D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision Site visit made on 10 November 2025 by N Robinson BA (Hons) MA MRTPI an Inspector appointed by the Secretary of State Decision date: 2nd December 2025 Appeal Ref: APP/P1940/W/25/3370028 D K Engineering, Little Green Street Farm, Green Street, Chorleywood, Hertfordshire WD3 6EA • The appeal is made under section 78 of the Town and Country Planning Act 1990 (as amended) against a refusal to grant planning permission. • The appeal is made by Mr J Cottingham (D K Engineering) against the decision of Three Rivers District Council. • The application Ref is 25/0080/FUL. • The development proposed is creation of a 2-storey underground storage facility, demolition and replacement of existing buildings above ground, hard and soft landscaping areas. Decision 1. The appeal is allowed and planning permission is granted for creation of a 2-storey underground storage facility, demolition and replacement of existing buildings above ground, hard and soft landscaping areas at D K Engineering, Little Green Street Farm, Green Street, Chorleywood, Hertfordshire WD3 6EA in accordance with the terms of the application, Ref 25/0080/FUL, subject to the conditions in the attached schedule. Preliminary Matters 2.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision The appeal includes documents which did not form part of the planning application: Dusk Emergence Bat Surveys (Middlemarch, June 2025), Flood Risk Assessment and drainage/suds strategy (Jomas, June 2025) and FRA and drainage/suds strategy addendum (Jomas, October 2025). The Council has had the opportunity to comment on these documents. On this basis, I do not consider that any party would be unfairly prejudiced. I therefore have had consideration to these documents in determining this appeal. 3. One of the reasons for refusal related to the proposal’s ecological impact, in particular in relation to roosting bats. The Council has confirmed that, following the findings of the Dusk Emergence Bat Surveys submitted with the appeal, it is satisfied that the proposal would not have an unacceptable ecological impact, and the Council does not seek to defend this reason for refusal. Based on the evidence before me I see no reason to find otherwise. I shall phrase the main issues accordingly. Main Issues 4. The main issues are: - whether the proposal would be inappropriate development in the Green Belt, with regard to the openness of the Green Belt; and https://www.gov.uk/planning-inspectorate

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision Appeal Decision APP/P1940/W/25/3370028 - whether the development would be acceptable in relation to flooding and drainage. Reasons Whether inappropriate development 5. The site contains a cluster of former farm buildings used as workshops, offices and storage facilities by D K Engineering, who specialise in the sale, procurement, servicing, storage and restoration of vehicles. DK Engineering store vehicles in off- site storage facilities, and vehicles are moved to the site for servicing and restoration. The site employs 40 members of staff and visitors pre-book prior to visiting the site, which receives, on average, 7 visitors per week. 6. The proposal is for the erection of a car park providing storage for 172 vehicles. This would comprise 2 subterranean storeys accessed via an entrance building accommodating 2 lifts. This would consolidate the existing off-site storage facilities into one site. The surface of the subterranean car park would be a landscaped lawn containing solar panel arrays. It is proposed to erect 2 single storey above-ground buildings and to demolish 4 single storey buildings, resulting in a loss of approximately 27m2 of above-ground built form.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision The proposal also includes a courtyard and parking area. 7. The site is in the Green Belt. The National Planning Policy Framework (the Framework) identifies that the fundamental aim of Green Belt policy is to prevent urban sprawl by keeping land permanently open. It goes on to state that inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances. Policy CP11 of the Core Strategy (2011) (CS) and policy DM2 of the Development Management Policies Local Development Document (2013) (DMPLDD) echo this. 8. The appellant suggests that the subterranean garage is an engineering operation as it would not be visible above ground and thus would be an exception to inappropriate development in the Green Belt. The terms ‘building’ and ‘engineering operation’ are not defined in the Framework. Nonetheless, considering the works as a whole including the proposal’s form, size and the presence of walls and a roof, I consider that the garage comprises a building, therefore, it would not meet the exception to inappropriate development outlined at paragraph 154hii. 9.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision The appellant also states that the site comprises Previously Developed Land (PDL) and thus meets the exception to inappropriate development at Framework paragraph 154g which allows for the partial or complete redevelopment of PDL which would not cause substantial harm to the openness of the Green Belt. The Framework states that PDL comprises land which is or was occupied by a permanent structure, including the curtilage of the developed land and any associated fixed surface infrastructure. The location of the storage facility comprises a grassed area which includes some built form and hardstanding. This part of the site is clearly visually and functionally related to the remainder of the appeal site. I am satisfied that this land is within the curtilage of and functions as part of the engineering compound and is clearly separated and distinguishable from the open fields which border the site. I am satisfied therefore that the site comprises PDL and that the proposal comprises the redevelopment of PDL. https://www.gov.uk/planning-inspectorate 2

