1)
Policies of Particular Relevance
You are advised that this application was determined by the Local Planning authority with regard to Development Plan policies including relevant policies contained within the London Plan 2015 (Consolidated with Alterations since 2011); the Consolidated Local Plan 2015 and the 'Saved' policies of the Unitary Development Plan adopted 25 May 2002.
2)
Refused/No pre-app or discussion
To assist applicants in finding solutions to problems arising in relation to their development proposals the Local Planning Authority has produced planning policies, and provided written guidance, all of which are available on the Council's website. A pre-application advice service is also offered.
In this case the proposal does not comply with guidance and policies. No pre-application discussions were entered into, but the Council is ready to enter into discussions with the applicants through the advice service to assist in the preparation of any new planning application.
3)
Unique text
The Council's Environmental Quality Officer has advised as follows:
The proposed use would not be particularly vulnerable to the presence of contamination, although the inclusion of the basement requires appropriate assessment of ground conditions, particularly with regard to ground gas/vapour. Some information on contamination has been submitted with the application, and
question 14 on the application form appears to have been completed correctly.
The 2017 version of the Planning Statement makes a reference to policy CE7 and still states: 'No contaminated land issues have been identified in surveys. Elements of asbestos fibres were found however subject to mitigation measures this is considered to have a negligible to low risk for future users.' Asbestos in soil is a contamination issue. It should be noted the CARD Geotechnics Ltd Basement Impact Assessment (BIA), dated November 2015 included a contamination preliminary risk assessment which identified risk to the future development and off site receptors as low to medium. The site investigation undertaken at the site appears to be limited and incomplete and further investigation and assessment is required, including the completion.
The ground investigation indicated 0.5 to 1.7 metres of made ground based on the limited areas investigated, over London Clay. Soil sampling consisted of eight mostly shallow soil samples. Only seven samples appear to have been screened for asbestos and asbestos was detected in all seven samples. Asbestos needs to be considered further with regard to safely undertaking development works (for construction workers and neighbours as well as remedial works. Whilst the levels of other contaminants were considered acceptable given the proposed use, it should be noted the shallow soils on site would be considered unsuitable for landscaping purposes, especially based on samples taken at TP01, which had elevated PAHs (polycylic aromatic hydrocarbons - Total WAC-17 PAHs 410 mg/kg), and generally elevated lead, particularly TP02 at 1000 mg/kg. If it is intended the current investigation data is to be used as part of the site investigation submission in future, the laboratory report needs to be reviewed and updated by the laboratory to address irregularities to determine is the data is still usable.
One sample of groundwater tested is indicated to be likely perched water (no groundwater strikes occurred during borehole installation) in a shallow made ground installation within the London Clay. Testing of groundwater did not include VOCs (volatile organic compounds), which were identified as potential contaminants in the desk study. It is noted none of the soil samples tested, were tested for VOCs (except
BTEX) or vapours in general. Groundwater was indicated at depth in the gas monitoring borehole. Further groundwater assessment is required.
Ground gas monitoring has been undertaken in one borehole (separate readings for shallow and deep) only, which is not consistent with good practice guidance. Two rounds of monitoring indicate gas risk is low at the site. A PID (photo-ionisation detector) was used in one monitoring round only to monitor vapour and the results all suggest it was below the limit of detection. It is recommended further monitoring at the site is undertaken in accordance with CIRIA C665, which has been referenced in the report. The report identifies further gas/vapour monitoring is required and recommends investigation of the western garden area of the site where access was not possible at the time of the current ground investigation.
It is recommended the desk study undertaken more specifically considers the former on site uses and potential for contamination (although the preliminary risk assessment (PRA) appears to be broad enough with regard to potential contaminants) to determine if the PRA needs updating and use this to design a suitable ground investigation to address what is missing in the current site investigation. The desk study needs to ensure local authority information is adequately reviewed to identify the former onsite uses. Groundwater monitoring for contamination is recommended, as a precaution if practicable. Suitable remedial measures need to be proposed based on the investigation findings (the BIA does identify remedial measures in spite of the investigation being incomplete. What is in the document would not be considered sufficient to discharge related conditions even on the assumptions the site investigation is satisfactory. As indicated above, the investigation undertaken to date should be reviewed including ensuring the reissue of the laboratory report to address any discrepancies to determine if the investigation data is usable). This should include the details regarding the maintenance of a contamination watching brief/discovery strategy when undertaking development works. This information needs to be provided prior to development works commencing on site.
The contamination criteria for 'clean' landscaping soils and any specification for the investigation and landscaping works would need to be agreed with the Environmental Quality Unit (EQU) prior to implementation. Prior to the development commencing or being brought into use verification information to demonstrate any remedial works have been carried out as required, landscaping works were carried out as agreed and the soils are suitable for use will need to be provided. This should also include information on any unsuitable material on site that was retained and/or removed along with the relevant duty of care.
