North Yorkshire Council

Executive Member for Culture, Arts and Housing

12 November 2025

Princess Close, Ripon - Structural Concerns and Options Appraisal

Report of the Corporate Director Community Development

1.0 PURPOSE OF REPORT

1.1 To present options for addressing significant structural concerns at a block of four flats at Princess Close, Ripon, and to determine the preferred course of action.

2.0 SUMMARY

2.1 This report outlines the background to structural concerns at Princess Close, Ripon, and presents three options for consideration:

- Option 1 - Retain and Monitor

- Option 2 - Remedial Works

- Option 3 - Demolition (Preferred)

2.2 Should demolition be agreed as the preferred course of action, an options appraisal will be undertaken to determine the future use of the site, including potential for redevelopment, disposal, or conversion to managed green space. While disposal of the site in its current condition was considered, it has been discounted due to the severity of structural and geological risks.

2.3 Extensive investigations have confirmed that the site is affected by severe geological instability, including gypsum dissolution and saturated peat. These conditions present an ongoing and unpredictable risk of structural failure. While remedial works are technically possible, they are complex and offer no guarantee of long-term success or safety.

2.4 The recommendation for demolition is primarily driven by the need to eliminate unacceptable risks to public safety, legal liability, and insurance exposure. Although the building is vacant, its unstable foundations present a persistent hazard. Retention could lead to increased insurance premiums, limited coverage, or denied claims due to the site’s known subsidence history. Demolition removes these risks and ensures a safer, more sustainable outcome.

2.5 Demolition offers the most responsible and future-proof approach to managing the asset. It removes immediate safety concerns, avoids escalating and uncertain costs, and enables the Council to redirect investment towards safe, sustainable housing stock. This aligns with the strategic management of the Housing Revenue Account and broader housing regeneration priorities.

2.6 The decision also reflects the Council’s duty of care and risk management obligations. Retaining a structurally compromised building on a high-risk site would not meet acceptable standards of public safety, financial stewardship, or environmental responsibility.

3.0 BACKGROUND

3.1 The block at Princess Close (Nos. 1–7) comprises of four flats previously tenanted under the Housing Revenue Account. All tenants have been decanted into alternative, permanent accommodation, and the building is vacant, with no plans for the tenants to return.

3.2 Structural concerns were first raised in early 2023 following reports of external cracking and visible signs of ground movement. A visual structural survey conducted in August 2023 revealed misaligned drainage gullies, exposed foundation piles, and differential settlement of concrete paving slabs. A GPR scan was undertaken in December 2023, followed by further inspections in April 2024, which confirmed significant movement, particularly at the north and northwest corners of the building (see Appendices A and B).

3.3 A follow-up structural inspection in April 2024 included internal access to Flat 7 and further observations (see Appendix B). This survey identified:

- Vertical and diagonal cracking in masonry and internal blockwork.

- Separation of window frames from walls.

- Sloping floors and soft spots in the beam and block floor system.

- Water ingress and pooling beneath the building, with a strong smell of foul water.

- Blocked gullies and misaligned downpipes.

- Vegetation growth between the ring beam and paving slabs.

- Signs of historic and ongoing settlement.

3.4 Historical mapping and site records indicate the presence of a diverted watercourse (Skittergate Gutter) and a sulphur spring approximately 50m east of the site. These features are indicative of underlying gypsum deposits, which are known to dissolve in the presence of water, forming voids and subsidence hollows. The British Geological Survey confirms that the site lies within a high-risk subsidence zone (see Appendix A and discussion in Appendix B).

3.5 Two blocks of flats on the opposite side of the road (Princess Close), numbers 2 to 8 and 10 to 16 were demolished in 2009 and 2010 respectively due to structural damage caused by ground movement. A property at Magdalen’s Close, located near Princess Close, was demolished in 2014 following the formation of a sinkhole caused by gypsum dissolution. In 2016, a second large sinkhole appeared in nearby Magdalen’s Road, resulting in the evacuation of seven properties and emergency ground stabilisation works. These events highlight the ongoing geological instability in the area and reinforce the risk of future ground movement near Princess Close.

