BY: ALI KHALILIAN, P.E.
The author is Takoma Park’s City Engineer.
If a tree is planted in the median of Baltimore Avenue or Garland Avenue, in addition to providing shade and cooling the air, it intercepts rainfall reducing the amount of runoff generated on the pavement. Our valuable tree canopy is now considered by many experts a cost effective Best Management Practice (BMP) for storm runoff pollution control. Once a drop of rain becomes run-off, it accelerates and gathers speed and energy digging into the top soil and the soil beneath carrying the mud (sediments) into the creek. The turbid (muddy) water depletes the dissolved oxygen, and negatively impacts aquatic life.
It can be clearly seen that it makes sense to retain, absorb, and purify the run-off rain before releasing it into the natural path. It makes even more sense to refrain from creating water-pollution by substituting household chemicals, pesticides, and other harmful agents with natural, organic, and/or modified alternatives that nowadays are readily available at most local specialty or commercial stores. A simple and profoundly effective Best Management Practice (BMP) is not to dump any substance into our street side storm drains. That includes water-based paint, mud, water, or detergents from our cleanup activities.
Rain- and traffic-calming
A recent addition to our micro bio-retention/street scope facilities are a collection of four bio-retentions at the intersection of Ritchie and Oswego Avenues. This project was done through a grant from the State Department of Environment and complements a long awaited neighborhood traffic-calming project.
Ritchie and Oswego Avenues.
Since building Cleveland Avenue’s rain garden and infiltration basin in 2007-2008, in partnership with the neighborhood, we have added some 20 or more bio-retention facilities throughout the City. Additionally, several more are at various stages of design development to be installed in the period 2014 through 2017.
To date, the micro-bio-retention gardens have provided water quality treatment for over 16 acres of impervious surfaces retrofit. Baring efficiency reduction, it is to say they act as if we were to replace 16 acres of pavement and water shedding non-source pollution generating hard surfaces with pristine green grassland.
Stabilization of streambeds or stream restoration prevents erosion, loss of trees, and plant life sustained by the stream flow. All of the 400 linear feet of stream-bed within Circlewood Park was stabilized during 2013. In terms of sediment transport reduction and ecosystem benefits, a 400 linear foot stream restoration can be thought of as being equivalent to roughly four acres of impervious area reduction. We aim to continue installation of street-scaping and bio-retention facilities at every opportunity in the coming years. Several such facilities are already in the pipeline! We (the people) can locally meet the challenges of global water resources crisis, indeed.
I welcome anyone willing to help by placing “No Dumping” stickers on our storm drains. Our own local troop of Boy Scouts undertook this good deed in the spring and marked over 200 drain inlets. There are some 600 inlets throughout the City ready to be marked.
Epic scale crisis
David Greshner, author and one of the world’s authorities on community engagement, believes cities need to convince citizens to change current behavior if they hope to adopt or mitigate the now unfolding consequences, of the climate change.
Startled by the enormity and complexity of the strategic water resources crisis, on a local level, the question, “Where do we begin” is being frequently asked and often answered, “Right here.” The question frequently expands into “How does a local community begin the work of confronting such an epic scale crisis?”
Follow the drop
Taking a hint from the hydrological cycle, we follow a drop of rain as it falls on the Earth’s surface. If it is not absorbed through the soil, then it runs off over the paved streets, parking lots, roofs, lawns and farms. During flash flood events, runoff over the street picks up exhaust emission, oil residues, beer cans, grocery bags, milk cartons, pesticides, herbicides, and other household chemicals to name a few.
Droughts followed by downpours intensify pollution that is carried into the rivers through an urban storm drain network. Non-point source pollution generated through urban and agricultural land use, therefore, becomes a moving target yet presenting a localized challenge. Nonpoint source terminology refers to the fact that the source of pollution is spread over an area say the expanse of the city streets or farmland. The amount and the duration of presence of pollutants such as nitrogen (N) and phosphorous (P) fluctuate widely.
“Looking out to a sustainable future,” the view from Takoma Park’s Public Works facility.
