Features

June 2013, Vol. 25, No.6

Who owns the rain?  

 Water rights for rainwater harvesting 

Owns The Rain James E. Scholl

Rainfall is a diffuse and natural resource that falls on all land surfaces as part of the hydrologic cycle. Harvesting rainwater is a physical process that requires landowners to manage the impacts on downstream users.   

In many cities, this practice is gaining new visibility as a means to control wet weather management needs and provide cost-effective, sustainable stormwater management solutions. However, water rights precedents and allocation practices can establish legal constraints that may limit the ability of property owners to harvest the rainwater that falls on their property. Read full article (login required)

 

 

 Up a creek with a paddle

A visual stream assessment in a nonwadeable river is a fast way to flag areas for future improvement efforts 

Up A Paddle Michelle Hatcher

While cities implement aggressive stormwater management programs to protect watershed health, many regulatory agencies are moving toward watershed-based approaches to improve water quality. As part of the municipal separate storm sewer system (MS4) permit issued in Tennessee, each MS4 is required to develop a program to meet total daily maximum load (TMDL) requirements for the watersheds within the permit-holder’s jurisdiction.   

A visual stream assessment was used in an urbanized portion of a western Tennessee watershed to quickly identify improvements in nonwadeable rivers and to prioritize the complexity of issues. Read full article (login required) 

 

 Images of improvement

Satellite remote sensing of a Utah reservoir demonstrates how TMDLs may not achieve load reductions year-round

Images Improvement M. Brett Borup and David Fayol

The East Canyon Reservoir, located in the mountains northeast of Salt Lake City, was included in the “high priority” group for Utah’s impaired waters in the 1998 list and thus required a total maximum daily load (TMDL) plan for total phosphorus to restore beneficial uses and water quality standards. 

The TMDL was completed in 1999, and strategies were implemented in 2000 to reduce phosphorus levels in the reservoir. A study was conducted using data from the Landsat 5 Thematic Mapper satellite to determine chlorophyll-a concentrations in the reservoir during summer and fall from 1994 to 2010. The study has demonstrated that chlorophyll-a concentrations as measured by satellite imagery are a useful tool in the evaluation of the effects of pollution control strategies. Read full article (login required)

 

Operations Forum Features

When it rains, it pours  

A rainfall monitoring approach for the sewer community 

Rain Pours Kevin L. Enfinger and Patrick L. Stevens

Accurate measurement of rainfall is a critical but often overlooked factor needed to evaluate the wet weather performance of sewer systems. Poorly performing or sparsely located rain gauges can result in significant uncertainty and error in evaluating sewers. By examining the best management practices that several organizations have developed to gather and use representative rainfall data, a technically based approach for rainfall measurements is revealed. Read full article (login required) 

 

 Restricted access

Detroit Water’s operational data are both protected and accessible with unidirectional security gateways. 

Restricted Access Biren Saparia and Andrew Ginter

Computer and network security at water utilities has been the topic of much press over the last several years. Little of that news is good. There have been widespread reports that operations networks and control systems at critical infrastructures are poorly secured and that not enough is being done to correct the problem. 

The Detroit Water and Sewerage Department, however, found a new solution that moves security from a software fix to a hardware platform. Read full article (login required)

 

 Consolidating clarification  

Using dissolved-air flotation as secondary clarification improves activated sludge treatment and reduces space requirements

Consolidating Clari Houston Flippin, Larry Cuomo, and Lynn Petersen

Dissolved-air flotation (DAF) units have long been used in the food industry to remove fats, oils, and grease (FOG); total suspended solids (TSS); and biochemical oxygen demand (BOD). DAF effluent often has been discharged to a downstream activated sludge treatment facility complete with conventional gravity secondary clarification. The activated sludge from these facilities frequently exhibits filamentous sludge bulking that requires large secondary clarifiers, high return activated sludge (RAS) pumping rates, and supplemental waste activated sludge (WAS) thickening to reduce sludge disposal volumes. 

This treatment system can be greatly simplified by eliminating the primary DAF, conventional gravity clarification, and WAS thickening and replacing them with a more robust activated sludge treatment system with DAF as the secondary clarifier. Read full article (login required)