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Construction and Maintenance Presented by: The Low Impact Development Center, Inc. A non-profit water resources and sustainable design organization www.lowimpactdevelopment.org.

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Presentation on theme: "Construction and Maintenance Presented by: The Low Impact Development Center, Inc. A non-profit water resources and sustainable design organization www.lowimpactdevelopment.org."— Presentation transcript:

1 Construction and Maintenance Presented by: The Low Impact Development Center, Inc. A non-profit water resources and sustainable design organization www.lowimpactdevelopment.org Presented by: The Low Impact Development Center, Inc. A non-profit water resources and sustainable design organization www.lowimpactdevelopment.org

2 The Low Impact Development Center, Inc. has met the standards and requirements of the Registered Continuing Education Program. Credit earned on completion of this program will be reported to RCEP at RCEP.net. A certificate of completion will be issued to each participant. As such, it does not include content that may be deemed or construed to be an approval or endorsement by RCEP.

3 COPYRIGHT MATERIALS This educational activity is protected by U.S. and International copyright laws. Reproduction, distribution, display, and use of the educational activity without written permission of the presenter is prohibited. © Low Impact Development Center, 2012

4 The purpose of this presentation is to describe the importance of proper construction and maintenance to the success of LID At the end of this presentation, you will be able to: Explain the importance of construction oversight Discuss maintenance requirements of bioretention and permeable pavers Describe how to repair or restore failed systems Purpose and Learning Objectives

5 Key Points Construction Observation Maintenance for Bioretention and Pavers (Softscape and Hardscape) Corrective Actions General Environmental Monitoring

6 Permeable Paving Types Concrete or plastic grid pavers Permeable interlocking concrete pavers Porous asphalt Pervious concrete

7 PICP Concrete pavers Open-graded subbase reservoir Uncompacted subgrade soil Open-graded base reservoir Underdrain (as required) Optional geotextile under the subbase Permeable joint material Open-graded bedding course System Components

8 Construction: Subbase & Base Preparation

9 3.5” - 4” pervious Bituminous asphalt placed directly on stone base Rolled to a finished depth of 2.5” - 3” 1 ½” Open Graded Friction Course (OGFC) 3” Asphalt Treated Permeable Bases (ATPB) Installation of Porous Asphalt Source: CA Coastal Commission

10 Installation of Porous Concrete

11 Jointing Roughly ½ the shrinkage of normal concrete Joints are typically placed every 20’ Best practice is to tool joints o Sawing can cause raveling

12 Curing pervious concrete is critical due to the porosity and low W/C ratio Without curing, surface will dry out and deteriorate easily Moist cure (7 days preferred) Curing

13 Permeable Paver Installation

14 PICP Joint Aggregate Installation

15 Bioretention

16 Bioretention: Media Placement Add media in 6” lifts Thoroughly wet and allow soil to drain Make sure the media is at specified height below overflow

17

18 Inadequate Erosion Control or Protection of BMP Areas

19 Keep Erosion Controls in Place Until Drainage Area is Stabilized Slide 19 Irving St Images P5240081 & P4260061

20 Unapproved Material Substitutions

21 Irving St Image (DSCN3901) Unapproved Material Substitutions

22 Plant Density Plant Location

23

24

25 Naval Workshop on Low Impact Development (LID) Isolation of Hazards

26 Regulatory requirement o NPDES MS4 permit o Other State storm water regulations (new) o Documentation may be required Necessary to continue function as designed Proper maintenance lowers long term costs Less costly to maintain than repair or replace Maintenance Drivers

27 Maintenance – Bioretention Primary maintenance requirement - regular inspection and repair / replacement of damaged components Can be incorporated into regular landscaping maintenance contract, as the routine periodic maintenance for bioretention areas is similar to what is required of any landscaped area

28 Maintenance – Bioretention Planting Maintenance Routine maintenance should include a biannual health evaluation of the plantings, and removal and replacement of any dead or diseased vegetation. The use of native plant species in the bioretention cell will reduce fertilizer, pesticide, water, and overall maintenance requirements. Level of pollutants in the soil can become toxic, impair plant growth

29 Naval Workshop on Low Impact Development (LID)

30 Maintenance – Bioretention Planting maintenance Immediately after installation, water plant material for 14 consecutive days (unless sufficient natural rainfall). When trees have taken root, or at least by 6 months, remove stakes and wires Visually inspect vegetation for disease or pest problems at least once in the spring, once in the fall, and more frequently in the summer. If treatment is warranted, use the least toxic approach During extended drought, look for physical signs of stress (unrevived wilting; yellow, spotted or brown leaves; loss of leaves, etc.). Water in the early morning if needed Prune excess growth annually in the spring and throughout the growing season if desired. Trimmed materials may be recycled back in with replenished mulch or landfilled if there is a concern of heavy metals accumulation. Weed regularly, as necessary

31 Maintenance – Bioretention RequirementsTestingRemediation Soil pH should reflect local plant materials Obtain a kit and instructions from the State Cooperative Extension Office. Apply the necessary amount of limestone or compost to get the pH in the correct range. Soils Visually inspect and repair erosion at inflow points once in the spring and once in the fall, at a minimum. Use small stones to stabilize erosion along drainage paths. Check the soil’s pH once or twice a year. Apply an alkaline product, such as limestone, if needed.

