The City of Chicago has enacted a Stormwater Management Ordinance in order to promote programs that minimize the negative stormwater impacts of new development and redevelopment. The City of Chicago is the permitting authority for all land disturbing activities and requires the land owner to maintain all on-site stormwater control facilities and all open space areas (e.g. parks or “green” areas) required by the approved stormwater control plan. The City of Chicago will only provide construction permits to projects that establish a plan to manage stormwater runoff occurring during the construction process. The City of Chicago, under the NPDES program, also has the authority to inspect properties for noncompliance and can issue a notice of violation (NOV) for any deficiency or infraction onsite. Property owners are responsible for the maintenance of any stormwater facilities or practices located on the property. The City of Chicago has the authority to inspect stormwater facilities and practices in order to ascertain that they properly maintained and functioning. Mismanagement of stormwater facilities and practices can be considered a public nuisance as it could potentially harm the water quality of the water bodies of the city or have other negative consequences.
Chicago Environmental Protection and Control
Public nuisance cessation and abatement.
For the purposes of the Environmental Protection and Control Chapter of this Code, “imminent and substantial risk to the public health or safety or to the environment” shall include a threat to human health or safety or to the environment that is expected to occur within a reasonably short time, or that is present now, although the impact of the threat may not be felt until later.
(b) Emergency cessation and abatement.
(1) Emergency cessation – Authority. The commissioner is hereby authorized to issue an emergency cessation order to any person who the commissioner concludes is (i) causing, creating or contributing to any activity or condition that poses an imminent and substantial risk to the public health or safety or to the environment; or (ii) operating a facility or conducting an activity without a required permit or other written authorization issued by the commissioner.
(2) Emergency abatement – Authority. In the event that the commissioner concludes that any person is causing, creating or contributing to any activity or condition that has created, or is creating, an imminent and substantial risk to the public health or safety or to the environment, then the commissioner may order such person to abate the risk within a time frame prescribed by the commissioner.
(3) Duty to comply. Upon service of an order issued under this subsection (b), the person to whom the order is issued shall immediately comply with the requirements of the order. The duty to comply with such order shall arise at the moment of service of the order and shall continue until the time of cancellation, if any, of such order by the commissioner, or until the order automatically expires in accordance with subsection (b)(9) of this section. Submittal of a demand for hearing as set out in subsection (b)(6) of this section shall not relieve any person of the duty to comply with the order issued by the commissioner.
(4) Authority to abate.
(i) If the person to whom an order was issued under this subsection (b) does not comply with the requirements in the order as ordered by the commissioner, then the commissioner may undertake any abatement activities reasonably necessary to correct any imminent and substantial risk to the public health or safety or to the environment.
(ii) Nothing in this subsection shall be construed to prevent the commissioner from acting without issuing an emergency abatement or emergency cessation order, where issuing such order is not practicable and the activity or condition poses a current threat to public health or safety or to the environment, nor shall this section be construed to deny any common law right to anyone to abate a nuisance.
(5) Cancellation of order. The commissioner shall cancel a cessation or abatement order issued by the commissioner in accordance with this subsection (b) when the commissioner determines that the person to whom an order was issued has complied with the requirements in the order as ordered by the commissioner. Cancellation of the commissioner's order shall be made in writing and shall be served in the same manner as an order or notice may be served.
(6) Demand for a hearing. The person to whom an order was issued pursuant to this subsection (b) shall have 14 calendar days from the service date of the order to notify the commissioner, on the appropriate form as provided by the commissioner, of her or his demand for a hearing. Failure to notify the commissioner of a demand for a hearing in accordance with this subsection shall constitute a waiver of the opportunity for a hearing.
(7) Initiation of a hearing. Within 7 calendar days of receiving a demand for a hearing on the appropriate form as provided by the commissioner, the commissioner shall initiate an administrative hearing in the department of administrative hearings, environmental safety hearings division, specifying the basis for the order, any related violations alleged in the order, and any allegation of noncompliance with such order. At the time of initiating such hearing, the commissioner shall serve notice upon the person demanding the hearing of the date, time, the location of the hearing, and the penalties for failure to appear at the hearing.
(8) Hearing. The hearing shall be commenced in the department of administrative hearings, environmental safety hearings division, no later than 14 calendar days after the date on which the commissioner received the demand for such hearing, unless a later hearing date is scheduled upon mutual consent of the parties. Upon the conclusion of the hearing, in addition to the finding of liability or no liability and imposing of fines and penalties consistent with this section, the administrative hearings officer shall have the authority to affirm or vacate the commissioner's order.
