Green Roof Resource

After four years, Green Roof Resource is getting a new look. I am currently updating the site for better readability and organization.

While on the topic of renewing resources, this week I came across the International Stormwater BMP Database. The resource provides data from over 300 BMP (best management practice) studies evaluating performance of these systems. While the database was initiated in 1996, I stumbled across it after reading an article in the May issue of Stormwater. “Can Stormwater BMPs reduce bacteria?” reports that bacteria counts in BMP outlets vary widely, but in general retention ponds and media filters have the potential to reduce bacteria. There is concern that vegetative swales and other similar BMPs may attract wildlife and domestic animals increasing the concentration of fecal coliform in stormwater runoff from these systems. The concentration often exceeds the standard for recreational primary contact in waterways.

It was exciting to see that green roof runoff was included in the evaluation. However, with data being obtained from only one site (Hamilton Ecoroof in Portland, Oregon), analysis of the data was limited.

It would be interesting to evaluated BMPs in combination. For example, if retention ponds are effective at reducing fecal coliform concentration, can bioswales or green roofs reduce the size of a downstream retention pond to enable use of the BMP in areas where land is limited? Or is the apparent reduction simply an artifact of where these systems are typically used? For example, are retention ponds able to reduce fecal coliform concentration in the effluent simply because there is less in the influent? Perhaps in areas where fecal coliform is a greater problem, more conventional methods are appropriate. While fecal coliform concentration is a health concern and is contribute to beach and water closings access after rain events, one must not forget about the volume of storm events. BMPs are effective at reducing total volume of runoff entering waterways, and one should also consider the total load of contaminants exiting these systems in addition to the concentration of contaminants.

BBC News yesterday reported that Beijing plans to ban building activities prior to the Olympics to improve air quality for the games. As part of the The National Building Museum’s series For the Greener Good, on April 22nd there will be a discussion on this and similar actions that China is taking to green the games.

After reading the article, I was immediately struck with this question: how much pollution is emitted from the construction of buildings? This isn’t a highly researched area due to the challenges of measuring the emissions, which are assumed to be primarily particulate matter. The US EPA does have a method for estimating particulate matter emissions from construction activities. Depending on the soil moisture and silt content, single family homes produce 0.032 tons
PM10/acre/month while apartment construction produces 0.11 tons PM10/acre/month.

In 2005, an article by Muleski et al, in the Journal of Air and Waste Management, sampled emissions from various construction activities. The focus was on earthmoving operations although other activities were also considered. It was found that the estimating methods for emissions by other similar industries (AP-42) underpredicted the emissions on site due to earthmoving activities suggesting a need for improved estimation methods.

Specific activities that contributed to construction emissions included truck loading and dumping, with loading activities contributing 100 times more particulate matter than dumping activities. This is due to the type of equipment used and the height at which fill material is loaded into dump truck. Unloading material is completed at a lower height with less risk to dispersal by winds.

In addition to loading activities, trackout on roadways was also responsible for significant emissions. The authors stated that the PM10 emissions due to trackout of 1400 ft of roadway was equivalent to total emissions found on 6 miles of normal roadway (without construction activities).

With this in mind, it appears that ceasing construction activities should have some impact. However, with the magnitude of the air quality problem, it is unclear whether this is the most effective method for improving air quality at the games.

Recently the Associated Press reported that the Bush administration appealed a court ruling on the clean air mercury rule (CAMR), a rule that established a market based cap and trade program mercury emissions similar to those in practice in sulfur oxides and nitrogen oxides.

In February, the US Court of Appeals District of Columbia Circuit ruled that the CAMR violates the Clean Air Act. Essentially, the ruling states that EPA cannot delist electric utility steam generating units (EGUs) from section 112 of the Clean Air Act (“CAA”), 42 U.S.C. § 7412 as they emit hazardous air pollutants (HAPs). As a result, cannot set performance based standards pursuant to section 111, 42 U.S.C. § 7411, which established the market based emission program under the CAMR.

The administration presently argues that the court misinterpreted the law and that forcing EPA to draft a new rule will delay mercury emission reductions. The Utility Air Regulatory Group, which served as intervenors in the initial case and represent a group of electric utilities have also filed for review.

While I recognize and applaud the benefit of market-based approaches for effectively reducing sulfur oxides and nitrogen oxides in the atmosphere, I’ve had mixed feelings on the inclusion of mercury with these contaminants due to its hazardous characteristics. Expanding market based approaches to hazardous compounds presents its own set of challenges, and it’s exciting to see how the judicial and executive branches wrestle with these issues.