3.6 A Phase 1 Desk Study and Phase 2 Ground Investigation were commissioned to assess the geological and structural risks (see Appendix C and D). These investigations included:

- Cable percussive boreholes and Standard Penetration Testing (SPT) to assess shallow ground conditions, including peat and alluvium. These confirmed the presence of compressible ground and soft deposits. Results indicated extremely low to very low strength soils, contributing to subsidence risk.

- Deep rotary boreholes to depths of 60m to assess the extent of gypsum dissolution and weak ground conditions. These revealed zones of rapid drill penetration and poor core recovery, indicating potential voids and very loose ground associated with gypsum dissolution.

3.7 The investigations concluded that the site is at high risk of ground instability due to a combination of shallow compressible soils and deeper dissolution features, with implications for structural safety and future development.

3.8 Borehole logs (BH01 and BH02) (see Appendix E and F) confirmed:

- Made ground overlying loose sandy gravel and soft silty clay.

- A thick band of very low-strength peat to depths of 11.3m.

- Rapid drill penetration and no recovery between 22–33m, suggesting voids or highly disturbed ground.

- Presence of gypsum veining within mudstone, confirming dissolution risk.

- Groundwater encountered at:

o 3.5m and 16.5 in BH01

o 13.5 in BH02

 3.9 A full drainage CCTV survey conducted in June and August 2024 covered 11 pipe sections totalling 78.76 metres. (see Appendix G). Key findings include:

- No grade 4 or 5 structural defects identified.

- One section showed an open joint classified as a grade 1 structural defect).

- Two sections showed service defects requiring medium-term rehabilitation (grades 2 and 3).

- Several sections were blocked or required cleaning, with some surveys abandoned due to obstruction.

- One section may be dropping into a culvert, pending Yorkshire Water review.

3.10 Estimated costs for remedial works exceed £200,000. However, even at this level, remediation would not guarantee resolution of the underlying geological issues, and there is a significant risk of cost escalation and continued structural problems in the future.  Initial engagement with the Council’s insurers indicates that cover may be subject to limitations or conditions for these properties, and future claims could be affected. Demolition of the properties is estimated at approximately £70,000.

4.0 STRUCTURAL AND GROUND INSTABILITY AT PRINCESS CLOSE, RIPON – ASSESSMENT OF RISK AND OPTIONS

4.1 The structural integrity of the building at Nos. 1 - 7 Princess Close is compromised due to a combination of geological, hydrological, and structural factors. As outlined in Section 3.6, the site is underlain by a complex mix of peat, alluvium, and gypsum-bearing mudstone. The presence of sulphur springs and a diverted watercourse suggest active dissolution processes, which are known to cause sudden and unpredictable ground collapse.

4.2 The building is founded on a reinforced concrete ring beam supported by 300mm diameter piles. While the piles were originally designed for end-bearing capacity, the ground investigations suggest that the bearing strata may have deteriorated due to gypsum dissolution. This has likely reduced the safe working load (SWL) of the piles, resulting in differential settlement and structural distortion.

4.3 Structural inspections have identified multiple signs of distress, including external masonry cracks up to 8mm wide, internal cracking in blockwork and ceilings, sloping floors, separation of window frames, and vegetation growth between structural elements. Water ingress beneath the building, accompanied by a strong foul odour and milky appearance, suggests contamination from misaligned or blocked drainage systems. These issues have likely saturated the underlying peat, accelerating settlement. The CCTV drainage survey identified multiple blockages, misaligned pipework, and a potential culvert connection. These defects are likely contributing to water ingress and saturation of the underlying peat, exacerbating ground instability and accelerating structural deterioration.

4.4 The ground beneath the site is highly variable and includes materials prone to movement, compression, and dissolution. This presents a significant and ongoing risk of subsidence, not only to the building itself but also to surrounding infrastructure and neighbouring properties. Conventional shallow foundations are unsuitable, and any future development would require specialist engineering solutions. The presence of saturated peat, as confirmed by both ground investigations and drainage surveys, increases the risk of ongoing settlement and collapse. The drainage system’s poor condition may be a contributing factor to the high groundwater levels and soft ground conditions observed.

