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Page 3 of 6 Cost to Retrofit Existing Dairies That Do Not Have Tier 1 Or Tier 2 Lagoons the "liquid and wet solid" cleanout cost in parentheses in Table 1 to provide an understanding of the range of costs that could be expected to clean the old lagoon to close the project. Table 1. Costs to retrofit lagoons based on dairy size and retrofit type. Existing Location* New Location Wet Cleanout** 300 MC, 2.1 ac lagoon Single $198,000 $180,000 (+$37,000) Double $270,000 $252,000 (+$37,000) 750 MC, 3.4 ac lagoon Single $300,000 $275,000 (+$78,000) Double $425,000 $399,000 (+$78,000) 1,500 MC, 6.0 ac lagoon Single $521,000 $482,000 (+$171,000) Double $753,000 $714,000 (+$171,000) 3,000 MC, 10.7 ac lagoon Single $948,000 $887,000 (+$357,000) Double $1,383,000 $1,321,000 (+$357,000) An existing location estimate includes the cleanout of liquid and solid manure from the lagoon before construction can begin. A new location estimate does not include any cleanout cost of the old lagoon. This wet cleanout cost could be expected if performed while water is in the old lagoon. Issues There are many issues that may arise with the retrofitting or replacement of a lagoon. Each dairy has a different set of circumstances that may require additional effort to be expended in locating and designing a lagoon. Tier I Lagoon (Double Liner) vs. Tier 2 Lagoon (Single Liner) From the estimated costs shown in Table 1, a single liner appears to be a more cost-effective option. However, to obtain approval for a single liner, the design must show that groundwater will not be impacted via a model, and a monitoring system must be installed and maintained. Groundwater models that are currently used to predict the performance of a liner are simplified models that are highly conservative. Conditions contributing to passing the modeling are low nitrate levels in background groundwater samples, high velocity groundwater flow beneath the site, low permeability soils, and minimal defects in the post-construction liner. Currently, we are finding that most sites do not pass the simplified model and a single liner is thus not an eligible option. If a detailed modeling effort were performed, the modeling cost could equal the cost of the extra liner layer in question, without a guarantee of positive results. Thus, detailed modeling is generally not pursued at this time. A single liner requires some type of accompanying groundwater monitoring, as noted above. Monitoring wells focused around the subject lagoon (outside of the representative monitoring program) are the typical monitoring system proposed. When depth to first encountered water is