Long-Term Performance and Life-Cycle Costs of Stormwater Best Management Practices (2014) / Chapter Skim
Currently Skimming:
Pages 55-71
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 55... ...
55 C H a P T E r 5 This chapter provides an overview of inspection protocols, maintenance triggers, and maintenance actions for the selected BMPs. Information available on maintenance practices for BMPs from DOTs around the country is assessed, and suggestions for the frequency of BMP maintenance are provided.
|
From page 56... ...
56 5.2 Caltrans Prototype BMP Field Investigation Caltrans completed a prototype-scale research program assessing the maintenance requirements of BMPs used to control runoff from highway infrastructure. This 7-year, multimillion dollar study examined the costs (life cycle)
|
From page 57... ...
57 5.2.1 Vegetated Swales Five vegetated swales were inspected, as shown in Table 5-2. In four cases, the original vegetation planted at the sites had been replaced or had been taken over by vegetation from the surrounding landscape and had vegetation coverage of varying degrees.
|
From page 58... ...
58 performance or requiring maintenance. The maintenance intervals for these sites were judged to be sufficient to maintain the BMP performance.
|
From page 59... ...
59 problems prior to the wet season. Other general maintenance items are limiting vegetation growth, removal of trash/debris when they inhibit BMP function, and erosion control.
|
From page 60... ...
60 The wet and dry ponds required sediment removal and clearing and grubbing. These costs were used as verification points for BMPs located in a medium-level maintenance region.
|
From page 61... ...
61 at different distances from the edge of the pavement to determine the effect of vegetated strip length on constituent removal. This study also evaluated vegetated cover with respect to performance for strip length.
|
From page 62... ...
62 The annual sediment load for a vegetated swale was estimated by rainfall region. Using average TSS values from the highway research database and TSS removal efficiency from the International Stormwater BMP Database, it takes between 12.5 and 91 years to fill the swale with sediment to the height vegetation (4 in.)
|
From page 63... ...
63 Climate Region Annual Rainfall (in.) Annual Stormwater Volume (ft3/acre)
|
From page 64... ...
64 Climate Region Annual Rainfall (in.) Annual Stormwater Volume (ft3/acre)
|
From page 65... ...
65 are as shown in Table 5-14. Similar calculations for the main pool were performed indicating 20 to 140 years before sediment accumulated to fill 10% of the main pool capacity.
|
From page 66... ...
66 bed media cleanouts. Based on a review of the maintenance records, inspection of the sand filter locations, and review of volume of water received, the estimated treatment volume to a sand filter before it clogs is 600 ft3 of runoff per square foot of sand surface area.
|
From page 67... ...
67 expected for overlays placed on asphalt pavements, and 6 to 10 years of life can be expected for overlays placed on concrete pavements before they must be replaced. 5.5 Suggested Maintenance Tasks The suggested maintenance tasks by BMP, including the hours and equipment requirements, were based on collected inspection and maintenance data from the Caltrans pilot sites and the records obtained during this study from DOTs and from the literature review.
|
From page 68... ...
68 ment is the removal of trash and debris. Intermittent maintenance, including sediment management, vegetation repair, and slope repair, is suggested to occur every 2, 5, or 10 years, based on calculations for sediment buildup within the vegetated swale.
|
From page 69... ...
69 5.5.4 Bioretention Bioretention maintenance activities are presented in Table 5-19. All vegetation management tasks are included within vegetation repair and are suggested to occur semiannually, annually, or every 3 years.
|
From page 70... ...
70 of the aesthetic needs of the community. The hours associated with trash removal are included in vegetation management.
|
From page 71... ...
71 5.6.1 Vegetated Strips Sediment accumulation within the strip will need to be removed and the strip regraded to reestablish sheet flow every 8 to 60 years, based on solids loading to the BMP. This would essentially be a complete rebuild of a vegetated strip.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.