Mitigation Plan for City of Lawrence and 31st Street Impact

 

Implementation:

 

Wetlands

            Once Tract 9A is available in fall 2013 a temporary fifteen point grid (3x5) will be established (See Appendix A for wetlands mitigation map). This grid will be established to conduct a pre-construction plant survey.  The percent coverage of each plant species within a meter square grid located 2 meters east and west of the stake will be recorded. This survey will determine what plants are present prior to construction.  After the plant survey has been completed the location of berms and swales will be determined. The swales will provide a variation in water depths which will in turn lead to a variation in plant species present.  As soon as dirt moving has been concluded, or in spring 2014, the 60 species of seeds that have been collected will be dispersed by hand and lightly harrowed.  See Appendix B for the list of seed species we anticipate collecting.  Early successional invasives, e.g. thistles and purple loosestrife, will be eliminated as soon as identified.

 

Riparian

            A reference site along the Wakarusa River west of East 1500 Rd was surveyed June 2012 to determine typical diversity and density of trees and shrubs.  The diameter at breast height as well as species of all trees equal to or greater than three inches in diameter was recorded.  Three linear transects 3 ft x 100 ft were used to determine diversity and density of shrubs.  The survey revealed 17 species of trees and an average density of 183 trees/acre.   The diversity of shrubs was only 4 species and a density of 1,000/acre.  Most of the shrubs surveyed, however, were invasive bush honeysuckle.  The data from this reference survey is in Appendix C.  Since many of the lesser quality trees are already present on the river bank in Tract 10C there will be an effort to plant trees that will improve wildlife value.  The density of the tree plantings will be 250 trees/acre in the new buffer and 50 trees/acre in the existing buffer.  Placement of trees will be random rather than linear and generally averaging at 13’ x 13’ centers.  The density of shrubs will be 500/acre in the new buffer only.  The spacing of the shrubs will also be random rather than linear and average 9’ x 9’ centers.   The species and number of trees and shrubs that will be planted in the restoration area is also shown on Appendix C.  The location of the riparian buffer restoration project is shown in Appendix D.  The new buffer has been previously planted to a standard Conservation Reserve Program mix of native warm season grasses.  This will be burned prior to planting in the spring 2014 in order to facilitate planting of the trees and shrubs.

 

Monitoring Protocol:

 

Wetlands

The same fifteen point grid (3x5) used in the pre-construction survey will be re-established within Track 9A as soon as dirt moving has been completed.  A quantitative assessment of vegetation will be made by conducting a one square meter sample two meters to the east and a replicate sample two meters to the west of each grid stake. In each one meter sample plot a visual estimate of % cover of each plant species will be made.  This is an estimate of spatial coverage of each species.  Due to the potential of multiple layers of overlap, the total % coverage for any one plot could total to more than 100%.  The percent of bare ground and/or standing water will also be quantified.  This assessment will be made in for three years in early June.  The start date is undetermined as it is dependent upon when the dirt work is concluded. The success criteria will be a stabilized vegetation buffer adjacent to the restored habitat and a percent plant coverage of greater than 50% Facultative or wetter. The USDA plant list will be used to determine current hydric plant classification for Region 5.  Voucher specimens will be made of all new or difficult to identify plant species found.  Identifications will be verified using specimens at the Baker University Herbarium.  Baseline photographs will be taken from each corner of the tract as well as follow-up photos during mid-June of the following three years.  Photos will include buffer areas as well as the wetland basin.   A Wetland Delineation Survey will be conducted at the four corner grid points during the June plant survey for each of the three years of the survey.  The collected data will be digitized, analyzed, and summarized in a report to Lawrence Public Works in October for three years after dirt moving has been completed.

 

Riparian

            The trees and shrubs that are planted will be flagged by species so they can be more easily monitored.  The success criteria will be 400 live shrubs/acre and 180 live trees/acre in the new buffer and at least 40 live trees planted in the existing buffer.  The goal of 14 tree species and 8 species of shrubs will also be part of the success criteria.  The surviving trees and shrubs will be surveyed each June.  The first report on success rates will be provided to Lawrence Public Works in the Fall of 2014.  The buffer will be monitored for a minimum of three years to determine success.  Photos of the site will be taken prior to planting as well as during the June survey of the first 3 years.

 

Operating and Maintenance Plan:

 

Wetlands

The main objective of long-term operation and maintenance will be to determine if site conditions are continuing to meet project goals and criteria.  In the first three years after implementation of this plan, monitoring will be more intensive in order to detect potential problems with site design, water conditions, and vegetation establishment.  Conditions should stabilize during this early period and the scope and frequency of monitoring activities for the purpose of this project, will decrease.   Monitoring activities that will be conducted on a periodic basis are listed below:

 

  1. Check sites after heavy rains to determine if berms and any water-ways are functioning properly, if erosion problems exist, and if water holding capacities continue to meet design criteria.

 

  1. Monitor water levels in the various swales of the project periodically during spring and summer.  Determine if the pools are holding water as designed.

 

  1. Determine that vegetation along the unit perimeters remains intact to prevent erosion or damage to berms.

 

  1. Ensure that outflow points continue to function appropriately so that spring inundation occurs followed by mid- to late-summer draw-downs.  This will maintain appropriate vegetation and invertebrate biodiversity.

 

  1. Continue to assess the area during the growing season for invasive and unwanted species.  These will be treated early to prevent establishment.

 

  1. Periodically mow the berms to maintain herbaceous vegetation.  Roots of woody vegetation tends to damage the berms.

 

Riparian

The goal of the riparian buffer restoration and mitigation is to achieve a natural state that does not depend upon maintenance.  This mitigation is designed to be naturally sustaining without human input once it has been established.  It area will be monitored into the future to insure that no problems arise.