(9) Expiration of order. If a hearing is not initiated or commenced in accordance with the terms set out in subsection (b)(7) or subsection (b)(8) above, then the order that would have been the subject of such hearing shall expire at 11:59 P.M. on the fourteenth calendar day after the date on which the commissioner received notice of the demand for a hearing or at 11:59 P.M. on the hearing date scheduled upon mutual consent of the parties.
(c) Non-emergency cessation and non-emergency abatement.
(1) Non-emergency cessation – Authority. The commissioner is hereby authorized to issue a non- emergency cessation order to any person, in the event that the commissioner determines that any such person is violating any of the provisions of this Code which are under the jurisdiction of the commissioner or the rules and regulations promulgated thereunder or the conditions of any permit or authorization issued thereunder, but such violation does not pose an imminent and substantial risk to the public health or safety or to the environment as defined above.
(2) Non-emergency abatement – Authority. If the commissioner determines that any person is violating any of the provisions of this Code which are under the jurisdiction of the commissioner or the rules and regulations promulgated thereunder or the conditions of any permit or authorization issued thereunder, but such violation has not created, or is not creating, an imminent and substantial risk to the public health or safety or to the environment as defined above, then the commissioner may provide the person with a written order to address and correct the violation(s) within a time frame prescribed by the commissioner.
(3) Cancellation of order. The commissioner shall cancel a cessation or abatement order issued by the commissioner in accordance with this subsection (c) when the commissioner determines that the person to whom an order was issued has complied with the requirements in the order as ordered by the commissioner. Cancellation of the commissioner's order shall be made in writing and shall be served in the same manner as an order or notice may be served.
(4) Duty to comply and demand for a hearing. Any person to whom the commissioner issues an order under this subsection (c) shall comply with such order as ordered by the commissioner; provided, however, that if the person contests the order, she or he shall notify the commissioner within 15 calendar days from the service date of the order, on the appropriate form as provided by the commissioner, of her or his demand for a hearing. If the person notifies the commissioner of her or his demand for a hearing in accordance with this subsection, the order shall be stayed by the commissioner until the department of administrative hearings issues a final determination finding the person liable for one or more of the violations, or not liable for any of the violations, specified in the commissioner's order, or affirming or vacating the commissioner's order. Failure to notify the commissioner of a demand for a hearing in accordance with this subsection shall constitute a waiver of the opportunity for a hearing, and the person to whom the commissioner issued an order shall comply with the order and shall not recommence any operations or activities prohibited by such order unless the order is cancelled by the commissioner.
(5) Initiation of a hearing. Within 30 calendar days of receiving a demand for a hearing on the appropriate form as provided by the commissioner, the commissioner shall initiate an administrative hearing in the department of administrative hearings, environmental safety hearings division, specifying the basis for the order, and any related violations alleged in the order. At the time of initiating such hearing, the commissioner shall serve notice upon the person demanding the hearing of the date, time, the location of the hearing, and the penalties for failure to appear at the hearing. Upon the conclusion of the hearing, in addition to the finding of liability or no liability and imposing of fines and penalties consistent with this section, the administrative hearings officer shall have the authority to affirm or vacate the commissioner's order.
(6) Expiration of order. If a hearing is not initiated in accordance with the terms set out in subsection (c)(5) above, then the order that would have been the subject of such hearing shall expire at 11:59 P.M. on the thirtieth calendar day after the date on which the commissioner received notice of the demand for a hearing.
(7) Authority to abate. If (i) the person to whom an order was issued under this subsection (c) does not comply with the requirements in the order as ordered by the commissioner, and does not notify the commissioner of her or his demand for a hearing as provided in subsection (c)(4), or (ii) if any person does not comply with the requirements in the order after the department of administrative hearings has affirmed the commissioner's order, and such order has not been stayed by a court of competent jurisdiction, then the commissioner may proceed to control, remove, dispose or otherwise abate the nuisance.
(d) Order or notice.
