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Line 1: ==Overview==LID techniques and technologies are new to many municipalities, consulting engineers, and contractors. STEP's construction guidance aims to give practical advice, specific to LID, to enable practitioners to successfully construct LID practices.
Construction inspections and communication between project managers, engineers, and contractors are the keys to success.*''Importance of construction inspections''*''Contractor familiarity & incremental changes in the construction industry''*''What you can expect from STEP guidance: practical advice, specific to LID, on how to ensure successful construction''
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LID techniques and technologies are new to many municipalities, consulting engineers, and contractors. STEP's construction guidance aims to give practical advice, specific to LID construction, to enable practitioners to successfully construct LID practices.
Common reasons project failure at the construction stage are:
*'''Lack of detail in designs and construction documents.''' Contractors will struggle to properly build LID facilities without enough detail and instruction.
*'''Lack of knowledge.''' Designers often do not understand the complexities of the construction process, and contractors often don't understand the purpose of LID practices or the technologies they employ.
*'''Lack of effective erosion and sediment control during construction.''' LID practices are most vulnerable to sedimentation and clogging during their own construction or construction of adjacent lands.
*'''Lack of planning and communication.''' The pace and extent of construction may preclude proper inspections and certifications.
STEP's construction guidance aims to give clear direction to project managers, engineers, and contractors to avoid these common pitfalls.
==Construction stages and LID types==
==Construction stages and LID types==
Most LID practices work at the sub-surface and ground-level by routing stormwater flows from impervious surfaces into excavated or natural depressions or by allowing stormwater to pass through a pervious surface, as is the case with permeable pavements. These depressions are designed and constructed to the meet goals of the LID practice, which may be quality control, quantity control, or water balance restoration. [[Bioretention]] gardens, [[bioswales]], [[rain gardens]], [[enhanced swales]], [[exfiltration trenches]], [[permeable pavements]], and infiltration systems ([[infiltration chambers|chambers]], [[infiltration trenches|trenches]], and [[soakaways]]) all fall into this category.
Most LID practices work at the sub-surface and ground-level by routing stormwater flows from impervious surfaces into excavated or natural depressions or by allowing stormwater to pass through a pervious surface, as is the case with permeable pavements. These depressions are designed and constructed to the meet goals of the LID practice, which may be quality control, quantity control, or water balance restoration. [[Bioretention]] gardens, [[bioswales]], [[rain gardens]], [[enhanced swales]], [[exfiltration trenches]], [[permeable pavements]], and infiltration systems ([[infiltration chambers|chambers]], [[infiltration trenches|trenches]], and [[soakaways]]) all fall into this category.
For this reason, Stages 1-2 and 5 of the LID construction process are fundamentally similar for all '''sub-surface''' and '''ground-level LID''' types. To illustrate, STEP's recommended processes for excavation do not differ between LID practice types. Excavation procedures are the same, whether for a bioretention garden or a permeable pavement parking lot. On the other hand, stage 4 sub-tasks will vary depending on whether the LID practice's surface is vegetated or permeable pavement. Some sub-tasks in stage 3 will also vary depending on the LID type. For example, permeable pavements often require compaction of sub-surface storage layers. The following sections give a brief description of each over-arching stage, a list of sub-tasks for each stage, and links to the page dedicated to each main LID construction stage.
For this reason, Stages 1-2 and 5 of the LID construction process are fundamentally similar for all sub-surface and ground-level LID types. To illustrate, STEP's recommended processes for excavation do not differ between LID practice types. Excavation procedures are the same, whether for a bioretention garden or a permeable pavement parking lot. On the other hand, stage 4 sub-tasks will vary depending on whether the LID practice's surface is vegetated or permeable pavement. Some sub-tasks in stage 3 will also vary depending on the LID type. For example, permeable pavements often require compaction of sub-surface storage layers. The following sections give a brief description of each over-arching stage, a list of sub-tasks for each stage, and links to the page dedicated to each main LID construction stage.
'''Green roofs, blue roofs, stormwater planters, and rainwater harvesting systems have specific construction sequences that differ from the main sequence described above. One day we will write guidance for these LID practices as well.'''
'''Green roofs, blue roofs, stormwater planters, and rainwater harvesting systems have specific construction sequences that differ from the main sequence described above. One day we will write guidance for these LID practices as well.'''