STORMWATER IN THE EARLY YEARS
In the early days of Columbia, Flat Branch Creek was the main waterway through town. It not only received stormwater runoff, but sewage discharge from the growing community. In the early 1900’s Columbia started constructing a sanitary sewer system to separate sewage from our waterways and improve the health of the community.
At one time, stormwater was a “common enemy” and the goal of any stormwater system was to get water away as quickly as possible. Treating stormwater as a nuisance included replacing meandering streams and riparian corridors with underground pipes and straightened ditches.
Development in Columbia included constructing storm drainage systems in conjunction with the street and sanitary sewer systems. However, the storm systems were not designed per a specific standard. As the City became more urbanized, property owners and citizens experienced a wide range of stormwater problems. The effects of urbanization are uncontrolled or poorly controlled stormwater runoff, increased stormwater runoff and erosion of land, and sedimentation and deposition in creek channels and other conveyance systems downstream from development. The damage caused by flooding and erosion affect homes, businesses and all infrastructures (roads and utilities).
On August 4, 1969, the City Council adopted a manual titled “Storm Drainage Standards” to require more control of stormwater design and construction. The standardization of stormwater design criteria and construction procedures address issues related to stormwater conveyance in development. However, the document did not address the issues of increased stormwater runoff because of urbanization and those problems associated with erosion and sedimentation due to site development.
In the early 1970s, the City of Columbia was one of the first in the state to complete a flood plain study and enact a flood plain ordinance. The flood plain ordinance regulates development in flood prone areas. By meeting these FEMA requirements, Columbia is able to participate in the National Flood Insurance Program that provides a means for homeowners, renters, and business owners to protect themselves financially. Flood plain regulation also reduces the occurrence of flooding damage to structures.
In 1982, Public Works updated the Storm Drainage Design Manual. The objective of the revision was to establish a level of service for protecting structures and vehicle access to roadways during storm events. Establishing specific levels of service improves the safety of citizens and further protects their property. The revised manual also sought to improve the review process for new development by standardizing engineering plan submitions.
DEVELOPMENT OF THE 1980’s STORMWATER MANAGEMENT PLAN
Heavy rains in 1982 increased complaints about local flooding. The City contracted with Black & Veatch Consulting Engineers to prepare a comprehensive stormwater management plan. Completed in March 1983, the plan identified ten primary drainage basins within the City and problems that existed within those basins. The plan provided recommendations and cost estimates to correct the identified drainage problems. The plan recommended formation of a stormwater utility to be funded by a monthly fee based on impervious surface.
City Council appointed a task force to review the plan and make recommendations. Submitted in December 1984, the task force’s preliminary report prioritized the identified projects, recommended a bond issue, formation of a stormwater utility and preparation of ordinances to prevent the creation of new stormwater problems. In 1986, the Stormwater Management Task Force submitted its final recommendations that included a draft of a stormwater detention ordinance. The recommendations were:
- Adopt a new storm drainage design manual.
- Enact an ordinance to require stormwater control facilities.
- Request voter approval for stormwater utility fee.
- Adopt policy and procedure guidelines for addressing stormwater issues.
A stormwater control ordinance was enacted for high density Planned Unit Developments (PUD). Stormwater controls for other developments were approved and subsequently repealed. At that time, there was concern about many small detention basins causing more flooding problems than are caused by having no stormwater control. It was determined that regional detention basins would be more effective for flood reduction. Council deferred creation of the stormwater utility at that time. In the late 80’s, the Columbia community became increasingly aware of environmental concerns from stormwater runoff. Additionally, Federal regulations requiring municipalities to monitor and treat stormwater as a point source discharge were to be finalized in 1993.
