Treating runoff

Abstract

Systems and methods for treating water passing through a catch basin may include filters. In some embodiments, the filter(s) can have a plurality of regions with different nominal flow rates.

Claims

1. A system for treating water, the system comprising: a catch basin defining an inlet, a storm sewer outlet in fluid communication with a storm sewer system, and an infiltration outlet to allow water to flow out of the catch basin and return to groundwater; a filter having a first end portion having a first perimeter and a second end portion having a second perimeter, the first end portion of the filter mounted below the inlet of the catch basin, and the second end portion of the filter secured to an inner surface of the catch basin at a location spaced apart from the inlet of the catch basin, such that the filter defines a surface separating an inner portion of a cavity of the catch basin from an outer portion of the cavity of the catch basin; a member extending between the filter and the inner surface of the catch basin such that the member defines a surface separating the outer portion of the catch basin into an upper portion including the storm sewer outlet of the catch basin and a lower portion including the infiltration outlet of the catch basin; and a lever attached to the filter and to the catch basin with a portion of the lever extending outside the catch basin such that passage of a vehicle over the inlet of the catch basin engages the portion of the lever and moves the filter.

2. The system of claim 1, wherein the member comprises a separator skirt mounted to the inner surface of the catch basin below the storm sewer outlet of the catch basin outlet.

3. The system of claim 1, wherein the member comprises filter material.

4. The system of claim 1, further comprising a spray system operable to spray fluid on the filter.

5. The system of claim 4, wherein the spray system comprises a spray head is mounted inside the catch basin.

6. The system of claim 1, comprising an inlet pipe extending from the storm sewer inlet into the interior portion of the catch basin.

7. The system of claim 6, wherein the inlet pipe is positioned such that an axis of the inlet pipe is substantially tangential to an inner surface of filter.

8. The system of claim 1, wherein the filter is formed from material whose coarsest mesh is small enough to limit the movement of insects through the filter.

9. The system of claim 8, wherein the largest opening in the filter is less than or equal to 850 microns in a bypass region.

10. A system for treating water passing through a catch basin, the system comprising: a catch basin defining an inlet and an outlet and including an inlet grate extending over the inlet; a filter mounted in the catch basin below the inlet of the catch basin to receive water from the inlet of the catch basin; and a lever attached to the filter and to the catch basin with a portion of the lever extending outside the catch basin such that passage of a vehicle over the inlet of the catch basin engages the portion of the lever and moves the filter.

11. The system of claim 10, wherein at least one connector extends between the lever and the filter.

12. The system of claim 11, wherein the least one connector comprises cables extending between the lever and the filter.

13. The system of claim 10, wherein inlet grate extends upwards in a convex shape.

14. The system of claim 13, wherein the inlet grate comprises a flexible or semi-flexible material such that the inlet grate will flex downward and flatten under pressure of a vehicle tire and return its original convex shape after the vehicle tire is no longer present.

Description

DESCRIPTION OF DRAWINGS

(1) FIGS. 1A and 1B are, respectively, a cut-away view and a cross-sectional view of a two-filter system installed in a catch basin.

(2) FIGS. 1C and 1D are perspective views of, respectively, the inner filter and the outer filter of the two-filter system shown in FIGS. 1A and 1B.

(3) FIGS. 2A-2D are cross-sectional views of the two-filter system shown in FIGS. 1A-1D during a runoff event.

(4) FIGS. 3A-3C are side views of a method of cleaning a two-filter system.

(5) FIGS. 4 and 5 are side views of filter embodiments.

(6) FIG. 6 is a schematic view of a filter-catch basin system configured to enhance infiltration.

(7) FIG. 7 is a schematic view of a spray head mounted in a catch basin.

(8) FIGS. 8A and 8B are, respectively, perspective and top views of a modular filter.

(9) FIGS. 9A-10B are schematics of a mechanism for moving a filter.

(10) FIG. 11 is a schematic view of a two filter system.

(11) FIGS. 12A-12F are schematic views of systems configured to treat water flowing into a catch basin from upstream portions of a storm sewer system.

(12) FIGS. 13A-13E are schematic views of filters incorporating media liners.

(13) FIGS. 14A-14B are side schematic views of a bottom-outlet catch basin and treatment system.

(14) FIG. 15 is a side schematic view of a bottom-outlet catch basin and a treatment system.

(15) FIG. 16 is a side schematic view of a treatment system installed in a side-outlet catch basin.

(16) Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

(17) Referring to FIGS. 1A and 1B, a system 1000 configured to remove particulate matter and debris from runoff entering catch basins is installed in catch basin 9000. System 1000 includes a first filter 1100 and a second filter 1200. Both filters 1100, 1200 are configured with multiple regions with each region having a relatively greater nominal flow rate than an adjacent lower region. The lower regions with a lower nominal flow rate provide a relatively higher degree of filtration for treating the runoff from small storm events. For larger storm events, as the rate of runoff entering catch basin 9000 exceeds the rate at which water flows through the lower regions with a lower nominal flow rate, the level of runoff on the inlet side of the filters increases bringing the higher regions with a higher nominal flow rate into operation. These higher regions with a higher nominal flow rate provide less filtration but provide greater flow capacity than the lower regions with a lower nominal flow rate.

(18) First filter 1100 is a bag filter (e.g., a filter with an open end, sides, and a closed bottom) suspended within catch basin 9000. First filter 1100 can be formed of a flexible material (e.g., a fabric or fabrics) to facilitate installation before use and removal for cleaning. Runoff entering catch basin inlet 9010 falls into bag filter 1100, which absorbs the kinetic energy of the falling material. As runoff passes through the porous walls of bag filter 1100, some of the particulate matter and debris in the runoff is retained within bag filter 1100. Although water, particulate matter, and debris can overflow during periods of high runoff flows, bag filter 1100 generally serves to detain the water and release it into the catch basin, and hence the storm drain system, over time. This detention and filtering limits the undesirable discharge of particulate matter and debris into the storm drain system and eventually into potentially environmentally-sensitive dispersal locations. This detention also reduces the likelihood of large surges of water from being released into the storm drain system and re-suspending previously settled material (e.g., silt).

(19) Water that passes through or overflows bag filter 1100 tends to flows down the side(s) of bag filter 1100. Bag filter 1100 can be sized to extend to the standing water level in catch basin 9000 so that water, particulate matter, and debris that move from bag filter 1100 into catch basin 9000 are less likely to freefall and usually gain only small amounts of kinetic energy. Thus, water that leaves the bag filter is unlikely to disturb the water, particulate matter, and debris already present in catch basin 9000. This limits the re-suspension of sediments 9040 (e.g., particulate matter and debris) from the floor of catch basin 9000 and also allows newly-introduced particulate matter and debris to settle to the floor of catch basin 9000.

(20) Rising water in catch basin 9000 passes through second filter 1200 and exits through catch basin outlet 9020, while some additional particulate matter and debris is retained within catch basin 9000. Second filter 1200 can expand toward the walls of catch basin 9000 during periods of excessive runoff so that more of the internal volume of catch basin 9000 is utilized for storage and detention.