(1) Content. The order or notice issued by the commissioner under this section shall (i) be in writing; (ii) specify the activities to be ceased or the nuisance to be abated or the violation(s) to be corrected; (iii) specify the time frame within which the activities must be ceased or the nuisance must be abated or the violation(s) must be corrected; (iv) specify any related violations, for which the commissioner seeks any remedy, that the person to whom such order or notice is issued is alleged to have committed; (v) inform such person of the time and manner to request a hearing before the department of administrative hearings, to present evidence as to why the person is not liable for all or any of the violations specified in the commissioner's order, and/or why the order should be vacated, and to contest any allegations specified in the order; and (vi) inform such person of the consequences of failing to request a hearing, and the consequences of failing to comply with the order or notice.
(2) Manner of service. An order or notice issued by the commissioner under this section shall be served (i) by first class or priority mail, or express courier service at the person's residence address or, if the person is a business entity, at any mailing address identified for its registered agent or at its principal place of business; or (ii) by facsimile transmission or e-mail at the person's facsimile or e-mail address or, if the person is a business entity, at the facsimile or e-mail address identified for its registered agent; or (iii) by personal service, including personal service upon an employee or agent of the alleged violator at a place of business of the alleged violator or otherwise if such service is reasonably calculated to give the alleged violator actual notice; or (iv) if service cannot be made by either of (i) or (ii) or (iii) above, when the alleged violator is the owner or manager of the property by posting a copy of the order or notice on the front entrance of the building or other structure where the violation is found, or if the property is unimproved or fenced off, by posting a copy of the order or notice in a prominent place upon the property where the violation is found.
(3) Date of service. An order or notice issued by the commissioner under this section shall be deemed served (i) four days after mailing if issued by first class mail, (ii) upon delivery confirmation or four days after delivery to the United States Postal Service for delivery by priority mail with delivery confirmation if issued by priority mail, whichever occurs sooner, (iii) upon delivery confirmation or four days after delivery to an express courier service if issued by express courier service, whichever occurs sooner, (iv) at 9:00 A.M. on the next business day if issued by facsimile transmission or e-mail, (v) upon delivery if issued by personal service, or (vi) upon posting of the copy of the order or notice if issued as provided in subsection (d)(2)(iv) above.
(e) Penalty, cost recovery and remedies.
(1) Penalty. Failure to comply with an order or notice issued under this section constitutes a violation of this section and is a separate and distinct violation from any related or unrelated violations of any other provision of this Code. Any person who violates subsection (b) of this section shall pay a penalty of $5,000 per day for every day the person is in violation; and any person who violates subsection (c) of this section shall pay a penalty of $500 per day for every day the person is in violation. Such person incurs daily penalties for her or his violations of an order or a notice during the pendency of that order or notice, regardless whether that order or notice is ultimately cancelled or modified by the commissioner.
(2) Cost recovery. The city shall be authorized to bring a civil action to recover penalties from the person to whom an order or notice was issued under this section, and up to the amount of three times the abatement costs incurred by the department plus its attorney fees may be recovered in an appropriate action instituted by the corporation counselor or in a proceeding initiated by the commissioner at the department of administrative hearings.
(3) Liability. In addition to the penalties set forth herein-above, any person adjudicated liable for any related or unrelated offenses alleged by the commissioner in an administrative hearing held pursuant to this section shall also be liable for all applicable penalties for those violations.
(4) Injunction. In addition to any other remedies, penalties or means of enforcement, the commissioner may request the corporation counsel to make application on behalf of the city to any court of competent jurisdiction for an injunction requiring compliance with this section or for such other order as the court may deem necessary or appropriate to secure such compliance.
Enforcement – Interference with inspection.
The commissioner, or anyone authorized to act for him, in the performance of his duties and for the purpose of enforcing and administering this chapter or any order, regulation or rule promulgated pursuant thereto, or for the purpose of obtaining facts with respect to any complaint or noncompliance, is hereby authorized and empowered to enter into any building, structure, establishment, premises or enclosure or other place at all reasonable hours for the purpose of inspecting any regulated equipment, area, site, or facility. If any person in any way denies, obstructs or hampers such entrance or inspection or refuses to provide requested information during inspection, the commissioner is hereby authorized to refuse the issuance of any certificate or permit for any regulated equipment, area, site, or facility with respect to which entrance or inspection has been denied in the event one has not been issued; or to revoke any outstanding certificate or permit issued for such regulated equipment, area, site, or facility.
Except as otherwise provided herein, no person shall discharge or cause to be discharged any of the following described wastes or waters into any sewer, watercourse, natural outlet or waters within or partially within or adjoining the boundaries of the City of Chicago:
(1) Maximum concentrations acceptable for discharge into the sewage system of the City of Chicago shall be as set forth by the Metropolitan Water Reclamation District ordinance titled the Sewage and Waste Control Ordinance enacted September 18, 1969, and as amended from time to time.