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision Appeal Decision APP/P1940/W/25/3370028 10. The exception to inappropriate development at Framework paragraph 154g requires that the development not cause substantial harm to the openness of the Green Belt. Openness is an essential characteristic of the Green Belt that has spatial and visual aspects. The main parties agree that the proposal would result in a reduction in the amount of above-ground built form. By introducing development where presently there is none, the development would also have a spatial component. Nonetheless, the storage facility would be subterranean and would not be perceptible above the ground and there is no indication that the use of the building for the storage of vehicles would involve a level of activity that would be perceptible beyond the building’s confines. 11. Reflecting the approach in the PPG1, when considering the effect on openness, it is necessary to consider whether the activities associated with the development would result in a loss of openness to the Green Belt. The proposal would not result in an increase in staff or visitors and would result in a reduction in vehicular movements.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision However, the proposal would consolidate areas of hardstanding into one part of the site, and this would bring with it the parking of staff and visitor cars. This concentrated area of hardstanding, and the parking taking place on it, would result in a reducing effect on the Green Belt’s openness. Nonetheless, the hardstanding would not spread further south or east than the existing hardstanding or encroach into the open countryside. It would have a low profile, and, as the site is flat, would be imperceptible in long distance views. Vehicles parked on the hardstanding would be seen in the context of the existing hardstanding and structures. Given this, the reducing effect on the openness of the Green Belt arising from the hardstanding and parking on it would be limited. 12. Drawing on the above, the characteristics of the proposal and site are such that the built form would not have a reducing effect on the openness of the Green Belt. Whilst there would be a reducing effect associated with the hardstanding and vehicles parked on it, this would be limited.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision As the development comprises the development of PDL, and the effect on the openness of the Green Belt would be limited, it accords with the exception to inappropriate development at Framework paragraph 154g and would not be inappropriate development in the Green Belt. 13. In arriving at this conclusion, I have taken into account an appeal decision for a basement extension to a dwelling 2 (the 2020 appeal) to which my attention has been drawn. Given the different nature of the appeals, different Framework tests are applied to establish if they are inappropriate development. Given this, and reflecting on my observations regarding the visual and spatial effects of the appeal proposal, the Inspector’s findings in the 2020 appeal do not draw me away from my conclusions regarding the proposal’s effects on the openness of the Green Belt. 14. The proposal would not be inappropriate development in the Green Belt. It would not be contrary to the Framework in this regard and would not conflict with CS policy CP11 and DMPLDD policy DM2, the aims of which are set out above. Flooding and drainage 15. To facilitate the subterranean structure, it would be necessary to excavate the existing land up to a depth of 12m.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision The Council and the Lead Local Flood Authority 1 Paragraph: 013 Reference ID: 64-013-20250225 2 APP/J1535/D/20/3244998 https://www.gov.uk/planning-inspectorate 3

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision The Council and the Lead Local Flood Authority 1 Paragraph: 013 Reference ID: 64-013-20250225 2 APP/J1535/D/20/3244998 https://www.gov.uk/planning-inspectorate 3