(21) Bag filter 1100 is configured for removal from catch basin 9000 by equipment such as backhoes or vacuum trucks for cleaning. Between periods of runoff, bag filter 1100 can be removed to allow for disposal of the particulate matter and debris retained within bag filter 1100. Eventually, enough particulate matter and debris may collect in catch basin 9000 (by passing through the porous walls of bag filter 1100 or overflowing bag filter 1100 altogether) to necessitate the removal of such particulate matter and debris using a vacuum truck or other means. Because most of the particulate matter and debris that falls through catch basin inlet 9010 will be collected in bag filter 1100, the cleaning frequency of catch basin 9000 can be reduced. Thus, bag filter 1100 and second filter 1200 can prevent particulate matter and debris from clogging storm drain systems and damaging environmentally-sensitive dispersal locations while also reducing the costs of maintaining the storm drain systems and increasing their effectiveness.

(22) Referring also to FIGS. 1B and 1C, a bag filter 1100 includes a closed end 1105, a sidewall portion 1110, and an open end 1115. Open end 1115 is opposite closed end 1105, and may be removably mounted in a region of a catch basin inlet 9010 or to a frame 1300. Frame 1300 may be removably mounted to catch basin inlet 9010.

(23) Sidewall portion 1110 of bag filter 1100 may include a first bag region 1120, having a first nominal flow rate; a second bag region 1125, located between first bag region 1120 and open end 1115, and having a second nominal flow rate relatively greater than first nominal flow rate; and a third bag region 1130, located between first bag region 1120 and second bag region 1125, and having a third nominal flow rate relatively greater than first nominal flow rate and relatively less than second nominal flow rate. Generally, first bag region 1120 also includes closed end 1105 of bag filter 1100 in addition to the lower part of sidewall portion 1110. However, in some embodiments, closed end 1105 is made of or lined with an impermeable material and does not transmit water through the bag filter.

(24) Bag filter 1100 is configured to overflow when incoming runoff flows are greater than the flow capacity of bag regions 1120, 1125, 1130 (e.g., the amount of water that can flow through the bag regions for given water levels in the system). In this embodiment, bag filter 1100 is suspended in catch basin 9000 and such overflows pass through the space between the top of sidewall portion 1110 of bag filter 1100 and catch basin inlet 9010. In some embodiments, sidewall portion 1110 includes an overflow region (not shown) that does not provide significant filtering and allows the generally free passage of such overflows. Bag regions 1120, 1125, and 1130 may be sized equally or differently; any one bag region may be larger or smaller than other bag regions, i.e., may cover more or less surface area of sidewall portion 1110, than any other bag region. In any implementation of bag filter 1100, the sizes of bag regions 1120, 1125, 1130, and of any other bag region or regions may be optimized for a given geographical region, locality, or climate, or for average or expected flow through a specific catch basin, to ensure the proper balance between filtration and water flow.

(25) Referring now also to FIGS. 1B and 1D, second filter 1200 is a tent filter that includes a first end portion 1205 and a second end portion 1210. The perimeter of second end portion 1210 is greater than the perimeter of first end portion 1205. First end portion 1205 may be attached to catch basin inlet 9010, or it may be attached to frame 1300. Second end portion 1210 may be attached (e.g., bolted) directly to an inner surface 9030 of catch basin 9000 at a location spaced apart from catch basin inlet 9010, or it may be attached to a support member 1400 that is removably securable to inner surface 9030. In certain implementations, tent filter 1200 defines a continuous surface 1215 separating a inner portion 9005 of the cavity of catch basin 9000 from an outer portion 9007 of the cavity of catch basin 9000, with catch basin outlet 9020 located in the outer portion 9007 of the cavity of catch basin 9000. For example, tent filter 1200 can provide a truncated conical surface between outer and inner portions 9005, 9007 of the cavity of catch basin 9000 such that the inner portion 9005 of the cavity of the catch basin is below as well as within the outer portion 9007 of the cavity of catch basin 9000. In some cases, catch basins 9000 receive water from upstream portions of drainage system through inlet pipes 9025. In these cases, tent filter 1200 can be disposed such that inlet pipe 9025 discharges into the outer portion 9007 of the cavity of catch basin 9000.

(26) In some embodiments, tent filter 1200 may have a system of regions with graduated nominal flow rates similar to the systems described above with respect to bag filter 1100. For example, as shown in FIG. 1C, tent filter 1200 may have a first filter region 1220 adjacent to second end portion 1210, a second filter region 1225 adjacent to first end portion 1205 and between first end portion 1205 and first filter region 1220, and a third filter region 1230 located between first filter region 1220 and second filter region 1225. Each filter region has a corresponding nominal flow rate. Each nominal flow rate is relatively greater than the nominal flow rate of the adjacent filter region in the direction of second end portion 1210 and is relatively less than the nominal flow rate of the adjacent filter region in the direction of first end portion 1205.

(27) In some embodiments, tent filter 1200 may have only first filter region 1220 having first nominal flow rate, and second filter region 1225 having second nominal flow rate. In some embodiments, tent filter 1200 may have more than three filter regions. In certain embodiments, tent filter 1200 may have a filter overflow 1240, located adjacent first end portion 1205 or located between first end portion 1205 and second filter region 1225.

(28) The sizes of the various filter regions may be equal or different. For example, the sizes of any or all of the filter regions may be optimized for a given geographical region, locality, or climate, or for the needs of a particular catch basin, to ensure a proper balance between filtration and water flow.

(29) A optional spacing member 1500, such as that shown in FIGS. 1A and 1B, may also be used in conjunction with tent filter 1200. Spacing member 1500 may be removably securable to an inner surface of catch basin outlet 9020 to prevent tent filter 1200 from directly contacting catch basin outlet 9020 and, in some embodiments, may be attached to second end portion 1210 of tent filter 1200. Spacing member 1500 is a perforated, quarter-spherical metal member that extends into the catch basin 9000 from the sides and bottom of catch basin outlet 9020. Spacing member 1500 has an open top to allow water to enter the catch basin outlet 9020 even if the perforations in the surface of spacing member 1500 become clogged. In some embodiments, spacing member 1500 can have other shapes (e.g., an open-top rectangle or a hemisphere) and/or can be formed of other materials (e.g., plastics). A spacing member 1500 can also be provided adjacent inlet pipes 9025 when inlet pipes 9025 are present. However, the flow of water from upstream portions of a drainage system will tend to push tent filter 1200 away from the opening of the inlet pipes.

(30) In some embodiments, bag filter 1100 is manufactured by forming a support structure from a strong, coarse mesh. Inner surfaces of support structure are then lined with materials having varying flow rates to form bag regions 1120, 1125, 1130. The liner may include multiple pieces of fabric of varying nominal flow rate sewn together to correspond with the various bag regions, or it may be a single piece of fabric manufactured to have a graduated nominal flow rate. In other embodiments, bag filter 1100 can be manufactured by directly attaching (e.g., by sewing) filter materials with desired strength and flow to each other to form a single piece of material with graduated nominal flow rate along the sidewall portion 1110 that increases with distance from closed end 1105. Formed of flexible material such as fabrics, bag filter 1100 can be easily compressed for passage through catch basin inlets during installation.

