Custom onsite treatment required for high-end dwellings
Rural location required careful design
Nitrate removal capability considered in nutrient neutrality calculations
The developers of high-end properties built on a historic Hampshire estate have selected WCS Environmental Engineering (WCSEE) technology to treat wastewater flows to strict environmental standards.
The Home Farm development of 23 properties is situated in Embley Park, Romsey, a picturesque 18th century estate. The wider park houses Florence Nightingale’s former family home, now an independent school, and is located at the edge of the New Forest.
Because of its rural location, the new development is unable to connect to the public sewer network and therefore onsite wastewater treatment is required. Environment Agency discharge permit requirements are particularly stringent, due to the park’s sensitive receiving waters.
The high environmental standards required include 10mg/l biological oxygen demand (BOD), 15mg/l suspended solids, and 5mg/l ammonia. To ensure compliance is met, WCSEE has designed a custom onsite solution, comprising a below-ground HiPAF® (high performance aerated filter) treatment plant and 3.1 x 2.6m sand filter, also below ground.
The sand filter will remove any excess suspended solids from the treated wastewater before it is discharged, providing a level of tertiary treatment to bring discharge consent standards above what is normally expected from a biological process.
Additionally, the planning authority – Test Valley Borough Council – has a nutrient neutral policy in place for new residential developments. Nutrient neutrality is a means of ensuring new residential developments do not increase the nutrient burden of nearby protected waters.
WCSEE liaised with developer Capital Homes’ nutrient neutrality adviser throughout the design of the plant, to ensure the technology’s nitrate removal capability was considered as part of the neutrality calculations, submitted as part of the planning application.
WCSEE technical manager Dominic Hamblin: “We are proud that our technology has been selected by Capital Homes for this historic and environmentally sensitive site.
“Working closely with Capital Homes and their engineering consultants BP Civils, we have designed a high-end solution that is fully compliant and offers the highest levels of environmental protection, even in this sensitive spot.
“Due to the site’s rural location, our engineers have been conservative in the plant’s design, including reducing the tank’s original size by one metre, taking into account narrow access roads to avoid future issues when it comes to installation and maintenance.
“The nutrient neutrality approach was another area that made this project particularly interesting, and we were pleased to offer our technical expertise to help bring the desired outcome.”
Capital Homes managing director Mike Paddock said: “We have been pleased to work with WCSEE to bring the highest quality wastewater treatment to Home Farm. We have collaborated closely with their technical experts throughout the design process and we look forward to the installation and commissioning stage, expected this summer.”
WCSEE’s HiPAF technology is suitable for properties from 60 up to 2,000 population equivalent (PE) where mains drainage is unavailable. Modular in design and built off site, the units are simple to install, operate and maintain.