Drain tiles are located on properties throughout the County and play a critical component in site drainage and flood storage.  Consequently, we feel it is important to take their presence into consideration when projects are being developed to accommodate, bypass, modify, or abandon  them in a manner that will not impact onsite or offsite areas in ways that were not expected.  The consulting team thinks that drain tile survey requirements are best handled under Article 5, for sites whose immediate use is agriculture.  Attached are draft provisions.  We are looking for any feedback regarding this requirement.

Drain Tile Draft Provisions

For Stormwater Management, comments have been received from March through August 2010 regarding removal rates and efficiencies, the first flush or Water Control Volume, BMP selection, and the recommendation that a fee-in-lieu option be considered. The draft ordinance proposes 80% TSS removal for new development and 40% TSS removal for redevelopment. A variety of BMPs will be available to meet these requirements so that the best combination of BMPs can be chosen for the site and receiving waters. For the DuPage County Ordinance Update, a Water Control Volume will be required and will depend on the impervious area of the site. BMPs may provide any of the required Water Control Volume. The Water Control Volume will be calculated as the product of the applicable impervious area and the specified rainfall depth. These factors vary by development size and type. The Water Control Volume will be held onsite for infiltration or evapotranspiration, or released over 48 hours where the soils are inappropriate. For smaller sites, it is proposed that the 100 year detention requirement be eliminated in order to balance the costs of stormwater infrastructure. A fee-in-lieu program is being considered for water quality BMPs.

For Wetlands, comments have been received regarding riparian buffers, riparian habitat, manmade wetland requirements, temporary impacts and restoration to wetlands, wetland delineation, and critical wetland definition.

• Given that riparian areas are a form of buffer, riparian buffers will be combined with wetland buffers since it makes more sense to regulate all buffers under one section of the ordinance instead of having two sections which would nearly mirror each other.
• Wetland buffers are 50 and 100 feet.  We selected 50’ because that is comparable to a regulatory wetland buffer.  If a stream has critical wetland associated with it then a 100’ buffer would apply.  Buffers of wider widths become more of a land use or tree protection issue.  Based on research, the greatest effectiveness is in the 50-100’ range.  Widths greater than that have a diminishing return of effectiveness as compared to the constraint placed on development of the land.
• The jurisdiction of wetlands will follow the Clean Water Act.  If an area is abandoned and it converts to wetland regardless of how it came to be it would be regulated.  If the area is a constructed facility that has not been abandoned and requires maintenance, for example, that would be allowable.  If an area is desired to be filled that has not been abandoned and all other aspects of the Ordinance can be met, then the area could be filled as it would not be a regulated area.
• Critical wetlands status will be applied using either the wetland Qualitative Value, the Floristic Quality Index, or the existence of endangered species.
• Temporary wetland impacts will be restored in place to existing conditions such that they are capable of and FQI no lower than that of the original wetland within 2 years of restoration.
• Wetland delineation shall be performed by a DuPage County Certified Wetland Specialist.

For Floodplains, comments have been received regarding accessory structures in the floodplain. It is recommended in the proposed ordinance draft that accessory structures to single family residences, such as detached garages, attached garages, and sheds, may be constructed with the lowest floor at or above the BFE.

For Permit Application and Review Process, comments have been received regarding the review procedure, specifically the fee structure, submittal requirements, and self or 3^rd party certification. The draft ordinance will have different requirements for different types of development.

After today’s Municipal Engineers Meeting,  there are a few revisions and tweaks to the proposed water quality control volume (wcqv) and Site Stormwater Storage (detention) approach.  This is introduced below in the previous post.

 First the applicability of the “roadway” category needs clarification.  Roadway was intended to apply to projects within publically owned rights of way under the jurisdiction of a unit of government.  It was not intended that the new roadways that are part of a site development proposal would fall under this category, but instead be considered as part of a larger development.

 The “thresholds” embodied in “note 4.” Of the blog were discussed at some length.  The current ordinance requires a permit to be submitted for any development that disturbs more than 5000 sq. ft. of area.   The WCQV-Detention proposal  is that developments that add 500 sq. ft to 5000 sq. ft. of additional impervious area are required to provide BMP’s.  This could lead to situations where a submittal and some form of permit would be required in cases that under the current ordinance are exempt.  While true, this is justified by the number of drainage complaints that occur between neighbors, even with projects at this small of a scale.  One suggestion was to create a very simple and “light” permit for these small projects, focused strictly on the installation of an appropriate BMP.  It was discussed and generally agreed that “policing” these BMP’s could be a bit of a challenge as projects change ownership, but even if all that is really accomplished is the initial installation that will be an improvement over continuing to ignore the cumulative effect of small projects.