(2) Any discharge of wastes or water into a sewer which terminates in or is a part of the sewage system of the City of Chicago must not contain the following:
(a) Water or wastes containing more than 100 parts per million (833 pounds per million gallons) of fats, oils or greases if such water or wastes are in the opinion of the commissioner sufficient (1) to interfere with the biological processes of a sewage treatment plant, (2) interfere with proper operation of the sewage works, (3) cause obstruction to flow in sewers or (4) cause pollution as herein defined;
(b) Liquids, solids or gases which by reason of their nature or quantity are sufficient to cause fire or explosion or be injurious in any way to the structures making up the sewage works or to the operation of the sewage works;
(c) Noxious or malodorous liquids, gases or substances which whether singly or by interaction with other wastes are sufficient to create a public nuisance or hazard to life or are sufficient to prevent entry into the sewers for their maintenance and repair;
(d) Water or wastes containing toxic substances in quantities which are sufficient to pose a hazard to life or interfere with the biological processes of the sewage treatment works;
(e) Garbage that has not been ground or comminuted to such a degree that all particles will be carried freely in suspension under conditions normally prevailing in public sewers with no particle greater than one-half inch in dimension;
(f) Radioactive wastes unless they comply with the Atomic Energy Commission Act of 1954 (68 Stat. 919 as amended and Part 20, Subpart D – Waste Disposal, Section 20.303 of the regulations issued by the Atomic Energy Commission) or amendments thereto;
(g) Solid or viscous wastes which cause obstruction to flow in sewers or other interference with the proper operation of the sewerage system or sewage treatment works, such as grease, uncomminuted garbage, animal guts or tissues, paunch manure, bone, hair hides, fleshings, entrails, feathers, sand, cinders, ashes, spent lime, stone or marble dust, metal, glass, straw, shavings, grass clippings, rags, spent grain, waste paper, wood, plastic, gas tar, asphalt, residues, residues from refining or processing of fuels or lubricating oil, gasoline, naphtha and similar substances;
(h) Liquids or vapors having a temperature higher than 150 degrees Fahrenheit at the point of entrance into a public sewer;
(i) Waters or waste-containing substances which are not amenable to treatment or reduction by the sewage treatment process employed or are amenable to treatment only to such degree that the water reclamation plants effluent cannot meet the requirement of other agencies having jurisdiction over discharge to the receiving waters;
(j) Excessive discoloration (such as but not limited to dye waste and vegetable tanning solutions);
(k) Mercury as Hg. Concentrations of mercury shall not exceed the standards set forth in the Illinois Pollution Control Board's Mercury Regulation No. R70-5; adopted March 31, 1971.
(3) The commissioner and the commissioner of health shall have authority to enforce the provisions of this section.
Gauging and sampling.
The commissioner shall have the right to enter and set up, on the owner's property, such devices as may be necessary to conduct a gauging and sampling operation after first giving ten days' advance notice of his intention so to do. While performing said gauging and sampling, the commissioner, his representative or anyone performing said work in his behalf, shall observe and comply with all safety rules applicable to the premises, established by the said owner or occupant.
The commissioner is hereby authorized to make arrangements for the Metropolitan Water Reclamation District, without incurring any legal or financial obligation upon the City of Chicago, to undertake and conduct such gauging and sampling operations, in its behalf; and to provide the necessary devices and facilities as well as the personnel and also to make the analyses of samples of such wastes, as hereinafter provided, in its own laboratories and other facilities or equipment; provided, that no such arrangements with the district shall place any personnel of the district under the control of the commissioner or cause such personnel of the district to be treated as employees of the City of Chicago for any purpose whatsoever.
POLLUTION OF WATERS
Disposal in waters prohibited.
No person shall throw, discharge, dump, dispose or deposit, or cause, suffer, allow or procure to be thrown, discharged, disposed or deposited in Lake Michigan within three miles of the corporate limits or in any other waters within the corporate limits any waste or material of any kind unless such person has obtained (a) permits pursuant to the Clean Water Act from all applicable federal or state agencies and (b) all other necessary approvals and permits from federal, state and local regulator bodies or special districts.
