Hydroseeding as a Best Management Practice (BMP)

University of WashingtonHydroseeding as a Best Management Practice (BMP)Investigation of pathogens and storm water runoff from a hydroseeded site

Larry Yenko Student Number 08602588/15/2012

Hydroseeding is a Best Management Practice (BMP) that is often used today to stabilize disturbed soil on construction sites by establishing vegetation to reduce or eliminate stormwater sediment runoff. Hydroseeding is used to establish vegetation that meets EPA statutes and regulations. Successful hydroseed revegetation is dependent on proper seedbed preparation. A hydroseed mixture contains seed, tackifier mulch and fertilizer. Often times, the hydroseed mixture contains compost as a fertilizer component. Compost is made from animal manure, sewer sludge, grass clippings, food waste or many different organic waste. Compost is created by mixing and remixing the organic ingredients over several weeks. The compost mixture includes pathogens and coliforms along with naturally occurring bacteria that decomposes the organic solids. Mixing these components as set out in the statutes and regulations, create heat that reduces or eliminates the pathogens and coliforms. Does the required process of mixing the compost reduce or eliminate pathogens and coliforms permanently or is there regrowth after application of the hydroseed mixture making the pathogens and coliforms available for transport as part of stormwater runoff? Available research provides an unanticipated answer, stormwater runoff generally, does not contain pathogens and coliforms from a hydroseeded compost.

Abstract

Table Of ContentsIntroduction................................................................................................... 3Literature Review........................................................................................... 5Seedbed Preparation..................................................................................... 5Seeds.............................................................................................................. 9Tackifier......................................................................................................... 13Mulch............................................................................................................. 15Fertilizer ........................................................................................................ 17Materials and Methods................................................................................. 20Conclusion..................................................................................................... 26Bibliography.................................................................................................. 27

IntroductionRunoff pollution, including sentiment movement, created by the disturbance of soil on a construction site is prohibited by the Environmental Protection Agency (EPA) statutes and regulations. The EPA requires contractors or owners to install various mitigating systems that eliminate or mitigate sentiment in storm water runoff. These systems are called Best Management Practices (BMPs). Hydroseeding is a BMP recognized by the EPA, state and local agencies. 33 USC 402(5)(b) Hydroseeding is a process of combining seed, tackifier, mulch and fertilizer with water and spraying this mixture on disturbed soil to establish plants or grasses to minimize sediment runoff from the disturbed soil. Each element of hydroseeding is examined for its effectiveness as a component of the hydroseeding application. Seeds are selected for their germination and growth rate usually limited by contract or statute requiring native varieties. (Bouchet 2010) Tackifiers are used in hydroseeding mixtures to maintain cohesiveness (organic glue) of the hydroseed mixture to the soil, especially when applied to slopes. (Merlin 1999) Mulch (wood chips or shreds of wood fiber, paper, cotton, flax, etc.) is another component of hydroseeding. Mulch dissipates the energy of falling raindrops and prevents the seeds within the mixture from being washed away during a storm event. (Robichaud 2010) The hydroseed mixture also contains fertilizer. The fertilizer accelerates germination, growth and facilitates soil improvement by adding organic matter and bacteria. The current most effective fertilizer component of hydroseeding is compost.Compost is created by mixing organic matter such as grass clippings, leaves, food scraps, animal waste or sludge (treated residue from sewage treatment plants) with water in a heated environment. . In addition, animal waste and sludge contain pathogens (Staphylococcus aureus, Streptococcus, etc.), coliforms (E. coli), viruses, helminthes (parasitic worms) and protozoans (Zalenski 2005). Pathogens, fungi and viruses effect the health of animals, fish, humans and the environment. Analysis of storm water runoff containing such pathogens, fungi and viruses is one way to maintain health and safety of all life forms. Introduction of additional bacteria and virus into the water cycle (evaporation-rain-runoff-receiving body of water) is a concern of public health.Because composting contains dangerous bacteria and viruses etc., the government regulates compost processing to protect workers as well as the public. Compost production is regulated by either the federal government (40 CFR part 503b ) or