Conditions are advised to ensure a suitable contaminated land assessment is undertaken prior to development commencing and appropriate remedial measures are implemented if required to ensure the development is made suitable for use. This includes assessment of any site derived and imported soils used for planting and landscaping purposes. Any soils/materials reused or imported to site as part of the development should be uncontaminated.
The BIA by CARD should not be submitted to discharge the condition.
There is guidance available on the RBKC website for land contamination and planning at: https://www.rbkc.gov.uk/environment/landcontamination.aspx. If anything is unclear, you can contact the Environmental Quality team ([email protected], 0207 3613002) to discuss the work/steps required to discharge the conditions.
4)
Unique text
Thames Water has advised as follows:
Groundwater
You are advised that the basement should be waterproofed to protect it from groundwater flooding.
Groundwater discharges typically result from construction site dewatering, deep excavations, basement infiltration, borehole installation, testing and site remediation. Any discharge made without a permit is deemed illegal and may result in prosecution under the provisions of the Water Industry Act 1991.
A Groundwater Risk Management Permit from Thames Water will be required for discharging groundwater
into a public sewer. Any discharge made without a permit is deemed illegal and may result in prosecution
under the provisions of the Water Industry Act 1991. Thames Water would expect the developer to demonstrate what measures he will undertake to minimise groundwater discharges into the public sewer. Permit enquiries should be directed to Thames Water's Risk Management Team by telephoning 02035779483 or by emailing [email protected]. Application forms should be completed on line via www.thameswater.co.uk/wastewaterquality.
Sewer water
You are advised to seek confirmation from Thames Water that the sewerage system is able to take the proposed surface and foul water flows. Following initial investigation, Thames Water has identified an inability of the existing wastewater infrastructure to accommodate the needs of this application.
To avoid sewage flooding; to ensure that sufficient capacity is made available to cope with the new development; and in order to avoid adverse environmental impact upon the community, Thames Water has requested a drainage strategy detailing any on and/or off site drainage works. No discharge of foul or surface water from the site would be accepted into the public system until the drainage works referred to in the strategy have been completed.
The drainage strategy must satisfy a minimum of 50% reduction of current surface water runoff rates or equate to greenfield runoff rates of 5 l/s/ha.
Our preferred option would be for all surface water to be disposed of on site using SUDs as per policy 5.13 of the London plan. The London plan Policy 5.13 identifies a hierarchy of drainage options for surface water drainage and as such we would expect the development proposal to follow this.
Policy 5.13: The Mayor will, and boroughs should, seek to ensure that surface water run-off is managed as close to its source as possible in line with the following drainage hierarchy: >Store rainwater for later use >Use infiltration techniques, such as porous surfaces in non-clay areas >Attenuate rainwater in ponds or open water features for gradual release to a watercourse >Attenuate rainwater by storing in tanks or sealed water features for gradual release to a watercourse >Discharge rainwater direct to a watercourse >Discharge rainwater to a surface water drain >Discharge rainwater to the combined sewer.
The use of sustainable urban drainage systems should be promoted for development unless there are practical reasons for not doing so. Such reasons may include the local ground conditions or density of development. In such cases, the developer should seek to manage as much run-off as possible on site and explore sustainable methods of managing the remainder as close as possible to the site.
The Mayor will encourage multi agency collaboration (GLA Group, Environment Agency, Thames Water) to identify sustainable solutions to strategic surface water and combined sewer drainage flooding/overflows. Developers should aim to achieve greenfield run off from their site through incorporating rainwater harvesting and sustainable drainage. Boroughs should encourage the retention of soft landscaping in front gardens and other means of reducing or at least not increasing the amount of hard standing associated with existing homes.
Trade Effluent
A Trade Effluent Consent will be required for any Effluent discharge other than a 'Domestic Discharge'. Any discharge without this consent is illegal and may result in prosecution. (Domestic usage for example includes - toilets, showers, washbasins, baths, private swimming pools and canteens). Typical Trade Effluent processes include: - Laundrette/Laundry, PCB manufacture, commercial swimming pools, photographic/printing, food preparation, abattoir, farm wastes, vehicle washing, metal plating/finishing, cattle market wash down, chemical manufacture, treated cooling water and any other process which produces contaminated water. Pre-treatment, separate metering, sampling access etc, may be required before the Company can give its consent. Applications should be made at https://wholesale.thameswater.co.uk/Wholesale-services/Business-customers/Trade-effluent or alternatively
to Waste Water Quality, Crossness STW, Belvedere Road, Abbeywood, London. SE2 9AQ. Telephone: 020 3577 9200.
Water pressure
Thames Water will aim to provide customers with a minimum pressure of 10m head (approx 1 bar) and a flow rate of 9 litres/minute at the point where it leaves Thames Waters pipes. The developer should take account of this minimum pressure in the design of the proposed development.