We have discussed now on several occasions using Total Impervious Area (TIA) to determine what requirements apply for Site Runoff Storage (detention) and Water Quality Control Volume (WQCV).

The table or attached is our first specific proposal on how that might work.  Recall that the “water Quality Control volume” is targeted to smaller but more frequent events and is effective in reducing the volume of stormwater runoff, while detention is what we do in the current ordinance in specifying a release rate for peak discharge in an extreme event.  This proposal balances expenditures for stormwater infrastructure between frequent events which are associated with volume and pollutants and extreme events associated with peak discharge.   Stream stability would increase  and stream bank erosion would be reduced to some degree as well with the WCQV requirement.

Proposed Site Runoff Storage Table

Please take notice in the table of the notes, particularly the 4^th one.  This note sets the threshold at which the requirements would apply,  please review these thresholds and let us know what you think of them.

Consider these three single family lot scenarios.  Imagine these scenarios with very small lots and very large lots.

• A vacant lot in an already platted development with no detention.
• A built lot where the home is adding an addition, or a patio, or completely replacing the driveway, or some combination of the usual “building permit” situations our residents bring to us.
• A previously built lot, where a “teardown” is proposed and a new very large home is to be built.

With these rules, detention would apply only if the vacant lot was large enough that the combination of new impervious (home, garage, driveway, patio, sidewalk) was over 5000 sq.ft. and the total area disturbed was over 25,000 sq. ft.  If the lot is smaller, say 10,000 sq.ft., and the new impervious was 5000 sq ft (which seems unlikely on a 10,000 sq. ft. lot) then since the finished project is 50% impervious, the WCQV is 0.75 inches multiplied by 5000 sq. ft, or a total of 312.5 cubic feet.   A 15” rock blanket placed under a 10’x16’ patio and 20′x25′ driveway would hold the volume required.  It would also hold all of the runoff from more than half of the rainfall events that occur in a year-which would go a long way in relieving the inevitable Neighbor vs. neighbor drainage complaints when “the last vacant lot on the block” gets built.

Do you agree with the direction this is heading:  frequent event volume control?  “Zoningless” thresholds?

Based on the discussions during February’s Steering Committee (SC) meeting, we looked into what the communities covered in the National Ordinance Review Technical Memorandum require in terms of BMPs for small or single family residential properties, and how they enforce BMP maintenance. It came out in this SC meeting that there was interest in knowing what other progressive communities are doing to deal with this issue, but the original Technical Memorandum didn’t investigate this in great detail. Discussion topics included how small projects and individual homeowner activities (additions, teardowns, etc.) are managed across the Nation, and if BMPs must be implemented in the projects, as well as who is responsible for the maintenance. Thus, we took the initiative to do some investigation and create the attached summary document, for the Steering Committee’s review and consideration.

National Ordinance Review Additional Investigation: BMP Requirements and Enforcement for Small Properties

We welcome any comments or questions.

We have posted before regarding an approach to integrating water quantity regulation with water quality regulation.  We have reviewed other programs nationally and surveyed the literature and trends in this regard, and believe that designating a “water quality control volume” would meet the goal of integrating the Counties strong water quantity regulatory program with water quality.

Many studies already have identified that pollutants accumulate on impervious surfaces, such as parking lots, roofs, driveways and roads.  Drainage from these surfaces is almost always “improved” by addition of storm inlets and storm sewers.  Unlike pervious surfaces, impervious surfaces begin to discharge stormwater in much smaller events, contributing to annual Runoff volume significantly as well as washing the accumulated pollutants into the water column in what we generally have called the “first flush”.  As we have been discussing, the impervious surfaces of the developed site are a “marker” for stormwater quantity and quality, and  in concept then, whatever is the “right” water quality control volume should be applied to the impervious area of a site.

Designing for water quantity in terms of flood damages, we typically target much larger storms.  Our small release rates tend to mimic the effect of measures which are explicit for “runoff volume control”, but do not capture and treat the first flush.