(31) Bag filter 1100 is configured with a cross-section substantially identical in shape and size to an inner perimeter of catch basin inlet 9010. Constructed of flexible material, bag filter 1100 generally can be pulled out of catch basin 9000 through catch basin inlet 9010 for cleaning even in the event that bag filter 1100 expands somewhat in response to the accumulation of particulate matter and debris. Bag filter 1100 can be sized such that the length of bag filter 1100 from closed end 1105 to inlet 1115 substantially corresponds to the distance between catch basin inlet 9010 and the invert (e.g., lowest point) of catch basin outlet 9020 which tends to be the standing water level within catch basin 9000. Thus, when bag filter 1100 is suspended from catch basin inlet 9010 or frame 1300, closed end 1105 reaches the standing water level inside catch basin 9000. In some implementations, the length of bag filter 1100 from closed end 1105 to inlet 1115 may be greater than the distance from catch basin inlet 9010 to the bottom of catch basin outlet 9020, i.e. to the standing water level of catch basin 9000, such that, in use, closed end 1105 of bag filter 1100 extends beneath the standing water level of catch basin 9000.

(32) The material used in or on any part of bag filter 1100 may be woven or non-woven. In some cases, woven material may be less likely to cake up or clog with silt and small particulate matter than non-woven material. The support structure and/or the liner/filter material can be chosen from materials (e.g., polypropylene fabrics) with sufficient strength that a bag filter 1100 suspended by its top is unlikely to break as particulate matter and debris accumulates within bag filter 1100. For example, the bag filter can be configured having a breaking load of at least 1000 pounds (e.g., breaking load can be defined as the maximum load (or force) applied to a specimen in a tensile test carried to rupture). Individual materials may be high-strength. In some embodiments, individual materials can have minimum tensile strengths of between about 80-380 lbs. (e.g., between, 100-260 lbs., or 120-180 lbs). Tensile strength can be measured using ASTM D-4632. In some embodiments, the material may be UV-resistant. The hydraulic characteristics of the liner/filter material can be defined by apparent opening size (e.g., United States standard sieve sizes) or flow rates (e.g., as measured by ASTM D-4491). Liner/filter material can have apparent opening sizes ranging of 25-150 (e.g., 40-120 or 80-100) United States standard sieve size and/or flow rates of 1-200 (e.g., 1-150, 1-100, or 1-20) gallons per minute per square foot. In some cases, material with a nominal flow rate in the range of about 2 to about 6 gallons per minute per square foot, e.g. about 4 gallons per minute per square foot can be used for a first filter material, other material with a nominal flow rate in the range of about 16 to about 20 gallons per minute per square foot, e.g. about 18 gallons per minute per square foot can be used for a second filter material, and still other material with a nominal flow rate in the range of about 6 to about 16 gallons per minute per square foot, e.g. about 12 gallons per minute per square foot, can be used for the third filter material. The materials in or on bag filter 1100 can also be selected to provide additional treatment. For example, the liner can include oil absorbent materials to remove hydrocarbons from runoff being treated by system 1000.

(33) In one exemplary embodiment, the support structure was formed from a trampoline bed. The seams of bag filter 1100 and the top edge of sidewall portion 1110, i.e. the edge of sidewall portion 1110 that defines open end 1115, were sewn with at least 10 rows of heavy-duty thread to provide structural stability. Galvanized rings or other fasteners were sewn into the top edge of sidewall portion 1110 to facilitate the mounting of bag filter 1100 to a frame 1300 or to a region of catch basin inlet 9010. Geotextiles were sewn to the support structure to form three bag regions. A silt fence material was sewn to the support structure to form the bottom bag region. Two layers of inch thick felt filter material were sewn to the support structure to form the intermediate bag region. A single layer of inch thick felt filter material was sewn to the support structure to form the top bag region. A portion of the support structure was left unaltered to provide an overflow region.

(34) Tent filter 1200 may be manufactured by forming a support structure in the shape of a truncated cone or pyramid including a first end portion 1205 having a first perimeter, a second end portion 1210 having a second perimeter greater than the first perimeter. The first end portion 1205 and the second end portion can have different shapes (e.g., one could be square and the other could be round). Filter 1200 defines a continuous surface 1215 between first end portion 1205 and second end portion 1210. A liner may be attached to the support structure on the inside of continuous surface 1215. The liner may be a single piece of fabric having a graduated nominal flow rate, or it may include various pieces of fabric of various porosities sewn together and/or onto the support structure, such that filter regions 1220, 1225, and any other filter region or regions have desired nominal flow rates, respectively. In some implementations, a tent filter 1200 may include a single, continuous piece of fabric or material, and having a graduated nominal flow rate, such that the highest nominal flow rate occurs nearest second end portion 1210 and the lowest nominal flow rate occurs nearest first end portion 1205.

(35) Optionally, tent filter 1200 may be formed from a pleated material (e.g., a material having a series of substantially parallel folds). In embodiments including this feature, the tent filter 1200 has a natural state in which the pleats or folds are contracted, and an expanded state (discussed in detail below with reference to FIG. 2C) in which the pleats flatten out to some extent as tent filter 1200 is circumferentially stretched (especially at the top), i.e. by rising water, particulate matter, and debris within catch basin 9000. In order to maintain filter capacity, the tent filter 1200 can be sized and configured such that tent filter does not touch the walls of the catch basin even when stretched. In such an expanded state, tent filter 1200 can utilize more of the internal volume of catch basin 9000 for storage before overflowing. In some cases, tent filter 1200 is made of material with sufficient stiffness that the pleats do not completely unfold even when tent filter is completely full of water, Thus, the pleated material can also provide additional filter area for a given circumference of tent filter 1200. Tent filter 1200 may also be formed of fabric or material that is inherently stretchable to provide a similar effect.

(36) Frame 1300 may be manufactured by welding sections of angle iron in the shape of a catch basin inlet 9010, such that the angle irons are arranged, and frame 1300 is sized, to rest on a perimeter of catch basin inlet 9010. Frame 1300 can be thin enough to allow the original catch basin inlet grate to rest on top of frame 1300 without being significantly raised. Hooks may be attached to frame 1300 and arranged to engage one or both of the top edge of sidewall portion 1110 of bag filter 1100 and first end portion 1205 of tent filter 1200. Alternatively, frame 1300 may be manufactured of any material strong enough to support one or both of tent filter 1200 and bag filter 1100, i.e. when bag filter 1100 is full of particulate matter and debris and water. Frame 1300 may be manufactured in any shape that allows or facilitates the mounting of frame 1300 in a region of catch basin inlet 9010.

(37) In some embodiments, frame 1300 comprises two nested members. A first member is sized and configured to fit within and engage the rim of catch basin inlet 9010 and a second member is sized and configured to fit within and engage the first member. The first member is attached (e.g., by ropes or chains) to tent filter 1200 and the second member is attached (e.g., by ropes, cables, straps with carabineer-type fasteners, or chains) to bag filter 1100. Thus, bag filter 1100 can be removed by lifting on the second member of frame 1300 while the first member of frame 1300 and the attached tent filter 1200 remain in place.

