Water and Sewerage Tsarevo: Denies Link Between Repair and Disaster - Official Position

Regarding the widespread claims in the media about a connection between poor quality water and sewage repairs and the disaster that occurred in the town of Tsarevo, "Water Supply and Sewerage" EAD Burgas has issued an official statement.

The company categorically rejects such insinuations, defining them as unfounded and contradicting the facts. To support this position, "Water Supply and Sewerage" EAD provided detailed information about the actions taken and the circumstances surrounding the project for the reconstruction of the sewage network in the town of Tsarevo.

According to the provided data, the completion of the sewage network in Tsarevo, particularly in the "Mandra" district (also known as "White Beach"), is planned within an investment project. This project was developed in the Conceptual Design phase, based on a contract between the Client – Ministry of Regional Development and Public Works (MRDPW), and the Contractor – Consortium DZZD "RPIP Water Supply and Sewerage Burgas, Sliven, Shumen".

The contract, dating from 31.03.2016, was concluded for the execution of the order "Regional pre-investment studies for separate territories served by Water Supply and Sewerage operators – Separate position No. 1 for "Water Supply and Sewerage" EAD, Burgas, "Water Supply and Sewerage" Ltd. Sliven and "Water Supply and Sewerage" Ltd. Shumen".

The work on the project was accepted by a commission composed of representatives of the MRDPW, the Ministry of Environment and Water (MEW), the Water Supply and Sewerage operator and other interested parties.

As a result of the activities under this contract from 2016, after conducting the relevant coordination procedures, Building Permit No. 7 was issued on 21.01.2021 by the Chief Architect of Tsarevo Municipality.

The project provides a solution for crossing the Cherna River at the bridge on "Nestinarka" street. The crossing level is fixed in the project with a pipe bottom elevation of 4.61 m (absolute elevation in the Baltic height system) in the middle of the crossing. The financing of the project in this form was approved by the Operational Program "Environment 2014-2020", which is co-financed by the European Union through the Cohesion Fund. An Administrative Agreement for non-refundable financial assistance was signed with "Water Supply and Sewerage" EAD Burgas.

After securing financing and conducting a public procurement procedure in accordance with the Public Procurement Act (PPA), a contract was concluded between "Water Supply and Sewerage" EAD Burgas and the Contractor on 19.08.2022.

The subject of this contract is "Engineering for facilities: Reconstruction of Water Supply and Sewerage networks of the town of Primorsko; town of Kiten; town of Tsarevo; village of Lozenets; town of Sozopol and town of Chernomorets", Separate Position 3: FACILITY: Reconstruction of the Water Supply and Sewerage network of the town of Tsarevo.

According to the terms of the contract, the Contractor is obliged to further develop the investment proposal from the conceptual to the technical phase, to perform construction and installation works, to carry out author's supervision during construction and to participate in the commissioning of the facility.

The conditions of the concluded contract, the technical specification and the requirements for the contractor are provided to "Water Supply and Sewerage" EAD Burgas as mandatory standardized documents and requirements for the award of public procurement for engineering (design and construction) of wastewater treatment plants (WWTP) and water and sewage networks.

These standards are in accordance with the Order of the Minister of Finance of the Republic of Bulgaria and are mandatory in procedures for the award of public procurement for infrastructure projects in the "Water" sector, financed under the Operational Program "Environment 2014-2020".

The documents are available on the website of the Public Procurement Agency in the section "Samples and lists", subsection "Standardized documents".

According to the defined conditions, changes to the conceptual design are allowed in the technical design, which do not change the scheme and system of the networks. These changes are limited to those related to diameters, routes, lengths and other elements, in the presence of justification and coordination with the Engineer and the Client, in accordance with the requirements of the Contract.

During the preparation of the technical design, the designer informed that, based on a field survey, the conditions for crossing the new domestic sewage - branch 12.02 with the Cherna River immediately after the bridge on "Nestinarka" street are outdated. The reason for this is that high waves have formed in the riverbed, which have undermined the foundations of the bridge. As a result, the transverse and longitudinal profiles of the Cherna River have changed, which is why the provisions of the Conceptual Design no longer correspond to reality.