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision Appeal Decision APP/P1940/W/25/3370028 (LLFA) raised concerns that the planning application did not include adequate information in relation to surface water and ground water flooding and it was considered that it had not been demonstrated that the flooding and drainage impacts of the proposal would be acceptable. The appeal proposal is supported by an updated FRA and drainage strategy which considers all sources of flooding including an allowance for climate change. It is considered that the proposal is supported by an acceptable drainage strategy. 16. Given the above, the development’s flooding and drainage impacts would be acceptable. It would therefore accord with CS policy CP1 and DMPLDD policy DM8 which state that development will only be permitted where it would not be subject to unacceptable risk of flooding or exacerbate risk of flooding elsewhere. Other Matters 17. The site is located in the Chilterns National Landscape (NL). There is limited evidence before me in relation to the characteristics and qualities of the NL. I observed on my site visit that the site is located in an area comprising mixed farmland, with fields surrounded by hedgerows.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision The statutory purposes of National Landscapes are to preserve and enhance their natural beauty. The Levelling-Up and Regeneration Act 2023 amends the duty on relevant authorities in respect of their functions to now “seek to further” the statutory purposes of protected landscapes. Meanwhile, the Framework sets out that great weight should be given to conserving and enhancing their landscape and scenic beauty, which have the highest status of protection in relation to these issues. 18. The above-ground structures would be small in scale and in keeping with the form of buildings within the site. The subterranean development would be imperceptible in the wider landscape and proposed hardstanding would be seen in the context of the existing hardstanding and built form within the wider engineering complex. I therefore find that the proposal would not result in harm to the character and appearance of the area including the special qualities and the scenic beauty of the NL. This view is shared by the Council. Conditions 19. I have had regard to the conditions suggested by the Council, on which the appellant has had the opportunity to comment.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision Where necessary I have made revisions to some of the conditions put to me to ensure that they meet the tests in the Framework and PPG, without altering their fundamental aims. 20. Planning permission is granted subject to the standard 3 year time limit condition for implementation. In addition, it is necessary to specify the approved plans in the interest of certainty. I have imposed conditions requiring the submission of a drainage scheme including detailed infiltration testing and drainage calculations to ensure that the final location of the proposed soakaway is acceptable and to ensure that flood risk is adequately addressed. I have attached a condition requiring details of the maintenance and management of the sustainable drainage scheme, including the timetable for implementation and arrangements for adoption to ensure that flood risk is adequately addressed. A condition requiring the submission and approval of a survey and verification report is necessary to ensure adequate drainage and to ensure that flood risk and pollution offsite is adequately addressed. https://www.gov.uk/planning-inspectorate 4