4.5 The site lies within a mapped subsidence zone and has a documented history of sinkholes and structural failures in the immediate vicinity. The proximity of active watercourses and historic dissolution features further increases the likelihood of future ground movement.

4.6 The building is currently unoccupied. However, it remains a liability due to reports concluding that the building is at risk of sudden and uncontrolled structural failure. Demolition down to ground level has been recommended, leaving piles in situ to avoid triggering further ground movement. The recommendation for demolition is based on the severity and unpredictability of the structural risk, which cannot be reliably mitigated through remedial works. The cost of £200,000 is not prohibitive in isolation, but the absence of a guaranteed outcome renders the investment unjustifiable from a risk management perspective.

5.0 FUTURE USE OF THE SITE

5.1 Should demolition be approved as the preferred option, officers will undertake an options appraisal to determine the most appropriate future use of the site.

5.2 The appraisal will consider:

- The extent of the ground remediation that would be required to enable safe redevelopment.

- Whether the underlying geological risks (e.g. gypsum dissolution, saturated peat) would affect the viability of new build.

- Planning and environmental constraints.

- Alternative uses such as open space, landscaping, or disposal for community-led or other appropriate development.

5.3 The appraisal will be informed by the technical evidence already gathered, but there is the potential that further site investigations or surveys will be required to fully assess redevelopment potential. The process will seek to balance safety, cost-effectiveness and alignment with wider housing regeneration priorities. This ensures that any future proposals are viable, sustainable and in the best interests of the Council and the local community.

5.4 Given the extent of ground instability, it is unlikely that the site could safely accommodate new build development without extensive and potentially costly remediation, and even then, safety could not be guaranteed.  While redevelopment will be considered as part of the appraisal, current evidence suggests that alternative, lower-impact uses such as managed green space or low-impact landscaping may be more appropriate and environmentally sustainable.

5.5 In the interim, and potentially as a longer-term outcome, the site may be grassed over and maintained as open green space. This would improve the visual amenity of the area, contribute positively to the local environment, and avoid the higher maintenance and cost implications associated with alternative interim uses such as car parking. Any costs associated with this approach will need to be identified and confirmed, and clarity provided on whether these remain within the Housing Revenue Account (HRA). No transfer of costs to other services, such as Parks, will occur without prior agreement.

5.6 Should any form of redevelopment prove technically viable, the Council may explore opportunities to secure external funding, such as through the Brownfield Land Release Fund. Eligibility would depend on the outcome of site investigations and alignment with programme criteria, including deliverability and housing need. Disposal of the site following demolition may also be considered, subject to legal and technical feasibility.

6.0 CONSULTATION UNDERTAKEN AND RESPONSES

6.1 A comprehensive programme of consultation has been undertaken throughout the investigation and assessment process. This includes:

- Align Property Partners who were commissioned to undertake both the initial and follow-up structural condition surveys (August 2023 and April 2024). Their reports provided detailed visual and internal assessments, identifying significant structural defects and recommending demolition as the safest course of action.

- Solmek Ltd who were appointed to carry out Phase 1 and Phase 2 ground investigations. Their borehole logs and interpretive reporting confirmed the presence of deep peat, voids, and gypsum dissolution features, which pose a serious risk to structural stability.

- Tex Services Group who conducted CCTV drainage surveys in June and August 2024. Their findings revealed multiple defects, blockages, and potential culvert collapse, contributing to water ingress and ground saturation beneath the building.

- Tenants of the block of flats, as all residents of Nos. 1-7 have been decanted into alternative accommodation.

6.2 All consulted parties have acknowledged the severity of the structural and ground instability issues. The consensus from technical experts is that demolition is the most appropriate course of action to mitigate risk and liability.

7.0 CONTRIBUTION TO COUNCIL PRIORITIES

7.1 Supports safe and sustainable housing stock management. Reduces liability and risk to residents and the public. Enables future redevelopment aligned with housing and regeneration priorities.