Based on an inspection and geodesic surveys, it was established that the most expedient solution is for the sewer to cross the Cherna River aerially immediately before the second entrance to the bridge. There, the erosion of the riverbed and banks is less. The crossing will be carried out at equivalent elevations of the water object and the sewage branch, and the route will be located in municipal public property.

The bottom of the air pipe in the middle of the crossing of the Cherna River is located at a bottom elevation of approximately 4.81 m in the same height system, which means that the crossing conditions are not worsened. On the contrary, the pipe is raised by 0.20 m.

The necessary documents have been issued, including an opinion of the Regional Inspectorate of Environment and Water (RIEW), the Black Sea Basin Directorate and Order No. 04.04.2023 of the Chief Architect of Tsarevo Municipality for amending and supplementing Building Permit No. 7 of 21.01.2021.

All constructions in the Republic of Bulgaria are designed and executed with specific security, determined normatively in the specialized legal framework. This depends on the class and category of the facility, its complexity and its impact on human health and the environment.

In the present case, it is determined that the crossing of the river by aerial means must be carried out above the level of flow of a high wave (maximum water quantity) with a probability of occurrence P=1% (recurrence period of the hydrological event 1 time in 100 years).

An engineering-hydrological study was carried out in the Conceptual Design phase, and the characteristic water levels were determined. The excerpt from the conceptual design shows that there is a high reserve of 1.34 m between the top of the hundred-year wave and the bottom of the air pipe for sewage.

After the disaster declared in Tsarevo Municipality in 2023, an additional independent engineering-hydrological assessment was prepared at the request of "Water Supply and Sewerage" EAD Burgas. It has been proven that there is no design error that would lead to the damming of the hundred-year wave in the Cherna River by the air pipe for sewage.

In both the initial and the additionally commissioned hydrological report, it is illustrated that approximately 75% of the catchment area of the Cherna River is located on the northern slopes of the territory of the village of Izgrev.

According to the hydrological report, the average-weighted maximum daily rainfall height for the considered catchment with a 0.10% security amounts to 283.17 mm. This means that the probability of 283 liters of rain per square meter falling within 24 hours is once in 1000 years. The maximum daily rainfall height with 1% security (1 time in 100 years) amounts to 185.94 mm (liters per square meter).

According to data provided by the press center of Tsarevo Municipality as of 03.10.2025, over 410 l/sq. m fell in the village of Izgrev and 225 l/sq. m in the town of Tsarevo in five hours. This shows that in the main part of the catchment area of the Cherna River, there was a historical hydrological event, which is unprecedented for the considered territory.

The rainfall formed a water quantity in the river, far exceeding the regulatory requirements for the location of the air pipe above the top of the hundred-year wave, formed by a rainfall of 185.94 liters per square meter. Both the registered rainfall height and the short period in which it occurred led to the formation of a high wave, which in its water quantity and level exceeded the regulatory requirements. This wave even exceeded the level of the two bridges on "Nestinarka" street and in the area of the "Lidl" hypermarket.

From the reports from the scene of the event, it is clearly visible that the high wave passed over the two bridge structures. According to the information and facts provided, the air pipe for connecting the sewage of the "Mandra" district (White Beach) to the central sewage network and the treatment plant in Tsarevo was designed and executed in accordance with national legislation and there is no evidence of illegal or poor-quality execution.

Both in the project itself and in the coordination and approval documents, there is no evidence that the facility could lead to the "blocking" of the bridge on "Nestinarka" street over the Cherna River.

It is evident from the official data and report footage that the high wave formed in the Cherna River far exceeded the expected rainfall quantities with a recurrence of 1 time in 1000 years. Therefore, it can be concluded that the events in Tsarevo on 03.10.2025 represent a disaster and a natural disaster, beyond the capabilities of urban engineering facilities – roads, bridges and engineering infrastructure.

"Water Supply and Sewerage" EAD calls on the media and the public to refrain from hasty conclusions and speculative claims that undermine the professional reputation of the company. The Water Supply and Sewerage operator has provided the full set of technical documentation and expert opinions to the relevant authorities and is ready to assist in clarifying all the circumstances.