(a) (1) Violations of Section Disposal in waters prohibited shall be punished by a penalty of not less than $1,500.00 and not more than $2,500.00 for the first offense, not less than $2,500.00 nor more than $4,000.00 for the second offense, and not less than $4,000.00 nor more than $10,000.00 for each third and subsequent offense, or may be imprisoned for not more than six months, or may be ordered to perform up to 200 hours of community service, or any combination thereof. Each day that the violation continues shall be deemed a separate offense.
(b) In addition to any other penalties imposed under this section the registered owner of record of any vehicle who knew or should have known that his or her vehicle was used in violation of Section Disposal in waters prohibited shall be jointly and severally liable with any person operating or in control of the vehicle at the time of the violation.
(c) In addition to any other penalties imposed under this section, the commissioner shall have the authority to issue an emergency or a non-emergency cessation order in accordance with the provisions of this Code to stop any person from proceeding with any activity regulated under Section Disposal in waters prohibited when the commissioner has reason to believe that such activity either is proceeding in violation of any provision under those sections or is otherwise in contravention of the public interest.
(d) (1) Emergency abatement. In the event that the commissioner determines that any activity in violation of Section Disposal in waters prohibited has created, or is creating, an imminent and substantial risk to the public health or safety or to the environment, then the commissioner may issue an emergency abatement order or may abate the nuisance in accordance with the provisions of this Code.
(2) Non-emergency abatement. In the event that the commissioner determines that any activity in violation of Section Disposal in waters prohibited has not created, or is not creating, an imminent and substantial risk to the public health or safety or to the environment, the commissioner may provide the owner of the vehicle, the operator of the vehicle or any other person involved in the performance of the subject activity with written notice to abate the nuisance within a time frame prescribed by the commissioner. In the event that any person fails to abate such nuisance in accordance with the commissioner's notice to abate, the commissioner may proceed to control, remove, dispose or otherwise abate the nuisance in accordance with the provisions of this Code.
(3) In addition any other penalties imposed in this subsection (a), the city shall be entitled to recover a penalty or cost as provided in this Code.
(f) (1) In addition to any other penalty imposed in this section, the owner of record of any motor vehicle used in violation of Section Disposal in waters prohibited shall be liable to the city for an administrative penalty of $500.00 plus any applicable towing and storage fees. Any such vehicle shall be subject to seizure and impoundment pursuant to this section.
(2) Whenever a police officer has probable cause to believe that a vehicle is subject to seizure and impoundment pursuant to this section, the police officer shall provide for the towing of the vehicle to a facility controlled by the city or its agent. When the vehicle is towed, the police officer shall notify any person identifying himself as the owner of the vehicle or any person who is found to be in control of the vehicle at the time of the alleged violation, if there is such a person, of the fact of the seizure and of the vehicle owner's right to request a preliminary hearing.
(g) The city may obtain permanent or temporary injunctive relief in the Circuit Court of Cook County, Illinois, for any violation of Section Disposal in waters prohibited.
BEST MANAGEMENT PRACTICES
“Green” roofs are layers of living vegetation installed on top of buildings, from small garages to large industrial structures. They help manage stormwater and contribute to improved water quality by retaining and filtering rainwater through the plant’s soil and root uptake zone. The water that does leave the roof is slowed, kept cooler and is filtered to be cleaner. Green roofs can also further insulate the building, reducing cooling and heating costs.
Key considerations for implementing green roofs include the structural and load-bearing capacity of the building, plant selection, waterproofing, and drainage or water storage systems. The quantity of rainfall retained or detained by a green roof can vary. For small rainfall events little or no runoff will occur and the majority of the precipitation will return to the atmosphere through evaporation and transpiration. It has been estimated that green roofs, in comparison to conventional roofs, can reduce cadmium, copper and lead in runoff by over 95 percent and zinc by 16 percent; nitrogen levels also can be diminished.
In addition to the stormwater benefits, green roofs extend the life of roofs two to three times. They can help preserve habitat and biodiversity in an otherwise sterile urban environment. Green roofs can also improve air quality by helping to reduce the “urban heat island” effect. Finally, they can provide garden areas and attractive views for other buildings.
Once a green roof is well established, maintenance requirements are usually minimal. Maintenance requirements may include inspection of the roof membrane and drainage flow paths. Some watering may be required during the first few years when root systems are getting established. Depending on the dimensions of the planting, some weed removal may be necessary as well. Of course, the more complex the garden, the more it needs to be maintained like a typical garden.