(38) Support member 1400 may be a strip of plastic, metal, or other material configurable into a shape identical to the perimeter of catch basin 9000. Support member 1400 may also include a mechanism that allows support member 1400 to be expanded and contracted. For example, support member 1400 may be a ring formed from a metal strip, with the two ends of the metal strip joined by a mechanism that adjusts the amount by which the two ends overlap, much like the mechanism on a hose clamp, such that the strip can expand to create a tight seal at a fixed elevation. Alternatively, support member 1400 may be a plastic strip formed into a square, i.e. to fit into a square catch basin, and the plastic strip may be temporarily deformable, such that it can be compressed to fit through catch basin inlet 9010 and returns to its original shape once the compressive force is released.

(39) FIG. 1B and FIGS. 2A-2D illustrate representative water levels and flow patterns in system 1000 at different points during a runoff event (e.g., a rain shower or activation of nearby lawn sprinklers). For example, system 1000 can be in an inactive state as illustrated by FIG. 1B. The water level (as indicated by the inverted triangle) in catch basin 9000, both inside and outside bag filter 1100, matches the invert of catch basin outlet pipe 9020. In this condition, no flow is occurring.

(40) As a runoff event begins, water, particulate matter, and debris begin passing through catch basin inlet 9010 and are initially collected in bag filter 1100. Lower bag region 1120 is made of material with a small apparent opening size. Lower bag region 1120 provides a high degree of filtration but has a low nominal flow rate. For a small runoff event, water may be able to seep through lower bag region 1120 as quickly as runoff enters catch basin 9000 and/or lower bag region 1120 may provide sufficient volume to store water that begins to collect within bag filter 1100 when the flow rate of runoff entering bag filter 1100 exceeds the flow rate of water being filtered through lower bag region 1120. In such events, all of the water exiting bag filter 1100 passes through lower bag region 1120 and is highly filtered with, typically, all debris and most or all particulate matter retained within bag filter 1100. For example, some silts may pass through lower bag region 1120 with sands, gravels, and debris retained within bag filter 1100.

(41) Closed end 1105 of bag filter 1100 touches or extends beneath the surface of the standing water within catch basin 9000. The water and silts seeping through lower bag region 1120 will tend flow down the outer surface of bag filter 1100 and mix with the water already present in catch basin 9000. Limited kinetic energy is associated with this process. The sediments 9040 already present at the bottom of catch basin 9000 are not likely to be disturbed. As the water level in catch basin 9000 outside of bag filter 1100 begins to rise above the invert of catch basin outlet 9020, water will begin to pass through lower tent region 1220 and the perforations in spacing member 1500 and flow out of catch basin 9000. Lower tent region 1220 is also made of material with a small apparent opening size that provides a high degree of filtration and has a low nominal flow rate. The material making up lower tent region 1220 can have the same or a different apparent opening size than the material making up lower bag region 1120. Tent filter 1200 helps retain particulate matter and debris within catch basin 9000 where, due to the low levels of kinetic energy in the system, the particulate matter and debris are likely to settle to sediments 9040 at the bottom of catch basin 9000. When inlet pipes 9025 are present, tent filter 1200 separates water entering catch basin 9000 from upstream portions of the drainage system from the inner portion 9005 of the cavity of catch basin 9000 where particulate matter has settled and/or is settling.

(42) Referring to FIG. 2A, during some runoff events (e.g., during intense and/or prolonged storms), the flow rate of runoff entering bag filter 1100 exceeds the flow rate of water being filtered through lower bag region 1120 and the amount of runoff accumulating within bag filter 1100 exceeds the storage capacity of specific portions or all of bag filter 1100. As discussed with reference to small runoff events, the water level within bag filter 1100 begins to rise when the flow rate of runoff entering bag filter 1100 exceeds the flow rate of water being filtered through the bottom 1105 and sidewalls 1110 of bag filter 1100. Initially, only small amounts of highly filtered water seeps through lower bag region 1120. As the water level within bag filter 1100 rises into middle and upper bag regions 1125, 1130, water begins to pass through bag filter 1100 in these regions. The flow capacity of a given bag region is a function of factors including the nominal flow rate (gallons per minute per square foot) of the material and the flow area. As each bag region has larger apparent opening sizes and a higher nominal flow rate than the lower, adjacent bag region, each bag region has a greater flow capacity but provides less filtration than the lower, adjacent bag region. The flows of water through system 1000 are generally indicated by the black arrows on FIGS. 2A-2D with larger arrows schematically indicating higher flow rates and/or velocities. In this embodiment, each of the bag regions is approximately equal in size. However, in some embodiments, the sizes of individual bag regions vary (e.g., lower bag region 1120 may be larger than middle and upper bag regions 1125, 1130) as a means of adjusting the filtration and retention characteristics of a specific bag filter.

(43) Referring to FIGS. 2A and 2B, water passing through bag filter 1100 is initially provided with secondary filtration by the lower tent region 1220 before flowing out of catch basin 9000 through catch basin outlet 9020. As water begins to pass through middle and upper bag regions 1125, 1130, the flow rate of water out of bag filter 1100 can be greater than the flow rate of water through lower tent region 1220. When this occurs, the water level between bag filter 1100 and tent filter 1200 begins to rise. As this occurs, water flowing out of catch basin 9000 has been provided with some degree of primary filtration by bag filter 1100 and a high degree of secondary filtration by lower tent region 1220. As the surface level of the water is rising, the distance between the more turbulent surface level and the volatile silt on the bottom of the catch basin increases and can provide an increasing buffer zone as flow through the overall system increases.

(44) When inlet pipe(s) 9025 are present, tent filter 1200 separates water entering catch basin 9000 from upstream portions of the drainage system from the inner portion 9005 of the cavity of catch basin 9000 where particulate matter has settled and/or is settling. Water flowing into catch basin 9000 from inlet pipe(s) 9025 mixes with water already present in the outer portion 9007 of the cavity of catch basin 9000 (e.g., outside of tent filter 1200) and flows out of catch basin 900 through outlet pipe 9020. Water from upstream effectively bypasses treatment system 1000 but is separated from sediments 9040. The sediments 9040 already present at the bottom of catch basin 9000 are not likely to be disturbed by water from upstream portions of the drainage system. Referring to FIG. 2B, spacing member 1500 holds lower tent region 1220 away from catch basin outlet 9020. If lower tent region 1220 is pressed against the inner wall of catch basin 9000 covering catch basin outlet 9020, flow out of catch basin 9000 can be limited by the flow capacity of an area of lower tent region 1220 the size of catch basin outlet 9020. With lower tent region 1220 spaced apart from the inner wall of catch basin 9000, water can flow through various portions of tent filter 1200 and into the open top of spacing member 1500 as well as through portions of lower tent region 1220 in contact with the sidewalls of spacing member 1500. In other embodiments, tent filter 1200 can be mounted in catch basin 9000 with support member 1400 located in a position which holds tent filter 1200 taut to provide separation between lower tent region 1220 and walls of catch basin 9000 in the vicinity of catch basin outlet 9020.

