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This study series module focuses on understanding landscape specifications from a manager's perspective, including drawings, written specifications, quantity takeoffs, and cost development. It also covers the importance of landscape standards, hardscape installation, grading and drainage regulations, and drainage systems.
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Certified Landscape Professional Exam Study Series Exterior Production Operations and Horticulture Module: A managers perspective
Landscape Specifications Include: • Drawings - scaled visual representation • Written specifications • Quantity takeoffs from drawings • Develop a cost to carry out • Large dollar tenders will often be drafted according to CCDC standards (Canadian Construction Documents Committee) • www.ccdc.org/home/html
Written Specifications • A precise, formal, detailed description of the work to be done. • Including: the way the work is to be done, procedures, materials, and quality required. • Describe how assemblies go together and the necessary quality and quantity of materials required to meet code. • Written specs. take precedence over drawings in the eyes of the court
Written Specifications Generally include 3 parts: ShouldReflect Industry Standards • General – specific administrative and procedural requirement unique to the project • Products – detailed description and quantity of products to be incorporated in the project • Execution – detailed description of preparations required and the who, what, where, when and how the products are to be incorporated into the project
Specifications Terminology • Open specifications - use a generic description of an item to be supplied. For example, a wooden patio table of a certain size and dimension • Closed specifications – use a specific description of the item. For example, the specification could call for a specific model from a specific manufacturer
Carrying Out Basic Landscape Calculations • Managers should be able to check landscape calculations and carry them out on their own
Landscape Standards • A good manager has good working knowledge of local industry standards and government landscape standards • Operates business accordingly • CNLA + Landscape Ontario
Landscape Standards in Canada • Produced by Canadian Nursery Landscape Association (CNLA) • Available at www.horttrades.com • Not enforceable by law unless the standards are specifically referred to in the contract specifications
Landscape Standards • Standards are usually voluntary unless they are written directly into contract specifications – however we should always maintain standards! • If they are in the specifications, they form part of the legal contract
Hardscape Installation • Manager and / or other personnel in the company must have a good working knowledge and required expertise of hard landscape materials and processes of installation for their geographic areas
Grading and Drainage - Codes and Regulations • There are regulations/ codes for grading and drainage installations - commercial and residential sites • Commercial projects – specified in the contract and contract drawings - engineer/architect • Residential projects – often contractor does drawings; must ensure grading and drainage meets codes • Many municipalities require a sewer layer license or other special license to lay drain line of any type
Drainage Systems • Includes subsurface and surface drainage systems for: interception, collection, conduction, and disposal of storm runoff and subsurface water • Designed and sized to deal efficiently with projected precipitation, infiltration, and flow rates • Large projects – designed by engineer to meet local building code
Drainage Systems • Must ensure the safety of the property owner and the protection of dwellings, site elements, and properties from water damage, flooding, and erosion. • If storm drain water flow accumulates - requires storm-water retention ponds to prevent erosion damage or flooding on the site or adjacent properties
Drainage Systems - Installation • Contractor must be aware of measurements and installations that have been made off-site and on-site as part of the “hard” construction to ensure that the work specified in the landscape contract can be properly carried out re: site drainage. • Contractor must take measures to prevent siltation of existing drainage systems and watercourses during all on-site work
Subsurface Drainage • Any drainage method installed below the soil surface to move water out of the soil • A detailed subsurface drainage plan is prepared by engineers - not the landscape contractor • Before installing on residential and commercial sites – Contractor must consult prepared engineering drainage plan that should be supplied as part of the contract drawings
Subsurface Drainage Plan Includes: • Drain outlet locations • Location, size, depth, spacing, and slope or drains • Location of any obstructions, such as trees, buildings, etc. • Surface runoff from adjacent properties • Back-filling requirements
Drain Outlet Locations 2 types of outlets for subsurface drains: • 1. Gravity – most common for landscape purposes; discharge water into storm sewers or open waterways • 2. Pump
Gravity Drain Outlet The next slide shows a typical gravity outlet that discharges into an open ditch. Its is critical when installing the outlet that the end of the pipe should not extend too for beyond the ditch bank, since the force of the falling water will cause erosion, creating the potential for serious environmental problems. The installation of riprap below the outlet to prevent erosion is a common procedure
French Drains • Essentially a trench
Surface Drainage • Final grading must conform to grade elevations + contours on approved plan • Water flows away from all structures = positive drainage • Maximum settling of 30 mm or 1.25 inches
Open Channel Drainage • Ditches + swales to direct water from a site • Vegetated waterways are effective in erosion control • Not to be used when water flow – continuous or constant ground water sits • Engineered drawings must be provided
Important Soil Properties • Important to understand the basic properties of soils that have a direct impact on the success of plant and turf establishment.
