Animal Waste, Water Quality and Human Health

236Animal Waste, Water Quality and Human Health6.5 BMPs TO ATTENUATE PATHOGEN TRANSFERSTO WATERCOURSES6.5.1 Containment of farm steading/feedlot sourcesContaminated water from farm steadings (i.e. yards and associated buildings) andcattle feedlots, if not intercepted and stored as part of a manure handling system forultimate application to land, represents a potentially significant source of pathogentransmission to watercourses. Edwards et al. (2008), for example, report medianFC concentrations of between 1.2 × 10 5 and 1.4 × 10 7 cfu 100 ml −1 in runofffrom three farm steadings frequented by cattle in Scotland, and note that in onecase steading runoff and dairy washings are piped to an adjacent watercourse. Inorder to minimise the volumes of dirty water generated during rainfall (to reducestorage requirements or the flow rate through treatment systems), CoGAPsgenerally recommend that relatively clean runoff from roofs is conveyed awayfrom yard areas.6.5.2 On-farm treatment of contaminated waterIn general terms, three options for on-farm treatment of dirty water from steadingsand feedlots can be distinguished: ponds, vegetative treatment areas for treatingfeedlot runoff and constructed farm wetlands, and these are discussed in detailbelow.Ponds (see: Table 6.2, Section A). As noted above, ponds provide idealconditions for microbial attenuation. However, they can also be a source ofinfection where livestock and/or birds have access (Jones 2005, Oliver 2007,Edwards 2008). Since the 1970s, two-stage waste stabilisation ponds (WSPs),comprising an anaerobic pond (AP) and a facultative pond (FP), have beenwidely used to treat dirty water on dairy farms in New Zealand. Laboratorystudies have shown UV light to be the dominant cause of disinfection withinWSPs (Davies-Colley 1999). While effective in lowering BOD and suspendedsolids, WSPs are less effective in removing FIOs. Sukias et al. (2001), forexample, report median outflow FC concentrations of 3.5–8.0 × 10 4 cfu 100ml −1 for traditional WSPs, while 1996 guidelines recommend a reduced medianconcentration of 2.4 × 10 4 cfu 100 ml −1 in the larger ponds. To address thisconstraint, advanced pond systems (APSs) are being developed and tested inwhich the FP is replaced by a high rate pond (HRP), algae settling ponds(ASPs) and a maturation pond (MP). Many investigators (Sukias, Tanner et al.2001, Craggs, Tanner et al. 2003, Craggs 2004) found that APS effluent has amuch lower EC concentration (median, 1.5 × 10 2 cfu MPN 100 ml −1 ) than aconventional WSP (1.6 × 10 4 cfu MPN 100 ml −1 ) treating the same farm