(45) Referring to FIG. 2C, in some runoff events, the water level in bag filter 1100 rises to the point that some runoff begins to spill over the top of bag filter 1100 rather than passing through bag filter 1100. When this occurs, only a portion of the water between bag filter 1100 and tent filter 1200 has received primary filtration. As the water level between bag filter 1100 and tent filter 1200 rises, water begins to pass through middle and upper tent regions 1225, 1230. Thus, in this flow regime, all water flowing out of catch basin 9000 that entered through catch basin inlet portion 9010 has received at least some degree of treatment from tent filter 1200. In this embodiment, tent filter is made of a pleated material and expands to provide additional storage as the water level between bag filter 1100 and tent filter 1200 (e.g., particularly when the water level between bag filter 1100 and tent filter 1200 is significantly higher in the water level between tent filter 1200 and the walls of catch basin 9000). In some embodiments, tent filter 1200 is not made of pleated material.

(46) Referring to FIG. 2D, in some extreme runoff events, the water level between bag filter 1100 and tent filter 1200 rises to the point that some runoff begins to spill over the top of tent filter 1200. When this occurs, some of the water flowing out of catch basin 9000 has passed through both bag filter 1100 and tent filter 1200, some of the water has passed through only tent filter 1200, and some of the water has not been treated by either bag filter 1100 or tent filter 1200.

(47) As time passes, the amount of particulate matter and debris collected in bag filter 1100 and catch basin 9000 increases. Most large particulate matter and debris will remain in bag filter 1100, while smaller particulate matter and debris, for example sand and sediment, will collect both in bag filter 1100 and in catch basin 9000. Periodical removal of this particulate matter and debris from bag filter 1100 and catch basin 9000 will ensure that each operates effectively.

(48) Referring to FIGS. 3A-3C, bag filter 1100 may be removed from catch basin 9000 uses various machines (e.g., machines common to construction sites and/or commonly owned by municipalities such as loaders, backhoes, bobcats, excavators, and hoists installed on municipal trucks or other vehicles). Removal of bag filter 1100 is accomplished by attaching inlet 1115 to a machine capable of lifting bag filter 1100 vertically. Alternatively, if inlet 1115 is attached to frame 1300, then frame 1300 may be attached to a machine capable of lifting bag filter 1100 vertically. Using the machine, bag filter 1100 can then be lifted vertically through the catch basin inlet 9010 and placed, for example, on the ground. Formed of flexible material, bag filter can be squeezed through catch basin inlet 9010 if bag filter 1100 has expanded somewhat due to the accumulation of particulate matter and debris. Inlet 1115 or frame 1300 is then detached from the machine. To empty the contents of bag filter 1100, closed end 1105 is attached to a machine capable of lifting bag filter 1100 with its contents. As closed end 1105 is lifted above inlet 1115, particulate matter and debris collected in the bag will exit bag filter 1100 through inlet 1115. This procedure may be used to empty the particulate matter and debris, for example, onto the ground, or into a truck or other vehicle that can transport the particulate matter and debris for offsite disposal.

(49) With bag filter 1100 removed from catch basin 9000, particulate matter and debris collected in catch basin 9000 can be removed (e.g., using a vacuum truck to vacuum out the particulate matter and debris, or manual removal of the particulate matter and debris with a shovel or other suitable tool).

(50) Once particulate matter and debris has been removed from either or both of bag filter 1100 and catch basin 9000, bag filter 1100 can be re-installed as described above. In this manner, bag filter 1100 may be re-used. In some instances, bag filter 1100 and/or tent filter 1200 can be rinsed (e.g., with freshwater) from within to remove attached particular matter and/or debris before bag filter 1100 is reinstalled in catch basin 9000. The gap between bag filter 1100 and tent filter 1200 can also allow tent filter 1200 to be rinsed from outside inward (i.e., towards the center of the catch basin) as is discussed further with respect to FIG. 7.

(51) Tent filter 1200 can also be configured for ease of cleaning. For example, as discussed above, tent filter 1200 can be configured to provide a truncated conical surface between outer and inner portions 9005, 9007 of the cavity of catch basin 9000 such that the inner portion 9005 of the cavity of the catch basin 9000 is below as well as within the outer portion 9007 of catch basin 9000. Flow of runoff through tent filter 1200 can cause particulate matter to accumulate on what is, in effect, the underside of tent filter 1200. Thus, in the absence of internal water pressure, gravity will tend to pull accumulated particulate matter off tent filter 1200 into the bottom of the catch basin 9000 to settle. Spraying tent filter 1200 from the outer portion 9007 of the catch basin towards the inner portion 9005 of the cavity of the catch basin to backwash the tent filter is also aided by the effects of gravity.

(52) In some cases, system 1000 includes bag filter 1100 and tent filter 1200 jointly installed in catch basin 9000. Bag filter 1100 may be installed by mounting open end 1115 to a region of catch basin inlet 9010, or by attaching open end 1115 to frame 1300 (e.g., using ropes or chains), and mounting frame 1300 to region of catch basin inlet 9010. When installed, open end 1115 of bag filter 1100 should be suspended beneath catch basin inlet 9010, such that closed end 1105 reaches or extends beneath the standing water level inside catch basin 9000. Tent filter 1200 may be installed by attaching first end portion 1205 to either catch basin inlet 9010 or frame 1300, and by attaching second end portion 1210 to an inner surface 9030 of catch basin 9000 separated from catch basin inlet 9010. Second end portion 1210 may be attached using a support member 1400 that presses all or part of second end portion 1210 against inner surface 9030. Alternatively, second end portion 1210 may be attached to inner surface 9030 using fasteners (e.g., staples, hooks, nails, or adhesives). Additionally, second end portion 1210 may be attached to support member 1400, which may in turn be attached to inner surface 9030.

(53) In some systems, bag filter 1100 is used without tent filter 1200. In these embodiments, bag filter 1100 is generally as described above. However, once water, particulate matter, and debris enter catch basin 9000, there is no additional filter to help retain the particulate matter and debris in catch basin 9000. Similarly, in some systems, tent filter 1200 is used without bag filter 1100. In these embodiments, tent filter 1200 is generally as described above. However, the kinetic energy of water, particulate matter, and debris falling through catch basin inlet 9010 are not dissipated by bag filter 1100 and particulate matter and debris inside the catch basin may be re-suspended in the water. However, there is still the benefit of the rising water level increasing the distance between the more turbulent surface level and the volatile silt on the bottom of the catch basin increases.

(54) Various modifications may be made to the systems and methods described above. For example, bag filter 1100 may include a handle attached to closed end 1105 to aid in removal of particulate matter and debris as explained above. In another example, referring to FIG. 4, some embodiments of bag filters 1100 have only first bag region 1120 and second bag region 1125. In another example, referring to FIG. 5, in some embodiments bag filter 1100 have first region 1120 having a first nominal flow rate, a second region 1125 having a second nominal flow rate, and a plurality of intermediate bag regions 1135 located between first bag region 1120 and second bag region 1125 and having a plurality of nominal flow rates. The nominal flow rate of each of intermediate bag regions 1135 is greater than the nominal flow rate of the adjacent bag region in the direction of first bag region 1120, and is less than the nominal flow rate of the adjacent bag region in the direction of second bag region 1125. Thus, the various nominal flow rates of the various bag regions are aligned such that the lowest nominal flow rate occurs nearest closed end 1105 and the greatest nominal flow rate occurs nearest open end 1115. Each of the first, second, and plurality of intermediate bag regions, individually or collectively, may be equal or different in size.

