Brief

To monitor the remedial works to ensure implementation of the specified remediation strategy previously prepared by others and provide verification testing and reporting for approval by the local authority.

Project

The site was one part of a formerly part of a military site allocated for redevelopment. The remediation strategy set out different levels of works for each zone on site, depending on the contamination found. At one end of the scale the remedial works comprised testing the subgrade and importing 150mm of topsoil and at the other, 1m Engineered Cover System comprising a 200mm ‘No Dig’ layer, a geotextile membrane, 650mm subsoil and 150mm topsoil.

The development comprises twenty-one properties, some terraced, others detached, with three, four and five bedrooms.

We have been involved in this project from the start, and first visited site on 16 January 2017 to undertake a site walkover for our phase 1 desktop study. Subsequently we undertook an intrusive investigation and produced a remediation strategy to deal with the contamination identified.

We returned in January 2021 to undertake verification sampling in the gardens of the completed project. It is a truly splendid building, more details can be found on Simon Gill Architects website. If you want to see the interior and follow the development you can watch the Grand Designs episode of More 4.

Project:

The site is located on the Edgware Rd in Maida Vale. The Parson’s North project has changed an underused parcel of land with a bleak paved podium and underground car park in a great location in Westminster. The project comprises a part 4, part 5 and 6 storey block with 60 new homes, 19 of which are affordable, a landscaped area next to Parson’s House and retail space on Edgware Rd.

Brief:

Our brief initially was to scope and obtain a detailed unexploded ordnance report, review the previous desktop studies and site investigation reports and provide a current phase 1 contaminated land desktop study with conceptual model, risk assessments and recommendations.

We then scoped and undertook an intrusive investigation, developed a remediation strategy and finally completed verification of the remedial works.

Photograph by kind permission of David Miller Architects and Photon Studios

The proposed development site is located on the side of the valley adjacent to a shaft and engine house for a former copper mine that worked between 1817 and 1874 producing almost 25,000 tons of copper ore. This site has also been used as a telephone exchange and radio hut during the war as well as a private workshop and printers.

It was an interesting challenge to attempt to offer pragmatic cost effective options for safe development for residential use. With risk of contamination and possibility of ground instability the structural integrity of the mine shaft, the surrounding wall and the nearby chimney all to be considered it certainly makes for an interesting project.

Lace House, a detached office building occupied the entire site with the proposal to be converted to residential. Access is by a double width timber doorway set within an impressive stone entrance portico.

The building is constructed in rendered masonry with feature margins and cornicing to the north and east elevations and a timber mansard roof.

Concerns had been raised about potential underground tanks on site due to the former use as a car showroom. To address this issue and any other potential risk due to contamination a pre-sale report was commissioned.

The site was visited, the petroleum officer’s report obtained and a final draft issued for the client’s comment within two weeks of instruction..

Our brief commenced with a phase 1 desktop study and continued through to the phase 4 verification report.

Elevated levels of hydrocarbons were found in one location, the affected soil was removed and testing undertaken around the perimeter of the excavation prior to refilling with clean material. In other areas the contaminants could be left in place and capped with clean soil in order to reduce the risks to an acceptable level.

During the course of the works an unsightly scrap yard was transformed into a very desirable development comprising four substantial detached dwellings.

The photos show the site before and after.

The proposed development for this vacant site was to comprise a two bedroom residential dwelling with associates parking and soft landscape.

Whilst doing a phase 1 desktop study we found a site nearby was used as a sewage treatment plant from around 1901 until 1950. The site was then used as a landfill between 1950 and 1970.

Prior to the Landfill site, now Jarman Fields, being redeveloped to its current commercial and leisure use a number of ground investigations were performed to assess the potential for landfill gas and land contamination issues. The investigations identified some elevated levels of landfill gas from the decomposition of fill materials, including domestic refuse.

A study of old survey plans shows a steep sided natural valley originally ran across the eastern side of the site in a north east to south west direction. From about 1950 this valley was gradually filled in with domestic refuse and builder’s rubble when the site was used for landfill tipping. This work ceased around 1970 when the valley was completely filled leaving a steep embankment across the SW of the site. No records of materials tipped have been discovered.

As a result of our investigation a specialist was engaged and gas protection measures were designed and installed.

Dunwich, also known as the lost city of England, was once a large international seaport and the medieval capital of East Anglia. The Doomsday book of 1086 records the population as 3000 however large storms in 1286 and 1347 destroyed a large portion of the town. After centuries of coastal erosion all that is left of this once bustling port is a small village.

Go Contaminated Land Solutions were asked to investigate potential contamination of the site due to flooding with sewage contaminated water.

Due to a combination of a tidal surge, high winds and heavy rainfall the site had flooded, and flood waters had entered the house. The floodwater had been contaminated by sewage from the local sewage pumping station, which is only a few meters from the property.

Some soil samples were taken from the front and rear gardens. A water sample was taken from the pond. One soil sample was selected for testing for e-coli as an indicator of sewage contamination. The test results did not detect any colony forming units.

Brief:

Complete a Phase 1 Environmental Report to assess the risks to sensitive receptors both on and off-site due to soil and groundwater contamination as a result of the proposed development.

Project:

The proposed development is for a detached dwelling with a conservatory, a private garden and a detached garage, together with the associated gravel access drive and hard standing areas. The remainder of the site has areas of lawn and soft landscaping. Access to the property is gained via a dedicated entrance from Main Street. The Allerston Beck ran along the west boundary, this was an obvious sensitive potential receptor for any contamination on site. Gas monitoring, or installation of gas protection, was recommended due to the nearby brick field and clay pit.

Our brief was to undertake a phase 1 environmental report.

The proposals comprise the demolition two end of terrace properties and construction of a residential development of 37 dwellings

comprising four one bedroom units, twelve two bedroom units, thirteen three bedroom units and eight four plus bedroom units with associated car and cycle parking and landscaping.

The site use at the time of the walk over was partly residential and partly commercial, mainly vehicle repairs and spraying and some areas with abandoned cars.

The report concluded that it was likely some superficial contamination would be found and gave appropriate recommendations .

During the course of the walk over Japanese Knotweed was identified, enabling timely action to be taken to eradicate this invasive species.