8.0 ALTERNATIVE OPTIONS CONSIDERED

8.1 Three options have been considered in detail.

8.2 Option 1 – Retain and Monitor

8.2.1 This option involves maintaining the building in its current vacant state, with fencing and periodic monitoring of structural and ground conditions. While this avoids immediate capital expenditure, it retains significant liability for public safety, especially given the risk of sudden collapse due to gypsum dissolution. Ongoing costs would include fencing, inspections, insurance premiums, and potential emergency response. In addition, the properties would remain void within the housing portfolio, negatively impacting performance indicators and resulting in continued loss of rental income as outlined in Section 10 and 16. This option is not recommended due to high risk, reputational impact, and lack of long-term viability.

8.3 Option 2 – Remedial Works

8.3.1 This option would involve extensive ground stabilisation (e.g. pressure grouting), drainage repairs, structural reinforcement, and internal refurbishment. Estimated costs exceed £200,000, with no guarantee of long-term success due to the unpredictable nature of gypsum dissolution and peat compression. Works would be highly disruptive, require specialist contractors, and carry a risk of triggering further ground movement. Even if successful, the building would remain on a high-risk site, and future monitoring would be essential. This option is not recommended due to complexity, and residual risk.

8.4 Option 3 – Demolition (Preferred)

8.4.1 Controlled demolition of the block at Nos. 1–7, leaving piles in situ to avoid disturbing the ground. Site clearance and reinstatement would allow for future redevelopment or landscaping. The estimated cost is £70,000, based on quotes. This option removes all immediate safety risks and liability and aligns with recommendations from structural and geotechnical consultants. This option is recommended as the safest, most cost-effective, and future-proof solution.

8.4.2 Should demolition be agreed as the preferred course of action, an options appraisal will be undertaken to determine the most appropriate future use of the site, including potential for redevelopment, disposal, or conversion to managed green space

8.5 Note on Disposal of site in Current Condition

8.5.1 Disposal of the site in its current condition (i.e. without demolition or remediation) was considered as an alternative to demolition or remedial works. However, this option has been discounted due to the significant structural and geological risks associated with the building and land. The presence of gypsum dissolution, saturated peat, and historical subsidence events presents a high risk of future ground movement, which would be difficult to transfer responsibly to a third party.

8.5.2 While disposal could theoretically reduce direct Council liability, it would require Secretary of State consent under Section 32 of the Housing Act 1985, unless the disposal qualifies under the General Housing Consents 2013.

8.5.3 Given the severity of the risks and the likelihood of limited market interest, particularly from community-led or owner-occupier groups, disposal in its current state is not considered a viable or responsible option. It has therefore not been included among the three formal options presented for decision.

8.5.4 Disposal of the site following demolition may still be considered as part of the future options appraisal, subject to further investigation and legal safeguards.

9.0 IMPACT ON OTHER SERVICES/ORGANISATIONS

9.1 Potential future redevelopment of the site may involve Planning and Housing. Demolition will reduce pressure on Housing Standards and reduce the corporate risk.

10.0 FINANCIAL IMPLICATIONS

10.1 The following costs have been incurred or estimated:

Item	Description	Cost
Ground Investigation	Phase 1 and 2 GI (Solmek)	£29,887
Drainage Surveys	Ground Penetrating Radar Survey	£3,066
Structural Surveys	Original (Aug 2023) and Follow-up (Apr 2024) Structural Reports (Align)	£5,496
Monitoring	Installation of tell-tale crack monitors	£705
Demolition	Estimated cost	Approx £70,000
Remedial Works	Estimated cost	Approx £200,000
Loss of Rent	Per year * Present value of net rent loss	£18,566 £244,529
Home Loss Payments	Statutory payments to 3 tenants	£24,300

*Net rent loss (income less assumed costs at 30% operating margin) in perpetuity

- Total committed to date: approx. £63,450

- Total projected cost if demolition proceeds: approx. £133,450 + £244,529 Present value of net rent loss in perpetuity

- Total projected cost if remedial works pursued: approx. £263,450+

10.2 While the estimated cost of remedial works is estimated at approximately £200,000, it is important to note that this figure, when considered across four flats may not appear excessive, particularly when compared to recent investment levels in individual tenanted properties. However, the concern is not simply the upfront cost, but the absence of any long-term guarantee that such investment would resolve the underlying structural and geological issues. The financial viability of retention is compromised not by the headline cost alone, but by the absence of any assurance that such investment would eliminate the underlying risk.