THE FEDERAL CLEAN WATER ACT
Since 1972, the U.S. Clean Water Act and its amendments have prohibited the discharge of any pollutant to a water of the United States unless authorized by a national pollutant discharge elimination system (NPDES) permit. The NPDES program initially targeted easily detected sources of water pollution such as municipal sewage and industrial process wastewater and was successful in improving water quality. Subsequent amendments to the Clean Water Act helped fund many improvements to the Columbia wastewater treatment system removing many of the smaller sewage treatment facilities that discharged directly into Hinkson Creek and its tributaries. However, the NPDES program was not addressing other significant sources of water quality impairment: nonpoint sources such as runoff from agricultural, forestry and construction operations, and stormwater runoff.
The Clean Water Act was amended in 1987. As part of the amendments, Congress addressed the environmental impact of stormwater by establishing a comprehensive, two-phase approach to stormwater control. Phase I and Phase II stormwater regulations took a new approach and began to treat stormwater discharges from municipalities as point sources of pollution. As a result, local governments covered by the Phase I and II regulations must, like all point source dischargers, obtain federally enforceable NPDES permits under the Clean Water Act.
COLUMBIA LAND PRESERVATION ACT 1991
In March 1991, the City adopted a revised storm drainage manual. In addition to refining the standards for conveyance of stormwater runoff, the 1991 manual established standards for detention and retention of storm water and provided guidelines to minimize soil erosion and prevent sedimentation associated with land disturbing activities.
In July 1991, this city enacted a comprehensive Land Preservation Act which requires a land disturbance permit for any site two acres or larger. The permit required preservation of existing trees on site, a landscaping plan in conformance with zoning requirements, an erosion control plan for containing sediment on site during development, and a stormwater management plan for sites greater than 5 acres.
This ordinance initiated some stormwater management for development. However, the ordinance did not provide funding or the ability to address existing stormwater problems or to maintain stormwater management facilities.
COLUMBIA STORMWATER UTILITY 1993
In April 1993, Columbia voters approved creation of the Stormwater Utility. This vote authorized the City to establish a stormwater development charge on new construction and to issue stormwater management system revenue bonds to be repaid by revenues from stormwater utility charges on monthly utility bills. Stormwater management would require this dual approach. Monies from the development charges would address the effects of new development and the problems associated with increased stormwater runoff. Monthly charges provide income for long range planning, construction and maintenance.
A six-year Capital Improvement Plan was prepared from the prioritized list that the citizen task force had recommended. In addition to funding specific projects, the development charge provides annual funding for other identified but unprogrammed needs. The monthly utility charge funds stormwater management planning and maintenance activities.
Monthly utility charges are billed to the owner or occupant of all developed property. Rates are based on whether the property is residential or non-residential. Residential charges include four different rates correlating to the total impervious area on the lot ranging from $0.65 to $1.35 per unit per month. Non-residential charges are based on the total impervious area of the property.
New development charges are a per square foot of floor construction fee with the rate based on the zoning of the property and range from $0.195 to $0.09 per square foot. New development charges are paid at the time the building permit is issued.
Once funding for the utility was in place in 1994, work began on the Capital Improvement Plan. Instead of issuing bonds, the City decided to pay for Capital Improvements as money was available. Large and small drainage improvement projects started to be constructed. More than $10 million has been spent on major drainage improvement projects since 1994.
PHASE I & II OF THE FEDERAL CLEAN WATER ACT
Phase I of the Federal Clean Water Act was promulgated on November 16, 1990. The Phase I regulations require large sources of stormwater discharge to apply for NPDES permits. Large sources include medium and large municipal storm sewer systems, usually serving 100,000 people or more, as well as several categories of industrial activity including construction activity disturbing five or more acres of land. The NPDES permits require cities to develop a stormwater management program, track and oversee industrial facilities that are also regulated under the NPDES stormwater program, conduct monitoring, and submit periodic reports.
