measurements can be made in the concrete invert at the outfall if the flow can be adequately confined. For stages of 0.25 ft. to 0.50 ft., wading measurements can be made in the channel below the concrete invert, but is only recommended with a field crew of 2 or more. In June of 2000, a slope-area reach was set up in the channel about 200 feet below the concrete invert to indirectly measure higher flows.

Floods - Storm of August 14, 1999, reached a stage of 1.02 ft., gage datum.

Point of Zero Flow - 0.06 ft, gage datum (based on control conditions after patching/reforming pipe outlet).

Winter Records - During winter months, gage pool is subject to freezing during periods of extended cold. Source water may freeze and thaw, causing sudden drops and increases in stage.

Regulation - None.

Diversion - None.

Accuracy - Stage-discharge relationship is good to fair above 0.33 ft with direct use of the area/velocity meter. Probe is capable of measuring mean velocity at stages of 0.33 ft. or greater. Meter provides only approximations of velocity at stages below 0.33 ft. Volumetric measurements of discharge at lower stages provides greater accuracy at the low end of the rating.

Cooperation - Baltimore Ecosystem Study, Long-Term Ecological Research; University of Maryland, Baltimore County.

Photographs - See station files.

Additional Information - Recording tipping bucket rain gage (J+S rain gage, serial # 2299) is located at the Carrie Murray Outdoor Education Center, approximately 0.9 mile northwest of the gage.