Site no H794 Dunbotle lane flash lane a word of warning whats coming
Site no H794 Dunbotle lane flash lane a word of warning whats coming Site no H794 Site address Flash Lane, Mirfield Application number 2017/60/94124/E
Several incidents were recorded at the end of St. Mary’s Avenue. This is due to a failing soakaway. The proposed development is not at risk of flooding, however, beyond the development will suffer!!!.
An analysis of potential re-emergence should be included in the flood risk, assessment should be provided given that there are existing properties at lower levels adjacent to
the proposed site.
It is my understanding that this site has been identified as high risk in terms of former coal workings and grouting of bell pits mine workings and shafts are likely. An analysis and demonstration of how this will affect infiltration via soakaways.
Holst soil engineering carrid out boreholes in 1973 the deepest investiagtion bore hole was 5m deep, however the Blocking seam sites at 10-20m deep guidelines state, seasonal testing will be required. BRE Digest 365, however, would the testing be carried out before or after any ground remediation works are completed.
Shallow mine workings and historic mine entries can present a hazard to existing or new development potentially adversely impacting the stability of surface structures and infrastructure. They can also present a risk to public safety. Since 1872, there has been a law that requires all coal mine operators to deposit working plans of the mine with the Government following the cessation of operations. Prior to this date the plans were often destroyed or kept in private ownership due to competition between the mine operators. The Coal Authority has over 120,000 mine plans. Shallow coal mining is defined as lying at a depth of up to 10 x the thickness of coal seam extraction down to a maximum depth of 30 metres Shallow workings do not have sufficient overlying strata, therefore, any movement has the potential to reach the surface and cause damage; approx 50% of the accepted surface hazards are related to shallow workings, both recorded and unrecorded.
The site also conflicts with surface water flood maps that show a linear pattern (depression) flow route where houses are to be located. more information is required to demonstrate that there is a commitment to ensure houses are protected from such events and overland flows, and it is feasible that water from the highway will not enter curtilage in the final promoted design.
I would advise land drainage protection will be required for the properties located at lower levels from landscaped areas that could generate runoff from saturated land. Mitigation proposals should be stated. Temporary Drainage Strategy Protection of existing properties during the construction phase post soil and vegetation strip will be required as increased runoff is envisaged on this sloping site. A suitable plan, including protecting existing drainage infrastructure from blockages and sedimentation should be formulated alongside a construction phasing plan.This can be conditioned. Section 106 Unilateral Undertaking – SUDS & Management Companies The LPA is obligated to ensure that SUDS are maintained and managed for the lifetime of the development. This could, therefore, involve management companies and individual owners. In order to enforce against this obligation, a section 106 agreement/undertaking incorporating a detailed agreement maintenance plan with assigned roles and frequencies will be required.