Phase II of the Federal Clean Water Act was promulgated on December 8, 1999. Phase II expanded the scope of the NPDES program to include smaller local governments, municipal separate storm sewer systems (MS4s) serving populations of less than 100,000 or 1000 people or more per square mile. The stormwater Phase II final rule requires these entities to obtain NPDES permit coverage. These local governments must design a stormwater management program to include the development and implementation of six specified measures that reduce stormwater pollution. Evaluation and reporting measures are also required. In addition, the rule sets requirements for construction activity that disturbs between one and five acres and extends a previously set deadline for municipalities that operate industrial activities regulated under Phase I.
SUMMARY OF COLUMBIA’S MS4 PHASE II PROGRAM
While work on Capital Improvement Projects was a priority in the 90’s, the City was preparing to become compliant with Clean Water Act regulations and the utility helped to provide funding for those activities. The City population was growing aggressively. If the population exceeded 100,000, the City would be required to meet Phase I regulations. Even if the City did not top 100,000 people, it would be required to meet Phase II regulations.
The NPDES Phase II regulations require local governments to have a stormwater management program that will include the development and implementation of six specified measures that reduce stormwater pollution. These “six minimum measures” include:
- Public education and outreach,
- Public participation and involvement,
- Illicit discharge detection and elimination,
- Construction site runoff control,
- Post-construction runoff control, and
- Pollution prevention / good housekeeping.
In Missouri, the Department of Natural Resources (MDNR) issues permits for the NPDES program. Once an NPDES permit is obtained, the conditions of the permit must be satisfied and periodic reports must be submitted on the status and effectiveness of the local government program. The Columbia MS4 includes the City of Columbia, Boone County and University of Missouri. The MS4 submitted its first joint NPDES operating permit to MDNR in 2002. The permit cycle is five years and the Columbia MS4 is currently in the second permit cycle.
IMPLEMENTATION OF THE COLUMBIA MS4 PHASE II PERMIT
The City portion of the NPDES Phase II permit discusses the goals and strategies to implement the minimum control measures. The City has been moving forward on each of these measures. The City employs a stormwater educator to perform education and outreach activities. Ordinances and programs to address illicit discharge have been implemented. The City has improved requirements for construction site runoff control to meet state and federal requirements. All City Departments have updated policies for pollution prevention and good housekeeping.
Addressing post-construction runoff control, and all the minimum control measures, requires a multi-faceted approach including ordinances, planning, engineering design, inspection and education. In January 2007, the City passed a stream buffer ordinance to protect the riparian corridor along streams. Protecting the riparian corridor reduces runoff and erosion and improves water quality.
In March 2007, the City issued “Stormwater Management and Water Quality Manual”. The manual provides methods and means for stormwater runoff quantity control and stormwater runoff quality improvement. Now, all developments must have stormwater runoff controls and water quality controls. Previously, only PUDs or critical locations were required to have stormwater runoff controls. Now, all developments are required to have stormwater runoff controls such as retention or detention basins. Water quality improvement practices, called BMPs or Best Management Practices, include bioretention, pervious pavement, sand filters and many other techniques that require a combination of stormwater, geotechnical and landscape practices. Improving and protecting the water quality of Columbia’s waterways is best accomplished by mimicking natural hydraulics, hydrology and rainwater treatment where more water stays on the site and is infiltrated in the ground or transpired through vegetation.
In summary, Columbia has evolved from treating stormwater as a nuisance and convenient dumping area to recognizing our natural streams as an asset to the community and respected as such. The presence and protection of natural resources is fundamental to the quality of life of the citizens of Columbia and every facet of the stormwater system must recognize this. The best method of management is to preserve, restore and mimic natural processes. One of the best ways to manage stormwater runoff is to generate as little as possible and treat stormwater as near the source as possible.
The stormwater management ordinance can be found in Chapter 12A of the City Code of Ordinances.
You can also view the full manual online: Stormwater Management & Water Quality Manual.
Boone County, City of Columbia and the University of Missouri coordinate stormwater activities. The three institutions are joint holders of a Phase II Stormwater Permit issued by the Missouri Department of Natural Resources under the National Pollutant Discharge Elimination System (NPDES).