(55) Referring to FIG. 6, in some embodiments, catch basin 9000 has an opening 6000 that allows water to flow out and return to groundwater. Opening 6000 may be a static portal, a valve, or another kind of opening. Opening 6000 may allow water to flow to a carrier medium 6010 such as a pipe, a French drain, gravel, sand, or another medium that can carry the flow of water. Further, opening 6000 may be configured to prevent backflow of water into catch basin 9000. In these embodiments, tent filter 1200 can be mounted to support member 1400 at a position in catch basin 9000 lower than opening 6000 so that unfiltered water does not flow into groundwater. Instead, water is filtered through region 1220 of tent filter 1200.

(56) In some embodiments, tent filter 1200 is connected to a separator skirt 6020 mounted to a support member 1410 just below catch basin outlet 9020. Separator skirt 6020 is configured so that the flow of particulate matter from catch basin 9000 into groundwater is reduced (e.g. limited or prevented). Instead, most or all particulate matter flows into catch basin outlet 9020. In these embodiments, separator skirt 6020 may be made of the same material as first filter region 1220 of tent filter 1200, providing greater filtration and a low nominal flow rate. Additionally, separator skirt 6020 may be made of or lined with an impermeable material and does not transmit water to catch basin 9000 such that only water that passes through panel 1220 enters the lower portion of the catch basin outside the filter that includes the infiltration outlet of the catch basin and ultimately exits through port 6000. The system shown in FIG. 6 includes a tent filter 1200. However, some systems include other filters. For example, the system shown in FIG. 6 can be implemented using a bag filter instead of or in addition to the tent filter 1200.

(57) Referring to FIG. 7, in some embodiments, a spray head 7000 is mounted on the interior of catch basin 9000. Spray head 7000 can spray a fluid 7010, e.g. water or a cleaning solution, onto a filter installed in the catch basin 9000. Some of the fluid (particularly the upper streams) from the spray head 7000 can penetrate the outer filter, reaching the surfaces of the inner filter and underside of outer filter. In the illustrated system, the filter installed in the catch basin 9000 is a tent filter 1200. Some systems include other filters. For example, the system shown in FIG. 7 can be implemented using a bag filter instead of or in addition to the tent filter 1200.

(58) The impact of liquid 7010 on surface 1215 of tent filter 1200 has a backwashing effect, so that particulate matter is loosened from tent filter 1200. Storm water can then flow through the filter more freely, impeded less by attached particulate matter. Spray head 7000 receives the liquid 7010 from a liquid supply pipe 7020 that leads to e.g. a water supply or water tank. In some embodiments, catch basin 9000 has more than one spray head 7000 so that liquid 7010 is sprayed on the filter 1200 and from multiple angles. In some embodiments, multiple taps are formed through walls of the catch basin with each tap leading to a spray head. In some embodiments, a single tap is formed through a wall of the catch basin with the single tap connected, for example, to piping extending around the interior wall of the catch basin to feed the spray heads.

(59) Referring to FIG. 8A, in some embodiments, tent filter 1200 is made up of panels 8000 that are rigid or semi-rigid and self-supporting. Panels 8000 are sized so that they can be individually lowered through inlet 9010 and rest on support member 1400. Each panel 8000 can have interlocking sides 8010 configured to connect to the interlocking sides of other panels 8000 comprising tent filter 1200. In some embodiments, interlocking sides 8010 are lined with zipper teeth and can be connected together using a zipper. FIG. 8B shows a top view of seven panels 8000 together comprising tent filter 1200.

(60) Some systems include a mechanism for shaking or otherwise moving filters installed in a catch basin. Shaking or movement of the filters can dislodge dried material (e.g. leaves, paper, and/or dried particles) from the filters to improve their flow characteristics.

(61) Referring to FIG. 9A, in some embodiments, a member 9100 (e.g., a lever) is mounted high in catch basin 9000 e.g., near or within inlet 9010. For example, lever 9100 could be attached to an inlet grate 9150 by a strap, by welding, or by another attachment method. A free end 9110 of lever 9100 is attached to the inside of surface 1215 of tent filter 1200 by connectors. In the illustrated system, the connectors are cables 9120 (e.g., flexible or semi-flexible cables) that extend from the free end 9110 of the lever 9100 to the tent filter 1200. Cables 9120 can pass through bag filter 1100, for example, cables 9120 can be threaded through holes or sleeves 9160 in bag filter 1100, or cables 9120 can pass through bag filter 1100 in a different manner. In some embodiments, the cables run outside the bag filter rather than through the bag filter. In some embodiments, each cable 9120 can be separated from lever 9100 to aid in the removal of inlet grate 9150. Some systems include other mechanisms for connecting the lever 9100 to the filter. For example, some systems include rigid rods extending between the lever 9100 and the filter. In some systems, lever 9100 is directly attached to a portion of the filter.

(62) Lever 9100 protrudes slightly above the road surface 9130 such that a tire 9140 rolling over the exposed end of lever 9100 causes the other end of the lever to lift rapidly, shake, or oscillate. Referring to FIG. 9B, the movement of lever 9100 pulls cables 9120 causing tent filter 1200 to shake, and the shaking action tends to release built-up particulate matter that may be affixed to surface 1215 of tent filter 1200.

(63) In some embodiments, the lever/activator mechanism is mounted to an upper inner surface of the catch basin 9000 rather than the removable grate. For example, a hole could be drilled through the roof of the catch basin inside or outside the filters with a rod extending through the hole. One end of the rod can protrude slightly above the road bed to contact vehicle tires as they pass and the other end of the rod can be connected a lever/activator mechanism. The connectors/cables go directly to the outside of tent 1200 in embodiments where the lever/activator mechanism is mounted outside the filters.

(64) Similar activator mechanisms can be mounted in piping such a storm sewers to move, shake, or vibrate other types of devices and filters including, for example, cartridge filters.

(65) Referring to FIG. 10A, in some embodiments, lever 9100 is attached to inlet grate 9150 covering inlet 9010. In some of these embodiments, inlet grate 9150 can have a convex shape and be made of a flexible or semi-flexible material. As shown in FIG. 10B, when a tire 9140 rolls over inlet grate 9150 in this configuration, inlet grate 9150 will flex downward and flatten under the pressure of the tire, causing lever 9100 to shake or oscillate. After the pressure of tire 9140 is alleviated, inlet grate 9150 can pop up to its original convex shape.

(66) Referring to FIG. 11, in some embodiments, the outer filter has a shape other than a tent. For example, the outer filter could be a cylindrical filter 1201. In these embodiments, cylindrical filter 1201 surrounds bag filter 1100 inside catch basin 9000. Cylindrical filter 1201 may extend to the bottom of catch basin 9000, or it may extend only partially into catch basin 9000. Cylindrical filter 1201 can generally have the same optional features or configurations as tent filter 1200.