10.3 The site lies within a high-risk subsidence zone, with confirmed gypsum dissolution and saturated peat. Even after significant expenditure, the building would remain vulnerable to further movement and deterioration. This introduces the potential for substantial future costs related to emergency repairs, ongoing monitoring, insurance premiums, and liability, all of which could exceed the initial investment and undermine the financial viability of retention or refurbishment.

10.4 Demolition is therefore considered the most financially appropriate and strategic option. It removes the immediate liability, avoids unpredictable future expenditure, and enables potential future use of the site.

10.5 Insurance implications further support this recommendation. Should the building be retained, there may be increased premiums, reduced coverage, or denial of future claims if the condition is deemed pre-existing or undisclosed. These risks compound the financial uncertainty associated with retention.

10.6 In accordance with the Land Compensation Act 1973 and the Home Loss Payments (Prescribed Amounts) (England) Regulations 2023, Home Loss Payments have been made to the three remaining tenants who were permanently displaced from Nos. 1–7 Princess Close. Each tenant received the current statutory flat rate of £8,100 in September 2025, processed by the Council’s Housing team. These payments reflect the Council’s legal obligation to compensate tenants who have occupied the property as their main residence for at least one year prior to displacement. The total cost of these payments has been incorporated into the overall financial assessment of the demolition option.

11.0 INSURANCE IMPLICATIONS

11.1 Retaining a building with structural vulnerabilities on a geologically sensitive site presents potential insurance challenges. The Council is committed to managing these risks responsibly.

11.2 Initial engagement with insurers indicates that cover may be subject to limitations or conditions if the building remains in its current state. Future claims could be affected if risks are not fully assessed and managed.

11.3 Insurers have advised that subsidence cover for the building may be restricted unless appropriate mitigation measures are implemented. They have emphasised the importance of proactive steps to manage structural and liability risks.

11.4 The Council is gathering further information to support these discussions, including monitoring arrangements for nearby properties and actions taken to address previous site issues.

12.0 MONITORING OF OTHER BUILDINGS

12.1 In addition to investigations at Nos. 1–7 Princess Close, the Council is undertaking routine monitoring of other properties in the area to ensure ongoing safety and resilience. This includes checks where geological conditions may warrant precautionary observation. No immediate concerns have been identified, and no action is currently required. Monitoring is a standard measure to support early detection and maintain public confidence. This report may inform future reviews should similar considerations arise elsewhere.

13.0 LEGAL IMPLICATIONS

13.1 Retaining a structurally compromised building on a site known to be geologically unstable presents significant legal risks to the Council.

13.2 As the landowner, the Council has a legal obligation of duty of care to ensure that its assets do not pose a risk to public safety. The April 2024 structural report identifies a credible risk of sudden collapse, particularly at the north corner of the building.

13.3 Although the building is vacant, there are risks relating to occupiers liability, as should injury occur, the Council could be held liable under the Occupiers’ Liability Acts 1957 and 1984.

13.4 There are concerns regarding environmental liability as the presence of foul water beneath the building and potential drainage failure may result in environmental damage or pollution, triggering obligations under the Environmental Protection Act 1990.

13.5 There are also concerns regarding insurance limitations as the Council’s insurers may limit or withdraw cover if the building is knowingly retained in a hazardous condition, particularly given the known risks of gypsum dissolution and subsidence.

13.6 Legal Process for Demolition of HRA Stock

13.6.1 Early consultation with Legal Services confirmed that a formal legal process must be followed for the demolition of Housing Revenue Account (HRA) properties. This includes:

- Issuing a Demolition Order - A formal demolition order must be issued and become operative.

- Notice to Occupiers - Once operative, NYC must serve notice to any occupiers. The notice must:

§ State the effect of the demolition order.

§ Specify the date by which the premises must be vacated.

§ Require occupiers to leave by that date or within 28 days of service, whichever is later.

- Court Action (if required) - If any person remains in occupation after the specified date, NYC may apply to the County Court for an order requiring vacant possession within 2–4 weeks.

- Offence for Non-Compliance - Failure to comply with the order or permitting occupation after the specified date constitutes a summary offence.