Discussing this issue at the Ordinance Update Steering Committee, we agreed that a re-focusing and change in emphasis was needed to better meet these dual quantity and quality challenges.  The current ordinance demands a high level of stormwater infrastructure to meet it already, and it is not really necessary to think of adding new costs to meet these goals.  Instead, we would redistribute the emphasis to fully acknowledge the “water quality control volume” as a high priority, with a corresponding de-emphasis on the total volume of detention storage required.

How much is “enough” for a water quality control volume?  Again, we can turn to some analysis of rainfall statistics that compare total rainfall in each storm to the total numver of “rainfall events” in a year.  We find the following:

• 70% of all rainfall events in a year have a total rainfall depth of 0.54 inches or less
• 85% of all rainfall events in a year have a total rainfall depth of 0.85 inches or less
• 90% of all rainfall events in a year have a total rainfall depth of 1.06 inches or less

In the above analysis, “events” are separated from each other by a minimum of 3-hours.  How would this be applied?  The above list thought of another way says, I need to design to capture and treat 1.06 inches of rainfall, applied over the impervious area of a site (assuming it is basically all runoff) if I wish to treat 90% of all the storms that occur.  We are ignoring the pervious areas in these “small events, which is a simplification but is balanced by the differences in impervious surfaces runoff characteristics when not all of the drainage from impervious surfaces is “improved”.

So if a site came in that was 10 acres in size and in its developed state it would be 50% impervious, and we wanted to capture 90% of all the events that occur in a year, a simplified approach would be to apply 1.06” rainfall depth to 50% of 10acres, for a total “water quality control volume” of 0.42 acre-feet that would need to be intercepted, held and treated by the use of BMP’s.  Corresponding to that calculated volume would be the simplified approach of “subtracting” that volume from any  calculated site runoff storage (detention) volume requirement that applies.

So here are some questions for feedback.

• Is this a good idea?
• What percentage of storms, or what rainfall depth, should be used to define the water quality volume?  85% of events-0.85” of rain? More? Less?
• How should it be applied?

Response to public comments so far…

We have received a number of comments in the “Public Comment” section of the website.  Before we start into the thick of the real drafting of the Ordinance Update, I want to respond and acknowledge the comments we have received, and to the extent I can let commenters know what is being done about the comment.  Rather than respond to each comment individually, we have “collapsed” similar comments into a single concern.

1. Comments on BMPs:  Volume credits should be provided for BMPs, permeable pavers should be encouraged, wetlands should be given credit for higher evapotranspiration and since they are more effective than dry ponds, guidance should be provided on soak away systems.  Response:  We are looking for all opportunities to properly credit the multiple benefits of BMPs as we proceed into Drafting Ordinance Update language.
2. Comments on Redevelopment:  Redevelopment exemptions are too difficult to achieve, they should be expanded and simplified. Redevelopment should be encouraged to avoid sprawl.  Response:  Requirements related to redevelopment are being re-thought, recognizing that redevelopment is something that current trends in water quality and stormwater management, as well as urban planning, would encourage.
3. Comments on Easements and Deed Restrictions:  The Ordinance should clearly state when and where BMP and SMA easements and deed restrictions are required for both public and private development sites, and, how they shall be recorded.  Response: Noted.
4. Comments on Restoration:  There should be a separate category for projects that are for restoration work.  Response:  We have come to recognize that restoration, along with a whole class of projects whose purpose is to improve the ecological health of the project site, should be treated differently.  Watch for work under the project category “Naturalization”, as the real purpose of that category is to respond to this comment.
5. Comments on CLOMR:  CLOMR requirement should be eliminated for BFE reductions when there is no floodway impact.  Response:  This will be considered in discussions on Floodplain/Floodway regulations.  The enabling legislation says we must be consistent with IDNR.
6. Comments on FEQ:  Consider alternatives to FEQ.  Response:  The required use of FEQ will be made clearer in the ordinance update.  As stated in the Watershed Plan, alternative models will be acceptable where appropriate.
7. Comments on restrictors:  Eliminate small diameter/small volume restrictors that are prone to failure and need constant maintenance.  Response:  While we will review this situation carefully, the ordinance has been in place a long time and several designs have come into common usage that do not seem to be the source of a lot of complaints.
8. Comments on Roadways:  Roadway procedures should be formalized.  Response:  We all agree, and we are looking closely at that.

