3.2 Nullah Crossings
Contrary to its common use to mean drain, a nullah is a surface of overflows. Its identity hinges on the operation of devices that hold monsoon waters. When seen individually these devices are simple structures like bunds built to allow a spill-over at a certain height. Seen collectively and in operation, however, they activate a surface that gathers and dissipates with a complexity and temporality that beguile the eye. Their workings do not form lines like rivers that run through settlement, but rather the field of settlement itself.
The five projects in this section are each associated with a cluster of crossings of the Mithi: Mahim, Sion, Vakola, Airport and Aarey. Rather than acknowledge these crossings as connections across a flow, these projects appreciate them as grounded in a field that can be cultivated and calibrated to filter, treat, absorb and harness the waters of the monsoons as well as the dominantly grey waters of effluent coming to the Mithi through the year. Each project is a starting point that extends with operations that similarly treat the swales coming into the Mithi from either side, swales that are largely accepted today as drains. These extensions eventually do not have to distinguish between surfaces of earth and buildings. Instead they bring building into the field of cultivation, calling them to a different responsibility as part of the ground of a nullah. Each project responds to particular opportunities and together they work to recover a surface of holdings that has been lost in a city separated from the monsoon with the articulation of drains that exist merely to facilitate the exit of rain and other matters to the sea.
1. Mahim Crossing
The Mahim Crossing Project is anchored in and through a field of wells, which in Mumbai are more than sources of ground water. They drain a surface into a depth of aquifers and if dug strategically can even be ways to harness the pressure of fresh water aquifers to keep salt water on the surface at bay. Here, they are deployed across a surface that extends from Bandra Tank to a remnant talao near Mahim Station, and from Mahim Causeway to the sluice that once separated Mahim from Dharavi. They work to enhance talaos, gather water and people in maidans, and create fresh water holdings in the mangroves. Their task is supplemented with a new creek that follows an opportunistic path through the sand bank and settlement that has gathered against the embankment of the Mahim Causeway. This creek, which anchors a boat dock and market west of the causeway (Project 2), provides a corridor for bio-treating barges to service families on and around the Dharavi sluice. These paid-to-use amenities and floating fields/gardens circulate between their location here and processing grounds offshore (Project 1). Between the vertical intervention of wells and the horizontal extension of the new creek is a surface graded with biotic treatment fields, tanks, coconut oarts, and walls along the Mahim-Bandra railway corridor. These walls serve as boundaries but also as monsoon water collectors and opportunities for occupiable space.
2. Sion Crossing
The Sion Crossing Project recovers the resilience once afforded by the multiple exits of the Mahim Creek, which took advantage of the inevitable variations in sea levels around Mumbai. The creek, of course, has been disrupted by siltation and landfill that has extended far beyond the Sion Causeway that began its closure in 1800. But the overflow surface of a nullah can still be cultivated opportunistically, through infrastructural cracks and temporal appropriations to link the Mithi with the Mahul. To this end this project uses the Sion-Chunabhatti-Kurla railway corridor, the maidans on the Eastern Expressway, the ground beneath high tension electric lines, and existent drains to link the Mithi surface with the Mahul surface and as such Mahim Bay with Mumbai Bay. This web of links, which expands and contracts as required, is an opportunity to introduce a program of temporal appropriations. It is also an opportunity for an infrastructure of biotic treatment fields, tanks, oarts and walls along the railway corridor to serve, on the one hand, as critical dividers, and on the other hand, as energy and water collectors and providers of services and occupiable space that can be used for facilities on either side.
3. Airport Crossing
The Airport Crossing Project turns the Mithi into a treatment field: a corrugated surface of holdings planted with biotic material that filter, absorb and transform effluent, linked by overflows across sills. This surface extends from the Mithi up swales, which likewise are made to operate as processing grounds, reaching out where possible to appropriate available land within their operation. It is also extended through walls along the airport boundary that gather monsoon waters at an upper level while serving the needs of community and the airport on a lower level; through maidans that hold and absorb excess waters during the monsoon when these nomadic grounds are less used for other functions. The vectors of sills that hold and modulate overflows of this corrugated surface can serve as thoroughfares with all the other uses that make thoroughfares in Mumbai operate more as bazaars and maidans than merely service connections between origins and destinations. Most importantly, however, the surface of the Mithi is extended via carefully calibrated fields across the airport to Vakola Nullah (Project 8), giving the Mithi an auxiliary route to the sea if necessary.