Beef cattle lagoon seepage

Most compacted soils can be used for lagoon liners to achieve seepage guidelines established by the Kansas Department of Health and Environment.


Introduction
The protection of surface and ground-most important factor in the physical sealing water and the utilization or disposal of ani-process.However, research published in the mal waste are the primary functions of waste late 1980's has shown convincingly that a storage ponds and treatment lagoons.How-soil's equivalent pore size computed as a ever, seepage from these structures creates function of particle size distribution and risks of pollution to surface water and un-porosity is probably more important.Alderground aquifers.The permeability of the though research has shown that permeability soil in the boundaries of a constructed waste in all soils will decrease from 1 to 3 orders treatment lagoon or waste storage pond of magnitude because of manure sealing, this strongly affects the potential for downward sealing alone probably will not provide or lateral seepage of the stored wastes.
enough protection against excessive seepage Research has shown that many natural with a very high initial permeability.Other soils on the boundaries of waste treatment research has demonstrated that for soils with lagoons and waste storage ponds will seal at clay contents exceeding 5 percent for rumileast partially as a result of physical, nant or 15 percent for monogastric animal chemical, and biological processes.Sus-manure, a final permeability of 10 to 10 pended solids settle out of suspension and cm/sec usually results from manure sealing.physically clog the pores of the soil mass.
Clay content is defined as the percent by dry Anaerobic bacteria produce by-products that weight of a soil that is smaller than 2 miaccumulate at the soil-water interface and crons (0.002 mm) and is roughly equivalent reinforce the seal.Soil structure also can be to the percentage of soil that will pass altered as bacteria metabolize organic mate-through a No. 200 seive.rial.Chemicals in animal waste, such as salts, can disperse soil, which also may reduce seepage.Research has shown that soil permeability can be decreased by several The physical clogging of the soil is and the permeability, size, and geometry of soil pores.Until recently, research has focused on total solids of the waste as the and groundwater contamination for soils -6 -7

Site Investigation
An on-site investigation of a potential Soil mechanics laboratories of the Natuwaste storage site should include: evaluating ral Resources Conservation Service (NRCS) soils, bedrock, groundwater, climatic condi-have a database of permeability tests pertions, and local water uses, to provide in-formed on over 1,100 compacted soil samsight into the potential impact of the site on ples.Experienced NRCS engineers have groundwater resources.Data should include analyzed these data and correlated permethe presence of any water wells or any other ability rates with soil index properties and water supply sources, depth to the seasonal degree of compaction.Based on this analyhigh water table, general ground water sis, Table 1 (from NRCS Technical Note gradient, general geology of the site, and 716) has been developed to provide general depth to bedrock, if applicable.
guidance on the probable permeability char-Determining the intensity of any detailed the percent fines (percent by dry weight finer site investigation is the joint responsibility of than the #200 sieve, roughly equivalent to the designer and the person who has percent clay) and a plasticity index.This authority to approve the engineering job.
index represents the range of moisture con-The intensity of investigation required de-tents at which a soil remains cohesive.pends on past experience in a given area, the types of soils and variability of the soil de-Table 2 summarizes a total of 1,161 posits, the size of the structure, the environ-NRCS tests.Where tests are shown at 85 to mental sensitivity, and an assessment of the 90% of maximum density, the vast majority associated risks involved.State and local of the tests were at 90%.Where 95% is laws should be followed in all cases.
shown, data include tests at both 95 and The subsurface investigation can employ majority of the tests performed at 95% of auger holes, dozer pits, or backhoe pits.The maximum density.investigation should extend to at least 2 feet below the planned bottom of the excavation.
Table 2 gives a summary of the perme-A site investigation can include field perme-ability test data.The first column indicates ability testing and taking samples for labora-the general soil group described in Table 1.tory testing, or it can be limited to field The second column indicates the degree of classification of the soils.Information from compaction of the soil.The higher the the site investigation should be documented percent dry density, the greater the compacand included in the design documentation.
tion.The four soil types each have been When logging soils from auger holes, always tested at two different compaction rates.consider that mixing will occur and can The data indicate that additional compaction obscure the presence of cleaner sand or of the same soil reduces the permeability of gravel lenses.Pits and trenches expose more the soils by a factor of 2 to 13.The average of the foundation, which is helpful in detect-permeability values are listed in the fourth ing small, but important, lenses of permeable column.These values, when multiplied by soil.Always use safety rules around the depth of a lagoon and divided by the trenches.
thickness of the liner, predict the seepage

Soil Properties
acteristics of soils.The grouping is based on 100% degrees of compaction, with the rate.The last column of Table 2, shows the predicted seepage rate for a lagoon with an average depth of 4 feet and a liner thickness of 1 foot.Kansas Department of Health and Environment (KDHE) regulations require that initial seepage be less than .25 inches but the liners must be designed and installed per day.These data show that almost all correctly.Soil has an added benefit of soils in groups II, III, and IV can be ade-providing an attenuation medium for the quately sealed.The permeability values pollutants.shown are median values, so some soils in all the groups may have excessive seepage.
Those on-site soils in Groups I Testing of existing soils is recommended to considered to be unsuitable usually can be assess local conditions.treated with bentonite to produce a Soil liners are relatively impervious bentonite or soil dispersants should be added barriers used to reduce seepage losses to an and mixed well into a soil prior to acceptable level.One method of providing compaction.A soil liner may also can be a liner for a waste storage structure is to constructed by compacting imported clay improve the soils at the excavated grade by from a nearby borrow source onto the disking, watering, and compacting them to a bottom and sides of the storage pond.IV Soils that have 20 to 100% passing a No. 200 sieve and have a plasticity index of more than 30.Normally, these soils have a very low permeability.However, because of their sometimes blocky and fissured structure, they often can experience high seepage losses through cracks that can develop when the material is allowed to dry.They possess good attenuation properties, if the seepage does not move through the cracks.