state governments (California regulations Title 14 Article 5 etc.) who choose to regulate and this area. In each case, the regulations prescribe several methods of mixing components (windrow or vessel) to ensure most of the pathogens are destroyed.An essential element in the process is the aerobic breakdown of the mixture by bacteria. This process generates heat. The heat kills or reduces the pathogens in the composting mixture This is accomplished by maintaining heat within the compost mixture of 55C or above for a period of 15 days (Hassen 2002). This process is effective to meet the limited bacterial load allowed by statute or regulation.While the above process is effective, issues of storage, exposure to the elements, change in temperature and moisture content may provide favorable condition for the small population of pathogens to grow beyond acceptable standards (Zalenski 2005). This paper addresses the various components of the hydroseed mixture and composting in particular. This inquiry is to determine whether pathogens remain in the hydroseeding mixture and whether the bacteria is carried away by storm water runoff from a construction site. Data generated from related research will be used to interpolate the bacterial load carried away in storm water runoff from a construction site. Literature ReviewSoil PreparationSoil preparation is the first step in effective hydroseeding. Soil preparation includes removal and storage of topsoils, replacement of topsoils, amending the topsoil, amending subsoils when topsoil is unavailable and preparing both subsoil and topsoil for seed planting.Removal of topsoil should be the first consideration prior to any soil movement on a construction site. Removal and storage of topsoil is recommended (for improved revegetation). Revegetation on topsoil is more effective and less costly than attempting revegetation on subsoil lacking adequate minerals and organic components needed for long-term successful revegetation. In spite of the advantages of topsoil replacement, a construction site may be limited in the storage area available for top soil or the cost of off-site storage and hauling cost associated with off-site storage makes removal and storage impractical.When topsoil storage is practical as an option, location and classification of such topsoil should be made prior to removal. There are numerous indicators, including but not limited to color, structure, texture, salt deposition and roots to identify topsoil (Ferris 1996). Texture, pH, salinity, porosity, soil type (sandy , silty or clay etc.) and other properties of the topsoil should be made prior to removal. Depth of topsoil should be measured based on color of the soil and the above criteria. A soil map of the area should be made prior to disturbing the soil (Ferris 1996). Stakes should be placed throughout the area indicating the depth of topsoil at each location. Experienced operators make this operation cost-effective, even for operators not versed in the biology of the soil layers.In considering topsoil versus subsoil, color is a major indicator. Brownish gray to others similar earthtones indicate topsoil. The change of color in this soil indicates where topsoil leaves off and subsoil begins.Texture of the soil often indicates topsoil versus subsoil. Structure of topsoil appears to be regular in shape and contains roots, decaying plant matter and bacteria versus irregular clumps absent organic matter typical of subsoil. Extremely sandy soil, or sticky clumps of clay indicate subsoil as sandy soil retains little water (limiting growth) and clay soil is almost impenetrable to water (also limiting plant growth).Observation of salt or a change in pH indicates an area of topsoil were growth is limited due to the leaching of salt that makes this soil too saline or alkaline. Either way, including areas of salt diminishes the effectiveness of topsoil and may require extensive amendments to neutralize the salt to make the topsoil adequate for plant growth. When stripping topsoil, areas of salt should be avoided.Roots, along with leaves and other organic matter decay by means of worms and bacteria over long periods of time to create topsoil. Roots, therefore, are a good indicator of topsoil. Roots of bushes or shrubs run deeper and enter this subsoil. Caution should be exercised in defining topsoil as soil with roots. (Ferris 1996).Avoidance of mixing subsoil and topsoil is crucial to maintain topsoil sufficient for revegetation without amendments. Topsoil is often shallower on ridge tops and deeper draws and valley floors. (Ferris 1996). Detail to steaking will mitigate the difference in topsoil thickness.Stockpiling is a temporary storage condition. Topsoil continues to be an active ecosystem, even when it is removed and stockpiled (Norton 2009). Microbial decomposition continues in topsoil even when stockpiled (decomposition of organic material), however, without continued plant growth decomposition is limited. Active decomposition can be maintained at a more natural rate by immediately reseeding stockpiled topsoil (construction sites generally do not have the storage area to implement this method). This is done by spreading the stockpiled topsoil to a depth of about 6 inches and then reseeding it. The use of sterile annual fast-growing grains or native like bee plants or wheatgrass that will compete with weeds prior