J. agric. Engng Res. (1990) 46, 93-103 Geotextiles as Sealing Liners for Earthen Manure Reservoirs: Part 1, Geotextile Porosity S. F. BARRINGTON; S. O. PRASHER; R. J. RAIMONDO* The development of an inexpensive but durable sealing liner is required for earthen manure storage facilities built of coarse sand or gravel. Fine porosity geotextiles can be used for this purpose, as manures seal media of small pore sizes. Non-woven geotextiles of 20, 30 and 40 /~m in equivalent porosity were subjected to pressure heads of 0.9, 1.8 and 2-7 m of swine slurry for 1800 h. Infiltration rates decreased from 5 x 10-Sm/s to less than 1 x 10 -7 and 2 x 10 -8 m/s within 150 and 1000 h, respectively. Although some of the experimental combinations gave significantly higher infiltration rates, all geotextiles demonstrated minimum seepage rates ranging from 1-3 to 1-8 x 10 -g m/s after 100 to 1400 h. In all cases, seepages were highly contaminated. Highest COD levels were observed for the 2-7 m heads as well as the 20 /~m fabric. This 20 pm fabric produced significantly higher infiltration rates, probably because of its lower permeability which encourages a less compact manure seal at its surface. 1. Introduction Earthen manure storage facilities are accepted as environmentally safe if built of soils meeting specific requirements as to particle size distribution and porosity. Coarse sands and gravels do not satisfy these conditions and must be lined with an artificial seal. Clay layers, geomembranes and cement residues are impermeable liners used for such purpose. But, their cost of installation approaches that of concrete structures while their life span is relatively much shorter. Research on manure and wastewater clogging mechanisms indicates that sealing liners need not be impermeable but should be of fine porosity. Non-woven geotextiles offer exactly this characteristic while being inexpensive and stress resistant. In the present work, fine porosity geotextiles were subjected to swine slurry to measure the extent of sealing. This research did not aim to differentiate between sealing mechanisms. 2. Literature review Geotextile liners are developed from the premise that physical mechanisms are primarily responsible for the manure sealing of porous media. 1 Physical sealing mechanisms occur through the deposition of' organic particles at the entry of, or within, pores of the medium being infiltrated by the liquid waste. Deposition processes were demonstrated for soils infiltrated by wastewaters containing radioactive, carbon labelled, suspended solids. 2 The largest organic particles are screened at the soil surface while the medium sized particles are strained within the first 10 mm of soil. Very fine particles are removed by convection-diffusion processes but the initial retention process loses efficiency with time. 2 This deposition process has also been seen under the microscope within soils infiltrated with manures, a'4 * Department of Agricultural Engineering, Macdonald College of McGill University, Montreal, Canada, HX9 1CO Received 13 June 1989; accepted in revised form 11 November 1989 93 0021-8634/90/060093 + 11 $03.00/0 © 1990The British Societyfor Researchin AgriculturalEngineering