(67) Catch basins have various configurations that depend on factors including where a specific catch basin is located in an overall storm sewer system. For example, most of the water passing through some catch basins comes from upstream portions of the storm sewer system rather than entering these catch basins from inlets open to the environment (e.g., curb inlets). Some treatment systems are configured to treat water entering catch basins from upstream portions of a storm sewer system.

(68) Referring to FIG. 12A, in some embodiments, inlet 9025 extends to penetrate tent filter 1200 so that inlet pipe 9025 discharges within the tent rather than into the outer portion 9007 of the cavity of catch basin 9000. As shown in FIG. 12B, in some embodiments, inlet 9025 is positioned towards the center of tent filter 1200. As shown in FIG. 12C, in some embodiments, inlet 9025 is positioned tangentially to the outer surface of tent filter 1200 such that if there is substantial flow of water into tent filer 1200, disruption to any sediments at closed end 1105 will be minimized.

(69) Referring to FIG. 12D, in some embodiments, inlet 9025 extends to penetrate bag filter 1100 so that inlet pipe 9025 discharges into and within the bag rather than the outer portion 9007 of the cavity of catch basin 9000. As shown in FIG. 12E, in some embodiments, inlet 9025 is positioned towards the center of bag filter 1100. As shown in FIG. 12F, in some embodiments, inlet 9025 is positioned tangentially to the outer surface of bag filter 1100 such that if there is substantial flow of water into bag filer 1100, disruption to any sediments at closed end 1105 will be minimized.

(70) In the embodiments shown in FIGS. 12A-12D, the filters can act as deflectors or weirs to control the flow characteristics of water entering catch basin 9000.

(71) Similar systems can be installed in catch basin that have an access cover rather than an upper inlet. For example, the inlet grate 9010 (e.g., in FIG. 12A) could be a manhole cover and the filter could be used for treating only water from upstream portions of a storm sewer system.

(72) Referring to FIG. 13A, in some embodiments, a lining 1600 is attached outside of tent filter 1200, spaced apart from tent filter 1200 by approximately inch to 3 inches. Lining 1600 has substantially similar shape as tent filter 1200, but sized large enough to provide the inch to 3 inch cavity. For example lining 1600 can provide a truncated conical surface or a truncated pyramid surface. The material properties of the lining can be substantially similar to those of the bag filter or of the tent filter. At the bottom, the second lining end 1610 can be sealed to either tent filter 1200 and/or second end portion 1210. At a lining top end 1605, lining 1600 can have a closure mechanism 1700 that can seal lining top end 1605 to tent filter 1200. For example, a closure mechanism 1700 could be Velcro, snaps, buttons, hooks, and/or a zipper. Some systems include a series of ribs positioned between the tent filter 1200 and the lining 1600 to help maintain a specific separation between the tent filter 1200 and the lining 1600. The width of the ribs is typically less than 3 inches. In some implementations, the ribs are tapered with points at the upper and lower ends and a maximum width between the pointed ends.

(73) Referring to FIG. 13B, closure mechanism 1700 can be opened so that filtration media 1800 can be disposed into the cavity between tent filter 1200 and lining 1600. As discussed above, the bottom seal between lining 1600 and tent filter 1200 and/or second end portion 1210 prevents filtration media 1800 from spilling from the bottom of the cavity. As shown in FIG. 13C, once the cavity between tent filter 1200 and lining 1600 is filled with filtration media 1800, the closure mechanism 1700 can be closed to prevent filtration media 1800 from spilling out into catch basin 9000. Filtration media 1800 in the cavity provides additional treatment for water that passes through the cavity.

(74) Additionally, in the event that bag filter 1100 fills with water and overflows, the overflowing water may flow down the outer surface of the tent filter 1200. As the water flows down the outer surface of the tent filter 1200, the water may flow through lining 1600 and filtration media 1800. Therefore, although the water may not pass through the entire system of filters by flowing out through them in the conventional manner, the water may receive some level of treatment as it flows down filtration media 1800.

(75) In effect, this system can act as a way of directing filtered water up and over annular weirs in order to send it down a long path of premium contact. In this embodiment, water flows down the outside of an inverted cone (i.e., tent filter 1200). In some embodiments, other configurations of filters (e.g., cylindrical filters or rectangular filters) can provide a similar feature. This can be particularly important in removing dissolved constituents (e.g., dissolved phosphorus or dissolved nitrogen) from water being treated.

(76) For example, it is generally accepted that about 50% of phosphorus pollution is particle bound and 50% is dissolved. Particle-bound phosphorus lines the surface of a particle and can be removed from runoff as the particle settles or is removed by filtration. However, dissolved phosphorus is not susceptible to removal through filtration or settling.

(77) Fine particles carry more phosphorus than coarser particles because they have more surface area per unit of mass. Fines are considered more of a problem because fine particles transport more phosphorus, carry it farther, and are easily re-suspended.

(78) For dissolved phosphorus, a desirable treatment approach is to first remove fines through settling or be filtration, then introduce a media that can adsorb the phosphorus as the water containing the dissolved phosphorus runs over the adsorbtive material. Removal increase with increased contact time between the water being treated and the media. Slow, thin sheet-flow of the water over the media is desirable, in particular, when the water flows through a long tortuous path. The outer surface of the filters in the systems (e.g. the outer tent filter surface) has a thin, sheet-flow that can be relatively slow.

(79) By incorporating an absorptive material (e.g., perlite, ground aluminum or an iron mix) on outer surfaces of the filters, the systems can provide a highly efficient sequential treatment using, for example, both filtration and absorptive removal of dissolved constituents as water being treated flows down the outside of the filters. In particular, the inverted cone filter, with its progressive filter sections (in relation to elevation) and progressive flow rate (in relation to head pressure) creates a good balance between physical treatment and contact time. For example, when a small storm only has water going though the low region, this water goes through the low media then turns downward and only has a few inches of contact distance before the water is out of the absorptive media. Even though the distance is low, the contact time can be acceptable as there is also a low volume of water being treated so the ratio of time per liter per surface contacted is acceptable. In larger storms, when the water is deeper in the cone, the water comes out of the filter and cascades down through the media on outside surfaces of the path is longer which helps as the contact time per liter per surface is less. The inner part of the filter can act as a place to let particles settle, and the cone can act as a weir to force some water back up and over the long route of treatment it needs in a higher flow situation.

(80) Filtration media 1800 can include activated carbon, anthracite, birm, calcite, filter sand, garnet, manganese greensand, MTM, coir fiber, resin based media, or similar type media. Filtration media 1800 is sized such that it is substantially larger than the porous holes in both lining 1600 and tent filter 1200. In some situations, the filtration media can be vacuumed out of the filter when it needs to be replaced.