to reapplication of the topsoil supplies ongoing organic matter that contributes to normal decomposition that occurred in undisturbed topsoil [id. at 2]. Stabilization of stored topsoil must meet EPA regulations concerning hydraulic erosion and dust erosion whether stockpiled in a pile or spreads out. Reseeding stored topsoil kills two birds with one stone, it reduces water and dust erosion while contributing organic matter for continued decomposition creating richer topsoil.Return of the topsoil to areas to be permanently revegetated should compensate the topography where the depth of topsoil is greater in areas of erosion susceptibility and shallow in areas likely to receive sediment runoff as the area ages. (Ferris 1996).Wyoming restoration of mining land happened upon an unanticipated successful topsoil redistribution. Topsoil removed and replaced as "Live" topsoil (stripped, and directly replaced on overburden) during the winter (frozen topsoil) generated unexpected growth of native grasses and shrubs. In addition, the vegetation generated the following spring contained very little noxious weed and the strong growth of the native vegetation tended to choke out the weeds. (id. at I-32).Soil amendments may be used to enhance soil productivity. Such amendments are applied to both topsoil lacking in sufficient nutrients and subsoil that contains little organic matter. They include lime, phosphorus, nitrogen, compost (see below), organic fertilizer and sludge, to name a few. Regardless of amendments or replacement of topsoil, seedbed preparations are generally the same. Soil preparation includes ripping, tillage, disking and rolling. The Handbook of Western Reclamation Techniques described a test for the establishment of the proper seedbed; dirt clods no larger than 2 inches in diameter and a footprint of a 170 pound man no deeper than 3/4 of an inch (Storm 2010).Soil on construction sites often contain compacted soils as a result of construction activity. Under such circumstances, a three-step process is used to establish an adequate seedbed.Primary tillage is used to rip and aerate compacted soil. Ripping is done to a depth of 12 to 24 inches. This is done with deep rippers, deep chisels or a deep disk. Ripping the soil loosens the underlying soil allowing for air pockets where moisture may be trapped and stored. If topsoil has already been placed, tillage with a plow must be avoided to allow the topsoil to remain on top. Deep disking (10 to 14 inches) may also be used after ripping avoiding mixing topsoil and subsoil (Storm 2010).Secondary tillage is recommended for soil still containing large dirt clods. Equipment used include disks, chisel plows or a moldboard plow. This equipment should not reach a depth greater than the thickness of topsoil. Secondary tillage busts dirt clods into finer soil and buries weeds and weed seed. (id. at 9).Lastly, final preparation of a seedbed includes additional clodbusting and rolling or firming of the soil to a condition cited above (170 pound man making a footprint impression no greater than 3/4 of an inch). The equipment used are a cultiplow , a roller harrow , a spring tooth harrow or a clot buster. A texturing roller is used to stabilize the soil before seeding. (id. at 9).Seedinghydroseeding was first developed in the early 1950s (Terraworx LLC 2012). The original hydroseed mixture was just seed and fertilizer (ibid at 1). The whole purpose of hydroseeding is to establish vegetation from seeds therefore it can be said that seeds are the most important component of a hydroseed mixture.Due to it's expense, hydroseeding is generally chosen as a means to revegetate slopes to stop erosion on construction sites as opposed to easily accessible disturbed soil (usually seeded by broadcasting the seed or the use of seed drills). Slopes are often times a component of highway construction cut and fills and can be part of other construction sites. It was originally thought that the use of non-native fast-growing grasses and leguminous species (Bouchet 2010) were most practical to establish vegetation cover because of their easy germination and rapid growth. In recent years, greater consideration has been given to revegetation by native fauna (Stromberg 2006). Scientific investigations have shown that in the long run native seeds outperform non-native seeds in the long run (Bouchet 2010).There are several reasons for the choice of non-native seeds in the hydroseeding mixture. Price, availability, long-term viability and environmental impact and contractual or statutory limitations.Non-native plants are available in commercial seed mix at a reasonable price (Bouchet 2010). As with anything in construction, price is generally the determining factor, however, contracts over the past decade and/or state or local statutes require native seeds to be used as the seed component of hydroseeding. Contracts or the law of many jurisdictions may require establishment and maintenance of soil stabilization to run beyond the one-year warranty most construction contracts require. Fast germination, growth and density of non-native plants, especially in semi arid climates, may grow well for the first year, however, continued growth beyond the first year may be diminished, sometimes disappearing altogether (Tormo 2007). If the contractor must come back after one year to reseed areas hydroseeded, the savings