On 6 April 2020 the EA published a regulatory position statement allowing permit holders to temporarily exceed storage limits, ONLY if you cannot remove waste from your site because of COVID-19 restrictions. Waste types must be those that are already permitted.
The RPS is on gov.uk here: https://www.gov.uk/government/publications/exceeding-waste-storage-limits-at-permitted-sites-because-of-covid-19-rps-c2/exceeding-waste-storage-limits-at-permitted-sites-because-of-covid-19-rps-c2
The RPS will be withdrawn on 30 September 2020 unless the EA extends it.