Recently in Hardscape Category

Did you know... 65% of new impervious cover can be classified as car habitat!

What is "car habitat"?  

"...the geometry of roads, parking lots, sidewalks, cul-de-sacs and other new development infrastructure."  That's car habitat.

Local development codes enforce how much impervious surface is allowed.  They take into consideration how water drains and is absorbed by local soil conditions, as well as the level of development already affecting the watershed.

Better site design can reduce flooding by improving absorption of heavy water deluges into nature's groundwater infrastructure.  Snowpack might be nature's LARGEST water reservoir, but groundwater is also a very valuable service provided by nature in lowlands. 

Better Site Design (BSD), can include greater use of

• swales
• relaxed lot geometry
• natural area conservation
• open-space subdivisions
• pervious paving
• and other site design techniques

Several dozen communities across the country have changed their local codes and ordinances to promote BSD through a roundtable process to gain consensus among development stakeholders.

Better Site Design Can Reduce Development Costs

The strength of the BSD approach is that numerous modeling studies have demonstrated it can reduce impervious cover, pollutants and development costs by as much as 10 to 40% at individual development sites.

The weakness of BSD is that it lacks a watershed context and therefore reductions in site IC may be not be enough to meet subwatershed objectives.

SOURCE:
Chesapeake Stormwater Network, CSN Technical Bulletin No. 3, "Implications of the Impervious Cover Model".

Wading through the sources of lake contamination

Contamination of urban lakes and streams by polycyclic aromatic hydrocarbons (PAHs) is widespread and has been increasing over the last 40 years in the United States.

PAHs are Toxic to Fish Humans and Other Organisms

These PAHs can be toxic to bottom-dwelling organisms, can cause tumors in fish, and several are believed to cause cancer in humans. 

In this study, researchers examined five sources of PAHs in 40 urban lakes from across the United States, including coal-tar-based pavement sealcoat, coal combustion, oil combustion, vehicle emissions and wood combustion.

Sealcoat Contributes to PAH Contamination

Of the five sources studied, sealcoat was the strongest contributor to PAH contamination in lake sediment. This research can help those trying to reduce pollution levels in the urban environment by providing them with a better understanding of PAH sources. 

This study, "Sources of PAHs to urban lakes in the United States," was conducted by USGS at the Society of Environmental Toxicology and Chemist