- Execution of Demolition - Once vacated, NYC is responsible for demolishing the property within the time specified in the demolition order.

13.6.2 This process can be initiated following approval of the recommendations in this report. Legal Services will support the preparation and issuance of the demolition order and any necessary notices or court applications.

14.0 EQUALITIES IMPLICATIONS

14.1 An Equalities Impact Assessment has been carried out (see Appendix H) which concluded that there are no disproportionate or adverse impacts on individuals with protected characteristics. This is because the building is currently vacant and all former tenants have already been rehoused in suitable alternative accommodation. The proposal relates to asset management and public safety, rather than changes to service provision, and reasonable adjustments have already been made through the rehousing process.

15.0 CLIMATE CHANGE IMPLICATIONS

15.1 A Climate Change Impact Assessment (CCIA) has been completed (see Appendix I) to evaluate the environmental effects of the three options under consideration for the structurally compromised flats. The assessment identifies short-term negative impacts associated with demolition, including increased greenhouse gas emissions and construction waste. However, demolition also removes a high-risk, inefficient asset. The CCIA confirms that demolition is the most environmentally manageable option when compared to retention or remedial works, which carry greater long-term risks and carbon intensity. Mitigation measures would be implemented during demolition.

16.0 PERFORMANCE IMPLICATIONS

16.1 Retaining the building negatively impacts housing performance indicators, including void property rates and asset condition scores. Demolition will improve performance by removing a high-risk liability. If a formal decision to demolish is made, the properties would be removed from void statistics and treated separately. However, until that point, the building remains a high-risk liability within the housing portfolio.

17.0 RISK MANAGEMENT IMPLICATIONS

17.1 Demolition removes high-risk liability. Retaining the building or undertaking remedial works retains significant risk of collapse, injury, and reputational damage.

18.0 COMMUNITY SAFETY IMPLICATIONS

18.1 Demolition removes a dangerous structure and improves public safety. It reduces the risk of trespass, vandalism, and injury.

19.0 CONCLUSIONS

19.1 The building at Princess Close is structurally compromised due to geological instability. Extensive investigations confirm that the site is affected by peat compression, gypsum dissolution, and drainage failure. Demolition is recommended as the most appropriate course of action to mitigate on-going risk and liability

20.0 REASONS FOR RECOMMENDATIONS

20.1 To mitigate risk, reduce liability, and enable future use of the site. Demolition is supported by structural and geotechnical evidence and aligns with council priorities.

21.0

RECOMMENDATION(S)

i. That the Executive Member notes the findings of the structural, geotechnical, and drainage investigation reports relating to Nos. 1–7 Princess Close, Ripon. ii. That the Executive Member considers the three options presented within the report: - Option 1 – Retain and Monitor - Option 2 – Undertake Remedial Works - Option 3 – Demolition of the block (noting this is the officer-preferred option) iii. That the Executive Member provides a steer on the preferred option to enable officers to progress with the appropriate next steps, including any legal or financial processes required. If demolition is agreed, this will include undertaking an options appraisal to determine the future use of the site.

            APPENDICES:

Appendix A – Structural Condition Survey (Align Property Partners, Sept 2023)

Appendix B - Structural Condition Survey (Align Property Partners, Sept April 2024)

Appendix C – Phase 1 Desk Study Report (Solmek, Jan 2024)

Appendix D – Phase 2 Report (Solmek, Feb 2024)

Appendix E – Borehole Log BH01 (Solmek, Dec 2023)

Appendix F – Borehole Log BH02 (Solmek, Dec 2023)

Appendix G – CCTV Drainage Survey Report (Tex Services Group, June-August 2024)

Appendix H – Equalities Impact Assessment (EIA)

Appendix I – Climate Change Impact Assessment (CCIA)

BACKGROUND DOCUMENTS: None

Nic Harne

Corporate Director – Community Development

County Hall

Northallerton

4 November 2025

Report Author – Imogen Downie, Housing Policy and Strategy Officer (Service Improvement)

Presenter of Report – Karl Hankey, Housing Standards Manager

Note: Members are invited to contact the author in advance of the meeting with any detailed queries or questions.