realized from the cost of commercial non-native seed may be completely offset by the replacement or maintenance of areas hydroseeded.The cost of commercial non-native seed can be 30 times less than native seeds (Bouchet 2010). Many geographical areas have no access to native seeds because seed suppliers have no incentive to grow and collect native seeds. This situation may be a vicious circle that can be argued in either direction i.e. requiring the use of native seed for revegetation on a construction project creates demand and thus seed growers have an incentive to grow and collect such seeds. The opposite is true, if there is no contractual or statutory requirement to use native seed, there was little incentive for a contractor to use native seeds creating no demand from seed growers.Commercial non-native seeds are readily available while native seeds are limited or commercially nonexistent especially in areas of low rainfall (see above) (Bouchet 2010). In areas of greater rainfall such as West Virginia, non-native plants germinate and populate disturbed soil quickly (Skousen 2007). This creates two separate problems. 1) failure of non-native seeds to reproduce after the initial application leaves slopes vulnerable to erosion and 2) where there is vigorous non-native revegetation, the exotic non-native plants may outcompete native flora caucusing an invasive menace upsetting the natural ecosystem (Stromberg 2006).There are several reasons to use native seeds in revegetation projects. Native seeds usually increase long-term viability of the revegetation , native seeding prevents non-native vegetation from establishing and changing the local environment, reestablishment of native seeds promotes and supports native animal diversity and native seeds can outcompete non-native species that may have invaded the local ecosystem even when non-native species are used to protect soil from erosion in the short term.Native seeds have shown to be effective even in parched semi arid areas (Bouchet 2010). Though native seeds may be more difficult to establish, their long term (greater than two years) viability justifies the additional expense and effort to establish their growth (Grant 2010).The use of non-native seeds in restoration projects in California (to quickly stabilize disturbed soil often times due to fire) have, in some instances, completely outcompeted native vegetation (Stromberg 2006). Some of these areas have been restored to their native conditions by using the appropriate native seeds that outcompete the exotic non-native plants and grasses (id ad 254).,States such as California (Caltrans 2002), Colorado (Grant 2010), West Virginia (Skousen 2007) and North Carolina (Roten 2011) have all studied the use of native seeds in their hydroseeding composition. Maintaining or reestablishing the native ecology has become the major emphasis throughout North America. The province of British Columbia in Canada has focused their restoration of abandoned logging roads, roadside slopes, mining sites and other industrial activities on establishing the native ecosystem (Burton 2001). In all the above examples, restoration of the complete ecosystem, including animal ecology is accomplished by the use of hydroseeding with native seeds. All of the above studies carried out long-term (two or more years) experiments to determine the effectiveness of native seeds. All studies included many varieties of native seeds to determine their viability. The studies recommended that the selection of the appropriate seeds should be determined by experimenting with various native species using the specific geological, meteorological and climatological for the for a specific area to be hydroseeded.Reseeding with native seeds can also be accomplished by placing native top soil on the disturbed soil (Tormo 2007) if that topsoil has not been stockpiled greater than three months and contains a seed bank sufficient to provide native seeds that may spontaneously revegetate the soil. Hydroseeding can play a part in this method of reseeding by the application of soil amendments including fertilizer or compost. Hydroseeding TackifierThere are two general types of tackifier, organic and synthetic. All tackifiers added to a hydroseed mixture, bind the seeds to the mulch and soil. Tackifiers also make the hydroseed mixture more viscous which makes application easier and minimizes nozzle clogging. Some inorganic tackifiers can also be used separately as a BMP to stabilize disturbed soils . Organic tackifiers are derived from plant materials such as guar and plantago or other plant starches. Inorganic tackifiers include polymers and copolymers such as polyacrylamide (PAM), acrylic polymers and copolymers methacrylates, acrylates and Hyde wrote: us hydro-collids (Seinfeld 2007).Guar is ground endosperm from the guar bean. It is principally grown in Pakistan and India though it is also grown in the US, Australia, China and Africa (Anonymous n.d.). It is non-gelling, however, it is easily catalyzed with Borax or calcium. Guar had been widely used as part of a hydroseed mixture, however, guar is now being used in the natural gas "fracking" industry and had therefore the increased demand has escalated prices making its use in a hydroseeding mixture cost prohibitive.Psyllium is derived from the plantago plant, often recognize as a weed. When the plant as processed