As new comments are received, we will post additional responses.

The National Ordinance Review Technical Memorandum has been finalized and posted to this site for several months. The Review helped to identify innovative practices and standards used by progressive stormwater programs across the Country, and included a number of recommendations for the update to DuPage’s Stormwater and Floodplain Ordinance. The key recommendations that may be considered for incorporation into the current update have been pulled into a separate document, with additional details and backup information that may be helpful.

We want to insure that the recommendations serve as input for the Steering Committee as it prepares to draft the ordinance update, and therefore we are posting this document (see attached) to this website so that each point can be discussed and refined.  We ask that Steering Committee members, designated municipal representatives, and the public provide comments on the recommendations pertaining to their feasibility for incorporation into the DuPage County Stormwater and Floodplain Ordinance. Your comments will be reviewed closely as decisions are made pertaining to each point.

Recommendations for Stormwater Ordinance Structure

EPA is announcing plans to initiate national rulemaking to establish a program to reduce stormwater discharges from new development and redevelopment and make other regulatory improvements to strengthen its stormwater program.

EPA has issued a Federal Register Notice (PDF) seeking stakeholder input to help EPA shape a program to reduce stormwater impacts. Input will be provided through both written comments and during a series of public listening sessions. As described in the FR Notice, EPA seeks input on the following preliminary regulatory considerations:

• Expand the area subject to federal stormwater regulations
• Establish specific requirements to control stormwater discharges from new development and redevelopment
• Develop a single set of consistent stormwater requirements for all MS4s
• Require MS4s to address stormwater discharges in areas of existing development through retrofitting the sewer system or drainage area with improved stormwater control measures
• Explore specific stormwater provisions to protect sensitive areas

Please see the website below for more information.

http://cfpub.epa.gov/npdes/stormwater/rulemaking.cfm

The Steering Committee has settled on a “structure” for the Ordinance update.  The Stormwater Ordinance will be reformatted to create a series of “upfront” sections that will steer an applicant directly to the applicable regulatory section for the specific development, and specific site characteristics under consideration.  This will be partly in the form of a matrix and partly in the form of text under appropriate front-end articles.

An applicant would first characterize the site he intends to build the project on.  The steering committee approved the following categories that pertain to the site pre-project.

1. The degree to which a site is already “developed”, as indicated by the “Total Impervious Area” (TIA) of the site.  Degrees of development threshold distinctions are contemplated at the less than 15% TIA, 15% to 50% TIA, and greater than 50% TIA.
2. Whether or not a site includes “Waters of DuPage County”.
3. Whether of not a site includes a “Regulatory floodplain”.

Note that a site may be included under more than one category.

Next, the applicant must characterize the proposed project.  The Steering Committee has given a conditional nod to the following project characterizations as a starting point to be used in determining which Ordinance requirements apply.

1. Those not meeting the requirements of the categories below will be classified by one or more of the following:
   1. Change in Impervious area
   2. Grade changes
   3. Modification of existing structures
   4. Construction of new structures
   5. Modifications of existing buildings
   6. Construction of new buildings
   7. Linear Transportation Project-Vehicle and pedestrian facilities in linear land holdings created for that purpose.
   8. Naturalization Project-A project, or a portion of a larger project, whose purpose is
      1. Streambank Stabilization
      2. Wetland Mitigation
      3. Wetland Mitigation Bank
      4. Water Quality Improvement
      5. Stream, Stream habitat, and Upland habitat Restoration; and Forestry management activities
      6. Watershed Plan Implementation Projects

Based on the characteristics of the site, and the characteristics of the project, the applicant will be directed to specific articles that will define limitations, methodologies, standards and mitigation requirements where appropriate.  It is anticipated at that all developments will have certain requirements they must meet, some of them procedural and some regulatory.  Procedural requirements that might apply to all include such things as the form and content of a permit submittal, development security, Maintenance requirements, violations, appeals, variances and the like.   Universal Regulatory requirements might include such topics as erosion and sediment control and incorporation of Best Management Practices.  Within those topics, specific requirements can be tailored to the site and project classifications as appropriate, instead of a one-size-fits-all approach.

This concept is a starting point in the Update, and of course will be more fully developed as we proceed.  What do you think?  What problems do your foresee with this approach as applied to your own community?