Name: wastewater irrigation impacts on soil hydraulic conductivity: coupled field sampling and laboratory determination of saturated hydraulic conductivity
Uploaded: 2018-08-19T12:30:00
Description: Watch this Scientific Journal Video about Wastewater Irrigation Impacts on Soil Hydraulic Conductivity: Coupled Field Sampling and Laboratory Determination of Saturated Hydraulic Conductivity at JoVE.

The authors would like to thank the Pennsylvania State University Office of Physical Plant for providing partial funding to support this project. Partial funding was also provided by the USDA-Regional Research Project W-3170. We would like to express our gratitude to Ephraim Govere for his assistance with the analytical work. Our deepest gratitude is to Charles Walker, whose engineering design and construction skills made it possible for us to conduct this work.

1. Selecting Soil Sampling Locations
<ol>
	<li>Identify through aerial photography and site visit(s) locations that have received irrigation by wastewater and those that have not.</li>
	<li>Select several representative sites from which to sample, paying close attention to possible landscape differences (particularly landscape location, such as summit, side slope, toe slope, and depression) on which water, soil, and plants may interact differently.</li>
	<li>Identify portions of the landscape as a summit, side slope, t...

<ol>
	<li>Kolpin, D. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pharmaceuticals,+hormones,+and+other+organic+wastewater+contaminants+in+U.S.+streams,+1999-2000:+a+national+reconnaissance.">Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: a national reconnaissance.</a> Environmental Science &amp; Technology. 36 (6), 1202-1211 (2002).</li><li>Duan, R., Sheppard, C. D., Fedler, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Short-term+effects+of+wastewater+land+application+on+soil+chemical+properties.">Short-term effects of wastewater land application on soil chemical properties.</a> Water, Air, &amp; Soil Pollution. 211 (1-4), 165-176 (2010).</li><li>Frenkel, H., Goertzen, J. O., Rhoades, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+clay+type+and+content+exchangeable+sodium+percentage,+and+electrolyte+concentration+on+clay+dispersion+and+soil+hydraulic+conductivity.">Effects of clay type and content exchangeable sodium percentage, and electrolyte concentration on clay dispersion and soil hydraulic conductivity.</a> Soil Science Society of America Journal. 42 (1), 32-39 (1978).</li><li>Goncalves, R. A. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydraulic+conductivity+of+a+soil+irrigated+with+treated+sewage+effluent.">Hydraulic conductivity of a soil irrigated with treated sewage effluent.</a> Geoderma. 139 (1-2), 241-248 (2007).</li><li>Halliwell, D. J., Barlow, K. M., Nash, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+the+effects+of+wastewater+sodium+on+soil+physical+properties+and+their+implications+for+irrigation+systems.">A review of the effects of wastewater sodium on soil physical properties and their implications for irrigation systems.</a> Australian Journal of Soil Research. 39 (6), 1259-1267 (2001).</li><li>Franklin, A. M., Williams, C. F., Andrews, D. M., Woodward, E. E., Watson, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uptake+of+Three+Antibiotics+and+an+Antiepileptic+Drug+by+Wheat+Crops+Spray+Irrigated+with+Wastewater+Treatment+Plant+Effluent.">Uptake of Three Antibiotics and an Antiepileptic Drug by Wheat Crops Spray Irrigated with Wastewater Treatment Plant Effluent.</a> Journal of Environmental Quality. 45 (2), 546-554 (2016).</li><li>Franklin, A. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antibiotics+in+agroecosystems:+introduction+to+the+special+section.">Antibiotics in agroecosystems: introduction to the special section.</a> Journal of Environmental Quality. 45 (2), 377-393 (2016).</li><li>Wolf, A. M., Beegle, D. B., Sims, J. T., Wolf, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recommended+soil+tests+for+macronutrients.">Recommended soil tests for macronutrients.</a> Recommended Soil Testing Procedures for the Northeastern United States. , 39-47 (2011).</li><li>Klute, A., Dirksen, C., Klute, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydraulic+conductivity+and+diffusivity:+laboratory+methods.">Hydraulic conductivity and diffusivity: laboratory methods.</a> Methods of Soil Analysis: Part 1-Physical and Mineralogical Methods. , 687-743 (1986).</li><li>Walker, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Enhanced techniques for determining changes to soils receiving wastewater irrigation for over forty years. , (2006).</li><li>Perroux, K. M., White, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Designs+for+disc+permeameters.">Designs for disc permeameters.</a> Soil Science Society of America Journal. 52 (5), 1205-1215 (1988).</li><li>Clothier, B. E., White, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+sorptivity+and+soil+water+diffusivity+in+the+field.">Measurement of sorptivity and soil water diffusivity in the field.</a> Soil Science Society of America Journal. 45 (2), 241-245 (1981).</li><li>Ankeny, M. D., Ahmed, M., Kaspar, T. C., Horton, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simple+field+method+for+determining+unsaturated+hydraulic+conductivity.">Simple field method for determining unsaturated hydraulic conductivity.</a> Soil Science Society of America Journal. 55 (2), 467-470 (1991).</li><li>Larson, Z. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Long-term treated wastewater irrigation effects on hydraulic conductivity and soil quality at Penn State's Living Filter. , (2010).</li></ol>