DOWNSPOUTS, RAIN BARRELS AND CISTERNS
Traditionally, roof runoff in Chicago has been routed via downspouts directly into the sewer system. However, the City of Chicago encourages the careful disconnection of downspouts so that roof runoff can flow directly into vegetated areas. There are several options for doing this:
- Runoff can be sheeted across the lawn.
- Runoff can be routed via a surface swale into a rain garden or onsite detention or retention facility.
- Runoff can be temporarily stored in rain barrels or cisterns.
Rain barrels can effectively capture and store the runoff from small to moderate storms. The stored water then can be used to irrigate lawns and landscaped areas in between storm events.
The effectiveness of rain barrels (or cisterns) is a function of their storage volume in comparison to the size of the roof. In a simple residential example, a 1,200 square foot roof could utilize 55-gallon barrels to store runoff from downspouts at the four corners of the house. The resultant storage is equivalent to about 0.3 inches of runoff. While this volume will not substantially reduce flooding from large storms, it can considerably reduce direct runoff from smaller storms and divert water from the combined sewer system. The actual effectiveness of this approach will depend on the regular draining of rain barrels (such as for irrigation) between storm events. In that respect, rain barrels are most effective when used during the growing season.
Occasional cleaning may be necessary to remove debris, such as leaves, coming off the rooftop. A mesh filter can be inserted at the top of a rain barrel. The barrel must be sealed during the warm months of the year to avoid mosquito breeding. To avoid freezing, the rain barrel should be drained prior to winter.
Permeable paving refers to paving materials – typically concrete, stone or plastic – that promote absorption of rain and snowmelt. The discussion that follows focuses primarily on one form of permeable pavement – paving blocks and grids, as they are the most common and available type of permeable paving. These modular systems contain openings that are filled with sand and/or soil. Some can support grass or other suitable vegetation, providing a green appearance. A portion of rainfall is trapped in the block's depressions and infiltrates into the underlying soil.
Permeable paving is effective in reducing the quantity of surface runoff, particularly for small to moderate-sized storms. It also reduces the runoff pollutants associated with these events. Permeable paving in Chicago will be most effective in areas closer to Lake Michigan that are underlain with sandy, permeable soils. Effectiveness can be improved by designs that:
- maximize the openings in the paving material and
- provide an effective permeable sub-layer (e.g., at least 12 inches).
Permeable paving may have aesthetic and marketing advantages over conventional paving, depending on the materials selected. Vegetated pavers, in particular, could substantially improve the aesthetic appeal of paved areas. Vegetated pavers also can be effective in reducing the “urban heat island” effect.
Vegetated paving blocks may require occasional mowing. Snow plowing may require special care due to the slightly uneven surface of the pavement.
Natural landscaping refers to the use of native vegetation – particularly prairie, wetland and woodland species – on a development or redevelopment site. Native vegetation is a low-cost alternative to traditional landscaping that utilizes turf grass and ornamental plantings.
A site that is naturally landscaped will produce substantially less stormwater runoff than a conventional landscape. Native vegetation enhances both absorption of rainfall and evaporation of soil moisture due to extensive root systems that extend down 3 to 10 feet or more. In contrast, the root zone of turf grass typically extends only about 3 to 4 inches. The benefits of natural landscaping are enhanced if runoff from impervious surfaces is routed across native vegetation buffer strips. A local residential site assessment indicated that annual storm runoff volumes from a residential development could be reduced by as much as 65 percent by utilizing swales and filter strips with native wet prairie and prairie vegetation. Similarly, natural landscaping reduces pollutants associated with urban runoff. In the residential site assessment, it was estimated that removal rates for suspended solids and heavy metals (such as cadmium and lead) could be as high as 80 percent and removal rates for nutrients (such as phosphorus and nitrogen) could be as high as 70 percent for a residential development utilizing natural drainage and native landscaped filter strips.
In addition to reducing stormwater runoff, natural landscaping provides a host of other benefits. Deep-rooted native plants effectively stabilize soils and prevent erosion along streambanks and detention basin edges. The reduced maintenance needs of natural landscaping not only save money, but also reduce air, water and noise pollution. Natural landscaping also provides habitat for native and migrating birds, butterflies, and insects. Natural landscapes, especially trees, also moderate temperature extremes (such as the “urban heat island” effect), resulting in reduced heating and air conditioning costs. Finally, natural landscaping provides four seasons of color and textures not commonly found in conventional landscapes and requires less maintenance over time.
