Households/establishments were not connecting to the sewerage network resulting in the under-utilization of STPs. Three STPs were over-stressed adversely impacting the treatment process and resulting in poor effluent quality.
Sewerage network connectivity
Low household connectivity with sewerage networks
Every household should connect to the sewerage network so that sewage is safely collected and treated and STP capacity does not remain underutilized. HP Municipal Act, 1994 provides that every household must take a sewerage connection, and the ULBs are empowered to deprive defaulting households of amenities such as water and electricity. This was reiterated by the Hon’ble High Court of Himachal Pradesh.
Scrutiny of records of the 10 test-checked ULBs having fully/ partially functional sewerage schemes showed that in five ULBs the number of released connections ranged between 71 and 115 percent (schemes completed between December 1997 and March 2009). However, in the remaining five ULBs the number of released connections ranged between only eight and 40 percent even though these schemes had been completed between February 2009 and March 2016. The low percentage of released connections was attributable to the following:
• As per instructions issued (September 2000) by the State Government, sewer lines are to be laid up to six meters from each house. However, it was observed that sewer lines had not been laid up to six meters of houses in a large number of cases.
The audit conducted a survey (April-June 2018) of 596 households in the 10 ULBs, in which 183 households (31 percent) reported that they were not connected to the sewerage network, of which 108 households85 (59 percent) reported the reason as a distance of nearest sewer line being more (eight to 205 meters) than six meters
from their houses.
This was a deficiency at the planning stage as the DPRs of these schemes did not contain any provision for laying sewer lines up to six meters of houses.
• In areas where sewerage systems did not exist, households would have already constructed domestic-level septic tank systems. Such households may not be willing to bear the additional one-time cost and recurring cost/ user charges of connecting to sewerage networks. EEs of IPH divisions (Paonta Sahib and Una) stated that beneficiaries had their own septic tanks and were not ready to dismantle their finished floors or bear the additional cost.
• ULBs had not initiated action (such as imposing fines or depriving defaulting households of other amenities) to ensure that households would connect to the sewerage network. Notices had not been issued by any ULB/ division except MCs Kullu (1,980 notices) Una (eight notices) and IPH divisions Paonta Sahib (574 notices) and Solan (238 notices). Even these ULBs/ divisions had not followed up the notices with any subsequent action against defaulting households.
Thus, the low connectivity to sewerage networks was due to the non-providing of sewer lines up to the required distance of six meters of houses, additional cost to households, and non-initiation of penal action by the ULBs/ divisions concerned. The low percentage of released connections led to the underutilization of STP capacity, which in turn adversely impacted the effectiveness of sewage treatment.
The Principal Secretary, IPH accepted the observations (March 2019) and stated that the stipulated condition of laying sewer lines up to six meters of houses was being followed for new projects. While the reply indicated that corrective action had been initiated by IPH Department, there was also a need to ensure action by ULBs against defaulting households.
Connecting of greywater pipes with sewerage network
As per the CPHEEO Manual, it is mandatory to connect grey water pipes with the sewerage network. DPRs of sewerage schemes provide for connecting greywater pipes to the sewerage network.
In a survey conducted by Audit in 10 test-checked ULBs having sewerage systems, 227 (55 percent) out of 413 households reported that they had not connected greywater pipes with the sewerage network. This percentage was particularly high (over 80 percent) in six ULBs. Except for MCs Kullu (1,980 notices) and Shimla (11,403 notices), no other ULB had initiated any action against defaulting households.
Greywater pipes not connected with the sewerage network were flowing either into the storm-water drains or into the open. This also meant that the anticipated volume of sewage was not flowing into the sewerage network resulting in underutilization of STPs, thereby adversely impacting the effectiveness of sewage treatment.
In the exit conference the Secretary, IPH directed the Department to improve the connectivity of greywater pipes to the sewerage network.
The cases pointed out are based on the test check conducted by Audit. The Department may initiate action to examine similar cases and take necessary corrective action.
Recommendation: The State Government may ensure the laying of sewer lines up to the required distance from houses and initiate action against defaulting households not connecting to sewerage networks in order to improve sewerage connectivity.
Sewage Treatment and Disposal: Sewage Treatment Plants
In sewerage systems, the sewage is treated in an STP. An STP includes primary treatment to remove solid material, secondary treatment to digest dissolved and suspended organic material, and tertiary treatment for the advanced cleaning of wastewater (effluent) to remove nutrients and suspended solids. The process of sewage treatment and disposal in an STP. Raw sewage is screened to remove floating materials and grit (sand, ash, clinker, etc.). The flow equalization tank regulates the flow into subsequent components/ units. In the primary sedimentation tank/ clarifier suspended solids, organic and residual inorganic solids, free oil, grease, other floating material, and chemical flocs are settled and removed. In the aeration tank, soluble and suspended organic matter is removed by aerobic bacteria, thereby reducing the level of BOD and suspended solids. The secondary sedimentation tank/ clarifier settles bio-flocculated solids. The settled material from the primary and secondary clarifiers (sludge) is channeled into the sludge digestion tank where it is broken down by anaerobic bacteria. The solid/ semi-solid sludge is then routed to a sludge disposal facility for dewatering and converting into dried sludge cakes to be re-used as manure, etc. The treated effluent, before being discharged into surface waters, should be sent for tertiary treatment and disinfection for removal of nutrients (phosphorus and nitrogen) and water-borne pathogens. The treated effluent can be reused for various purposes such as agriculture, farm forestry, industrial cooling, etc.
The audit observations relating to the process of sewage treatment and disposal in STPs are discussed in the following paragraphs.
Capacity utilisation of STPs
According to an internal report of the Department, utilization of STPs should be at least 80 percent of the designed capacity, and a low percentage of sewage inflow may adversely affect design assumptions and render the treatment process inadequate. Out of the 24 test-checked STPs in 10 ULBs, it was observed that 11 STPs in six ULBs were functioning at severely underutilized capacities (below 50 percent), and three STPs in two ULBs were overstressed as detailed in the Table-2.2.3 below:
The capacity utilization of STPs at Summer Hill (Shimla), Chanderlok, and Rampur (Una) was less than 10 percent. The primary reasons for the underutilized capacity of STPs included: a large percentage of unreleased connections, non-connecting of greywater pipes to the sewerage network, and slow progress to address issues of leakages within the sewerage network.
Excess sewage in the range of 50 to 71 percent above installed capacity was being received in three STPs of two ULBs adversely impacting the treatment capability of these STPs. Samples of treated effluent collected by HPSPCB from these STPs during 2013-18 showed a high failure rate. These STPs required immediate up-gradation which should have been planned well before the STPs reached full capacity. However, the DPR for upgrading the STP in Hamirpur had not been finalized by the IPH Department as of January 2019, while a scheme for upgrading the STPs in Shimla had been proposed and approved under AMRUT only in 2017-18 (tendering was under process as of January 2019).
The divisions concerned had not demonstrated urgency to address the issue of underutilized and overstressed STPs which was adversely impacting the sewage treatment process resulting in the quality parameters of treated effluent being below prescribed standards.