The ability to collect field-based, undisturbed soil samples and obtain their hydraulic conductivity values is important in obtaining data representative of a site. In order to best represent field conditions, it is important to use soil samples which remain in a physical state representative of their environment in the field. Soil samples collected from a field site which are then disturbed by subsampling or by handling induced compaction, for example, will experience structural changes which impact the saturated hydrau...

Discharge of treated wastewater from municipalities into streams has been a standard practice for decades. Such wastewater is treated primarily for the purpose of reducing the potential for biological oxygen consumption by microorganisms in the receiving waters, as a result of the discharged wastewater effluent. Oxygen consumption by microorganisms degrades organic materials in the wastewater reducing the oxygen levels in the water body into which the effluent is discharged and thereby harm aquatic organisms, including fish.
In recent decades concerns have developed related to inorganic nutrients, some metals, and other chemicals within wastewater which create harm. Due to a study published by Kolpin et al.1, a greater focus on a range of chemicals not previously considered has evolved. This study, published by the United States Geological Society, raised awareness regarding the wide range of personal care products and other chemicals in rivers and streams across the US due to discharge from wastewater treatment facilities.
Since the early 1960s, researchers at Penn State University have investigated and developed an alternative wastewater discharge practice somewhat unique in a humid region. Rather than discharging treated wastewater to a stream, and thereby directly impacting the stream quality, the effluent is applied to the forested and the cropped land managed by the University. This application area, nicknamed &#34;The Living Filter&#34;, presently accepts all wastewater effluent generated from the campus plus some from the municipality. This reduces the likelihood for excess nutrients to enter streams which deliver water to the Chesapeake Bay, protects the local cold-water fishery from discharges of warm wastewater which is harmful to the fish, and prevents the delivery of other chemicals contained in the wastewater from directly contacting aquatic ecosystems.
However, there are always consequences of behavior changes, and this alternative use facility is not immune to such. Questions have arisen regarding whether the application of the wastewater effluent has negatively impacted the soil&#39;s ability to allow water to infiltrate the soil surface2,3,4,5 and caused greater runoff, whether there is a possible contamination of the local wells with chemicals (nutrients, antibiotics or other pharmaceutical compounds, personal care products) contained in the wastewater effluent, and whether those chemicals are creating negative environmental impacts, such as through the uptake of chemicals into plants6 grown on the site, or the development of antibiotic resistance in soil organisms7 at the site.
As a result of some of these concerns, this study is conducted to determine the impacts of the irrigation of wastewater effluent on soil hydraulic conductivity at saturation. The approach used involves collecting soils from selected sites either within or outside the irrigated area and matching the soil sample container size with the laboratory setup. It is important for the soil sample container to fit into the laboratory apparatus and for the water that moves downward through the soil matrix in the sample to be separated from the water that moves downward between the soil and the soil sample container. The protocol describes how the laboratory apparatus is constructed to ensure this occurred.
Soil samples are collected using a hydraulic core sampler attached to a tractor. Soil cores are collected from selected areas in the undulating landscape and retained in a plastic sleeve fitted into the soil core sampler. These cores are collected from a Hagerstown silt loam, located either in a summit landscape position or in a depressional area. Six representative summits and six depressional sites are sampled from the irrigated area (a total of 12 irrigated area sampling sites). In addition, three summits and three depressional sites are sampled from an adjacent, non-irrigated area (a total of six non-irrigated sites). A maximum of six cores is collected at each site to a maximum depth of approximately 1,200 mm, with each core sample being approximately 150 mm long (100 mm of the sample being contained in the plastic sleeve and 50 mm being contained in the cutting head of the metal sampler). After removal from the metal sampler, the plastic sleeves containing the collected soil cores are fitted with end caps, transported upright to the laboratory, and stored upright until they are used to determine the saturated hydraulic conductivity. Concurrently, soil samples are collected at each depth for the determination of soil and soil solution concentrations of Calcium (Ca), Magnesium (Mg), and Sodium (Na) using a Mehlich 3 extraction for estimates of soil concentrations8 and deionized water extracts at a 1:2 ratio of soil mass:water mass. The chemical analyses of the water extracts were obtained from Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and were used to calculate the Sodium Adsorption Ratio (SAR).
The determination of the saturated hydraulic conductivity is carried out primarily using a constant head method9. A solution containing Ca and Na salts to mimic the effluent electrical conductivity (EC) and SAR of the effluent is created so the soil will be exposed to water quality variables similar to the wastewater applied in the field. In this case, the EC is 1.3 dS/m and the SAR is 3, reflecting the EC and SAR of the effluent in recent years prior to the sample period. [Technically, the units for SAR are (milliequivalents/liter)&#189; and are not usually identified in the literature.]
The modification to the constant head method of Klute and Dirksen9 is the development of a flow separator by Walker8 to prevent flow through the column which occurred outside the soil matrix from being included in the estimate of the soil hydraulic conductivity. The flow separator is built using polyvinyl chloride (PVC) tubing selected and machined to match the soil sample size. A screen supports the soil sample and allows the water that has moved through the soil matrix to flow out the bottom of the sample. A second outlet emits the water that has flowed down the inside of the plastic sleeve, thereby eliminating so-called &#34;wall flow&#34; from being incorrectly included in the estimate of the amount of water that moves through the soil matrix.

