Q: What is the drainage area for the VUSP bio-infiltration Traffic Island?
A: The drainage area for this site is approximately 50,000 sq.ft or 1.15 acres

Q: How much rain can the VUSP-TI retain in a given even?
A: This site is designed to hold approximately 1.0 inches of rain over the watershed. When the water level in the basin reaches the level of the overflow weir (at 1.72 ft.), this site begins to overflow and any rain into the system is bypassed to a stormwater basin off site. Click here to see how this site performed during an event of July 12, 2004 where approximately 4.00 inches of rain fell over a 16 hour period.

Q: How does the site overflow?
A: This site has a unique design in that it was retrofit from an existing storm drain. The original drain was bypassed so that it enters the BMP prior to continuing downgrade to a stormwater detention basin. Thus, when this site overflows, the water in the system backs up into the original drain and continues to the original stormwater detention basin.

Q: What percentage of annual rain does the site retain?
A: We currently do not have figures for the exact percentage of annual rainfall retained by this system due to difficulties in measuring precipitation during the winter months because of snow and icing at the site. It is interesting however to note that during the month of July 2004 a total of 10.48 inches of rain fell at the site. During this particularly rainy month, a total of 3.39 inches of rain overflowed from the BMP which reflects a performance of 67.7%. Click here to see an interesting summary of our research for the month of July 2004.

Q: What are the water quality parameters studied at the VUSP bio-infiltration BMP?
A: At the moment VUSP is monitoring a number of water quality parameters at this site to determine the effectiveness of bio-infiltration in reducing pollutants. Our water resources laboratory at Villanova University uses a variety of methods to analyze pollutants. Using HPLC we analyze stormwater runoff samples for Chlorides, Nitrite, Nitrate and Phosphate. Using spectrophotometery we analyze for total Nitrogen and Phosphorous. We analyze for a variety of metals including copper, lead, zinc, chromium and cadmium using a graphite furnace and, we also analyze for suspended and dissolved solids as well as conductivity, pH and temperature using standard laboratory techniques. Click here to see a summary or water quality parameters analyzed on July 12, 2004.

Q: What other water quality issues should be considered when using bio-infiltration BMP?
A: (1) Organic Carbon is an important parameter because as organics decompose, they can deplete dissolved oxygen in lakes and rivers which adversely impacts aquatic life.

(2) Hydrocarbons can be be an issue due to oil and grease which leaks from vehicles onto roadway surfaces and is carried to streams by precipitation runoff. Low concentrations of some hydrocarbons can be toxic to aquatic life.

(3) Pesticides, insecticides and herbicides used in agricultural lands as well as in suburban areas have been detected in stormwater runoff.