for fiber (Metamucil etc.), the extraneous husks are ground to produce a tackifier. It has good adhesive properties and the cost is low. Most organic tackifiers have limited longevity, usually about three months (Seinfeld 2007).Cornstarch had been used as a tackifier, however, and must be applied using cold water.Inorganic tackifiers are man-made synthetics. They have photo and chemical decomposition properties that are generally environmentally friendly. They do last longer than organic tackifiers (Seinfeld 2007) but remain degradable within one year.Anionic polyacrylamides (PAMs) bind to fine particles of soil, nutrients, heavy metals, bacteria, pesticides, phytoplankton (suspended algae), decaying vegetation and endocrine disruptors (Lwinski 2010). PAMs are used in water treatment and sewage treatment plants as a flocculant (coagulation of organic and organic particles). This same property binds seed, mulch and fertilizer to soil particles as the hydroseed mixture is sprayed on the disturbed soil. PAMs help protect the hydroseed mixture from the kinetic energy of raindrops and the sheer force of accumulated rainwater flowing down the hydroseeded slope.There is a concern that PAMs may be toxic to the environment and human health. Acrylamide is a known neurotoxin and carcinogen. The main composition of polyacrylamide is acrylamide. Anionic polyacrylamides are themselves non-toxic, however, cationic polyacrylamides are extremely toxic (id at 4). There is also concerned that anionic polyacrylamides may release acrylamide as it breaks down. In the Roadside Revegetation manual, the authors argue that there is no scientific evidence to support the release of acrylamide with the decompensation of polyacrylamide. Even if polyacrylamide decomposes to some acrylamide, because of the slow decomposition there would be no significant health risk due to low or nonexistent accumulation of acrylamide (Seinfeld 2007). Regardless of the toxicity of the polymer, a Material Safety Data Sheet should be a included with all chemical additives in the hydroseed mixture.Hydrocolid polymers are various combinations of dry-flow polyacrylamides, copolymers and hydrochloride polymers. A list has been compiled by the State of California that includes many of these in organic polymers (State of California 2011).MulchMulch encompasses a large set of fibrous materials used to cover disturbed soil (from construction sites to fire aftermath). The materials include wood shreds, tree bark shreds, paper, cotton etc.. Mulch is part of the hydroseed mixture whose purpose is to retain moisture, bind to the soil (combined with the tackifier), improve seed germination, protect seeds from ultraviolet rays and soil from the kinetic energy of raindrops and, with the tackifier, resist sheer forces of water runoff. Mulch decomposes and enriches the soil, however, their rate of decomposure is much slower. In addition, wood chips on the perrifeary of disturbed soil removes nitrogen from the soil and keeps then nitrogen from the leaching into storm water runoff (Perry 2012).Mulch may be applied using a hydroseeder as part of a hydroseed mix or may be applied by helicopter or fixed wing aircraft applying the hydroseed mixture. Aircraft application has become the most efficient way to apply the hydroseed mixture in wildfire burned areas.Before applying a hydroseed mixture, including mulch, it is necessary to determine if the disturbed soil is best stabilized by hydroseeding. Factors to be considered are then need for quick soil stabilization, the need for quick revegetation and the need for moisture retention. All hydroseeding components are successfully determined by taking into account the topography to be applied to, the soil makeup to be stabilized, natural surroundings and habitat, precipitation of the area to be stabilized and costs. Each location will have unique properties so that a determination of components should be determined for each application.Environmental concerns should also be considered when deciding on the mulch used. Chemical modifications may also be included in the hydroseed mixture to modify the effect of mulch. Consideration of the toxicity of the tackifier and soil amendments, their ability to leach into the ground water or the surface water must be considered.Because Hydromulching/seeding has been a process practiced since the early 1950s, much data had been generated for many parts of the country. General recommendations for a hydroseed mixture can be found from commercial and governmental agencies. A Department of Defense bulletin lists many defense locations throughout the United States and what hydroseed mixture worked best. (Id at C-1)FertilizerThere are two basic types of fertilizer that are included in a hydroseed mixture, inorganic or organic. Inorganic fertilizers are minerals mined or the result of a manufacturing chemical process. They can come in the form of crystals, pellets, granules or dust. They can be an individual element or a compound containing several elements. Organic fertilizers by contrast, are products of either plant or animal materials. Either can be incorporated into a hydroseed mixture to improve soil quality and provide nutrients for the seeds contained in the hydroseed mixture to grow.The focus of this paper is a hydroseed mixture containing compost, therefore a description, process, application and results