Nautilus Pond™

Nautilus Pond™

A Nautilus Pond™ (U.S. Patent No. 8,333,895; Canada Patent No. 2,704,715) is a high performance surface water treatment environment in both form and function. The core “pond” portion of the environment is specifically designed to allow water that is resident in the pond prior to a stormwater inflow event to be displaced toward a central drain rather than mixing with the inflowing stormwater. Resident water is then preferentially flushed in favour of retaining newly inflowing stormwater to a greater degree than is typically possible using designs consistent with current stormwater best management practices. The result is a longer average stormwater retention time and better opportunities for achieving sediment and nutrient removal objectives.

The conceptual sketch illustrates how a representative forebay cell in a Nautilus Pond™ layout directs water to enter near and generally tangential to the pond perimeter. Water generally follows an inward spiraling path and leaves the pond by a central drain. An inner berm is shown that functionally separates an outer annular channel from the central portion of the pond. This inner berm will be submerged under relatively small inflow events but ensures that the intended general spiral flow pattern will be maintained in the pond even under very large inflow events. Since the inner berm is submerged under relatively low flow events, the illustrated Nautilus Pond™ forebay cell maintains almost the same active storage volume as a simple circular pond with a 100 m diameter.

General hydraulic control over the outflow is achieved within the control structure located outside the pond perimeter for easy access by maintenance staff. A single pipe can be used to draw water from the pond centre and deliver it to the control structure. Water may be drawn from one or multiple elevations in the water column.

HOW IT WORKS

A Nautilus Pond™ is based on an elegantly simple and robust hydraulic form that generates very long flow paths when compared to traditional pond designs. See below how the performance of a traditional pond design on the left compares with a Nautilus Pond™ design on the right for a simulated inflow event where blue dye enters each of the two models. Unlike a traditional stormpond design, the Nautilus Pond™ preferentially discharges clean resident water instead of allowing new inflow water to short circuit to the outlet. Note how traditional stormpond designs suffer from reverse flow over shallowly submerged berms which is a behaviour completely contrary to how pond designers and operators believe their ponds are behaving.

The computer modeling results depicting the “Middle of Storm Event” illustrate similar general behaviour the key feature of which is that a Nautilus Pond™ style layout is much less susceptible to short circuiting than a traditional layout. Remarkable, both the computer modeling and physical modeling results express the tendency for traditional pond designs to suffer from reverse flow over shallowly submerged berms. Note that resident water in the computer simulation is coloured blue, pure inflowing water is coloured yellow and a mixture of the two is coloured varying shades of green. These computer modeling results were presented in the paper called “Changing the Stormwater Pond Design Game” which was presented at the NOVATECH conference in Lyon, France in 2010.

Physical flow modeling

KEY BENEFITS

RESISTANT TO Short-circuiting and the formation of dead zones.
DENSITY BASED SEPARATION A Nautilus Pond™ is more capable than conventional designs at separating both sediments and floatables from stormwater inflows.
STORAGE EFFECTS Local storage in a Nautilus Pond™ allows for outflow infrastructure to be smaller than inflow infrastructure.
OPERATION UNDER HIGH AND LOW FLOWS Unlike large and expensive manhole vault oil-grit separators, which typically operate under low flow conditions with a high flow bypass, a Nautilus Pond™ operates under both low and extreme high flow conditions.
MODULAR DESIGN Individual Nautilus Pond™ treatment cells can be placed in series and/or parallel to take advantage of challenging sites that are highly constrained or discontinuous in terms of the footprint area or in terms of changes in grade across or between sites.
WETLAND HABITATS Relative to conventional designs, a larger fraction of the stormwater pond area can be developed into wetland habitats when implementing a Nautilus Pond™ design.
STORMWATER HARVESTING By preferentially discharging resident water before newly inflowing stormwater, a Nautilus Pond™ may be used to support the beneficial reuse of stormwater to offset against withdrawals from fresh water sources.

WHAT WE PROVIDE

The long term vision of Source2Source Inc. is to enable the widespread adoption of Nautilus Pond™ based designs in both domestic and international markets.

We provide clients with access to proprietary Nautilus Pond™ technology through technology licensing agreements.

We also provide project coordination for firms specializing in the execution of Nautilus Pond™ specific professional Hydraulic Engineering and Environmental Design services.

SYSTEMS APPLICATION

Many legacy stormwater ponds were originally designed primarily for peak flow shaving, that is, to control flooding risk or to reduce the need to increase conveyance capacity for downstream stormwater trunks. Such legacy systems exhibit poor performance for water quality enhancement and usually suffer from a variety of acutely problematic side effects, including but not limited to costly sediment removal requirements, excessive algae and odours. The system layouts illustrated below demonstrate how Nautilus Pond™ technology can be incorporated into any arbitrary pond footprint. Municipalities can realize enormous water quality and maintenance improvements from ponds that are initially designed with Nautilus Pond™ technology or by retrofitting existing poorly performing ponds during a major sediment removal maintenance operation.

Nautilus Pond™ System Example A below illustrates how an existing pond design (left hand side) could include Nautilus Pond™ forebays (right hand side) on major inlets that pretreat influent water before discharging to the main water body. Nautilus Pond™ cells can be maintained independently from the rest of the pond thus significantly reducing the scope and scale of maintenance activities. For more information, please see the Harvest Hills Pond Case Study.