<table>
	<tbody>
		<tr>
			<td>Sampling equipment:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Soil Sampler Drill Rig</td>
			<td>Giddings Machine Co. Inc</td>
			<td>#25-TS / Model HDGSRTS</td>
			<td>* NOTE: This model is comparable to the model we utilized but which is no longer produced</td>
		</tr>
		<tr>
			<td>Kelly Bar</td>
			<td>Giddings Machine Co. Inc</td>
			<td>#KB-208 8 Ft. Kelly Bar</td>
			<td></td>
		</tr>
		<tr>
			<td>Soil Sample Collection Tube</td>
			<td>Giddings Machine Co. Inc</td>
			<td>#ZC-180 4-3/4&#8221; X 7-1/4&#8221;</td>
			<td></td>
		</tr>
		<tr>
			<td>Soil Collection Tube Bit</td>
			<td>Giddings Machine Co. Inc</td>
			<td>#ZC-190 4-3/4&#8221; Standard Relief</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic Liner for Soil Sample</td>
			<td>Giddings Machine Co. Inc</td>
			<td>#ZC-208 3-5/8&#8221; x 6&#8221;</td>
			<td>Enough for the number of samples being collected</td>
		</tr>
		<tr>
			<td>Black end caps a for bottom of sample liners</td>
			<td>Giddings Machine Co. Inc</td>
			<td></td>
			<td>To retain samples in liners</td>
		</tr>
		<tr>
			<td>Red end caps a for top of sample liners</td>
			<td>Giddings Machine Co. Inc</td>
			<td></td>
			<td>To retain samples in liners</td>
		</tr>
		<tr>
			<td>Cooler Chest</td>
			<td></td>
			<td></td>
			<td>Store &#38; maintain samples upright in sample liners during transport from field to lab</td>
		</tr>
		<tr>
			<td>Protective gear:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Hardhats, googles, and gloves</td>
			<td></td>
			<td></td>
			<td>other items as needed for personal protection</td>
		</tr>
		<tr>
			<td>Saw</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Drill and bits</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PVC Cement</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>6 to 8 - 19 mm x 184 mm x 2438 mm boards</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2 &#8211; barbed fittings; 13 mm HB x MGHT</td>
			<td></td>
			<td></td>
			<td>to connect plastic tubing to supply gutter and to drainage gutter</td>
		</tr>
		<tr>
			<td>6 &#8211; barbed fitting</td>
			<td></td>
			<td></td>
			<td>to connect plastic tubing to outer PVC cylinder to allow for water drainage</td>
		</tr>
		<tr>
			<td>3000 mm long - 19 mm OD / 13 mm ID plastic tubing</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>6 &#8211; 85 mm diameter circular mesh pieces</td>
			<td></td>
			<td></td>
			<td>Can be cut from (e.g.) a 600 mm long, 6 mm x 18 gauge wire mesh (e.g. galvanized steel gutter guard)</td>
		</tr>
		<tr>
			<td>Schedule 40 PVC pipe &#8211; 96 mm ID / 114 mm OD</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Schedule 40 PVC pipe &#8211; 73 mm ID / 89 mm OD</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Schedule 40 PVC pipe &#8211; 63 mm ID / 73 mm OD, OR 6 - 73 mm plastic shower drains</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Schedule 40 PVC pipe &#8211; 25 mm ID</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>6 - 6 mm thick x 155 mm square sheets of PVC</td>
			<td></td>
			<td></td>
			<td>Can purchase 2 &#8211; 6 mm x 300 mm (appx) sheets for about $20 each from: https://www.interstateplastics.com/Pvc-Gray-Sheet-PVCGE~~SH.php?vid=20180212222911-7p</td>
		</tr>
		<tr>
			<td>6 &#8211; 140 mm by 19 mm plastic funnels</td>
			<td></td>
			<td></td>
			<td>To direct water flowing from soil sample into collection beaker</td>
		</tr>
		<tr>
			<td>Adhesive caulk</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1 &#8211; length of 150 mm x 1200 mm wire mesh cloth</td>
			<td></td>
			<td></td>
			<td>4 Mesh works well</td>
		</tr>
		<tr>
			<td>2 &#8211; 120 mm x 1219 mm plastic gutter with end caps</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4 &#8211; gutter hangers</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1 - additional gutter end cap</td>
			<td></td>
			<td></td>
			<td>To be cut as described in procedures to create a constant head in the supply gutter</td>
		</tr>
		<tr>
			<td>1 &#8211; large plastic tub</td>
			<td></td>
			<td></td>
			<td>Appx 65 L in volume, for example, to serve as water source for the hydraulic conductivity procedure</td>
		</tr>
		<tr>
			<td>1 &#8211; large plastic tub</td>
			<td></td>
			<td></td>
			<td>To serve for wetting up soil samples</td>
		</tr>
		<tr>
			<td>1 &#8211; Submersible pump</td>
			<td></td>
			<td></td>
			<td>e.g. Beckett M400 AUL or M400 AS</td>
		</tr>
		<tr>
			<td>Plastic tubing</td>
			<td></td>
			<td></td>
			<td>Various sized drainage tubes, water supply tube, and drain from drainage gutter</td>
		</tr>
		<tr>
			<td>Container of Cheese Cloth</td>
			<td></td>
			<td></td>
			<td>To place at bottom of soil sample help retain soil in plastic sample container during hydraulic conductivity and wetting up</td>
		</tr>
		<tr>
			<td>Rubber bands</td>
			<td></td>
			<td></td>
			<td>Large enough to fit around plastic sample liners tightly</td>
		</tr>
		<tr>
			<td>Scale which measures to at least 0.1 gram</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Beaker or other container to collect water from each sample</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td></td>
			<td></td>
			<td>For creating a water quality similar to that which is typically applied to the soil</td>
		</tr>
		<tr>
			<td>Calcium Chloride</td>
			<td></td>
			<td></td>
			<td>For creating a water quality similar to that which is typically applied to the soil</td>
		</tr>
	</tbody>
</table>