of compost as part of the hydroseed mixture will be discussed.Compost can be created from many different organic sources (biosolids) including dairy manure, feedlot manure, chicken or turkey manure, cotton gin burs, pulp mill waste, food waste from restaurant and food processing plants, grass clippings and organic solids from water and sewage treatment plants (Mukhtar 2005) to name just a few. The process of converting the biosolids into compost is generally the same. Because organic waste contains pathogens and coliforms which may be hazardous to human health, statutes and regulations have been established to prevent these pathogens from getting into the food cycle (40 CFR 503).Bio fertilizers are fertilizers containing bacteria (in addition to pathogens and coliforms) which increase activity in this soil. They convert ambient nitrogen into forms plants can use (nitrate and ammonia), they create air pockets by gluing soil particles together and they outcompete pathogens for food.Processed compost can be categorized into high nitrogen (N) biosolids and low N biosolids. High N biosolids have a shorter stabilization period (1-4 months) and are easily decomposed both anaerobically (without oxygen) and aerobically (with oxygen). They are commonly used in a hydroseed mixture. Low N biosolids are treated for several years, often times in lagoons or drying beds. Both types of biosolids must meet Class B regulations (40 CFR 503) as well as state and local statutes and regulations. California statute Title 14 chapter 3.1 sets out required facility design, operating procedures, reporting requirements and pathogenic content (see regulations in area to be hydroseeded). Pathogens and coliform content is controlled by digestion and heat (55C). Class B compost is limited to the type of application area (usually for agricultural application), however, application for soil restoration is usually exempt. 40 CFR 503 also provide minimum criteria for Class A compost. The compost must have undergone a process to reduce pathogens even further than Class B by high temperature digestion and heat drying (Brown 2010). Class A compost it more expensive due to the additional composting procedures.There are three ways usually used to produce compost. A bulking additive is used to aid in aeration. Wood products may be added to dry out the mixture. As the compost dries, it is reduced in volume by 25-50% (Brown 2010).Static pile composting is simply piling the biosolids into a pile and leaving in to digest four months or greater. Oder is produced only on the initial pile building.Aerated static pile composting it similar to static pile composting with the additional process of forcing air into the pile or introducing air by vacuum. Composting time as reduced to 1 to 3 months. Continuous aeration keeps the decomposure process arobic . Little odor is created except creating the pile as above.Windrow composting is the most used process. The biosolids and any additives are placed in a windrow. The windrows are turned over 1 to 3 times per week. The compost time is one to two months. Odor is created each time the windrow it turned. This process generates heat and eliminates or reduces pathogens.It should be noted that decomposing bacteria continue the decomposure of organic material even after the compost has been applied to disturbed soil. The result is a reduction of solids from 25 to 50% (Brown 2010).Compost can be combined with soil amendments to adjust pH of the disturbed soil. Other amendments to provide phosphorus (P), potassium (K) and other trace elements (micronutrients) to include zinc, copper, iron and manganese. Lime or limestone may be added to adjust pH. Lime is also used to reduce the number of pathogens in the compost (O'Ferrell 2000).Often times, hydroseeding follows one or several applications of compost only. Soil amendment of compost only is worked into the disturbed soil either by chisel plow or disc (Brown 2010). This method ensures high N ratio sufficient to support vigorous vegetation growth.An additional component of the hydroseed mixture is mycorrhizal fungi. These fungi are symbiotic with plants by gathering nutrients from the soil and passing them to the plant roots. There are two types of mycorrhizal fungi, ectomycorrhizal (AM ) fungi and endomycorrhizal (EM) fungi, the former are associated with Pine Beach and Oak trees and latter is associated with grasses, shrubs and some trees. EM is not symbiotic with most weeds, making it a weed suppressor (weeds are avoided if possible when establishing new vegetation).Plant roots provide food for bacteria and fungi which attract nematodes (worms). Nematodes process nitrogen compounds and secrete nitrogen that plants can use. This nitrogen is picked up by the fungi hyphae and transfers nitrogen to the plant for growth. The fungi also enhances the soil structure by secreting a gluey sugar substance that helps bind the soil. This helps with water and air filtration.Mycorrhizals are destroyed by erosion, grading, excavation and other top soil disturbing activities. Replacement of mycorrhizals can be accomplished by adding the fungi to a hydroseed mix simply by including the spores. No additional maintenance is required after broadcasting (Contra Costa County Clean Water Program, Urban Creek Council n.d.).Materials and MethodsThe following experiment is substituted for actual generation