Landscape Unit Research

Title: Evaluation of Crown Vetch (Coronilla varia) as a Sustainable Vegetation for Roadsides

Author: Robert LaRoche and Germain LaRoche
Performing Organization: Maine DOT

Date: 3/2001

Abstract: The Maine Department of Transportation (MDOT) needs to control unwanted woody plant growth along its roadsides in order to maintain safe roadways. Traditional methods to control this unwanted growth include hand cutting, mechanical mowing, and the application of herbicides. All of these methods have drawbacks which include expense, exposure to personal injury, use of large amounts of fossil fuel, and negative public perception.

This project looks at an alternative means to controlling unwanted brush by establishing plant species that will compete with and suppress its growth. Crown Vetch has been identified as a plant that will meet this need. Current seed bed preparation and seeding rates are based on establishment under new construction bare ground conditions. Presently there is a reduced amount of new construction projects while there are a great number of miles existing roadside. This research looks into ways to successfully establish Crown Vetch into existing vegetation.

Two sites were chosen, one in Bowdinham, Maine and the other in Benedicta, Maine. Variables identified and tested were: 1. Treatment of site to enhance growth, 2. Varying the rate of seed application per one thousand square feet and 3. Sowing the seed at different times of the year. To test these variables a randomized complete block design using twelve treatments and replicated three times was established at both sites during May, July, and October. The treatments consisted of three site preparation methods; cut existing vegetation, kill existing vegetation with a herbicide, and no treatment using four seeding rates.

Title: Performance Specifications for Wood Waste Materials as an Erosion Control Mulch and as a Filter Berm

Author: Kenneth R. Demars and Richard P. Long
Performing Organization: Department of Civil and Environmental Engineering, University of Connecticut

Date: 3/2001

Abstract: The filtration properties of wood waste mulch were evaluated for use in an erosion control berm application. Four wood waste materials were subjected to a laboratory testing to determine their hydraulic properties in the unaltered state and the modified state. The modifications consisted of adding small particles to the grain-size distribution of the wood waste. The filtration behavior of these materials was evaluated for the 1-D condition in a permeameter and for the 2-D flow condition in a sloping Plexiglas box. The 2-D tests simulated field use of wood waste as an erosion control berm. The tests used a series of glass beads of known size and an erodible soil from the field test site, consisting of silty fine sand, which was mixed with water and passed through the test apparatus. The suspended solids content of the effluent was used as a measure of filter effectiveness. The results of this study and the earlier phases were used to prepare model procurement specifications for wood waste material as erosion control mulch and as erosion control filter berm, which are appended to the report.

Title: Stormwater Monitoring, Collection and Analysis of Testplot Runoff
Performing Organization: Woods End Research Laboratory, INC.

Date: 9/30/2003

Abstract: A series of experimental plots were laid out utilizing different erosion control strategies on a 3:1 slope located in Kents Hill, ME. The objective of the study was to determine the capability of alternative soil treatment to retain and control water and nutrient runoff. Of particular interest in the runoff water was total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP) and algal-available phosphorus (AAP). Eutrophication of surface waters can be accelerated by agricultural inputs of phosphorus (P), provided that P is in a form that can be utilized by aquatic algae, and algal available P represents the non-apatite inorganic fraction, a high proportion of which is thought to be available to algae. The treatments examined in triplicate included the standard best management practice (BMP) of shredded hay, bare and berm plots, a manufactured topsoil, and three depths of woodwaste erosion control blend previously used successfully by ME-DOT. The test plots were maintained from June 2001 to June 2003, in which 10 storm events were monitored ranging in intensity of 0.23 to 1.81 inches of rain in a 48 hour period. Data considered in interpretation of treatment effects included volume of runoff, runoff as percent of rainfall, concentration of nutrients in runoff and total mass of nutrients. An additional influencing factor was variable plant cover evident over time on the treated plots. Bare and berm plots gave large flows of water and nutrients. There were no statistically significant differences in total water volume cumulatively for all alternative treatments. There were large inter-storm variations, with some dependence of total flow on intensity of rain. Concentration of nutrients in runoff was significantly and negatively correlated with total volume runoff. In runoff, TP, and AAP and TN were highly correlated. When the alternative treatments of woodwaste and compost were evaluated against the BMP of hay, there were no significant difference in total flow, and some significant differences in concentration of TP and AAP, with compost giving higher concentrations. Calculations of net analyte removal efficiency (NARE) of treatments vesus BMP showed that woodwastes were slightly but not significantly better in removal of TSS, TP and AAP, whereas compost was less efficient than the BMP for the same analytes and all were less with regard to total-N. The data indicate that a complex of factors must be considered in assessing overall performance and relative efficiencies of alternative soil erosion control treatments.

Title: Temperature Monitoring of Wet Pond Inlet and Outlet Water for Year 2000 and 2001

Author: Thomas C. Sanford and Aria Amirbahman
Performing Organization: Department of Civil & Environmental Engineering, University of Maine

Date: 10/3/2002

Abstract: The objective of this report was to monitor possible temperature increases on stormwater runoff when detained in a wet pond. It was also an objective to compare the discharge water temperatures of different pond discharge methods, i.e., by underdrain and by overflow through a standpipe. The results of this investigation are intended to better control the temperature of effluent water from a wet pond so that the effluent temperatures will not have a detrimental effect of the biota downstream.