11/19/18 - Laserfiche WebLink

Home

5.01: Discussion on Topsoil Requirement and Potential Amendments or Alternatives (Project No. 146) City Planner Anderson presented the staff report. He noted that the Board previously held a general discussion on the City's topsoil standard. The impetus for that discussion (and this case) was a request from a developer/builder that the City revise the topsoil standard by eliminating the specification for Premium Topsoil Borrow. The request identified two negative effects of the current topsoil requirement. First, that the topsoil is doing too good of a job in terms of holding water; they acknowledge that many homeowners are not adjusting their irrigation system to account for the topsoil and are actually contributing to the problem. Secondly, they identified price as a concern compared to the cost of"regular"black dirt. He stated that as part of the initial discussion, staff was asked to gather information on what similar peer communities (with similar sandy soils)require and what the purpose of the requirement was(to see if it is an apples-to-apples comparison). Additionally, staff has attempted to compile water usage data for the City over the past ten years in an attempt to assess the effectiveness of the current topsoil requirement to reduce water usage. City Planner Anderson noted that while topsoil is a beneficial addition,both for water conservation and vegetation establishment, the cost difference of an engineered soil compared to a more standard black dirt is significant. Focusing more on the irrigation systems and water efficient technologies rather than engineered soils, along with additional educational information on irrigation systems, should be as effective as the current standard regarding reducing demand on groundwater. It would certainly be accomplished at a lower cost to the future homeowner (and possibly current homeowners if a rebate program were implemented). Thus, staff would recommend proceeding with an Ordinance Amendment to modify the definition of topsoil consistent with other peer communities(such as"black dirt composed of unconsolidated material, largely undecomposed organic matter with no more than 35% sand"). City Engineer Westby stated that staff is involved with other groups on the topic of water supply, both regionally and across the metro, and provided background information on the groups that he is involved with. He stated that he has worked with Capstone over a number of years on the developments that they have been working on in Ramsey. He stated that he become more involved in the topsoil specification and the fallout caused by the specification,specifically in the Brookfield 7th and 8th additions. He provided examples of backyards in that neighborhood that consistently hold water after rain events or from upstream property owners overwatering their yards. He stated that staff worked with Capstone in those areas to use a Ramsey topsoil which has a higher portion of sand and lesser organic material as test cases and that seems to have worked well. He stated that since the time the topsoil requirement was enacted, the cost for smart sensor technology for irrigation has come down significantly and is a much more effective manner to conserve water. He stated that he has attended a lot of workshops, especially those sponsored by the University of Minnesota,to learn more on the topic. Board Member Hiatt asked if there is information in the infiltration and the improvement in infiltration that would be provided through the newly proposed topsoil compared to the current topsoil. Environmental Policy Board/November 19, 2018 Page 2 of 5