of data due to physical limitations of the author. Interpolation of data from storm water runoff in this experiment will be applied to runoff from compost containing hydroseeded land.The experiment measured pathogens and coliforms in urban storm water runoff from three land-use areas, high-density residential, low-density residential land landscaped commercial.Data was collected from five locations in Monmouth County New Jersey. The samples were taken from storm sewers that were separate from sanitary sewers. The locations chosen had different levels of imperviousness, high-density residential (65% imperviousness), low-density residential (17% imperviousness) and landscaped commercial (15% total area is vegetated).Organisms selected were Pseudomonas aeruginosa and Staphylococcus aureus base on their abundance in other storm water studies (Selvakumar 2006). Indicators selected were total coliforms, fecal coliforms, fecal streptococci, enterococci and Escherichia coli (E. coli). The indicators are commonly used as evidence of pathogens in water quality monitoring (id at 113)."Sewersheds" (experiment equipment location) were selected to measure drainage of small areas, free of cross-connections with sanitary sewers that represent the areas listed above. They were located in public access areas with reasonable equipment security. They were checked on two week increments at the beginning of the experiment to ensure water measurements were not due to car washing, land irrigation etc.. The measuring stations were located near each other while still maintaining drainage of individual areas described above. This was done to insure dry periods, rain duration, rain intensity and geology would not cause significant differences in a rain event. The equinox and solstice dates were used to divide the year into four quarters. Rain events were defined as sufficient runoff to meet analytical needs separated by 72 hours (id at114).Sampling equipment used included an American Sigma area velocity flowmaters installed at each station to measure flow depth and velocity at six minute intervals. Flow depth was also measured using this equipment. The equipment was calibrated for the storm sewer pipe geometry. A 1 gallon bucket was use to accommodate and instrument systems to measure pH, temperature, specific conductivity and desolved oxygen. A pre-calibrated tipping bucket rain gauge was used.The equipment was triggered by a depth of 1 inch waterflow. When tripped, the equipment automatically purged a pre-cleaned vinyl sample line before collecting samples. The equipment notified collection teams by cellular modem. Samples were immediately recovered and placed in a cooler with ice and transported to the EPA's laboratory for processing. Sample collection bottles were washed and rinsed with alcohol.Prior to subsample preparation, samples were continuously stirred prior to extracting the subsample from the middle of the water column. The samples were tested for the pathogens and coliforms listed above following the procedures listed in Standard Methods (APHA et al. 1998). Samples not immediately analyzed were refrigerated at 4C. No samples were filtrated greater than over 24 hours after collection. Each sample was diluted with distilled water using three dilution factors. Each analytical batch included blanks and positive controls. Verifications were performed on 10 colonies of each organism using incubated agar plates according to the procedures of Standard Methods (APHA et al. 1998). Each plate was manually analyzed.*It should be noted that analysis of samples used the filtration and incubated agar plates for microbe verification and quantification is time-consuming and somewhat imprecise. Scientific analysis of microbe identification and quantification can now be done with qPCR (real-time polymer chain reaction). qPCR was first developed in the early 90s. It is based on the discovery of identifying DNA (PCR) from a very small sample (a small amount of DNA is amplified to provide enough sample to analyze the DNA). qPCR is a new technology able to detect small amounts of DNA or RNA in a sample and with software (contained within the instrument). It analyzes a sample for both the identification and quantity of DNA (pathogens or coliforms DNA) in a sample in real time. The original qPCR instrument was susceptible to very small changes in the method of sampling, pipetting or a change in operators. The latest technology is an instrument that robotically takes the samples and analyzes them without variation (Gene Quantification, Inc. 2012).Samples were filtrated and colonies counted. The results were then computed sadistically with a confidence level of 95%. The statistical analysis was done with Statistica 98 (Statsoft 1998).Samples for a total of 14 rain events were collected over two years. Precipitation varied from 1.8 mm to 51.8 mm. Samples were collected from all locations for each rainfall event. Samples were not included for inlet tubes clogged by vegetation, ice or where debris clogged the sampling equipment. Pathogens and coliforms described above were found in concentrations from each area to be different, however, concentrations were similar to those reported to the National Pollution Discharge Elimination System (NPDES) database and other research. The results showed that urban stormwater runoff is a major nonpoint source of human