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision Appeal Decision APP/P1940/W/25/3370028 21. In the interest of the character and appearance of the site and the surrounding area, a condition is necessary to control the external materials of the development (which need not delay any development). In the interests of the character and appearance of the site and biodiversity I have attached conditions requiring the submission and approval of a Construction and Environmental Management Plan and a Landscape and Ecology Management Plan. Conditions requiring that the development is carried out in accordance with the biodiversity enhancement recommendations document and the implementation of the approved landscaping scheme are required in the interests of character and appearance and biodiversity. 22. Whilst noting that the submitted protected species surveys cover a larger site area, in the absence of updated surveys reflecting the reduced site area a condition is necessary requiring that the development be carried out in accordance with listed surveys in the interests of protected species. A condition relating to external lighting is necessary in the interests of protected species.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — Appeal Decision In the interests of the protection of trees a condition requiring that development be carried out in accordance with the Arboricultural Method Statement is required. 23. Conditions requiring that the development is implemented in accordance with the submitted Travel Plan and requiring the provision of cycle storage and electric vehicle charging spaces are necessary to encourage travel by sustainable means. In the interests of highway safety, I have attached a condition requiring the provision of the approved car parking spaces. I have attached a condition requiring that the development is carried out in accordance with the submitted Construction Method Statement as this detail forms part of the proposal. This is necessary in the interests of highway safety. 24. I have omitted a suggested condition relating to details of interim and temporary drainage measures during the demolition and construction phases as there is no evidence before me that this is necessary to render the development acceptable. Conclusion 25. For the reasons given above the appeal is allowed.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — N Robinson INSPECTOR SCHEDULE OF CONDITIONS 1.) The development hereby permitted shall be begun before the expiration of three years from the date of this permission. 2.) The development hereby permitted shall be built in accordance with the following approved plans: 21-23-00A, 21-23-100C, 21-23-20K, 21-23-27B, 21-23-31D, 21-23- 32A, C157558-PONDS REV 00. 3.) No development hereby approved shall take place until construction drawings of the surface water drainage network, associated sustainable drainage components and flow control mechanisms and a construction method statement have been submitted to and agreed in writing by the local planning authority. The scheme shall then be constructed as per the agreed drawings, method statement, FRA & Drainage/SuDS Strategy (Jomas Associates Ltd, Version 4, June 2025) and FRA & Drainage/SuDS Strategy Addendum (Jomas Associates Ltd, Version 1, October 2025), remaining in perpetuity https://www.gov.uk/planning-inspectorate 5

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — N Robinson Appeal Decision APP/P1940/W/25/3370028 for the lifetime of the development unless agreed in writing by the Local Planning Authority. The construction drawings should be accompanied by: i. Detailed infiltration testing in accordance with BRE Digest 365 (or equivalent) along the length and proposed depth of the proposed infiltration feature/s, ii. Drainage calculations (using the updated infiltration rates from part i) in the: -3.33% AEP (1 in 30 year) critical rainfall event plus climate change to show no flooding outside the drainage features on any part of the site. - 1% AEP (1 in 100 year) critical rainfall plus climate change event to show, if any, the depth, volume and storage location of any flooding outside the drainage features, ensuring that flooding does not occur in any part of the building or any utility plant susceptible to water (e.g pumping station or electricity substation) within the development. It will also show that no runoff during this event will leave the site uncontrolled. The development shall be carried out in accordance with the approved details.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — N Robinson 4.) No development hereby approved shall take place until a Construction and Environmental Management Plan (CEMP) has been submitted to and approved in writing by the local planning authority. The CEMP shall include details of the following: • Development standoffs and safeguards for all retained habitats (e.g. retained trees, hedgerows and adjacent woodland), • Safeguards to avoid harm or entrapment of terrestrial mammals, • Herpetofauna Reasonable Avoidance Method Statement, • Construction timetables to avoid sensitive periods such as nesting bird season, • Vegetation management measures to minimise the risk to protected or notable species; and, • Compliance with any specific mitigation measures that will be required to acquire a Development Licence for works affecting protected species. The development shall be carried out in accordance with the approved details. 5.) No development hereby approved shall take place until a Landscape and Ecology Management Plan (LEMP) has been submitted to and approved in writing by the Local Planning Authority.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — N Robinson The LEMP will be prepared in accordance with the agreed Biodiversity Net Gain Plan and Biodiversity Metric and shall include long term objectives and targets, management responsibilities and maintenance schedules for each ecological feature within the development, together with a mechanism for monitoring success of the management prescriptions, incorporating review and necessary adaptive management in order to attain targets. The LEMP shall be implemented in full for the lifetime of the development in accordance with the approved details. 6.) No development hereby permitted shall take place above foundation level until samples and details of all proposed external materials and finishes have been submitted to and approved in writing by the local planning authority. The development shall be completed only in accordance with the details approved. https://www.gov.uk/planning-inspectorate 6