wastewater irrigation impacts on soil hydraulic conductivity: coupled field sampling and laboratory determination of saturated hydraulic conductivity

Since the early 1960s, an alternative wastewater discharge practice at The Pennsylvania State University has been researched and its impacts monitored. Rather than discharging treated wastewater to a stream, and thereby directly impacting the stream quality, the effluent is applied to forested and cropped land managed by the University. Concerns related to reductions in soil hydraulic conductivity occur when considering wastewater reuse. The methodology described in this manuscript, matching soil sample size with the size of the laboratory-based hydraulic conductivity measurement apparatus, provides the benefits of a relatively rapid collection of samples with the benefits of controlled laboratory boundary conditions. The results suggest that there may have been some impact of wastewater reuse on the soil&#39;s ability to transmit water at deeper depths in the depressional areas of the site. Most of the reductions in the soil hydraulic conductivity in the depressions appear to be related to the depth from which the sample was collected, and by inference, associated with the soil structural and textural differences.

To investigate the question of whether the application of wastewater effluent at the Living Filter site has impacted the ability of the soil to transmit water, we conducted experiments to measure the saturated hydraulic conductivity of the soils. We compared hydraulic conductivity of soils from irrigated areas of the site with those in non-irrigated areas of the site. The impact of wastewater effluent on the soil hydraulic conductivity is a question of concern, as there have been some rep...

Watch this Scientific Journal Video about Wastewater Irrigation Impacts on Soil Hydraulic Conductivity: Coupled Field Sampling and Laboratory Determination of Saturated Hydraulic Conductivity at JoVE.

Wastewater Irrigation Impacts on Soil Hydraulic Conductivity: Coupled Field Sampling and Laboratory Determination of Saturated Hydraulic Conductivity

Here we present a methodology which matches a soil sample size and a hydraulic conductivity measurement device to prevent the so-called wall flow along the inside of the soil container from being erroneously included in water flow measurements. Its use is demonstrated with samples collected from a wastewater irrigation site.

Since the early 1960s, an alternative wastewater discharge practice at The Pennsylvania State University has been researched and its impacts monitored. ...

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