title: Design and performance evaluation of a 1000-year evapotranspiration-capillary surface barrier.
abstract: Surface barrier technology is used to isolate radioactive waste and to reduce or eliminate recharge water to the waste zone for 1000 years or longer. However, the design and evaluation of such a barrier is challenging because of the extremely long design life. After establishing a set of design and performance objectives, a package of design solutions was developed for 1000-year surface barriers over nuclear waste sites. The Prototype Hanford Barrier (PHB) was then constructed in 1994 in the field over an existing waste site as a demonstration. The barrier was tested to evaluate surface-barrier design and performance at the field scale under conditions of enhanced and natural precipitation and of no vegetation. The monitoring data demonstrate that the barrier satisfied nearly all objectives in the past two decades. The PHB far exceeded the Resource Conservation and Recovery Act criteria, functioned in Hanford's semiarid climate, limited drainage to well below the 0.5 mm yr-1performance criterion, limited runoff, and minimized erosion and bio-intrusion. Given the two-decade record of successful performance and consideration of the processes and mechanisms that could affect barrier stability and hydrology in the future, the results suggest the PHB is very likely to perform for its 1000-year design life. This conclusion is based on two assumptions: (1) the exposed subgrade receives protection against erosion and (2) institutional controls prevent inadvertent human activity at the barrier. The PHB design can serve as the basis for site-specific barriers over waste sites containing underground nuclear waste, uranium mine tailings, and hazardous mine waste.
authors.affiliation: Hydrology Group, Earth Systems Science Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA. Electronic address: fred.zhang@pnnl.gov.
authors.forename: Zhuanfang Fred
authors.initials: ZF
authors.lastname: Zhang
authors.affiliation: Hydrology Group, Earth Systems Science Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Strickland
authors.affiliation: Energy and Environmental Science Program, Department of Natural Resources, Confederated Tribes of the Umatilla Indian Reservation, 46411 Timine Way, Pendleton, OR 97801, USA.
authors.forename: Steven O
authors.initials: SO
authors.lastname: Link
mesh_terms: D002980:Climate; D006801:Humans; D062070:Hydrology / Q000379:methods*; D000091402:Prohibitins; D011850:Radioactive Waste; D012037:Refuse Disposal / Q000379:methods*; D014501:Uranium; D064091:Waste Disposal Facilities; D014867:Water
chemical_list: C000717328:PHB protein, human; D000091402:Prohibitins; D011850:Radioactive Waste; D014867:Water; D014501:Uranium
keywords: Infiltration control; Nuclear waste; Surface cover; Waste isolation