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — N Robinson Appeal Decision APP/P1940/W/25/3370028 7.) The development hereby approved shall not be first used until details of the maintenance and management of the sustainable drainage scheme have been submitted to and approved in writing by the Local Planning Authority. The drainage scheme shall be implemented prior to the first use of the development hereby approved and thereafter managed and maintained in accordance with the approved details in perpetuity. The Local Planning Authority shall be granted access to inspect the sustainable drainage scheme for the lifetime of the development. The details of the scheme to be submitted for approval shall include: i. a timetable for its implementation. ii. details of SuDS features and connecting drainage structures and maintenance requirement for each aspect including a drawing showing where they are located. iii. a management and maintenance plan for the lifetime of the development which shall include the arrangements for adoption by any public body or statutory undertaker, or any other arrangements to secure the operation of the sustainable drainage scheme throughout its lifetime. This will include the name and contact details of any appointed management company.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — N Robinson 8.) Upon completion of the surface water drainage system, including any SuDS features, and prior to the first use of the development; a survey and verification report from an independent surveyor shall be submitted to and approved in writing by the Local Planning Authority. The survey and report shall demonstrate that the surface water drainage system has been constructed in accordance with the details approved pursuant to condition 3. Where necessary, details of corrective works to be carried out along with a timetable for their completion, shall be included for approval in writing by the Local Planning Authority. Any corrective works required shall be carried out in accordance with the approved timetable and subsequently re-surveyed with the findings submitted to and approved in writing by the Local Planning Authority. 9.) Prior to the first use of the development hereby permitted the cycle storage shown on drawing no. 21-23-20K shall be provided and that space shall thereafter be kept available for the storage of bicycles. 10.) Prior to the first use of the development hereby permitted, the vehicle parking spaces shall be provided in accordance with drawing no 21-23-20K.

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — N Robinson Thereafter those spaces shall be retained for the parking of vehicles only. 11.) Prior to the first use of the development hereby permitted, the electric vehicle recharging points as shown on drawing no. 21-23-20K shall be installed. Once installed, the electric vehicle recharging points shall be retained thereafter. 12.) All soft landscaping comprised in the approved details of landscaping shown on drawing 21-23-32A shall be carried out in the first planting and seeding season following the first use of the building or the completion of the development, whichever is the sooner, or in accordance with any phasing agreed in writing with the Local Planning Authority. Any trees or plants which, within a period of five years, die, are removed, or become seriously damaged or diseased shall be replaced in the next planting season with others of a similar size and species, unless otherwise agreed in writing by the local planning authority. https://www.gov.uk/planning-inspectorate 7

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — N Robinson Appeal Decision APP/P1940/W/25/3370028 13.) The development hereby approved shall be carried out in accordance with the recommendations in the submitted Dusk Emergence Bat Surveys (Middlemarch, June 2025), Reptile Survey (Middlemarch, October 2022), Great Crested Newt Habitat Suitability Index Assessment and EDNA Survey (Middlemarch, September 2022), Badger Survey Rev A (Middlemarch, September 2025) and Preliminary Ecological Appraisal (Middlemarch, May 2022). 14.) The development shall be carried out in accordance with the Construction Method Statement (Danks Badnell, October 2024) throughout the construction and demolition period. 15.) The development hereby approved shall be carried out in accordance with the Arboricultural Method Statement (Merewood, October 2024). 16.) The development hereby approved shall be carried out in accordance with the recommendations in the ‘Outline of Biodiversity Enhancement Recommendations’ document. 17.) The development hereby approved shall be operated in accordance with the measures set out in the Workplace Travel Plan (i-Transport, October 2024).

D K Engineering, Little Greenstreet Farm, Little Green St, Chorleywood, Rickmansworth , Hertfordshire, WD3 6EA — Three Rivers District Council — N Robinson 18.) Prior to the installation of external lighting, full details including height, design, location and intensity shall be submitted to and approved in writing by the local planning authority. The lighting installation shall be carried out in accordance with the approved details. End of Schedule of Conditions https://www.gov.uk/planning-inspectorate 8