A majority of existing permeable pavement installations are related to parking lots and commercial areas with low speeds and light traffic loads. During the past two decades, a tremendous amount of progress has been made with regard to the application of permeable pavements regarding mix design, hydrologic design, water quality assessment and maintenance requirements. Review of the literature revealed, however, that there are still many important questions that must be answered before permeable pavements can be fully integrated in urban roads, especially in highways with high speeds and loads. This paper summarises the major research progress in the above listed areas and identifies research needs. Research needs are summarised under four topics: (1) structural and materials property, (2) hydrologic performance, (3) water quality and (4) maintenance. Research needs are further organised based on their immediate, short-term and long-term impact.

Green infrastructure designed to address urban drainage and water quality issues is often deployed without full knowledge of potential unintended social, ecological, and human health consequences. Though understood in their respective fields of study, these diverse impacts are seldom discussed together in a format understood by a broader audience. This paper takes a first step in addressing that gap by exploring tradeoffs associated with green infrastructure practices that manage urban stormwater including urban trees, stormwater ponds, filtration, infiltration, rain gardens, and green roofs. Each green infrastructure practice type performs best under specific conditions and when targeting specific goals, but regular inspections, maintenance, and monitoring are necessary for any green stormwater infrastructure (GSI) practice to succeed. We review how each of the above practices is intended to function and how they could malfunction in order to improve how green stormwater infrastructure is designed, constructed, monitored, and maintained. Our proposed decision-making framework, using both biophysical (biological and physical) science and social science, could lead to GSI projects that are effective, cost efficient, and just.

Six storm-water best management practices (BMPs) for treating urban rainwater runoff were evaluated for cost and effectiveness in removing suspended sediments and total phosphorus. Construction and annual operating and maintenance (O and M) cost data were collected and analyzed for dry extended detention basins, wet basins, sand filters, constructed wetlands, bioretention filters, and infiltration trenches using literature that reported on existing storm-water BMP sites across the United States. After statistical analysis on historical values of inflation and bond yields, the annual O and M costs were converted to a present worth based on a 20-year life and added to the construction cost. The total present cost of each storm-water BMP with the 67% confidence interval was reported as a function of the water quality design volume, again with a 67% confidence interval. Finally, the mass of total suspended solids and total phosphorus removed over the 20-year life was estimated as a function of the water quali...

Can iron enhanced sand filtration capture total phosphorus and soluble phosphorus (phosphate) from agricultural tile drainage? A monitoring study measured the total phosphorus and phosphate capture performance of an iron enhanced sand filter (IESF) installed to treat agricultural tile drainage in Wright County, MT, USA. Overall, for natural rainfall-induced tile drainage events monitored between June and November 2015 and again in 2016, the IESF captured 66% ± 7% (α = 0.05, n = 21) of the influent total phosphorus mass and 64% ± 8% (α = 0.05, n = 31) of the influent phosphate mass. Removal of total phosphorus and phosphate was approximately uniform for large and small rainfall-induced tile drainage events and varied from 42% to 95% for total phosphorus and 9% to 87% for phosphate. The IESF treated 290 m of treated depth since installation, and results indicate that performance is similar or better than constructed wetlands or other IESFs, though not as good as laboratory experiments of IESFs. Routine and non-routine maintenance was performed throughout the project to ensure adequate phosphorus capture and flow rate through the IESF.

As engineering curriculums strive to meet Accreditation Board for Engineering and Technology 2000 design criteria as well as the demands of prospective employers, educators must often develop and incorporate design projects into courses. Unfortunately, in the fluid mechanics/hydraulics disciplines, textbooks do not often provide sufficient design examples, leaving professors with little resources in this area. This paper presents hydraulic engineering design projects for use in the undergraduate classroom that mirror consulting practice. In addition to the presentation of the projects, the paper discusses enhancements to the design-oriented learning experience in the areas of written communication, computer competency, and synthesis and application of hydraulic engineering concepts.

Batch and column studies were conducted on several media to determine the most effective method to enhance the dissolved phosphorus retention capacity of C 33 sand filtration. This study found that C 33 sand alone could retain some dissolved phosphorus but its capacity was quickly exhausted and therefore required media enhancements to improve the phosphorus retention capacity. Batch studies evaluated calcareous sand, limestone, three blast oxygen furnace (BOF) by-products, aluminum oxide, and chopped granular steel wool and found that BOF by-products increased pH levels above EPA guidelines and aluminum oxide did not significantly retain phosphorus. Column studies determined that calcareous sand and limestone retained more phosphorus as compared to C 33 sand but their fine grain size clogged the filter very quickly. Steel wool also retained more phosphorus than C 33 sand and did not clog the filter. Additionally, cost estimates show that steel wool enhancement would increase construction costs by roughly 3–5%. Fine iron oxide particles from the steel wool were observed in the effluent from the columns but any phosphorus attached to these particles is of limited bioavailability. A mass balance model was developed to predict phosphorus retention capacity of steel wool enhanced sand filtration based on contact time, influent concentration, and sum of phosphorus mass retained. Based on the results of the study, it is evident that steel enhanced sand filtration is an effective solution for removing dissolved phosphorus from stormwater runoff.