Line 179: | Line 179: | ||
<td>Yes</td> | <td>Yes</td> | ||
<td>Proper design of the outlet structure can be the key to ponding effectiv</td> | <td>Proper design of the outlet structure can be the key to ponding effectiv</td> | ||
+ | </tr> | ||
+ | <td rowspan="2">Constructed Wetlands</td> | ||
+ | <td>Forebay</td> | ||
+ | <td>Yes</td> | ||
+ | <td>See comment for forebay above</td> | ||
</tr> | </tr> | ||
+ | <tr> | ||
+ | <td>Storage components</td> | ||
+ | <td>Yes-to marginal</td> | ||
+ | <td>Volume will be less than typical pond, but provide location for storage, some infiltration, filtration and some microbial activity; biological activity at a minimum</td> | ||
+ | </tr> | ||
+ | <td rowspan="8">Supplemental Treatment</td> | ||
+ | <td>Proprietary sediment removal</td> | ||
+ | <td>Yes</td> | ||
+ | <td>These devices are typically installed below ground and below the frostline, and can be effective in treating sediment-laden spring runoff</td> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>Catch basin insert</td> | ||
+ | <td>Marginal</td> | ||
+ | <td>The location of these in a very cold location often leads to icing conditions; can be marginally effective for solids even if frozen</td> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>Wet vault</td> | ||
+ | <td>Yes</td> | ||
+ | <td>See comment for proprietary devices</td> | ||
+ | </tr> | ||
+ | <tr> | ||
+ | <td>Chemical treatment</td> | ||
+ | <td>Yes</td> | ||
+ | <td>These systems are designed to inject treatment chemicals for all flows</td> | ||
+ | </tr> | ||
+ | <tr> | ||
+ | <td>Floatable skimmer</td> | ||
+ | <td>Yes-to-marginal</td> | ||
+ | <td>Proper installation of a floatable skimmer or baffle weir will allow water to pass even when thick ice is present; draws water from below ice layers</td> | ||
+ | </tr> | ||
+ | <tr> | ||
+ | <td>Sorbents</td> | ||
+ | <td>Yes</td> | ||
+ | <td>These absorb chemicals usually in sub-grade systems</td> | ||
+ | </tr> | ||
+ | |||
+ | <tr> | ||
+ | <td>Thermal protections</td> | ||
+ | <td>No</td> | ||
+ | <td>Do not apply to winter conditions</td> | ||
+ | </tr> | ||
+ | <tr> | ||
+ | <td>Biological additives</td> | ||
+ | <td>Yes</td> | ||
+ | <td>See comment for chemical treatment</td> | ||
+ | </tr> | ||
</table> | </table> |
BMP Family | BMP | Classification | Notes |
---|---|---|---|
PollutionPrevention | Housekeeping practices | Yes | Focus on rapid clean-up of paved surfaces after snowmelt |
Atmospheric control | Marginal | Control of auto emissions and industrial output usually not under local control, but exposed winter soils are controllable | |
Chemical controls | Yes | Salt management and chemical spill control can be local programs | |
Animal waste management | Yes | Strict waste control can be covered in local ordinance | |
Streambank stabilization | Yes | Attention to local erosion sites can reduce ice damage and sediment load from high spring flows | |
Runoff Volume Minimization | Natural area conservation | Yes | Preserving pervious areas for meltwater to infiltrate is effective way to control volume |
Soil amendments | Marginal | Enhancing soil permeability will increase infiltration of meltwater | |
Reduction of impervious surface | Yes | Preserving pervious areas for meltwater to infiltrate is effective way to control volume and to minimize mobilization of pollutants | |
Grass drainage channel | Yes | Routing meltwater over a pervious surface will yield some reduction in flow and improved water quality | |
Rain barrel/cistern | Marginal | Capturing meltwater from a building will reduce volume but ice build-up could be a problem unless collection occurs below frostline | |
Permeable pavement/blocks | Yes | Recent research has shown this approach to be successful in cold climates when properly installed and maintained, and when sanding kept to a minimum | |
Soakaway pit/drywell (designed so as not to qualify as a Class V injection well) | Yes | Effective as long as system is installed below the frostline to avoid ice build-up | |
Stormwater planter | Marginal | These are designed more for the growing season, but they do provide a sump area for runoff to collect and will infiltrate some of the volume | |
Rooftop garden | Yes | Recent research has shown that slow melting in the spring reduces the volume running off of roof surfaces | |
Temporary Construction Sediment Control | Preconstruction planning | Yes | Focus on sequencing to avoid open soils during winter and on limited grading prior to freeze-up |
Resource protection | Yes | Buffers reduce runoff by providing infiltration potential | |
Runoff control | Yes | Stable drainageways and sediment basins assure erosion control and provide storage opportunities for spring meltwater | |
Perimeter control | Yes | These practices are especially effective during winter construction | |
Slope stabilization | Yes | These must be installed prior to freeze-up to be effective; they must be checked often and maintained all winter | |
Stabilized soil | Marginal | Seeding, blankets and sprayed stabilizers must all be in place and working before freeze-up; if necessary, blankets can be laid and held in place with sandbags or rock logs | |
Inspection and maintenance | Yes | Essential for proper operation all winter | |
Bioretention | Rain garden | Marginal | By definition, these are growing season practices, but they do provide a sump area for storage and some infiltration during a melt |
Depressed parking islands | Yes | These can provide needed storage during the cold season and for spring runoff events; vegetation will not be a factor during winter | |
Filtration | Media filter | Yes-to marginal | Surface systems need to be fully dry before freezeup for these to work properly; sub-grade systems can be very effective for meltwater treatment |
Surface vegetative filter | Marginal | Vegetative filtering is reduced once vegetation dies back in the fall; some physical filtering will occur if vegetation density and depth are sufficient | |
Combination filter | Yes-to marginal | See comments above | |
Infiltration | Trench | Yes with caution | Effective when designed, installed and maintained properly; caution applies to limitations on source area to avoid high concentrations of Cl and toxics |
Basin | Yes with caution | See above comment | |
Stormwater Ponds | Forebay | Yes | Effective if designed with enough available volume to accommodate meltwater in the spring |
Storage components | Yes | Adaptations must be made to allow meltwater runoff to receive appropriate amount of treatment (see discussion following in this section); treatment effectiveness usually lower than warm weather | |
Outlet | Yes | Proper design of the outlet structure can be the key to ponding effectiv | |
Constructed Wetlands | Forebay | Yes | See comment for forebay above |
Storage components | Yes-to marginal | Volume will be less than typical pond, but provide location for storage, some infiltration, filtration and some microbial activity; biological activity at a minimum | |
Supplemental Treatment | Proprietary sediment removal | Yes | These devices are typically installed below ground and below the frostline, and can be effective in treating sediment-laden spring runoff |
Catch basin insert | Marginal | The location of these in a very cold location often leads to icing conditions; can be marginally effective for solids even if frozen | |
Wet vault | Yes | See comment for proprietary devices | |
Chemical treatment | Yes | These systems are designed to inject treatment chemicals for all flows | |
Floatable skimmer | Yes-to-marginal | Proper installation of a floatable skimmer or baffle weir will allow water to pass even when thick ice is present; draws water from below ice layers | |
Sorbents | Yes | These absorb chemicals usually in sub-grade systems | |
Thermal protections | No | Do not apply to winter conditions | |
Biological additives | Yes | See comment for chemical treatment |