32 Maintenance – Bioretention Soils - Maintain Infiltration Rates Runoff from impervious surfaces is directed to bioretention cells to infiltrate through the soil medium Once the infiltration capacity of the soil medium is exceeded, storm water begins to pool at the soil’s surface Ponding should only last 4-6 hours Mosquitoes larva need 4+ days of standing water

33 Maintenance – Bioretention Soils – Corrective Action Depending on pollutant loads, soils may need to be replaced within 5-30 years of construction. If standing water consistently over 4-6 hrs: o Clear the underdrain of potential clogs o Check filter fabric above the underdrain o Remove mulch and rake surface to remove surface blockages o Last resort - remove the soil mixture Before removing soil mixture, analyze for clay content and hazardous content If greater than 15% clay content, then: o Temporarily block end of discharge pipe, install appropriate E&S controls o Carefully dig up plants so that root systems are maintained (and return to cell following soil replacement) o Remove soil and dispose appropriately as clean fill or in an approved landfill o Inspect pipe and gravel layer, if pipe is clogged, then wash the gravel layer with a high-pressure hose – this should clean the pipe o Place new soil in the cell and replant vegetation

34 Maintenance – Bioretention Mulch Layer Uniformly applied approximately 2 to 3 inches deep. Do not pile the mulch around trees or other plantings Fresh redwood bark mulch. Make sure it is free from weed seeds, soil, roots or any other substance not consisting of bole, branch wood, or bark Do not use grass clippings as mulch Typically, every 6 months, in the spring and fall, add a fresh mulch layer. Once every 2 to 3 years, in the spring, remove the old mulch layer before applying the new one

35 DescriptionFrequency 1. Soil a) Inspect and Repair ErosionSpring and fall b) Check pHOnce a year 2. Organic Layer a) Re-mulch any void areasAs needed b) Add new mulch layerSpring and fall c) Remove old mulch layerThree (3) years 3. Plants a) Water plant material for fourteen consecutive days after planting has been completed unless there is sufficient natural rainfall Immediately after Completion of project b) Remove stakes and wires after six monthsAfter rooting c) Inspect for disease/pest problemsSpring/summer/fall d) Treatment of diseases As needed, refer to manufacturer Maintenance Schedule – Bioretention

36 3. Plants (continued) e) Removal and replacement of all dead and diseased vegetation considered beyond treatment Spring and fall f) During times of extended drought, look for signs of stress Water as needed. Summer g) Weed and prune excess growthSpring/summer h) Fertilize As needed, refer to manufacturer i) Remove tagsAfter warranty 4. General a) After major rainstorms, inspect site and make sure drainage paths are clear and that ponding water dissipates over time. Clear the drainage path of any accumulated sediment or debris. Seek remediation if drawdown times are consistently much longer than 4-6 hours After major rainstorms Maintenance Schedule – Bioretention

37 Tree box filter plant maintenance

38 Maintenance – Permeable Pavers Primary maintenance requirement - clean the surface drainage voids Can be incorporated into regular street sweeping program Annual inspections

39 After 10 years Some localized clogging and repairs

40 Inspections Routine maintenance is key: o Conventional street sweepers equipped with vacuum sweepers and high-pressure water can used to restore permeability o Street sweeping frequency varies depending on drainage area inputs (leaf debris, erosion, etc.). An active street sweeping program in the site’s drainage area will also help to prolong the functional life of the pavement o If necessary, add additional gravel chips to fill pore spaces after vacuum sweeping In case of localized settling, individual paver blocks can be removed, new gravel added, and the blocks replaced Maintenance – Permeable Pavers

41 Restrict use by heavy vehicles Limit use of de-icing chemicals and sand Implement stringent sediment control plan Failure of systems: o poor design o inadequate construction techniques o low permeability soils o heavy vehicular traffic o resurfacing with nonporous materials Maintenance – Permeable Pavers

42 Maintenance Schedule Permeable Pavers DescriptionFrequency Initial InspectionsMonthly for first several months following construction Vacuum sweeping and high pressure hosing 4 times/year Encourage active street cleaning in the site’s area Regularly Annual inspectionsYearly, after large storms Fill potholes and cracksAs needed Address spot-clogging problems by drilling holes As needed

43 Maintenance – Permeable Pavement Routine Maintenance Similar to permeable pavers Recommended: Vacuum sweep twice per year

44 Maintenance – Permeable Pavement Corrective Action Fill potholes and cracks with permeable patching mixes Fix spot clogging by drilling ~0.5-inch holes through the porous pavement layer every few feet Courtesy Cahill

45 Monitoring Programs Not typically a regulatory requirement (unimpaired) Potential requirement for discharges to sensitive or impaired waters Monitoring plan shaped by regulatory requirements, site characteristics, parameter(s) of concern, and use of the data

46 Water Quantity Monitoring Monitor the effectiveness of LID features either on a small scale (individual features) or large scale (stream flow): Small Scale Manual or automatic sampling methods can be used to calculate flow rates upstream and downstream of a LID feature, based on the depth measured using a weir or a rate of flow measured using a conveyance device. Large Scale Where LID features are being installed as retrofits in already developed areas, the effectiveness of the retrofits can be assessed by comparing pre-LID and post-LID flow rates downstream.

47 Thank you for your time. QUESTIONS? Low Impact Development Center, Inc. www.lowimpactdevelopment.org 301.982.5559


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