Water Quality
We continually work to improve water quality, in particular by reducing biodegradable organic materials in wastewater. When left untreated, biodegradable organic materials can contribute to low dissolved oxygen levels in receiving waters, which may harm some aquatic organisms. High levels of untreated solids, measured as total suspended solids, can reduce river clarity, inhibit photosynthesis, and damage fish and aquatic insect sediment habitat. All sites closely monitor their wastewater discharge to meet regulatory requirements, for efficient process operations and to reduce their impact on the environment.
All of our cellulose fibers mills have wastewater discharge permits that contain stringent limitations on wastewater discharge quality and monitoring requirements for physical, chemical, and biological measures of water quality. These mills have primary treatment for solids removal, followed by high efficiency biological treatment to removal biodegradable organics (BOD) and for additional solids removal. Mills use additional approaches to meet sensitive seasonal water quality needs: one facility uses constructed wetlands for additional BOD and solids removal; two facilities use treated wastewater holding ponds; and another facility injects high purity oxygen into treated wastewater. We also conduct instream biological studies to look for potential effects on biological populations and periodic bioassays to assure absence of potential aquatic toxicity in receiving waters. Additionally, we have participated in river basin and regional compacts to address our contribution to multi-user receiving waters to insure water quality standards are met.
We also work to protect water quality in areas where we grow and manage timber. We grade and maintain roads so runoff is channeled to the forest floor, keeping silt away from streams. We build culverts and bridges to allow fish passage, and we seed exposed road banks with grasses to prevent erosion.
WOOD PRODUCTS — WATER-QUALITY MEASURES
| Estimated discharge of selected pollutants in pounds per ton of production |
| |
2006 |
2007 |
2008 |
2009 |
2010 |
| Biochemical oxygen demand |
0.04 |
0.03 |
0.04 |
0.03 |
0.06 |
| Total suspended solids |
0.01 |
0.01 |
0.01 |
0.01 |
0.01 |
CELLULOSE FIBERS1 — WATER-QUALITY MEASURES
| Estimated discharge2 of selected pollutants in pounds per ton of production |
| |
2006 |
2007 |
2008 |
2009 |
20103 |
| Biochemical oxygen demand |
1.87 |
1.98 |
1.82 |
2.27 |
2.23 |
| Total suspended solids |
2.59 |
2.71 |
2.84 |
2.95 |
3.98 |
DISCHARGE OF ADSORBABLE ORGANIC HALIDES
Because we no longer use elemental chlorine for pulp and paper bleaching, our discharges of adsorbable organic halides have decreased by more than 93 percent between 1990 and 2010.
DISCHARGES OF ADSORBABLE ORGANIC HALIDES
| Pounds of AOX discharged per ton of bleached production from Weyerhaeuser's cellulose fibers mills2 |
| |
19901 |
2006 |
2007 |
2008 |
2009 |
2010 |
| AOX |
5.1 |
0.3 |
0.3 |
0.3 |
0.3 |
0.3 |
WASTEWATER DIOXINS
Weyerhaeuser eliminated the use of elemental chlorine to bleach and whiten pulp at all of our mills in the late 1990s. As a result, the concentration of dioxins—-a byproduct of elemental chlorine—has dropped to nondetectable levels in treated mill wastewater across company operations.
Our pulp is produced using advanced technologies such as extended pulping and oxygen delignification (removing lignin, a chemical that binds wood fibers together), that further reduce the amount of bleaching chemical used in the production process. These improvements have virtually eliminated dioxins from our wastewater while continuing to meet customer expectations for brightness in our paper products. Benchmarking research indicates that Weyerhaeuser's mills using elemental chlorine free (ECF) processes are in the top-quartile of their industry peers in terms of the quantity of bleaching chemicals used.
Dioxin is also found in some of the residuals, such as boiler ash, from our mill operations and in some solids that are removed during restoration work on our wastewater-treatment systems. These solids are handled according to federal, state and provincial regulations.