(81) Referring to FIG. 13D and FIG. 13E, lining 1600 and tent filter 1200 may include multiple closure mechanisms 1700 to create a system of lining cavity regions 1850. Lining cavity regions 1850 can be sized based on the desired filtration properties. For example, three lining cavity regions can be created so that three different types of filtration media can be chosen based on the flow rates of the adjacent tent filer 1200 and lining 1600 materials. Although lining cavity regions as shown correspond to portions of tent filter 1200 and bag filter 1100 regions having different material properties (i.e. different flow rates), seals and closure mechanisms may be added throughout the lining 1600 at different locations based on desired cavity size. In addition to allowing filtration media 1800 having various material properties to be used, creating multiple lining cavity regions 1850 prevents filtration media 1800 from settling substantially towards the bottom of the cavity one large cavity. In some embodiments, lining material may have a system of regions with graduated nominal flow rates similar to the systems described above with respect to bag filter 1100 and tent filter 1200. For example, lining 1600 may have a first lining region 1620 adjacent to the second lining end 1610, a second lining region 1625 adjacent to lining top end 1605, and a third lining region 1630 located between first lining region 1620 and second lining region 1625. Each lining region has a corresponding nominal flow rate. Each nominal flow rate is relatively greater than the nominal flow rate of the adjacent lining region in the direction of second lining end 1610 and is relatively less than the nominal flow rate of the adjacent filter region in the direction of lining top end 1605.

(82) In some embodiments, lining 1600 may have only first lining region 1620 having first nominal flow rate. For example, each of the multiple lining cavities extends vertically from an upper end with an opening in the vicinity the top of the tent filter 1200 to a lower end in the vicinity the lower end of the tent filter 1200. Such vertically configured lining cavities (as indicated by the dashed lines on FIG. 13D) can be easily filled and emptied of media from their openings near the catch basin inlet. The lining cavities can be filled with a single type of mediatypically chosen with a porosity great enough that the mesh of the tent filter rather than the media limits the flow of water through the tent filter-lining cavity system.

(83) In some embodiments, lining 1600 may have more than three lining regions.

(84) The sizes of the various lining regions may be equal or different. For example, the sizes of any or all of the lining regions may be optimized for a given geographical region, locality, or climate, or for the needs of a particular catch basin, to ensure a proper balance between filtration and water flow.

(85) Some catch basins are configured with an outlet at the bottom of the catch basin that discharges to a storm sewer underneath the catch basin. Unlike the side-outlet catch basins described above, these bottom-outlet catch basins do not include a naturally formed sump. Systems can be configured to treat runoff collected and discharged by these bottom-outlet catch basins.

(86) FIG. 14A illustrates a catch basin 9100 configured with an outlet 9110 at the bottom of the catch basin 9100 that discharges to a storm sewer 9112 underneath the catch basin 9100. FIG. 14B illustrates a treatment system 9114 that includes a filter separating the catch basin inlet from the outlet 9110. In the illustrated embodiment, the filter is a tent filter 9116 that extends between support members 1400 secured to the edges of the catch basin inlet and support members 1400 secured to side walls of the catch basin. Like the tent filters described above, the tent filter 9116 can include multiple regions with different nominal flow rates that provide different degrees of filtration or can have a single material throughout the tent filter 9116.

(87) The tent filter 9116 is different from the tent filters described above in having a sleeve 9117 that provides a relatively open flow path that extends between a portion 9118 of the catch basin cavity outside of the tent filter and the outlet 9110 to the storm sewer 9112. The sleeve 9117 can be formed of the same material as the bottom region of the tent filter. Runoff passing through upper portions of the tent filter 9116 runs down the outside of the tent filter and flows out through the sleeve 9117. Runoff can also pass directly though sides of the sleeve 9117 and drain out of the catch basin.

(88) In some embodiments, the tent filter 1200 is formed from material whose coarsest mesh is small enough that the tent filter 1200 limits the movement of insects (e.g., mosquitos) through the filter. For example, in some embodiments, the largest opening in the bag or tent filter is 850 microns, which is the Apparent Opening Size (AOS) of the bypass region. This region is sewn on to the rubber seal that presses as a gasket/internal pipe seal to the top of the cast catch basin 9000. This can provide a membrane of material extending between the open ends that has an AOS no larger than 850 Microns. The filter (e.g., the bag filter) has a frame that is sandwiched in between the catch basin grate and the frame and this frame is connected to the 850 micron material using a system of that substantially seals to avoid any openings. In the illustrated system, the bag filter can prevent insects such as mosquitos from getting to standing water in the sump from the street/atmosphere above and the tent filter can prevent migration of mosquitos up through an outlet pipe as the mosquitos can't get to the sump even if it does get into the upper/outer region of the catch basin. Likewise, a mosquito cannot get through to the sump by entering a catch basin without protection which is upstream (in the storm sewer system) of the catch basin in which the filter system is installed.

(89) In the illustrated configuration, the filter 1200 and supports 1400 are attached directly to sides of the catch basin inlet (i.e., rather being suspended hanging below the inlet as in some embodiments described earlier in this disclosure). In this configuration, the tent filter can act a barrier limiting the movement of insects such as mosquitoes and flies into and through storm sewers. Referring to FIG. 15, a similar system can be installed with lower supports 1400 attached to the bottom of the catch basin 9100 rather than to the sides of the catch basin 9100. The tent filter is installed with the outlet 9110 from the catch basin outside the tent filter. In this configuration, the filter does not need to include a sleeve. Other filters (e.g., bag filters) can also provide insect control when appropriate filter material isolates the catch basin inlet from the catch basin outlet.

(90) Implementations of filter systems can include a combination of the features of the specific embodiments described above. FIG. 16 illustrates a treatment system 1950 installed in the side-outlet catch basin 1952. The treatment system 1950 includes an inner three-zone tent filter 1954 and an outer lining 1955. The inner three zone tent filter 1954 extends between upper supports 1400 secured to sides of the catch basin inlet and lower supports 1400 secured to side walls of the catch basin below an outlet pipe 1956. The outer lining 1955 is formed from an insect screen material. Ribs 1958 hold the center of the tent filter 1958 and the center of the outer lining 1955 apart from each other. In this embodiment, the maximum width of the ribs is approximately 2 inches. The ribs can extend vertically or horizontally but are more likely to be vertical not horizontal in practice. The ribs can be horizontal if they had holes like a truss so that a tube could descend from top to bottom along the entire length of the outside of tent 1200. Other spacers such as, for example, upholstery buttons or similar point based spacers can be used to control the position of the lining and the filter relative to each make it easier to line the outside of tent 1200 with granular media.

(91) Both the inner three-zone tent filter 1954 and the outer lining 1955 are attached to the upper supports 1400 and the lower supports 1400. In this embodiment, both the upper supports 1400 and the lower supports 1400 are stitched into rubber supports which are attached to the sides of the catch basin. The space between the tent filter 1954 and the outer lining 1955 is filled with a filter media. In the illustrated embodiment, the space is filled with kitty litter which can be effective in removing dissolved phosphorus, nitrogen, and/or hydrocarbons.

(92) Filter systems can also include other features. For example, the outside surface of filters (e.g., bag filters, tent filters, or other filters) can be lined with a sheet form media. Water running down the outside surface of the filter travels through this media as it runs down the outside of the filter. Materials can include, for example, steel wool and/or aluminum to reduce phosphorus, nitrogen, or other dissolved constituents. Accordingly, other embodiments are within the scope of the following claims.