In 2017, GEO designed a state of the art regional treatment system to treat runoff from 128 hectares (316 acres, or 1/2 sq. mile) of intensely developed urban sources contaminated with stormwater illicit connections. This system owned by the local water utility, will treat runoff prior to it entering the Mengjiawan Reservoir, ZhenJiang, China. The system comprised of two Advanced Bioretention Systems (ABSs) with a combined treatment area of 3,600 sq. meters (0.9 acres). A high rate engineered media allowed for a compressed treatment footprint resulting in 0.3% of the source area.
Integrated into the reservoir’s landscape plan, this complex treatment facility now treats this entire area prior to discharge into the Mengjiawan Reservoir, the headwaters of the Yudai River. Completed in mid-2018, the system has now been operating for half a year with excellent results.
The Three Peninsula Wetland project – a 240 ha (2.4 km2) lake fringe wetland restoration will have significant ecological functional lift on a landscape level and help bring a lake viewed as a national treasure back to health. These fringe wetlands frame Dianchi Lake in Kunming, China’s 4th largest freshwater lake. This is one of China’s largest wetland restoration projects with a construction budget exceeding $100 million dollars. Dianchi Lake, a once healthy lake system the 1950s that supported Kunming’s population with an abundance of freshwater mollusks and fish is now a eutrophic system due to uncontrolled release of untreated sewage and agricultural runoff over the last 7 decades. Wetland plant diversity has plummeted from over 100 aquatic and emergent plant species to less than 20. Mark Merkelbach is leading China-based engineering and landscape design teams in treating 10 streams that enter the lake through the project site and restoring critical wetland and riparian habitats. Stream water treatment involves a multi-step process of pre-settling, vertical flow-through wetlands, aeration, and horizontal flow wetlands. These systems comprise of almost half of the project area fully integrated into the site’s new natural landscape. The government has set an aggressive construction schedule with ground breaking to begin in the fall of 2019 and activities completed within 2 years.
GEO’s work spans the globe from exotic resort master planning to supporting WA state local developers in developing strategies to minimize environmental impacts to critical areas. I am still lucky enough to get in the field and dig pits to identify hydric soils for projects. I am always in awe of how water, microbial communities, and soil create amazing underground art forms. This is a great example of depletions and concentrations in wetland soils.
Typhoon Nida caused substantial flooding in Guangzhou last week. GEO is working with Chinese cities (i.e. Wuhan, Ningbo, Zhenjiang) to optimize existing infrastructure and designing retrofits using SMART technologies to make cities more resilient to extreme events.
Two Anna’s hummingbird babies hatched about 15 days ago and are growing at exponential rates. The two of them barely fit in the nest. It will be a sad day to see them leave but we are hopeful to see mom next year, same time, same tree and start a new family. Happy spring to all!
We broke ground last month on a Low Impact Development (LID) project in Taipei, Taiwan. This is our first LID project in Taiwan and one of the first LID demonstration projects in Taiwan using US design methods.
The project site is located at the Dihua Sewage Treatment Plant in Taipei. This LID retrofit project provides pervious parking space and connection pathways for staff and visitors. The total area is about 9,530m2, which includes 98 “green” vehicle parking spaces while protecting 111 existing trees. To collect, treat, and detain stormwater onsite, we designed subsurface gravel storage, porous asphalt, rain gardens, and constructed wetlands.
All the LID tools will be constructed and fully functional prior to the rain season. On average, Taiwan experiences three typhoons every year (July-September), providing much of the water supply, but also causing damage, flooding, and landslides. This new infrastructure will help build in resiliency to combat more intense storm events resulting from climate change.
We are providing a comprehensive stormwater quality solution for all stormwater runoff generated within the university campus and entering the Yudai River which borders the campus. The goal of this project is to meet to meet Class IV water standards in the Yudai River. The design team developed treatment facility sizing tools to design 23 Gravity Swales™ at each stormwater outfall. The Gravity Swales™ is a gravity fed bio-retention technology using high performance media in combination of TSS removal technology. A total treatment area of 11,606 m2 is being provided.
Regional stormwater treatment facilities are an alternative solution to parcel based low impact development (LID) when trying to meet water quality treatment goals in urban settings. Urban retrofit projects are challenging due to many site constraints (i.e. narrow median strips, lack of green or open spaces, and areas built on structure) . Our design team needed to look beyond parcel scale approaches and identified larger sites to provide regional treatment. In ZhenJiang, China, we designed a system called the Waterfall Treatment System (WTS) that is only 2000m2 but capable of treating runoff from a surrounding 120 ha area. This high-performance system contains a gravity pre-filter bay, followed by dispersion weirs and four engineered media filter beds. Under drains collect the filtered water at an infiltration rate of 100 cm/hr. Currently under construction, the system is designed to removal 80% total suspended solids, 50% total phosphorus, 60% dissolved zinc, and 30% dissolved copper. This type of system should be added to your suite of tools when addressing stormwater water quality improvements in urban settings.