Natural landscaping requires much less maintenance – less irrigation, mowing, fertilizer and pesticides – than conventional landscaping. Natural landscape maintenance typically involves annual mowing or controlled burning. Burning may not be possible on small lots but it is one of the best methods of maintaining natural landscaping. Some initial watering and spot spraying to control invasive weeds also may be needed, but this need diminishes rapidly once the natural landscape is well established (generally within 3-4 years).
Filter strips are vegetated areas that are designed to receive runoff from adjacent impervious surfaces. They work by slowing runoff speed, trapping sediment and other pollutants, and providing some absorption. While frequently planted with turf grass, filter strips may also employ native vegetation, which is more effective in removing nutrients. Filter strips can reduce both the rate and volume of stormwater runoff on a site. This is achieved principally by absorbing runoff into the soil.
Well maintained filter strips can be very effective in reducing runoff volumes, particularly when the impervious drainage area is not overly large (such as more than 4 to 5 times the filter strip area.) Filter strips are most effective in reducing surface runoff volumes – by up to 40 percent – for small storm events (storms up to the magnitude that may occur, on average, once every year or every other year).
Filter strips remove suspended solids through settling and filtration. Dissolved pollutants are removed and/or transformed as runoff infiltrates into the ground. Effectiveness is improved when there is dense vegetation. The use of native vegetation can provide additional benefits for pollutant filtering and runoff absorption. The plants selected should be able to withstand flowing water, and both wet and dry periods. A properly designed and maintained filter strip may remove up to 70 percent to 95 percent of suspended solids and metals (such as cadmium and lead), 25 percent to 65 percent of nutrients (such as phosphorus and nitrogen), and biochemical oxygen demand (the degree of organic pollution in water leading to the depletion of oxygen). However, soluble inorganic compounds (most notably road salt) are generally not well removed in the soil and will eventually migrate downstream or into deep groundwater.
Filter strips function best when applied on gentle slopes, thereby keeping runoff speed low and maximizing opportunities for absorption of runoff and filtering of pollutants. The longer the water moves through a treatment such as this, the more it can be absorbed and the cleaner it will get. Filter strips must disperse the flow as evenly as possible to avoid straight, deep channels, which can reduce effectiveness. Where feasible, a filter strip width of at least 20 feet is recommended, although narrower widths can be effective on flat slopes.
Typically, maintenance involves normal activities such as mowing, trimming, removal of invasive species and additional planting if necessary.
BIOINFILTRATION: RAIN GARDENS
Bioinfiltration systems are shallow, landscaped depressions used to promote absorption and infiltration of stormwater runoff. This management practice is very effective at removing pollutants and reducing the volume of runoff, especially when used for parking lot islands. Stormwater flows into the bioinfiltration area, ponds on the surface, and gradually infiltrates into the soil bed. Filtered runoff is infiltrated into the surrounding soils via an absorption basin or trench. Excess water can be collected by an under-drain system and discharged to the storm sewer system or directly into receiving waters. Bioinfiltration systems typically are designed to store and treat runoff from relatively small storms, such as those that occur every year or every other year. Bioinfiltration systems should be located at least 10 feet away from buildings to ensure water does not drain into the foundations. Ideally, pretreatment should be provided to remove suspended solids from the runoff before it enters the system.
A rain garden is a simple form of bioinfiltration that typically relies on the underlying soils for drainage. Therefore it may not function properly if underlying soil is compacted by heavy equipment and/or its absorption rate is slow. Where appropriate, however, rain gardens can be fitted with French drains, or other types of underdrains, to move more water through the soil.
Rain gardens can be aesthetically pleasing. The plants provide food and shelter for many birds, butterflies, and beneficial insects, such as dragonflies, which eat mosquitoes. Plants can include a combination of shrubs, grasses and flowering perennials where the soil medium is between 6 and 8 inches deep. Ideally, plants should consist of native wetland and prairie grasses, and wildflowers. Suggested designs incorporate perennial flowers in the spring and summer, and vividly colored or patterned shrubs and grasses in the fall and winter. Some suggested plants for rain gardens include: Black-eyed Susan, Butterflyweed, Golden Alexander, Obedient Plant, Purple Coneflower, Spiderwort, Wild Columbine and Wild Geranium.