pathogens and coliforms. If sites containing hydroseeded and composted disturbed soil were specifically tested for and analyzed, a point source could be identified.A literature review, Survival, Growth and Regrowth of Enteric Indicator and Pathogenic Bacteria in Biosolids, Compost, Soil and Land Applied Biosolids, Zalenski, K., et al. reviewed experiments regarding regrowth of pathogens and coliforms. The question addressed:" Does regrowth occur following reintroduction or recolonization of pathogens after land application or during storage under favorable conditions." (Zalenski 2005)Several studies considered moisture content changing over time (autumn to winter, 24 week and summer to winter), experiments found the pathogens increased with rainfall events, however, rainfall did not add additional moisture to the compost pile. It was concluded that regrowth of pathogens was due to fecal contamination from birds. Moisture may be a growth factor in certain areas of the pile. Pathogens were reintroduced and incubated at different temperatures and moisture content with small initial growths but in all cases pathogens and indicators decreased your were undetectable. The researchers concluded that the advantageous conditions subjected indigenous microflora to the same growth factors and the microflora outcompeted the pathogens and indicators thus the reduction in the pathogens and indicators. The final conclusion was long-term storage of compost has the potential for regrowth.The authors reviewed other studies that dealt with sterilized biosolids. The studies found that inoculation of Salmonella and E. coli into sterile compost is possible. Non-sterilized compost inhibited their growth probably due to indigenous microflora. They also found that moisture is an important factor in the survival and potential regrowth of the pathogens and temperature and desiccation became more important as moisture decreases.In another study reviewed, Zalenski, K., et al. survival of Salmonella and indicators in soil increased with moisture, indigenous microorganisms are important in decreasing pathogens due to competition, multiple freeze-thaw reduced microorganism's survival in soil, E. coli does not enter a viable but non-culturaliable state and soil type effects Salmonella and E. coli.Zalenski, K., et al. reviewed studies analyzing Salmonella and indicators in biosolid amended soil. The studies found had mixed results, survival and regrowth of the pathogens was moisture dependent and survival of microorganisms increased in finer textured soil.Zalenski, K., et al. concluded that many of the studies were contradictory probably due to laboratory studies versus field studies. Regrowth of Salmonella and indicators in compost are probably due to external vectors. When Salmonella and indicators have been inoculated into nonsterile soil, indigenous microflora outcompete the pathogens maintaining a acceptable level of these pathogens or their complete elimination. Sterilization of the biosolids have been suggested as a means of producing safe compost. This cannot be recommended as sterilization kills all bacteria including the bacteria that continually decompose the biosolids making it easy to reestablish pathogen repopulation. Maintaining temperature and moisture content of stored compost helps prevent pathogens regrowth. Recolonization or regrowth is dependent on a threshold population of pathogens. Considering all the above criteria and conditions needed for pathogen growth, regrowth rarely occurs.

Conclusionhydroseeding remains a viable BMP. Hydroseeding consists of many different components scientifically determined. Proper seedbed preparation including reintroduction of top soil, when possible, preparation of subsoil and introduction of soil amendments are crucial for successful revegetation. Today's trend is to reseed disturbed soil with native vegetation both to maintain local ecology and long-term viability of the hydroseeded vegetation. Inconclusion of the appropriate tackifier (for existing conditions). Inclusion of mulch provides nutrients, helps maintain soil moisture, denitrifys the disturbed soil when needed and gives seeds protection from raindrop kinetic energy and minimizes water flow. Fertilizer can be and organic compounds or as is the focus of this paper, organic fertilizer in the form of compost. The authors are initial preception was compost contained pathogens and coliforms that would be part of storm water runoff from a composted and hydroseeded area. One study relied on confirmed the presence of pathogens and coliforms in the stormwater runoff analyzed. The study concluded those pathogens from a nonpoint source. The authors inquiry is specifically a point source-hydroseeded disturbed soil including compost. Further review of additional studies confirmed that pathogens and coliforms are nonexistent or reduced conforming to federal, state and local requirements. The studies speculate that the pathogens and coliforms bird waste, wild animal waste or even dog waste from residential yards or impervious soil cover (asphalt and concrete streets, driveways or sidewalks). Given the prior research review, it can be a concluded that pathogens and coliforms contained in stormwater runoff are not from the compost contained in a hydroseed mix but from several unknown vectors.

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