Soil Compaction: • Leads to problems with drainage and plant establishment • Compacted soils have very low filtration therefore can cause overland flow and erosion increases
Soil Compaction Caused By: • Quality, foot traffic, heavy equipment, vehicular traffic, and landscape maintenance equipment
Soil Compaction Management: • Good planning prior to construction can reduce some of the soil compaction that takes place during building and landscape construction by limiting the areas that construction equipment can drive on • Topsoil can be removed prior to construction so that only the subsoils are being driven on • After construction, the subsoil should be decompacted by ripping or subsoiling and the top soil should be replaced
Soil Compaction Consequences: • Impaired root growth • Poor aeration • Reduced drainage • Which causes……..
Soil Compaction Consequences: Some indirect consequences of soil compaction: • Nutrient deficiencies • Flooding • Soil erosion • Susceptibility to root rot
Impact of Pressure Applied to Soils on Compaction • When subsoils are compacted by heavy traffic, free drainage is impacted and saturation of the topsoil will occur • Effects of compaction by wheeled vehicles - usually within the top 4 inches (10 cm) of the soil • 80% of compaction will occur with the first wheel to travel over the soil • Heavier equipment – upper 6-8 inches (15-20cm) are seriously effected
Impact of Pressure Applied to Soils on Compaction Rules of thumb: • Keep foot and vehicle traffic to a minimum • Use the same path to confine compaction to a single area that can be repaired • Keep wheeled traffic away from tree roots • Schedule work when the soil is dry • Use low ground pressure vehicles whenever possible • Place a coarse mulch over heavily trafficked areas and remove it when project is done
Soil Erosion • Happens when particles are detached and transported by water or wind • On landscape sites, largest problem is erosion by water – initiated by the impact that raindrops have on bare soil • Soil should be covered, mulched, or seeded with annual grasses if it is being exposed to the elements for significant amounts of time
Soil Erosion Classified as gully, rill, and sheet erosion • Gully erosion – water concentrates in channels and deepen rapidly • Rill erosion – removal of soil on a side slope where small channels are formed • Sheet erosion – where there is little or no vegetation cover and the slopes are not steep; soil is removed in a relatively even plane
Erosion Control Measures • Important to reduce environmental damage • There are environmental regulations that specify the use of erosion control measures on construction sites • Good planning prior to the commencement of construction
Erosion Control Measures • Planning Stage: identify areas with high susceptibility to erosion - avoid disturbing these areas • If areas with high erosion potential are disturbed, - ensure that they are will protected until vegetation re-established • Establish vegetation as soon as possible • Cover soil with mulches, annual grasses, or erosion control fabric
Erosion Control Measures • Water erosion of soil = direct result of overland flow, the higher the water velocity, the greater the erosion • Important to keep runoff velocities as low as possible • Install straw bales or silt fences to help prevent/reduce • Retain on the site any sediment generated; by construction of small retention ponds in strategic areas/ silt fences/ straw bales
Irrigation Systems and Water Management Strategies The manager of a landscape company that sells + installs irrigation systems must understand the following 5 strategies:
Strategy 1 • Legal: – licences/codes/permits/design requirements/restrictions/ insurance etc. • Prevent contamination
Strategy 2 2. Design: basic concepts of: match system to site use, precipitation rates/efficiency (water conservation), head design/spacing, topography, soil type, water distribution, local codes, plant requirements
Strategy 3 3. Physics - basic physics of water flow (volume vs. pressure), electricity, pipe sizing, and low voltage limitations
Strategy 4 4. Mechanics - of an effective irrigation system ( nuts & bolts of system), including working knowledge types of backflow prevention and features, controllers, wiring, valves, pipe material, head types, and nozzles