To control pollution locally, we can refrain from generating and/or introducing it into the water bodies in the first place. This is more challenging that can at first be readily perceived, as is the case with many non-action items that in fact introduce a behavioral change on individual and social levels. The behavior patterns permeates the social and cultural stratum of communities with complicating socio-economical implications. On one hand, not allowing anything other than rain in the drain simply implies not throwing litter or used motor oil down the drain.
On the other hand, how do we deal with the exhaust fumes or oil residue which form a good percentage of non-point source pollution. Non-point source pollution is an unintended by product of modern life. The problem may become less complex and the solution simpler, if we were to mimic the hydrological cycle as the pollution removal model, once it is inevitably generated. We would have to choose the simplest way to remove the unavoidable pollution and replenish the whole source ground water.
To do so, the rain runoff generated only sidewalks, streets, pavement, and parking lots and backyards could be redirected and charged onto a patch of land where sandy soils and water-loving plants may be installed. Then we may call our creation a rain garden or a “bio-retention” facility. We now have constructed more than a couple of dozen of such facilities through Takoma Park. We, along with the larger community, have made strides to look into every opportunity to incorporate that into our routine street improvement activities, streetscaping, and renovation projects.
Bio-retention in Takoma Park.
To signify the scale of this solution, relative to epical dimension of the water resources crisis, which is a subsidiary to climate change, our recent Hudson and Jackson Avenues sidewalk and street improvement intended as non-source pollution control retrofit projects are identified as “micro-bio-retention.” A micro step towards solving the mega global water resource crisis as the term “micro” also refers to the limited and localized nature of the practice.
Once in use, a micro bio-retention point or a rain garden with our under drain, storm run-off, ponds it in depression, feds it to plants, and filters the pollutants through sandy soil and natural ground below then charges it down back to groundwater flow. The rainwater continues through the earth, or resurfaces as a spring flowing into a creek to navigate through the Bay into the Ocean. This intervention mimics the natural process we call hydrological cycle. It ponds and filters water before impacting the surface water.
“We [the people] are mostly water, so is most of the Earth’s surface.” Shimon C. Anisfled, in his brilliant book, “Water Resources,” a 2010 publication of the Foundation of Contemporary Environmental Studies by Island Press, reminds us once more that we are facing a serious problem with regard to continued utilization of the water resources on Earth. Population growth along with technology is advanced and climatic change resulting pollution have come together to create a clear and present threat to life on the planet, as we know it. Labeling an occurrence as “crisis” by implication communicates that, at the very least, there is a need for immediate action to mitigate the impact in the short run while devising strategic planning.
The book is presented as an “introduction to water resources management, exploring the interaction between people and water.” Two contrasting, but complementary ideas form the basis of the discourse. (1) We (the people) are facing a serious water problem/crisis in near term to long term and (2) Good news is that there is much that can be done to conserve and manage this vital resource.
Water is life and it is becoming a scarce commodity in our world. Increased demand, a result of population growth and the advent of technology, has all but ensured a serious water shortage alongside the imminent global warming.
Flood hazard remains
Awareness of melting glaciers and the depletion of the ozone layer has all but certified the looming global warming. It is constantly affirmed, negated, rejected, and debated, while more frequent snowing, flooding, and hurricanes manifest as climate patterns that are out of statistical precedent. Flooding in unprecedented frequency has been experienced within the past decade. Statistics that are now available suggest an upward trend in flooding frequency in many localities.
Historically, flood control has been done by construction of ever-larger dams. While they continue to provide their multifaceted benefits, dams large and small were a significant marvel of the 20th century. They will continue to be a major implement in storage, utility, and distribution of water resources. Canals played a vital role in management, conveyance, and navigation, whereas wells, the ancient means of water access, have deepened and grown to the point where in many places, they deplete ground water resources, faster than the aquifers are replenished, creating in some cases immediate and globally projected future shortages. Where surface and subsurface water collide in hydrological cycle, the probability of polluting the groundwater resources multiplies rapidly.
While flooding remains a hazard to our homes and businesses, pollution has often rendered water bodies from main ingredient and sustenance of life on this planet into a source of hazard endangering aquatic life.
If it remains unchecked, climate change and pollution will seriously threaten our water resources on an epic scale. Survival on the planet now depends on how and whether the human species confronts and solves this looming multitude of crises. In retrospect, immediate mitigation and strategic planning for action has never been as vital as in contemporary times.