Building standard 3.3 - flooding and groundwater guidance review: research

Appendix C Glasgow City Council Guidance

FRA Report Requirements

Base Data Requirements, the report should include:

• Geo-referenced location plans;
• Proximity to nearest watercourse;
• Plan of site illustrating Ordnance Datum levels to a recognised scale;
• Good use of photographs illustrating important features such as culverts etc;
• If appropriate, information of current flood alleviation measures including the level of protection and condition;
• Identification of the ownership of any water related structures and assessment of their condition;
• Information of past flood events; photographs, levels, trends;
• Clear drawings, plans and maps to a recognised scale relevant to the site;

Methodology used in carrying out the assessment

• A summary of the type or source of any present flooding risk;
• All technical records and datasets derived from the Flood Estimation Handbook;
• Details of flood mitigation methods, the proposals and the effects of the planned solution;
• All data must be reported against relevant standards set by SEPA, Scottish Water and Glasgow City Council policy

Hydrological methods used in the assessment

• A plan and description of any structures that may influence local hydraulics. This will include bridges and pipes/ducts crossing the watercourses together with culverts, screens, embankments or walls, overgrown or collapsing channels and their likelihood of choking with debris;
• All culverts, detailing condition and capacity;
• Any property and/or environment that will be affected by various degrees of flooding;

Hydrological methods used in the assessment

• An assessment of the return periods or probabilities including any observed trends and the extent and depth of floods for the location and, if appropriate, routes and speed of water-flow. At this stage, best estimates, based on the most up-to-date findings, should also be made of climate change impacts on probabilities;
• An estimation of the volume of water which would be displaced from the site during various flood events both during and following development of the site;
• Brief assessment/summary on the impact on river or coastal ecology, if applicable. More important issues should be included in a separate EIA (Environmental Impact Assessment);
• An assessment of the potential impact of any development on fluvial or coastal morphology and on the likely longer-term stability and sustainability;
• An assessment of the capacity of any drains or sewers, existing or proposed, on the site during various flood events and mitigation measures if required;
• Taking into account projected climate change, details illustrating how the development meets an acceptable standard of flood protection for the design life of the development.

FRA Check list

• The development will not be at risk or susceptible to damage due to flooding within the parameters set in City Plan and SPP February 2010;
• Normal operation of the development will not be susceptible to disruption as a result of flooding from the appropriate event;
• Safe access to and from the development will be possible during the appropriate design flood event;
• The development will not increase flood risk anywhere else;
• The development will provide for safe access for maintenance of watercourses or maintenance and operation of flood defences by the Glasgow City Council;
• The development will not lead to the degradation of the environment;
• The development will meet all the outlined criteria for its entire lifetime including consideration for climate change.

To complete a comprehensive assessment the developer must:

• Be aware of all the relevant planning policy and legislation;
• Complete technically accurate calculations;
• Follow professional guidelines and procedures;
• Certify that flooding will not pose a risk to the development;
• Complete the required Compliance and Independent Check Certificate;
• Submit evidence of appropriate Professional Indemnity insurance.

DIA Requirements may include:

• An examination of the current and historical drainage patterns;
• A concept drawing of the development;
• An outline drawing of how the drainage design provides sustainable drainage techniques in accordance with recognised design manuals;
• The soil classification of the site;
• Evidence of subsoil porosity tests including where possible at the location of any intended infiltration device and the proximity of the winter water table;
• Calculations showing that post development peak run-off volumes do not exceed that for pre-development for the critical rainfall event;
• Demonstration that the drainage solution selected will ensure that properties on and off the proposed site are not at risk of flooding from the appropriate rainfall return period relevant to the categories of development specified in City Plan Policy ENV 4– Sustainable Drainage Systems (SUDS), Policy ENV 5-Flood Prevention and Land Drainage and Sewers for Scotland 2nd edition;
• Details of the accountable body responsible for vesting and maintenance for individual aspects of the drainage proposals and confirmation in writing that these bodies will vest/adopt the system;
• Wastewater drainage proposals and confirmation in writing that they will vest in Scottish Water.

Drainage Impact Assessment Check List

• Any proposed drainage designs must, to a minimum, conform to the relevant specifications outlined in Sewers for Scotland-2nd Edition and must also comply with General Binding Rules issued by SEPA;
• The proposals must address the cumulative impact on infrastructure capacity of incremental growth of impermeable surfaces by not increasing the quantity and rate of surface water run-off from any site;
• Any flows that are to be discharged to a watercourse must have the appropriate permission from SEPA and Glasgow City Council;
• Submissions must include information on foul and surface water drainage and must show that Scottish Water and the appropriate authorities have been consulted.
• For large developments where there is an intention to separate the development into zones, which are to be constructed at different stages, or by different developers, a drainage master plan covering the whole area of development is submitted.