How a sewer line is refreshing the Nairobi River and its environs

The boisterous laughter of children playing outside welcomes you to the lively Tome area, a stark contrast to the unsavory environment that once haunted the estate due to the dangers of open drains and filth.

A few years ago, this was not the case.

The formerly clean, middle-class neighborhood was characterized by the pungent smell of untreated sewage and the appearance of open gutters full of garbage, which posed a serious health risk to the community, especially the growing children.

Struggling under an ever-growing urban population, Nairobi’s sewage system is currently unable to support the more than four million people who inhabit the city.

Open drains have blocked drains and flowing sewers are a nuisance in the Kenyan capital, contributing to an increase in cases of water-borne diseases such as cholera, typhoid and dysentery, especially among children.

To ensure that Nairobi’s streets have cleaner streets and proper garbage disposal systems, the government is working with the African Development Bank.

The second stage of the project will increase the city’s sewage coverage by more than 50 percent.

It is called the Nairobi Rivers Rehabilitation and Restoration Programme: Sewerage Improvement Project (NaRSIP).

The project started in August 2020 and is scheduled to be completed by December next year.

The first phase of the project was completed in 2017 and increased the city’s sewer coverage to 48 percent.

This was achieved through the construction of 56 km of main collectors and 40 km of network collectors.

During Phase 1, the Dandora Wastewater Treatment Plant was expanded to handle 40,000 cubic meters of waste per day, while the Kariobangi Treatment Plant was upgraded to a daily capacity of 32,000 cubic meters of waste treatment, up from the original 11,000 cubic meters.

The rehabilitation and restoration is being carried out under the leadership of the Athi Waterworks Development Agency, one of the nine waterworks development agencies established under the Ministry of Water Resources.

SEWAGE VISIT

To effectively serve the people of Nairobi, NarSIP has been divided into five precincts covering Kahawa West and Sukari, Githurai 44 and 45, Mwiki and Clayworks, as well as the Greater East and West areas of Nairobi.

After the construction of the sewage line, these areas have undergone significant changes.

A once unpleasant environment has been transformed into a peaceful space for residents.

Open drains and floating waste are now a thing of the past.

The air is cleaner, devoid of the unpleasant smell emanating from stagnant water.

You can hear children playing and laughing on the street, and parents are no longer worried about their health.

Susan Gaki, a resident of Marurui Estate, tells how she had to use a bucket to drain the sewage, which posed a great risk to her and her children’s health.

With the accumulation of filth in and around the apartments, mosquitoes began to actively appear, she said.

“Every 30 minutes, we emptied buckets of dirt, even the ones coming from the toilets. But now with the connection of the sewage line, life has become easy, children can now play outside freely,” she said.

Schools, hospitals and other public institutions are among those who have benefited from the sewage system in addition to residents of the nearby Thome estate.

Ruaraka Academy IT Head Karani Waruhiu said the institution has benefited greatly from the project.

During the rainy season, the school hired hood trucks to drain the sewage.

“Since we switched to sewage, it has been a great relief for us. The hoods cost a lot, which affected the school’s finances, and we constantly had to deal with overflowing sewage, which affected the children’s health,” he said.

Moreover, the noise from the extraction trucks interfered with activities and had a negative impact on the environment.

Grace Muthoni lives in Githurai and oversees several apartments in the area.

She had to deal with frequent drainage blockage problems before construction and connection to the sewer system.

Toilets would block and spill onto roads, exposing residents, especially children, to health risks.

In addition, the discharge of sewage by means of exhauser trucks resulted in unwanted noise, smoke and odor.

“Now sewerage has improved significantly, most apartments are connected to sewerage. The state of health of residents has also improved, there are reports of a decrease in morbidity,” she said.

GROWTH OF POWER

The renovation and duplication of the Dandora Estate treatment plant aims to double the capacity of the treatment plant.

The plant covers about 4,000 acres and is located 26 km from Nairobi on Kangundo Road, east of the city along the Eastern Bypass at Ruai.

The treatment plant treats about 120,000 cubic meters of domestic and industrial waste per day, which is equivalent to approximately 80 percent of the wastewater generated in the city of Nairobi.

NaRSIP II Lot 1 Resident Engineer Duncan Kamau said wastewater treatment involves two processes: physical and biological treatment.

In the first case, raw sewage is sent to a screening plant where large materials such as pieces of fabric or bag are removed.

“During physical treatment, the incoming wastewater is passed through coarse, intermediate, fine screens, a mud trap and a compactor to remove large materials from the wastewater,” Kamau said.

He said the wastewater passes through anaerobic ponds and facultative ponds and finally enters three maturation ponds during the biological process.

Kamau said the depth of the maturation ponds allows sunlight to penetrate to help kill pathogens such as E. coli.

Wastewater quality is monitored daily at the inflow, outflow, upstream and downstream, and monthly, he said.

The project envisages the construction of a secondary sewage network in order to eliminate existing gaps in the city’s sewage network coverage and increase the availability of sewage services.

This is especially true in informal settlements like Kibera, where sanitation is a major problem.

To promote environmental health and contribute to climate change mitigation, the project strategy involves planting trees along the sewer line to protect coastal areas.

Biogas will be converted into energy at treatment plants, methane collection will be introduced and greenhouse gas emissions will be reduced.

Kamau said Lot 1 has reached at least 74 percent and that it is nearing completion, adding that raw sewage is not being released into rivers.

The other four sites, located in Nairobi’s informal settlements, collect wastewater and discharge it to treatment plants for the remediation process.

This is possible thanks to manholes built around the communities to discharge sewage to the Dandora Sewage Treatment Plant in Ruai, where it is treated for safe discharge into the Nairobi River.

There is also a sewage pipe along the Nairobi River from Dandora Landfill to Gitwamba called the Dandora Landfill Main Sewer Pipe.

The focus is on connecting sewers to estates and institutions in Nairobi to ensure direct flow of sewage to treatment facilities.

RIVER POLLUTION MANAGEMENT

Nairobi is home to about nine percent of Kenya’s national population, which stood at 47 million in the 2019 census, but has since grown by about nine million.

The steady increase in rural-to-urban migration has led to a sanitation crisis in the city, putting strain on already existing sewage facilities that cannot accommodate the city’s growing population.

This, in turn, has harmed public health, the environment and the economy. Taking into account the lessons learned from phase 1 of the Nairobi River Sewerage Improvement Project, the government has embarked on the second phase of the project.

Acting Director of Infrastructure Development at Athi Water Development Agency Bonnie Nyandwaro said that the project is on time.

“The five rivers that flow through the city of Nairobi are severely polluted and degraded. They are Nairobi River, Ngong River, Mathare River, Kiu River and Riara River,” Nyandwaro said.

“The main objective of this project is to increase the city’s sewerage coverage from 48 to 55 percent.”

Upon completion, more than 400,000 Nairobi residents will have access to improved sanitation services.

The project is currently 82 percent complete and is being implemented in five lots spanning the eastern and western parts of Nairobi.

Nyandwaro said sewerage networks have been implemented around Githurai, Kahawa West and Mwiki Clay factories, eliminating open sewage flows and sewage flows into the Nairobi River.

According to her, there have been no reports of diseases, especially cholera, in areas connected to sewage systems since then.

“In areas with poor sanitation, there will be pollution, where children and young mothers are exposed to health risks. The project aims to eliminate this,” he said.