Bioinfiltration maintenance includes periodic inspection to ensure the system is operating properly, along with management of the vegetation. If a practice fails due to clogging, rehabilitative maintenance will restore it to proper operation. Incorporating pretreatment helps to reduce the maintenance burden of bioinfiltration and reduces the likelihood that the soil bed will clog over time. Rain garden maintenance is similar to that for a typical garden - including weeding and reestablishing plants as necessary. Periodically removing sediment may be required to ensure the proper functioning of these systems. It is best for runoff to be pretreated via swales and/or filter strips before entering the rain garden to avoid sediment accumulation. Plants should be selected to reduce maintenance needs and to tolerate snow storage and winter salt and sand, where appropriate.
A swale is a broad, vegetated channel used for the movement and temporary storage of runoff. Swales also can move a portion of the runoff into the ground and filter out runoff pollutants. Drainage swales that are planted with native vegetation are commonly called bioswales. Swales can be effective alternatives to enclosed storm sewers and lined channels, where their only function is to rapidly move runoff from a developed site. On some sites, natural drainage courses may still be present and it is recommended that they be retained as part of the site drainage plan. Drainage swales are different from filter strips in that swales are primarily used for conveying water.
In contrast to conventional curb-and-gutter/storm sewer systems, swales can reduce both the rate and volume of stormwater runoff on a site. Since this is achieved via absorption of runoff into the soil, swales in sandy soils will be much more effective than swales in clay soils. Swales are most effective in reducing runoff volumes for small storm events and on an annual basis can reduce storm runoff volumes by up to 15 percent in clay soils.
Pollutant removal rates in swales are highly variable depending on the condition of the swale, particularly its slope, soils, and vegetation. Estimated removal rates range from 30 percent to 70 percent of suspended solids and metals (such as cadmium and lead) and 10 percent to 30 percent of nutrients (such as phosphorus and nitrogen), biochemical oxygen demand, and other organic compounds. As discussed earlier, soluble inorganic compounds (most notably road salt) generally cannot be removed in the soil and will eventually migrate downstream or into deep groundwater.
Swales can provide limited wildlife habitat when planted with native vegetation. Preserving existing drainage-ways on a development site also protects aquatic habitat.
Drainage swales may require periodic cleaning but this cost should be minimized if upstream sources of sediment, particularly from construction activities, are well controlled. In comparison, storm sewer catch basins need to be cleaned periodically and manholes, storm sewer pipes, and curbs will need occasional repair.
Another maintenance issue sometimes raised for swales is ponding water and the potential to breed mosquitoes. This can be avoided by providing adequate slopes and/or underdraining to avoid ponding. Alternatively, the swale can be vegetated with wetland plants that can aid in the evaporation of water and provide habitat for mosquito predators such as dragonflies.
NATURALIZED DETENTION BASINS
Conventional detention is designed to prevent flooding by temporarily storing stormwater runoff and releasing it gradually to the downstream drainage system. Naturalized detention is intended to serve multiple functions, in addition to flood prevention, including pollutant removal and creation of wildlife habitat (where appropriate). Natural detention basin designs emulate natural lake or wetland systems by utilizing native plants along the water's edge and on side slopes. The design generally incorporates flat slopes at the edge of the water or wetland, shallow zones of emergent vegetation at the edge of wet basins, and a combination of vegetated and open water areas in wetland basins.
Effective detention designs will dramatically reduce runoff rates and prevent most increases in flooding associated with new development. However, unless underlying soils are highly permeable, detention will not significantly reduce flood volumes. The greatest benefit of naturalized designs is the reduction of runoff pollutants. Suspended sediments and attached pollutants, which are removed primarily by settling, can be reduced by 60 percent to 90 percent. Some dissolved pollutants, including nutrients and organic matter, can be reduced by 40 percent to 80 percent. Because wet basins are more effective at removing pollutants, in some instances they are a beneficial alternative to dry bottom basins.
Naturalized basins also will not experience shoreline erosion, further improving water clarity. Naturalized detention also can provide desirable habitat for birds and aquatic organisms and at the same time discourage nuisance populations of Canada geese that are commonly found around conventional basins. In addition, many property owners prefer the appearance of a well-designed natural basin over the more manicured look of a conventional basin (such as coarse gravel shorelines and/or concrete channels), thereby enhancing property values.
Conventional basins require regular mowing of side slopes and/or basin bottoms. In contrast, naturalized detention basins typically require only annual (or less frequent) mowing once the vegetation is established. Also, because native vegetation provides effective shoreline stabilization, there should be little need to repair shoreline erosion problems commonly found in conventional wet basins. Other maintenance concerns – occasional sediment removal and trash control – are similar for naturalized and conventional basins.